Lyle Tavernier is an educational technology specialist at NASA's Jet Propulsion Laboratory. When he’s not busy working in the areas of distance learning and instructional technology, you might find him running with his dog, cooking or planning his next trip.

Science fiction meets science fact in this Star Wars inspired Teachable Moment all about ion propulsion and Newton’s Laws.

### In the News

What do "Star Wars," NASA's Dawn spacecraft and Newton's Laws of Motion have in common? An educational lesson that turns science fiction into science fact using spreadsheets – a powerful tool for developing the scientific models addressed in the Next Generation Science Standards. Keep reading to learn more and find out how to get students wielding the force.

### Why It's Important

The TIE (Twin Ion Engine) fighter is a staple of the "Star Wars" universe. Darth Vader flew one in "A New Hope." Poe Dameron piloted one in "The Force Awakens." And many, many Imperial pilots met their fates in them. While the fictional TIE fighters in "Star Wars" flew a long time ago in a galaxy far, far away, ion engines are a reality in this galaxy today – and have a unique connection to NASA’s Jet Propulsion Laboratory.

Launched in 1998, the first spacecraft to use an ion engine was Deep Space 1, which flew by asteroid 9969 Braille and comet Borrelly. Fueled by the success of Deep Space 1, engineers at JPL set forth to develop the next spacecraft that would use ion propulsion. This mission, called Dawn, would take ion-powered spacecraft to the next level by allowing Dawn to go into orbit twice – around the two largest objects in the asteroid belt: Vesta and Ceres.

### How It Works

Ion engines rely on two principles that Isaac Newton first described in 1687. First, a positively charged atom (ion) is pushed out of the engine at a high velocity. Newton’s Third Law of Motion states that for every action there is an equal and opposite reaction, so then a small force pushes back on the spacecraft in the opposite direction – forward! According to Newton’s Second Law of Motion, there is a relationship between the force (F) exerted on an object, its mass (m) and its acceleration (a). The equation F=ma describes that relationship and tells us that the small force applied to the spacecraft by the exiting atom provides a small amount of acceleration to the spacecraft. Push enough atoms out, and you'll get enough acceleration to really speed things up.

### Why is It Important?

Compared with traditional chemical rockets, ion propulsion is faster, cheaper and safer:

• Faster: Spacecraft powered by ion engines can reach speeds of up to 90,000 meters per second (more than 201,000 mph!)
• Cheaper: When it comes to fuel efficiency, ion engines can reach more than 90 percent fuel efficiency, while chemical rockets are only about 35 percent efficient.
• Safer: Ion thrusters are fueled by inert gases. Most of them use xenon, which is a non-toxic, chemically inert (no risk of exploding), odorless, tasteless and colorless gas.

These properties make ion propulsion a very attractive solution when engineers are designing spacecraft. While not every spacecraft can use ion propulsion – some need greater rates of acceleration than ion propulsion can provide – the number and types of missions using these efficient engines is growing. In addition to being used on the Dawn spacecraft and communication satellites orbiting Earth, ion propulsion could be used to boost the International Space Station into higher orbits and will likely be a part of many future missions exploring our own solar system.

### Teach It

Newton’s Laws of Motion are an important part of middle and high school physical science and are addressed specifically by the Next Generation Science Standards as well as Common Core Math standards. The lesson "Ion Propulsion: Using Spreadsheets to Model Additive Velocity" lets students study the relationship between force, mass and acceleration as described by Newton's Second Law as they develop spreadsheet models that apply those principles to real-world situations.

### Explore More

This feature was originally published on May 3, 2016.

TAGS: May the Fourth, Star Wars Day, F=ma, ion propulsion, Dawn, Deep Space 1, lesson, classroom activity, NGSS, Common Core Math

Learn how pi is used by NASA and how many of its infinite digits have been calculated, then explore the science and engineering that makes the Pi Day Challenge possible.

Update: March 15, 2023 – The answers are here! Visit the NASA Pi Day Challenge page to view the illustrated answer keys for each problem.

This year marks the 10th installment of the NASA Pi Day Challenge. Celebrated on March 14, Pi Day is the annual holiday that pays tribute to the mathematical constant pi – the number that results from dividing any circle's circumference by its diameter.

Every year, Pi Day gives us a reason to celebrate the mathematical wonder that helps NASA explore the universe and enjoy our favorite sweet and savory pies. Students can join in the fun once again by using pi to explore Earth and space themselves in the NASA Pi Day Challenge.

Read on to learn more about the science behind this year's challenge and find out how students can put their math mettle to the test to solve real problems faced by NASA scientists and engineers as we explore Earth, Mars, asteroids, and beyond!

Visit the Pi in the Sky 10 lesson page to explore classroom resources and downloads for the 2023 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech | + Expand image

This illustration shows a concept for multiple robots that would team up to ferry to Earth samples of rocks and soil being collected from the Martian surface by NASA's Mars Perseverance rover. Image credit: NASA/JPL-Caltech | › Full image and caption

Image from animation comparing the relative sizes of James Webb's primary mirror to Hubble's primary mirror. Credit: NASA/Goddard Space Flight Center . | › Full animation

This illustration depicts the metal-rich asteroid Psyche, which is located in the main asteroid belt between Mars and Jupiter. Credits: NASA/JPL-Caltech/ASU | + Full image and caption

This image sequence shows an annular solar eclipse from May 2012. The bottom right frame illustrates the distinctive ring, or "annulus," of such eclipses. A similar eclipse will be visible from the South Pacific on May 10, 2013. Credits: Brocken Inaglory, CC BY-SA 3.0, via Wikimedia Commons | + Expand image

### How It Works

Dividing any circle’s circumference by its diameter gives you an answer of pi, which is usually rounded to 3.14. Because pi is an irrational number, its decimal representation goes on forever and never repeats. In 2022, mathematician Simon Plouffe discovered the formula to calculate any single digit of pi. In the same year, teams around the world used cloud computing technology to calculate pi to 100 trillion digits. But you might be surprised to learn that for space exploration, NASA uses far fewer digits of pi.

Here at NASA, we use pi to measure the area of telescope mirrors, determine the composition of asteroids, and calculate the volume of rock samples. But pi isn’t just used for exploring the cosmos. Since pi can be used to find the area or circumference of round objects and the volume or surface area of shapes like cylinders, cones, and spheres, it is useful in all sorts of ways. Transportation teams use pi when determining the size of new subway tunnels. Electricians can use pi when calculating the current or voltage passing through circuits. And you might even use pi to figure out how much fencing is needed around a circular school garden bed.

In the United States, March 14 can be written as 3.14, which is why that date was chosen for celebrating all things pi. In 2009, the U.S. House of Representatives passed a resolution officially designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi. And that's precisely what the NASA Pi Day Challenge is all about!

### The Science Behind the 2023 NASA Pi Day Challenge

This 10th installment of the NASA Pi Day Challenge includes four noodle-nudgers that get students using pi to calculate the amount of rock sampled by the Perseverance Mars rover, the light-collecting power of the James Webb Space Telescope, the composition of asteroid (16) Psyche, and the type of solar eclipse we can expect in October.

› Take the NASA Pi Day Challenge

› Educators, get the lesson here!

#### Tubular Tally

NASA’s Mars rover, Perseverance, was designed to collect rock samples that will eventually be brought to Earth by a future mission. Sending objects from Mars to Earth is very difficult and something we've never done before. To keep the rock cores pristine on the journey to Earth, the rover hermetically seals them inside a specially designed sample tube. Once the samples are brought to Earth, scientists will be able to study them more closely with equipment that is too large to make the trip to Mars. In Tubular Tally, students use pi to determine the volume of a rock sample collected in a single tube.

When NASA launched the Hubble Space Telescope in 1990, scientists hoped that the telescope, with its large mirror and sensitivity to ultraviolet, visible, and near-infrared light, would unlock secrets of the universe from an orbit high above the atmosphere. Indeed, their hope became reality. Hubble’s discoveries, which are made possible in part by its mirror, rewrote astronomy textbooks. In 2022, the next great observatory, the James Webb Space Telescope, began exploring the infrared universe with an even larger mirror from a location beyond the orbit of the Moon. In Rad Reflection, students use pi to gain a new understanding of our ability to peer deep into the cosmos by comparing the area of Hubble’s primary mirror with the one on Webb.

#### Metal Math

Orbiting the Sun between Mars and Jupiter, the asteroid (16) Psyche is of particular interest to scientists because its surface may be metallic. Earth and other terrestrial planets have metal cores, but they are buried deep inside the planets, so they are difficult to study. By sending a spacecraft to study Psyche up close, scientists hope to learn more about terrestrial planet cores and our solar system’s history. That's where NASA's Psyche comes in. The mission will use specialized tools to study Psyche's composition from orbit. Determining how much metal exists on the asteroid is one of the key objectives of the mission. In Metal Math, students will do their own investigation of the asteroid's makeup, using pi to calculate the approximate density of Psyche and compare that to the density of known terrestrial materials.

#### Eclipsing Enigma

On Oct. 14, 2023, a solar eclipse will be visible across North and South America, as the Moon passes between Earth and the Sun, blocking the Sun's light from our perspective. Because Earth’s orbit around the Sun and the Moon’s orbit around Earth are not perfect circles, the distances between them change throughout their orbits. Depending on those distances, the Sun's disk area might be fully or only partially blocked during a solar eclipse. In Eclipsing Enigma, students get a sneak peek at what to expect in October by using pi to determine how much of the Sun’s disk will be eclipsed by the Moon and whether to expect a total or annular eclipse.

### Teach It

Celebrate Pi Day by getting students thinking like NASA scientists and engineers to solve real-world problems in the NASA Pi Day Challenge. In addition to solving this year’s challenge, you can also dig into the more than 30 puzzlers from previous challenges available in our Pi Day collection. Completing the problem set and reading about other ways NASA uses pi is a great way for students to see the importance of the M in STEM.

#### Pi Day Resources

Plus, join the conversation using the hashtag #NASAPiDayChallenge on Facebook, Twitter, and Instagram.

#### Interactives

TAGS: Pi Day, Pi, Math, NASA Pi Day Challenge, sun, moon, earth, eclipse, asteroid, psyche, sample return, mars, perseverance, jwst, webb, hubble, telescope, miri

As NASA retires its InSight Mars lander, here's a look at some of the biggest discoveries from the first mission designed to study the Red Planet's interior – plus, how to make connections to what students are learning now.

After more than four years listening to the “heartbeat” of Mars, NASA is saying goodbye to the InSight lander as the mission on the Red Planet comes to an end. On Dec. 21, 2022 scientists wrapped up the first-of-its-kind mission to study the interior of Mars as dust in the Martian atmosphere and on the spacecraft’s solar panels prevented the lander from generating enough power to continue.

Read on to learn how the mission worked, what it discovered, and how to bring the science and engineering of the mission into the classroom.

### How It Worked

The locations of InSight's three main science tools, SEIS, HP3, and RISE are labeled in this illustration of the lander on Mars. | + Expand image | › Full image and caption

The InSight lander was designed to reveal the processes that led to the formation of Mars – as well as Earth, the Moon, and all rocky worlds. This meant meeting two main science goals.

First, scientists wanted to understand how Mars formed and evolved. To do that, they needed to investigate the size and make-up of Mars’ core, the thickness and structure of its crust, the structure of the mantle layer, the warmth of the planet's interior, and the amount of heat flowing through the planet.

Second, to study tectonic activity on Mars, scientists needed to determine the power, frequency, and location of “marsquakes” as well as measure how often meteoroids impacted the Red Planet, creating seismic waves.

Engineers equipped InSight with three main science tools that would allow researchers to answer these questions about Mars.

SEIS, a seismometer like the ones used on Earth to record earthquakes, measured the seismic waves on Mars. These waves, which travel through the Red Planet, can tell scientists a lot about the areas they pass through. They even carry clues about whether it was a marsquake or meteorite impact that created the waves.

InSight captured these images of clouds drifting in the distance, visible just beyond the dome-like top of the SEIS instrument. Credit: NASA/JPL-Caltech | + Expand image | › Full image and caption

InSight's Heat Flow and Physical Properties Package, or HP3, was an instrument designed to burrow 16 feet (five meters) into Mars to measure the temperature at different depths and monitor how heat flowed out toward the surface. However, the self-hammering probe, informally called the "mole," struggled to dig itself in due to the unexpected consistency of the top few inches of Mars regolith at the landing site. Using full-size models of the lander and probe, engineers recreated InSight’s environment here on Earth to see if they could find a solution to the issue. They tested solutions that would allow the probe to penetrate the surface, including pressing the scoop attached to InSight’s robotic arm against the probe. While the effort serves as a great real-world example of how engineers work through problems with distant spacecraft, ultimately, none of the solutions allowed the probe to dig past the surface when attempted on Mars.

In 2019, InSight mission scientist/engineer Troy Hudson shared the game plan for getting the mission's heat probe digging again on Mars. Ultimately, the team wasn't able to to get the "mole" working, but the effort is a great real-world example of how engineers work through problems with distant spacecraft. | Watch on YouTube

InSight’s third experiment, called RISE, used the spacecraft’s radio antennas to precisely measure the lander's position on the surface of Mars. The interior structure of Mars affects the planet’s motion, causing it to wobble. Measuring InSight’s position as the planet wobbled helped scientists gain a better understanding of the core and other layered structures that exist within the interior of Mars.

### What We Discovered

Using its seismometer, InSight gained a deeper understanding of the interior layers of Mars, as detailed in this graphic. Image credit: NASA/JPL-Caltech | + Expand image | › Full image and caption

InSight’s instruments enabled the mission science team to gain an understanding of not only the depth of Mars’ crust, mantle, and core, but also the composition of those features. They also learned just how active Mars really is.

#### The Structure of Mars

Working our way from the surface to the center of the planet, scientists found Mars’ crust was thinner than expected. Seismic waves detected by SEIS indicate that the crust is made up of three sub-layers, similar to Earth’s crust. The top-most layer of the crust is about six miles (10 kilometers) deep, while the denser layers of the crust, which contain more felsic, or iron-rich, material extend downward to about 25 miles (40 kilometers) below the surface. As seismic waves from a marsquake or a meteorite impact spread across the surface and through the interior of the planet, they can reflect off of underground layers, giving scientists views into the unseen materials below. Measuring how the waves change as a result of these reflections is how scientists unveiled the underground structure of Mars.

Like Earth, Mars has a lithosphere, a rigid layer made up of the crust and upper mantle. The Martian lithosphere extends about 310 miles (500 kilometers) below the surface before it transitions into the remaining mantle layer, which is relatively cool compared with Earth’s mantle. Mars’ mantle extends to 969 miles (1,560 kilometers) below the surface where it meets the planet’s core.

In this lesson from the "Pi in the Sky" math challenge, students use measurements from InSight along with pi to calculate the density of Mars' core. Image credit: NASA/JPL-Caltech | + Expand image | › Go to the lesson

Scientists measured the core of Mars and found it to be larger than expected, with a radius of 1,137 miles (1,830 kilometers). With this information, scientists were able to estimate the density of Mars' core, which turned out to be less dense than anticipated, meaning it contains lighter elements mixed in with iron. Scientists also confirmed that the planet contains a liquid core. While we know that Earth has a liquid outer core and solid inner core, scientists will need to further study the data returned from InSight to know if there is also a solid inner core on Mars.

As scientists continue to study the data returned from InSight, we could learn even more about how Mars formed, how its magnetic field developed, and what materials make up the core, which could ultimately help us better understand how Earth and other planets formed.

#### Marsquakes

InSight discovered that Mars is a very active planet. A total of 1,319 marsquakes were detected after the SEIS instrument was placed on the surface. The largest, which was estimated to be a magnitude 5, was detected in May of 2022.

Unlike Earth, where the crust is broken into large pieces called plates that continually shift around causing earthquakes, Mars’ crust is made up of one solid plate, somewhat like a shell. However, as the planet cools, the crust shrinks, creating breaks called faults. This breaking action is what causes marsquakes, and the seismic waves generated by the quakes are what help scientists figure out when and where the quakes occurred and how powerful they were.

In this math problem from the "Pi in the Sky" series, students use pi to identify the timing and location of a hypothetical marsquake recorded by InSight. Image credit: NASA/JPL-Caltech | + Expand image | › Go to the lesson

Nearly all of the strongest marsquakes detected by InSight came from a region known as Cerberus Fossae, a volcanic region that may have had lava flows within the past few million years. Volcanic activity, even without lava flowing on the surface, can be another way marsquakes occur. Images from orbiting spacecraft show boulders that have fallen from cliffs in this region, perhaps shaken loose by large marsquakes.

This seismogram shows the largest quake ever detected on another planet. Estimated at magnitude 5, this quake was discovered by InSight on May 4, 2022. Listen to a sonification of this seismogram. | + Expand image | › Full image and caption

Conversely, InSight didn't detect any quakes in the volcanic region known as Tharsis, the home of three of Mars’ largest volcanos that sit approximately one-third of the way around the planet from InSight. This doesn’t necessarily mean the area is not seismically active. Scientists think there may be quakes occurring, but the size of Mars’ liquid core creates what’s known as a shadow zone – an area into which seismic waves don’t pass – at InSight's location.

#### Meteorite Impacts

On Sept. 5, 2021, InSight detected the impacts of a meteoroid that entered the Martian atmosphere. The meteoroid exploded into at least three pieces that reached the surface and left behind craters. NASA’s Mars Reconnaissance Orbiter passed over the impact sites to capture images of the three new craters and confirm their locations.

This image, captured by the Mars Reconnaissance Orbiter, shows the craters (in blue) formed by a meteroid impact on Mars on Sept. 5, 2021. The impact was the first to be detected by InSight. Image credit: NASA/JPL-Caltech/University of Arizona | + Expand image | › Full image and caption

“After three years of waiting for an impact, those craters looked beautiful,” said Ingrid Daubar of Brown University, a Mars impacts specialist.

Mars’ thin atmosphere, which is less than 1% as dense as Earth’s, means meteoroids have a better chance of not disintegrating in the heat and pressure that builds up as they pass through the atmosphere to the planet’s surface. Despite this fact and Mars' proximity to the asteroid belt, the planet proved to be a challenging location to detect meteorite impacts because of "noise" in the data created by winds blowing on SEIS and seasonal changes in the atmosphere.

With the confirmation of the September 2021 impacts, scientists were able to identify a telltale seismic signature to these meteorite impacts. With this information in hand, they looked back through InSight's data and found three more impacts – one in 2020 and two in 2021. Scientists anticipate finding even more impacts in the existing data that might have been hidden by the noise in the data.

This collage shows three other meteoroid impacts on Mars that were detected by the seismometer on InSight and captured by the Mars Reconnaissance Orbiter. Image credit: Credit: NASA/JPL-Caltech/University of Arizona | + Expand image | › Full image and caption

Meteorite impacts are an invaluable piece of understanding the planet’s surface. On a planet like Earth, wind, rain, snow and ice wear down surface features in a process known as weathering. Plate tectonics and active volcanism refresh Earth’s surface regularly. Mars’ surface is older and doesn't go through those same processes, so a record of past geologic events like meteorite impacts is more apparent on the planet's surface. By counting impact craters visible on Mars today, scientists can update their models and better estimate the number of impacts that occurred in the early solar system. This gives them an improved approximation of the age of the planet’s surface.

Learn how InSight detected the first seismic waves from a meteoroid on Mars and how the lander captured the sound of the space rock striking the surface. | Watch on YouTube

### Why It's Important

Before InSight touched down, all Mars missions – landers, rovers, orbiters and flyby spacecraft – studied the surface and atmosphere of the planet. InSight was the first mission to study the deep interior of Mars.

Even with the InSight mission drawing to a close, the science and engineering of the mission will continue to inform our understanding of the Red Planet and our solar system for years as researchers further examine the data returned to Earth. Keep up to date with the latest findings from InSight scientists and engineers on the mission website.

### Teach It

Explore these lessons in geology, physics, math, coding and engineering to connect student learning to the InSight mission and the real-world STEM that happens at NASA.

### Explore More

TAGS: K-12 Education, Classrooms, Teaching, Teachers, Resources, Teachable Moments, Mars, InSight, Missions, Spacecraft, Marsquakes

Find out more about the historic first test, which could be used to defend our planet if a hazardous asteroid were discovered. Plus, explore lessons to bring the science and engineering of the mission into the classroom.

Update: Oct. 20, 2022 – The DART spacecraft successfully impacted the asteroid Dimorphos on September 26, reducing the period of the asteroid's orbit by 32 minutes. Scientists considered a change of 73 seconds to be the minimum amount for success. This article has been updated to reflect the latest data and images from the impact.

In a successful attempt to alter the orbit of an asteroid for the first time in history, NASA crashed a spacecraft into the asteroid Dimorphos on Sept. 26, 2022. The mission, known as the Double Asteroid Redirection Test, or DART, took place at an asteroid that posed no threat to our planet. Rather, it was an ideal target for NASA to test an important element of its planetary defense plan.

Read further to learn about DART, how it worked, and how the science and engineering behind the mission can be used to teach a variety of STEM topics.

### Why It's Important

The vast majority of asteroids and comets are not dangerous, and never will be. Asteroids and comets are considered potentially hazardous objects, or PHOs, if they are 100-165 feet (30-50 meters) in diameter or larger and their orbit around the Sun comes within five million miles (eight million kilometers) of Earth’s orbit. NASA's planetary defense strategy involves detecting and tracking these objects using telescopes on the ground and in space. In fact, NASA’s Center for Near Earth Object Studies, or CNEOS, monitors all known near-Earth objects to assess any impact risk they may pose. Any relatively close approach is reported on the Asteroid Watch dashboard.

NASA's Planetary Defense Coordination Office runs a variety of programs and initiatives aimed at detecting and responding to threats from potentially hazardous objects, should one be discovered. The DART mission is one component and the first mission being flown by the team. Image credit: NASA | + Expand image

While there are no known objects currently posing a threat to Earth, scientists continue scanning the skies for unknown asteroids. NASA is actively researching and planning for ways to prevent or reduce the effects of a potential impact, should one be discovered. The DART mission was the first test of such a plan – in this case, whether it was possible to divert an asteroid from its predicted course by slamming into it with a spacecraft.

Eyes on Asteroids is a real-time visualization of every known asteroid or comet that is classified as a near-Earth object, or NEO. Asteroids are represented as blue dots and comets as shown as white dots. Use your mouse to explore the interactive further and learn more about the objects and how we track them. Credit: NASA/JPL-Caltech | Explore the full interactive

With the knowledge gained from the demonstration, similar techniques could be used in the future to deflect an asteroid or comet away from Earth if it were deemed hazardous to the planet.

### How It Worked

With a diameter of about 525 feet (160 meters) – the length of 1.5 football fields – Dimorphos is the smaller of two asteroids in a double-asteroid system. Before DART's impact, Dimorphos orbited the larger asteroid called Didymos (Greek for "twin"), every 11 hours and 55 minutes.

The sizes of the two asteroids in the Didymos system relative to objects on Earth. Image credit: NASA/Johns Hopkins APL | + Expand image

Neither asteroid poses a threat to our planet, which is one reason why this asteroid system was the ideal place to test asteroid redirection techniques. At the time of DART's impact, the asteroid pair was 6.8 million miles (11 million kilometers) away from Earth as they traveled on their orbit around the Sun.

The DART spacecraft was designed to collide head-on with Dimorphos to alter its orbit, shortening the time it takes the small asteroid to travel around Didymos. Compared with Dimorphos, which has a mass of about 11 billion pounds (five billion kilograms), the DART spacecraft was light. It weighed just 1,210 pounds (550 kilograms) at the time of impact. So how did such a light spacecraft affect the orbit of a relatively massive asteroid?

You can use your mouse to explore this interactive view of DART's impact with Dimorphos from NASA's Eyes on the Solar System. Credit: NASA/JPL-Caltech | Explore the full interactive

DART was designed as a kinetic impactor, meaning it transferred its momentum and kinetic energy to Dimorphos upon impact, altering the asteroid's orbit in return. Scientists were able to make predictions about some of these effects thanks to principles described in Newton's laws of motion.

Newton’s first law told us that the asteroid’s orbit would remain unchanged until something acted upon it. Using the formula for linear momentum (p = m * v), we could calculate that the spacecraft, which at the time of impact would be traveling at 3.8 miles (6.1 kilometers) per second, would have about 0.5% of the asteroid’s momentum. The momentum of the spacecraft may seem small in comparison, but calculations suggested it would be enough to make a detectable change in the speed of Dimorphos' orbit. However, mission planners felt that changing Dimorphos’ orbit by at least 73 seconds would be enough to consider the test a success.

But there was more to consider in testing whether the technique could be used in the future for planetary defense. For example, the formula for kinetic energy (KE = 0.5 * m * v2) tells us that a fast moving spacecraft possesses a lot of energy.

When DART hit the surface of the asteroid, its kinetic energy was 10 billion joules! A crater was formed and material known as ejecta was blasted out as a result of the impact. Scientists are still studying the data returned from the mission to determine the amount of material ejected out of the crater, but estimates prior to impact put the number at 10-100 times the mass of the spacecraft itself. The force needed to push this material out was then matched by an equal reaction force pushing on the asteroid in the opposite direction, as described by Newton’s third law.

This animation shows conceptually how DART's impact is predicted to change Dimorphos' orbit from a larger orbit to a slightly smaller one that's several minutes shorter than the original. Credit: NASA/Johns Hopkins APL/Jon Emmerich | Watch on YouTube

How much material was ejected and its recoil momentum is still unknown. A lot depends on the surface composition of the asteroid, which scientists are still investigating. Laboratory tests on Earth suggested that if the surface material was poorly conglomerated, or loosely formed, more material would be blasted out. A surface that was well conglomerated, or densely compacted, would eject less material.

After the DART impact, scientists used a technique called the transit method to see how much the impact changed Dimorphos' orbit. As observed from Earth, the Didymos pair is what’s known as an eclipsing binary, meaning Dimorphos passes in front of and behind Didymos from our view, creating what appears from Earth to be a subtle dip in the combined brightness of the pair. Scientists used ground-based telescopes to measure this change in brightness and calculate how quickly Dimorphos orbits Didymos. By comparing measurements from before and after impact, scientists determined that the orbit of Dimorphos had slowed by 32 minutes to 11 hours and 23 minutes.

The green circle shows the location of the Dimorphos asteroid, which orbits the larger asteroid, Didymos, seen here as the bright line across the middle of the images. The blue circle shows where Dimorphos would have been had its orbit not changed due to NASA’s DART mission purposefully impacting the smaller asteroid on Sept. 26, 2022. The images were obtained from the NASA Jet Propulsion Laboratory’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia. Image credit: NASA/Johns Hopkins APL/JPL/NASA JPL Goldstone Planetary Radar/National Science Foundation’s Green Bank Observatory | + Expand image | › DART image gallery

One of the biggest challenges of the DART mission was navigating a small spacecraft to a head-on collision with a small asteroid millions of miles away. To solve that problem, the spacecraft was equipped with a single instrument, the DRACO camera, which worked together with an autonomous navigation system called SMART Nav to guide the spacecraft without direct control from engineers on Earth. About four hours before impact, images captured by the camera were sent to the spacecraft's navigation system, allowing it to identify which of the two asteroids was Dimorphos and independently navigate to the target.

A composite of 243 images of Didymos and Dimorphos taken by the DART spacecraft's DRACO camera on July 27, 2022, as the spacecraft was navigating to its target. Image credit: JPL DART Navigation Team | + Expand image | › DART image gallery

DART was not just an experimental asteroid impactor. The mission also used cutting-edge technology never before flown on a planetary spacecraft and tested new technologies designed to improve how we power and communicate with spacecraft.

Learn more about the engineering behind the DART mission, including the innovative Roll Out Solar Array and NEXT-C ion propulsion system, in this video featuring experts from the mission. Credit: APL | Watch on YouTube

One such technology that was first tested on the International Space Station and was later used on the solar-powered DART spacecraft, is the Roll Out Solar Array, or ROSA, power system. As its name suggests, the power system consisted of flexible solar panel material that was rolled up for launch and unrolled in space.

The Roll Out Solar Array, shown in this animated image captured during a test on the International Space Station, is making its first planetary journey on DART. Image credit: NASA | + Expand image

Some of the power generated by the solar array was used for another innovative technology, the spacecraft's NEXT-C ion propulsion system. Rather than using traditional chemical propulsion, DART was propelled by charged particles of xenon pushed from its engine. Ion propulsion has been used on other missions to asteroids and comets including Dawn and Deep Space 1, but DART's ion thrusters had higher performance and efficiency.

In the days following the event, NASA received images of the impact from a cubesat, LICIACube, that was deployed by DART before impact. The cubesat, which was provided by the Italian Space Agency, captured images of the impact and the ejecta cloud.

This image from LICIACube shows plumes of ejecta streaming from Dimorphos after DART's impact. Each rectangle represents a different level of contrast to better see fine structure in the plumes. By studying these streams of material, scientists will be able to learn more about the asteroid and the impact process. | + Expand image | › DART image gallery

Meanwhile, the James Webb Space Telescope, the Hubble Space Telescope, and the Lucy spacecraft observed Didymos to monitor how soon reflected sunlight from the ejecta plume could be seen. Going forward, DART team members will continue observing the asteroid system to measure the change in Dimorphos’ orbit and determine what happened on its surface. And in 2024, the European Space Agency plans to launch the Hera spacecraft to conduct an in-depth post-impact study of the Didymos system.

This animation, a timelapse of images from NASA’s James Webb Space Telescope, covers the time spanning just before DART's impact at 4:14 p.m. PDT (7:14 p.m. EDT) on Septtember 26 through 5 hours post-impact. Plumes of material from a compact core appear as wisps streaming away from where the impact took place. An area of rapid, extreme brightening is also visible in the animation. Image credit: Science: NASA, ESA, CSA, Cristina Thomas (Northern Arizona University), Ian Wong (NASA-GSFC); Joseph DePasquale (STScI) | + Expand image | › DART image gallery

Continue following along with all the science from DART, including the latest images and updates on the mission website. Plus, explore even more resources on this handy page.

### Teach It

The mission is a great opportunity to engage students in the real world applications of STEM topics. Start exploring these lessons and resources to get students engaging in STEM along with the mission.

#### Resources for Kids

Check out these related resources for kids from NASA Space Place:

### Explore More

TAGS: Asteroids and Comets, DART, near-Earth objects, planetary defense, Science, K-12 Education, Teachers, Educators, Parents, Teachable Moments

There’s no better time to learn about the Moon than during a lunar eclipse. Here’s how eclipses work, what to expect, and how to get students engaged.

This article has been updated to include information about the visibility and timing of the total lunar eclipse on Nov. 8, 2022. See What to Expect for details.

A full moon is always a good reason to go outside and look up, but a total or partial lunar eclipse is an awe-inspiring site that gives students a great opportunity to engage in practical sky watching. Whether it’s the Moon's reddish hue during a total lunar eclipse or the "bite" taken out of the Moon during a partial lunar eclipse, there's always something exciting to observe during these celestial events.

Read on to see what to expect during the next lunar eclipse. Plus, explore resources you can use at home or in the classroom to teach students about moon phases, craters, and more!

### How It Works

These side-by-side graphics show how the Moon, Sun, and Earth align during a lunar eclipse (left) versus a non-eclipse full moon (right). Credit: NASA Goddard Visualization Studio | + Enlarge image

Eclipses can occur when the Sun, the Moon and Earth align. Lunar eclipses can only happen during the full moon phase, when the Moon and the Sun are on opposite sides of Earth. At that point, the Moon could move into the shadow cast by Earth, resulting in a lunar eclipse. However, most of the time, the Moon’s slightly tilted orbit brings it above or below the shadow of Earth.

The time period when the Moon, Earth and the Sun are lined up and on the same plane – allowing for the Moon to pass through Earth’s shadow – is called an eclipse season. Eclipse seasons last about 34 days and occur just shy of every six months. When a full moon occurs during an eclipse season, the Moon travels through Earth’s shadow, creating a lunar eclipse.

When a full moon occurs during an eclipse season, the Moon travels through Earth's shadow, creating a lunar eclipse. Credit: NASA/JPL-Caltech | + Enlarge image

Unlike solar eclipses, which require special glasses to view and can only be seen for a few short minutes in a very limited area, a total lunar eclipse can last over an hour and be seen by anyone on the nighttime side of Earth – as long as skies are clear!

### Why It’s Important

Lunar eclipses have long played an important role in understanding Earth and its motions in space.

In ancient Greece, Aristotle noted that the shadows on the Moon during lunar eclipses were round, regardless of where an observer saw them. He realized that only if Earth were a spheroid would its shadows be round – a revelation that he and others had many centuries before the first ships sailed around the world.

Earth wobbles on its axis like a spinning top that’s about to fall over, a phenomenon called precession. Earth completes one wobble, or precession cycle, over the course of 26,000 years. Greek astronomer Hipparchus made this discovery by comparing the position of stars relative to the Sun during a lunar eclipse to those recorded hundreds of years earlier. A lunar eclipse allowed him to see the stars and know exactly where the Sun was for comparison – directly opposite the Moon. If Earth didn’t wobble, the stars would appear to be in the same place they were hundreds of years earlier. When Hipparchus saw that the stars’ positions had indeed moved, he knew that Earth must wobble on its axis!

Additionally, modern-day astronomers have used ancient eclipse records and compared them with computer simulations. These comparisons helped scientists determine the rate at which Earth’s rotation is slowing.

### What to Expect

The Moon passes through two distinct parts of Earth’s shadow during a lunar eclipse. The outer part of the cone-shaped shadow is called the penumbra. The penumbra is less dark than the inner part of the shadow because it’s penetrated by some sunlight. (You have probably noticed that some shadows on the ground are darker than others, depending on how much outside light enters the shadow; the same is true for the outer part of Earth’s shadow). The inner part of the shadow, known as the umbra, is much darker because Earth blocks additional sunlight from entering the umbra.

Here's what to expect during the total lunar eclipse on Nov. 8, 2022, which will be visible in North and South America, as well as Asia and Australia. Viewers in the most eastern parts of the continental U.S. will see the Moon set below the horizon as it exits Earth’s shadow in the second half of the eclipse.

At 12:02 a.m. PST (3:02 a.m. EST), the edge of the Moon will begin entering the penumbra. The Moon will dim very slightly for the next 67 minutes as it moves deeper into the penumbra. Because this part of Earth’s shadow is not fully dark, you may only notice some dim shading (if anything at all) on the Moon near the end of this part of the eclipse. Should you decide to skip this part of the eclipse, you won’t miss much.

During a total lunar eclipse, the Moon first enters into the penumbra, or the outer part of Earth's shadow, where the shadow is still penetrated by some sunlight. Credit: NASA | + Enlarge image

At 1:09 a.m. PST (4:09 a.m. EST), the edge of the Moon will begin entering the umbra. As the Moon moves into the darker shadow, significant darkening will be noticeable. Some say that during this part of the eclipse, the Moon looks as if it has had a bite taken out of it. That “bite” gets bigger and bigger as the Moon moves deeper into the shadow.

As the Moon starts to enter into the umbra, the inner and darker part of Earth's shadow, it appears as if a bite has been taken out of the Moon. This "bite" will grow until the Moon has entered fully into the umbra. Credit: NASA | + Enlarge image

At 2:16 a.m. PST (5:16 a.m. EST), the Moon will be completely inside the umbra, marking the beginning of the total lunar eclipse, also known as totality.

The total lunar eclipse starts once the moon is completely inside the umbra. And the moment of greatest eclipse happens with the Moon is halfway through the umbra as shown in this graphic. Credit: NASA | + Enlarge image

The moment of greatest eclipse, when the Moon is halfway through its path across the umbra, occurs at 2:59 a.m. PST (5:59 a.m. EST). As the Moon moves completely into the umbra – the part of the eclipse known as totality – something interesting happens: The Moon begins to turn reddish-orange. The reason for this phenomenon? Earth’s atmosphere. As sunlight passes through it, the small molecules that make up our atmosphere scatter blue light, which is why the sky appears blue. This leaves behind mostly red light that bends, or refracts, into Earth’s shadow. We can see the red light during an eclipse as it falls onto the Moon in Earth’s shadow. This same effect is what gives sunrises and sunsets a reddish-orange color.

As the Moon moves completely into the umbra, it turns a reddish-orange color. Credit: NASA | + Enlarge image

A variety of factors affect the appearance of the Moon during a total lunar eclipse. Clouds, dust, ash, photochemical droplets and organic material in the atmosphere can change how much light is refracted into the umbra. The potential for variation provides a great opportunity for students to observe and classify the lunar eclipse based on its brightness. Details can be found below in the Teach It section.

At 3:41 a.m. PST (6:41 a.m. EST), the edge of the Moon will begin exiting the umbra and moving into the opposite side of the penumbra, reversing the “bite” pattern seen earlier. At this point, the Moon will have just set in the most northeastern portions of the continental United States. More and more eastern states will see the Moon set over the next hour as the eclipse progresses.

At 4:49 a.m. PST, the Moon will be completely outside of the umbra and no longer visible in the eastern United States. Those in the central United States will see the Moon begin setting around this time (6:49 a.m. CST). The Moon will continue exiting the penumbra until the eclipse officially ends at 5:56 a.m. PST, remaining visible only to viewers in the western United States, including many in the Mountain Time Zone one hour ahead.

### Teach It

Ask students to observe the lunar eclipse and evaluate the Moon’s brightness using the Danjon Scale of Lunar Eclipse Brightness. The Danjon scale illustrates the range of colors and brightness the Moon can take on during a total lunar eclipse and is a tool observers can use to characterize the appearance of an eclipse. View the lesson guide here. After the eclipse, have students compare and justify their evaluations of the eclipse.

Use these standards-aligned lessons and related activities to get your students excited about the eclipse, moon phases, and Moon observations.

### Explore More

TAGS: Lunar Eclipse, Moon, Super Blue Blood Moon, Observe the Moon, Eclipse, K-12, Classroom Activities, Teaching

Here's what we learned from the first set of images captured by NASA's newest space observatory and how to translate it into learning opportunities for students.

NASA’s newest space observatory, the James Webb Space Telescope, has returned its first set of images and spectra of five different targets – from nebulae to exoplanets to galaxy clusters – revealing the universe in ways never before seen. These targets, selected by a team of experts, represent just the start of the telescope's science operations and the beginning of our ability to see the universe in a whole new way.

Read on to learn more about what the space-based observatory’s images can tell us about the cosmos, how they were captured, and how to engage learners in the science and engineering behind the mission.

### What JWST Saw

#### New Details Revealed About the Birth of Stars

What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth. Credit: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

Stellar nurseries, young stars, and protostellar jets, which are narrow, ultra-fast streams of gas emanating from baby stars, are all on display in this image of the Carina Nebula, a cloud of gas and dust approximately 7,600 light years away.

Nebulae are massive clouds of gas and dust, some spanning up to hundreds of light-years across. Thanks to its infrared cameras, JWST can peer into these dusty regions of space, revealing incredible details previously unseen by other telescopes.

Within the Carina Nebula, a star-forming region known as NGC 3324 was captured by the Webb telescope in this image. As the edge of this region moves inward toward the gas and dust, it may encounter unstable areas. The pressure changes can cause the gas and dust to collapse, forming a new star in a process called accretion. However, if too much material is pushed away, it may prevent a star from forming.

The Webb telescope’s observations in nebulae like this will help scientists answer some of the unknown questions of astrophysics, like what determines the number of stars in a certain region and why do stars form with certain masses.

Scientists can also learn how star formation affects these clouds. Little is known about the numerous small, or low-mass, stars within nebulae. But by studying the jets revealed in the new image, scientists can understand how these stars are expelling gas and dust out of the cloud, thereby reducing the amount of material available to form new stars. Furthermore, scientists will be able to get a full count of these low-mass stars and account for their impact throughout the nebula.

#### Signs of Water on a Distant Planet

A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

JWST's observations of exoplanet WASP-96 b, a planet outside our solar system, is not an image but a spectrum of light. Within the spectrum are highlights that indicate the presence of water molecules. The spectrum also shows evidence of clouds and haze, which were thought not to exist in WASP-96 b's atmosphere.

WASP-96 b is an exoplanet made up mostly of gas. About half the mass of Jupiter, but slightly larger, it orbits much closer to its star, completing a revolution every 3.4 days compared with 12 years for Jupiter.

This measurement, known as a transmission spectrum, was collected as WASP-96 b transited, or passed in front of, its host star from the perspective of the telescope. It compares the light that passed through the atmosphere of the exoplanet with the light from the planet's parent star alone. As a result, it is possible to see the amount of light at each wavelength blocked by the planet and absorbed by its atmosphere, telling scientists the size of the planet and the chemicals contained in its atmosphere.

While WASP-96 b’s spectrum had been captured before, the Webb telescope provided the most detailed view of its spectrum in near-infrared, and the improved resolution completely changed our understanding of the exoplanet’s atmosphere. Using this spectrum, scientists will be able to measure the amount of water in the exoplanet's atmosphere, determine how much oxygen and carbon it contains, infer the make-up of the planet, and even how, when, and where it formed.

#### Star Pair Coming Into Focus

NASA’s Webb Telescope has revealed the cloak of dust around the second star, shown at left in red, at the center of the Southern Ring Nebula for the first time. It is a hot, dense white dwarf star. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

Two distinct stars can be seen in this image of the center of the Southern Ring Nebula – a pairing that was believed to exist but was not visible in previous images.

The star pair came into view thanks to the space telescope's MIRI instrument, which is designed to capture wavelengths of light in the mid-infrared range of the electromagnetic spectrum. MIRI’s ability to see in the mid-infrared revealed that the older of the two stars is surrounded by dust. Seeing this dust clearly is what makes the second star visible in the image. While the brighter star is in an earlier stage of its life, it will likely form its own planetary nebula in the future.

About 2,500 light-years away from Earth, the Southern Ring is a planetary nebula – a shell of gas and dust shed from a dying white dwarf star at its center. Its gases stretch out for nearly half a light-year and are speeding away from the star at approximately nine miles per second!

The bright star at the center of NGC 3132, while prominent when viewed by NASA’s Webb Telescope in near-infrared light, plays a supporting role in sculpting the surrounding nebula. A second star, barely visible at lower left along one of the bright star’s diffraction spikes, is the nebula’s source. It has ejected at least eight layers of gas and dust over thousands of years. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The images from JWST reveal that starlight streams out of the nebula in fine lines, the result of holes in the surrounding gas and dust cloud. The types and locations of different molecules within the cloud, gleaned from the captured spectra, will help to fine tune our understanding of the structure, composition, and history of this nebula, and with future observations, other nebulae.

#### How Galaxies Interact

An enormous mosaic of Stephan’s Quintet is the largest image to date from NASA’s James Webb Space Telescope, covering about one-fifth of the Moon’s diameter. It contains over 150 million pixels and is constructed from almost 1,000 separate image files. The visual grouping of five galaxies was captured by Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The Webb telescope's capabilities bring new eyes to a cluster of galaxies first discovered in 1877 and known as Stephan’s Quintet. On display in this sharp new image are regions of new star birth containing millions of young stars as well as tails of gas, dust, and stars being ripped from galaxies as a result of gravitational forces between the galaxies.

Stephan’s Quintet is a dense cluster of galaxies located 290 million light-years away in the constellation Pegasus. Four of the five galaxies within the quintet are locked in orbits that repeatedly bring them close to one another. The fifth (leftmost) galaxy is seven times closer to Earth than the others. But its location within the line of sight of the distant four makes it appear to be grouped with them. What looks like speckles surrounding the nearby galaxy and could be mistaken for digital noise is actually individual stars from that galaxy.

It may seem distant in pure numbers, but Stephan's Quintet is relatively close compared to galaxies that are billions of light-years away. Its proximity gives astronomers a great view of the interactions that occur between galaxies that are near to each other.

The MIRI instrument measured the composition of gas around the black hole at the center of one of the galaxies in Stephan's Quintent to find a region filled with hot, ionized gases, including iron, argon, neon, sulfur and oxygen (top spectrum). The instrument also revealed that the supermassive black hole has a reservoir of colder, denser gas with large quantities of molecular hydrogen and silicate dust (bottom spectrum). Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The detail exposed will allow scientists to understand the interactions occurring in much more distant – and harder to observe – galaxies. Close inspections of galactic nuclei captured in mid-infrared by the telescope's MIRI instrument revealed hot gas being stripped of its electrons by winds and radiation from a supermassive black hole at the center of one galaxy. The new detail helped scientists determine that iron, argon, neon, sulfur and oxygen, as well as silicate dust are contained in these gases.

Meanwhile, the telescope's NIRSpec instrument – which can capture up to 100 spectra at a time – was able to identify atomic and molecular hydrogen as well as iron ions in the gases around the black hole. These observations will provide a greater understanding about the rate at which supermassive black holes feed and grow.

#### Thousands of Galaxies in a Grain of Sand

NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

This image contains thousands of galaxies as well as the faintest objects yet observed in the infrared. Known as a deep field image, it was made by pointing the telescope at the target for an extended period of time, allowing the detectors to collect as much of the faint, distant light as possible. JWST captured this deep field image in just 12.5 hours, while the Hubble Space Telescope spent two weeks capturing its deepest images. (Note that Hubble also observed this galaxy cluster, but not as a deep field image.)

Hold a single grain of sand at arm's length and you could cover the entire area of space captured by this image. Keen observers will notice what appear as warped or stretched galaxies. Those are the result of gravitational lensing, a phenomenon in which the gravity of the galaxy cluster centered in the foreground bends the light from background galaxies magnifying and distorting their light. Taking advantage of this phenomenon allows for viewing of extremely distant and very faint galaxies.

The galaxy cluster shown in the image is known as SMACS 0723 and it appears as it did 4.6 billion years ago – the length of time it took for its light to reach the telescope. Light from the oldest-known galaxy in the image had been traveling for 13.1 billion years before it reached JWST.

Galaxy cluster SMACS 0723 is a technicolor landscape when viewed in mid-infrared light by NASA’s James Webb Space Telescope. Compared to Webb’s near-infrared image at right, the galaxies and stars are awash in new colors. Credits: NASA, ESA, CSA, STScI | › Full image and caption | › Text description (PDF)

The MIRI instrument’s ability to detect longer infrared wavelengths provides additional information in the image about the make-up of those galaxies. Mid-infrared light highlights dust, an important star-forming ingredient. In this image, red objects contain thick dust layers, while blue galaxies contain stars but not much dust. Green objects contain dust filled with hydrocarbons and other compounds. With these data, astronomers will be able to better understand the formation and growth of galaxies.

As impressive as this image is, the JWST team has plans to capture more deep field images using even longer exposure times. Keep up to date with the latest images and spectra from JWST throughout the school year at the Webb Space Telescope Resource Gallery.

### How They Did It

The Webb telescope's ability to detect these objects in such great detail is enabled by its size, the way it observes the universe, and the unique technologies aboard. We went into more detail about how JWST works in a previous Teachable Moment, but below you’ll find a review of some of the important ways JWST was uniquely designed to capture these groundbreaking images.

#### Observing the Infrared

Light waves get stretched as the universe expands similar to how this ink mark stretches out as the elastic is pulled. Get students modeling and exploring this effect with this standards-aligned math lesson. Credit: NASA/JPL-Caltech | + Expand image

The Webb telescope was built with instruments like NIRSpec and MIRI that are sensitive to light in the near- and mid-infrared wavelengths to detect some of the most distant objects in space.

As light from distant objects travels to Earth, the universe expands, something it’s been doing since the Big Bang. The waves that make up the light get stretched as the universe expands. Visible lightwaves from distant objects that you would be able to see with your eyes get stretched out so far that the longer wavelengths shift from visible light into infrared. Scientists refer to this phenomenon as redshift – and the farther away an object is, the more redshift it undergoes.

#### Gathering Light

The light from some of these distant objects has traveled so far that it is incredibly dim. To see such dim light, the Webb telescope was built to be extremely sensitive. On the Webb telescope, 18 hexagonal mirrors combine to form a massive primary mirror that is 21 feet (6.5 meters) across – six times the surface area of Hubble.

The complete optical telescope element on display inside a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in 2017. Credits: NASA/Desiree Stover | › Full image and caption

To detect faint infrared light, the instruments inside the telescope have to be kept very cold, otherwise those infrared signals could get lost in the heat of the telescope. The spacecraft’s orbit and tennis-court-size sunshield keep light and heat from the Sun, Earth, and Moon from warming up its sensitive instruments. And the MIRI instrument, which needs to be even colder to capture mid-infrared wavelengths, is equipped with a special cryocooler.

The unique design and innovative techniques used by the James Webb Space Telescope are what made the first images possible. As the mission continues, more targets will be observed, more discoveries will be made, and more of our universe will unfold before our eyes.

“It’s not every day you can say you contributed to something that inspires the world in a positive way, but I believe that’s what JWST is doing for everyone of all ages,” said JPL engineer Analyn Schneider, who is the project manager for the telescope's MIRI instrument. “The telescope will help us learn more about our galaxy and the rest of the universe, and as a bonus we get these magnificent images. Learning is a big part of being in science and engineering and that’s what makes it interesting and challenging.”

### Teach It

Bring the excitement of these far-off observations closer to home by using the following resources in your learning environment, whether in-person, hybrid, or remote. Scientists and educators directly connected with the James Webb Space Telescope have teamed up to provide a collection of Webb resources to meet your needs. Find additional resources below and through NASA’s Universe of Learning project.

### Explore More

NASA's Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

TAGS: Stars & Galaxies, JWST, K-12 Education, Teaching

Learn about pi and some of the ways the number is used at NASA. Then, dig into the science behind the Pi Day Challenge.

Update: March 15, 2022 – The answers are here! Visit the NASA Pi Day Challenge slideshow to view the illustrated answer keys for each of the problems in the 2022 challenge.

### In the News

No matter what Punxsutawney Phil saw on Groundhog Day, a sure sign that spring approaches is Pi Day. Celebrated on March 14, it’s the annual holiday that pays tribute to the mathematical constant pi – the number that results from dividing any circle's circumference by its diameter.

Every year, Pi Day gives us a reason to not only celebrate the mathematical wonder that helps NASA explore the universe, but also to enjoy our favorite sweet and savory pies. Students can join in the fun by using pi to explore Earth and space themselves in our ninth annual NASA Pi Day Challenge.

Read on to learn more about the science behind this year's challenge and find out how students can put their math mettle to the test to solve real problems faced by NASA scientists and engineers as we explore Earth, the Moon, Mars, and beyond!

Visit the Pi in the Sky 9 lesson page to explore classroom resources and downloads for the 2022 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech | + Expand image

This artist's concept shows the Lunar Flashlight spacecraft, a six-unit CubeSat designed to search for ice on the Moon's surface using special lasers. Image credit: NASA/JPL-Caltech | › Full image details

Clouds drift over the dome-covered seismometer, known as SEIS, belonging to NASA's InSight lander, on Mars. Credit: NASA/JPL-Caltech. | › Full image and caption

This animation shows the collection of data over the state of Florida, which is rich with rivers, lakes and wetlands. Credits: NASA/JPL-Caltech | + Expand image

Illustration of NASA’s Transiting Exoplanet Survey Satellite (TESS). Credits: NASA | + Expand image

### How It Works

Dividing any circle’s circumference by its diameter gives you an answer of pi, which is usually rounded to 3.14. Because pi is an irrational number, its decimal representation goes on forever and never repeats. In 2021, a supercomputer calculated pi to more than 62 trillion digits. But you might be surprised to learn that for space exploration, NASA uses far fewer digits of pi.

Here at NASA, we use pi to understand how much signal we can receive from a distant spacecraft, to calculate the rotation speed of a Mars helicopter blade, and to collect asteroid samples. But pi isn’t just used for exploring the cosmos. Since pi can be used to find the area or circumference of round objects and the volume or surface area of shapes like cylinders, cones, and spheres, it is useful in all sorts of ways. Architects use pi when designing bridges or buildings with arches; electricians use pi when calculating the conductance of wire; and you might even want to use pi to figure out how much frozen goodness you are getting in your ice cream cone.

In the United States, March 14 can be written as 3.14, which is why that date was chosen for celebrating all things pi. In 2009, the U.S. House of Representatives passed a resolution officially designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi. And that's precisely what the NASA Pi Day Challenge is all about!

### The Science Behind the 2022 NASA Pi Day Challenge

This ninth installment of the NASA Pi Day Challenge includes four brain-busters that get students using pi to measure frost deep within craters on the Moon, estimate the density of Mars’ core, calculate the water output from a dam to assess its potential environmental impact, and find how far a planet-hunting satellite needs to travel to send data back to Earth.

› Take the NASA Pi Day Challenge

› Educators, get the lesson here!

#### Lunar Logic

NASA’s Lunar Flashlight mission is a small satellite that will seek out signs of frost in deep, permanently shadowed craters around the Moon’s south pole. By sending infrared laser pulses to the surface and measuring how much light is reflected back, scientists can determine which areas of the lunar surface contain frost and which are dry. Knowing the locations of water-ice on the Moon could be key for future crewed missions to the Moon, when water will be a precious resource. In Lunar Logic, students use pi to find out how much surface area Lunar Flashlight will measure with a single pulse from its laser.

#### Core Conundrum

Since 2018, the InSight lander has studied the interior of Mars by measuring vibrations from marsquakes and the “wobble” of the planet as it rotates on its axis. Through careful analysis of the data returned from InSight, scientists were able to measure the size of Mars’ liquid core for the first time and estimate its density. In Core Conundrum, students use pi to do some of the same calculations, determining the volume and density of the Red Planet’s core and comparing it to that of Earth’s core.

#### Dam Deduction

The Surface Water and Ocean Topography, or SWOT mission will conduct NASA's first global survey of Earth's surface water. SWOT’s state-of-the-art radar will measure the elevation of water in major lakes, rivers, wetlands, and reservoirs while revealing unprecedented detail on the ocean surface. This data will help scientists track how these bodies of water are changing over time and improve weather and climate models. In Dam Deduction, students learn how data from SWOT can be used to assess the environmental impact of dams. Students then use pi to do their own analysis, finding the powered output of a dam based on the water height of its reservoir and inferring potential impacts of this quick-flowing water.

#### Telescope Tango

The Transiting Exoplanet Survey Satellite, or TESS, is designed to survey the sky in search of planets orbiting bright, nearby stars. TESS does this while circling Earth in a unique, never-before-used orbit that brings the spacecraft close to Earth about once every two weeks to transmit its data. This special orbit keeps TESS stable while giving it an unobstructed view of space. In its first two years, TESS identified more than 2,600 possible exoplanets in our galaxy with thousands more discovered during its extended mission. In Telescope Tango, students will use pi to calculate the distance traveled by TESS each time it sends data back to Earth.

### Teach It

Celebrate Pi Day by getting students thinking like NASA scientists and engineers to solve real-world problems in NASA Pi Day Challenge. Completing the problem set and reading about other ways NASA uses pi is a great way for students to see the importance of the M in STEM.

#### Pi Day Resources

Plus, join the conversation using the hashtag #NASAPiDayChallenge on Facebook, Twitter, and Instagram.

### Explore More

#### Websites

TAGS: Pi Day, Pi, Math, NASA Pi Day Challenge, Moon, Lunar Flashlight, Mars, InSight, Earth, Climate, SWOT, Exoplanets, Universe, TESS, Teachers, Educators, Parents, Students, Lessons, Activities, Resources, K-12

Get a look into the science and engineering behind the largest and most powerful space telescope ever built while exploring ways to engage learners in the mission.

NASA is launching the largest, most powerful space telescope ever. The James Webb Space Telescope will look back at some of the earliest stages of the universe, gather views of early star and galaxy formation, and provide insights into the formation of planetary systems, including our own solar system.

Read on to learn more about what the space-based observatory will do, how it works, and how to engage learners in the science and engineering behind the mission.

### What It Will Do

The James Webb Space Telescope, or JWST, was developed through a partnership between NASA and the European and Canadian space agencies. It will build upon and extend the discoveries made by the Hubble Space Telescope to help unravel mysteries of the universe. First, let's delve into what scientists hope to learn with the Webb telescope.

A look at the James Webb Space Telescope, its mission and the incredible technological challenge this mission presents. | Watch on YouTube

#### How Galaxies Evolve

What the first galaxies looked like and when they formed is not known, and the Webb telescope is designed to help scientists learn more about that early period of the universe. To better understand what the Webb telescope will study, it’s helpful to know what happened in the early universe, before the first stars formed.

The universe, time, and space all began about 13.8 billion years ago with the Big Bang. For the first few hundred-thousand years, the universe was a hot, dense flood of protons, electrons, and neutrons, the tiny particles that make up atoms. As the universe cooled, protons and neutrons combined into ionized hydrogen and helium, which had a positive charge, and eventually attracted all those negatively charged electrons. This process, known as recombination, occurred about 240,000 to 300,000 years after the Big Bang.

This image shows the temperature fluctuations (shown as color differences) in the cosmic microwave background from a time when the universe was less than 400,000 years old. The image was captured by the Wilkinson Microwave Anisotropy Probe, or WMAP, which spent nine years, from 2001 to 2010, collecting data on the early universe. Credit: NASA | › Full image and caption | + Expand image

Light that previously couldn’t travel without being scattered by the dense ionized plasma of early particles could now travel freely. The very first form of light we can look back and see comes from this time and is known as the cosmic microwave background radiation. It is essentially a map of temperature fluctuations across the universe left behind from the Big Bang. The fluxuations give clues about the origin of galaxies and the large-scale structure of galaxies. There were still no stars in the universe at this time, so the next several hundred million years are known as the cosmic dark ages.

Current theory predicts that the earliest stars were big – 30 to 300 times the size of our Sun – and burned quickly, ending in supernova explosions after just a few million years. (For comparison, our Sun has a lifespan of about 10 billion years and will not go supernova.) Observing these luminous supernovae is one of the few ways scientists could study the earliest stars. That is vital to understanding the formation of objects such as the first galaxies.

By using the Webb telescope to compare the earliest galaxies with those of today, scientists hope to understand how they form, what gives them their shape, how chemical elements are distributed across galaxies, how central black holes influence their galaxies, and what happens when galaxies collide.

Learn how the James Webb Space Telescope's ability to look farther into space than ever before will bring newborn galaxies into view. | Watch on YouTube

#### How Stars and Planetary Systems Form

Stars and their planetary systems form within massive clouds of dust and gas. It's impossible to see into these clouds with visible light, so the Webb telescope is equipped with science instruments that use infrared light to peer into the hearts of stellar nurseries. When viewing these nurseries in the mid-infrared – as the Webb telescope is designed to do – the dust outside the dense star forming regions glows and can be studied directly. This will allow astronomers to observe the details of how stars are born and investigate why most stars form in groups as well as how planetary systems begin and evolve.

This mosaic image is the sharpest wide-angle view ever obtained of the starburst galaxy, Messier 82 (M82). The galaxy is remarkable for its bright blue disk, webs of shredded clouds and fiery-looking plumes of glowing hydrogen blasting out of its central regions.Throughout the galaxy's center, young stars are being born 10 times faster than they are inside our entire Milky Way Galaxy. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA); Acknowledgment: J. Gallagher (University of Wisconsin), M. Mountain (STScI), and P. Puxley (National Science Foundation) | › Full image and caption | + Expand image

#### How Exoplanets and Our Solar System Evolve

As we make more discoveries about exoplanets, artists at NASA are imagining what future explorers might encounter on these faraway worlds as part of the Exoplanet Travel Bureau poster series. Credit: NASA | › View and download the posters | + Expand image

The first planet outside our solar system, or exoplanet, was discovered in 1992. Since then, scientists have found thousands more exoplanets and estimate that there are hundreds of billions in the Milky Way galaxy alone. There are many waiting to be discovered and there is more to learn about the exoplanets themselves, such as what makes up their atmospheres and what their weather and seasons may be like. The Webb telescope will help scientists do just that.

In our own solar system, the Webb telescope will study planets and other objects to help us learn more about our solar neighborhood. It will be able to complement studies of Mars being carried out by orbiters, landers, and rovers by searching for molecules that may be signs of past or present life. It is powerful enough to identify and characterize icy comets in the far reaches of our solar system. And it can be used to study places like Saturn, Uranus, and Neptune while there are no active missions at those planets.

### How It Works

The Webb telescope has unique capabilities enabled by the way it views the universe, its size, and the new technologies aboard. Here's how it works.

#### Peering Into the Infrared

To see ancient, distant galaxies, the Webb telescope was built with instruments sensitive to light in the near- and mid-infrared wavelengths.

Light leaving these galaxies can take billions of years to reach Earth, so when we see these objects, we’re actually seeing what they looked like in the past. The farther something is from Earth, the farther back in time it is when we observe it. So when we look at light that left objects 13.5 billion years ago, we're seeing what happened in the early universe.

An illustrated timeline of the universe. Credit: WMAP | + Expand image

As light from distant objects travels to Earth, the universe continues to expand, something it’s been doing since the Big Bang. The waves that make up the light get stretched as the universe expands. You can see this effect in action by making an ink mark on a rubber band and observing how the mark stretches out when you pull on the rubber band.

Light waves get stretched as the universe expands similar to how this ink mark stretches out as the elastic is pulled. Get students modeling and exploring this effect with this standards-aligned math lesson. Credit: NASA/JPL-Caltech | + Expand image

What this means for light coming from distant galaxies is that the visible lightwaves you would be able to see with your eyes get stretched out so far that the longer wavelengths shift from visible light into infrared. Scientists refer to this phenomenon as redshift – and the farther away an object is, the more redshift it undergoes.

Webb telescope’s infrared sensing equipment will give scientists the chance to study some of the earliest stars that exploded in supernova events, creating the elements necessary to build planets and form life.

#### Gathering Light

The first stars were massive, their life cycles ending in supernova explosions. The light from these explosions has traveled so far that it is incredibly dim. This is due to the inverse square law. You experience this effect when a room appears to get darker as you move away from a light source.

To see such dim light, the Webb telescope needs to be extremely sensitive. A telescope’s sensitivity, or its ability to detect faint signals, is related to the size of the mirror it uses to gather light. On the Webb telescope, 18 hexagonal mirrors combine to form a massive primary mirror that is 21 feet (6.5 meters) across.

A technician inspects the Webb telescope's honeycomb-shaped mirror. The telescope's primary mirror is 21 feet (6.5 meters) across and is made up of 18 smaller hexagonal mirrors that must fold for launch and unfurl after the telescope reaches its orbit in space. Credit: NASA/MSFC/David Higginbotham/Emmett Given | › Full image and caption | + Expand image

Compared with the Hubble Space Telescope’s eight-foot (2.4 meter) diameter mirror, this gives the Webb telescope more than six times the surface area to collect those distant particles of light known as photons. Hubble’s famous Ultra Deep Field observation captured images of incredibly faint, distant galaxies by pointing at a seemingly empty spot in space for 16 days, but the Webb telescope will be able to make a similar observation in just seven hours.

This image, called the Hubble Ultra Deep Field, shows 28 of the more than 500 young galaxies that existed when the universe was less than 1 billion years old. Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz) | › Full image and caption | + Expand image

#### Keeping Cool

The Webb Telescope gathers its scientific data as infrared light. To detect the faint signals of objects billions of light years away, the instruments inside the telescope have to be kept very cold, otherwise those infrared signals could get lost in the heat of the telescope. Engineers accounted for this with a couple of systems designed to get the instruments cold and keep them cold.

The Webb telescope's orbit around the Sun – sitting about 1 million miles (1.5 million kilometers) from Earth at Lagrange point 2 – keeps the spacecraft pretty far from our planet's heat, but even that’s not enough. To further reduce the temperature on the instruments, the spacecraft will unfurl a tennis-court-size sunshield that will block light and heat from the Sun, Earth, and Moon using five layers of specially coated material. Each layer blocks incoming heat, and the heat that does make it through is redirected out of the sides of the sunshield. Additionally, the vacuum between each layer provides insulation.

The sunshield is made up of five layers of specially coated material designed to block the Webb telescope's sensitive instruments from incoming heat from the Sun, Earth, and Moon. This photo, taken in the cleanroom at Northrop Grumman in Southern California in December 2020, shows the sunshield fully deployed and tensioned as it will be in space. Credit: NASA/Chris Gunn | › Full image and caption | + Expand image

The sunshield is so effective that the temperatures on the Sun-facing side of the telescope could be hot enough to boil water, while on the side closest to the instruments, the temperature could be as low as -394 F (-237 C, 36 K).

That’s cold enough for the near-infrared instruments to operate, but the Mid-Infrared Instrument, or MIRI, needs to be even colder. To bring down the temperature of MIRI, the Webb telescope is equipped with a special cryocooler that pumps chilled helium to the instrument to reduce its operating temperature to about -448 F (-267 C, 6 K).

#### Spotting Exoplanets

The Webb telescope will search for exoplanets using two different methods.

Using the transit method, the Webb telescope will look for the regular pattern of dimming that occurs when an exoplanet transits its star, or passes between the star and the telescope. The amount of dimming can tell scientists a lot about the passing exoplanet, such as the size of the planet and its distance from the star.

This animation shows how the transit method is used to hunt for planets outside our solar system. When exoplanets transit their parent star, the Webb telescope (like the Kepler space telescope, depicted here) will be able to detect the dip in the star’s brightness, providing scientists with key information about the transiting exoplanet. Students can see this technique in action with this transit math problem. Credit: NASA/JPL-Caltech | + Expand image

The second method the Webb telescope will use to search for exoplanets is direct imaging – capturing actual images of planets beyond our solar system. To enable direct imaging of exoplanets, the Webb telescope is equipped with a coronagraph. Just like you might use your hand to block a bright light, a coronagraph blocks starlight from reaching a telescope’s instruments, allowing a dim exoplanet orbiting a star to be seen.

This “coronagraph” image taken by the Solar and Heliospheric Observatory, or SOHO, shows dim features around our Sun. Similarly, direct images of exoplanets captured by the Webb telescope will reveal details normally washed out by the brightness of stars. Credit: ESA&NASA/SOHO | › Full image and caption | + Expand image

The Webb telescope can uncover even more using spectroscopy. Light from a star produces a spectrum, which displays the intensity of light at different wavelengths. When a planet transits its star, some of the light from the star will pass through the planet's atmosphere before reaching the Webb telescope. Since all elements and molecules, such as methane and water, absorb energy at specific wavelengths, spectra from light that has passed through a planet’s atmosphere may contain dark lines known as absorption lines that tell scientists if there are certain elements present.

By looking at the unique spectrum produced when the light from a star shines through the atmosphere of a transiting exoplanet, scientists can learn whether certain elements are present on that planet. Credit: NASA | + Expand image

Using direct imaging and spectroscopy, scientists can learn even more about an exoplanet, including its color, seasons, rotation, weather, and vegetation if it exists.

All this could lead scientists to the ultimate exoplanet discovery: an Earth-size planet with an atmosphere like ours in its star’s habitable zone – a place where liquid water could exist.

#### Setting Up in Space

The Webb telescope will launch from French Guiana on top of an Ariane 5 rocket, a massive rocket capable of lifting the telescope, which weighs nearly 14,000 pounds (6,200 kilograms), to its destination.

The telescope's large mirror and giant sunshield are too big to fit inside the 18-foot (5.4-meter) wide rocket fairing, which protects the spacecraft during launch. To overcome this challenge, engineers designed the telescope's mirror and sunshield to fold for launch.

Two sides of the mirror assembly fold back for launch, allowing them to fit inside the fairing. The sunshield, which is 69.5 feet (21 meters) long and 46.5 feet (14 meters) wide, is carefully folded 12 times like origami so that it's narrow enough for launch. These are just two examples of several folding mechanisms needed to fit the massive telescope in its rocket for launch.

It will take about a month for the Webb telescope to reach its destination and unfurl its mirrors and sunshield. Scientists need another five months to cool down the instruments to their operating temperatures and align the mirrors correctly.

Approximately six months after launch, checkouts should be complete, and the telescope will begin its first science campaign and science operations.

Learn more and follow along with the mission from launch and unfolding to science observations and discovery announcements on the James Webb Space Telescope website.

### Teach It

Check out these resources to bring the real-life STEM behind the mission into your teaching with lesson guides for educators, projects and slideshows for students, and more.

### Explore More

NASA's Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory.

TAGS: JWST, James Webb Space Telescope, electromagnetic spectrum, exoplanets, universe, solar system, big bang, cosmology, astronomy, star formation, galaxy, galaxies, telescope, life, technology, MIRI, Mars, Engineering, Teaching, Education, Classroom, Science

Update: March 15, 2021 – The answers are here! Visit the NASA Pi Day Challenge slideshow to view the illustrated answer keys (also available as a text-only doc) with each problem.

Learn about pi and the history of Pi Day before exploring some of the ways the number is used at NASA. Then, try the math for yourself in our Pi Day Challenge.

Visit the Pi in the Sky 8 lesson page to explore classroom resources and downloads for the 2021 NASA Pi Day Challenge. Image credit: NASA/JPL-Caltech | + Expand image

Captured on Oct. 20, 2020, during the OSIRIS-REx mission’s Touch-And-Go (TAG) sample collection event, this series of images shows the SamCam imager’s field of view as the NASA spacecraft approached and touched asteroid Bennu’s surface. Image credit: NASA/Goddard/University of Arizona | › Full image and caption

In this illustration, NASA's Ingenuity Mars Helicopter stands on the Red Planet's surface as NASA's Perseverance rover (partially visible on the left) rolls away. Image credit: NASA/JPL-Caltech | › Full image and caption

This artist's concept shows what Deep Space Station-23, a new antenna dish capable of supporting both radio wave and laser communications, will look like when completed at the Deep Space Network's Goldstone, California, complex. Image credit: NASA/JPL-Caltech | + Expand image

Expedition 52 Flight Engineer Jack Fischer of NASA shared photos and time-lapse video of a glowing green aurora seen from his vantage point 250 miles up, aboard the International Space Station. This aurora photo was taken on June 26, 2017. Image credit: NASA | › Full image and caption

### In the News

As March 14 approaches, it’s time to get ready to celebrate Pi Day! It’s the annual holiday that pays tribute to the mathematical constant pi – the number that results from dividing any circle's circumference by its diameter.

Pi Day comes around only once a year, giving us a reason to chow down on our favorite sweet and savory pies while we appreciate the mathematical marvel that helps NASA explore Earth, the solar system, and beyond. There’s no better way to observe this day than by getting students exploring space right along with NASA by doing the math in our Pi Day Challenge. Keep reading to find out how students – and you – can put their math mettle to the test and solve real problems faced by NASA scientists and engineers as they explore the cosmos!

### How It Works

Dividing any circle’s circumference by its diameter gives us pi, which is often rounded to 3.14. However, pi is an irrational number, meaning its decimal representation goes on forever and never repeats. Pi has been calculated to 50 trillion digits, but NASA uses far fewer for space exploration.

Some people may think that a circle has no points. In fact, a circle does have points, and knowing what pi is and how to use it is far from pointless. Pi is used for calculating the area and circumference of circular objects and the volume of shapes like spheres and cylinders. So it's useful for everyone from farmers storing crops in silos to manufacturers of water storage tanks to people who want to find the best value when ordering a pizza. At NASA, we use pi to find the best place to touch down on Mars, study the health of Earth's coral reefs, measure the size of a ring of planetary debris light years away, and lots more.

In the United States, one format to write March 14 is 3.14, which is why we celebrate on that date. In 2009, the U.S. House of Representatives passed a resolution officially designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi. And you're in luck, because that's precisely what the NASA Pi Day Challenge is all about.

### The Science Behind the 2021 NASA Pi Day Challenge

This year, the NASA Pi Day Challenge offers up four brain-ticklers that will require students to use pi to collect samples from an asteroid, fly a helicopter on Mars for the first time, find efficient ways to talk with distant spacecraft, and study the forces behind Earth's beautiful auroras. Learn more about the science and engineering behind the problems below or click the link below to jump right into the challenge. Be sure to check back on March 15 for the answers to this year’s challenge.

› Take the NASA Pi Day Challenge

› Educators, get the lesson here!

#### Sample Science

NASA’s OSIRIS-REx mission has flown to an asteroid and collected a sample of surface material to bring back to Earth. (It will arrive back at Earth in 2023.) The mission is designed to help scientists understand how planets form and add to what we know about near-Earth asteroids, like the one visited by OSIRIS-REx, asteroid Bennu. Launched in 2016, OSIRIS-REx began orbiting Bennu in 2018 and successfully performed its maneuver to retrieve a sample on October 20, 2020. In the Sample Science problem, students use pi to determine how much of the spacecraft's sample-collection device needs to make contact with the surface of Bennu to meet mission requirements for success.

#### Whirling Wonder

Joining the Perseverance rover on Mars is the first helicopter designed to fly on another planet. Named Ingenuity, the helicopter is a technology demonstration, meaning it's a test to see if a similar device could be used for a future Mars mission. To achieve the first powered flight on another planet, Ingenuity must spin its blades at a rapid rate to generate lift in Mars’ thin atmosphere. In Twirly Whirly, students use pi to compare the spin rate of Ingenuity’s blades to those of a typical helicopter on Earth.

#### Signal Solution

NASA uses radio signals to communicate with spacecraft across the solar system and in interstellar space. As more and more data flows between Earth and these distant spacecraft, NASA needs new technologies to improve how quickly data can be received. One such technology in development is Deep Space Optical Communications, which will use near-infrared light instead of radio waves to transmit data. Near-infrared light, with its higher frequency than radio waves, allows for more data to be transmitted per second. In Signal Solution, students can compare the efficiency of optical communication with radio communication, using pi to crunch the numbers.

#### Force Field

Earth’s magnetic field extends from within the planet to space, and it serves as a protective shield, blocking charged particles from the Sun. Known as the solar wind, these charged particles of helium and hydrogen race from the Sun at hundreds of miles per second. When they reach Earth, they would bombard our planet and orbiting satellites were it not for the magnetic field. Instead, they are deflected, though some particles become trapped by the field and are directed toward the poles, where they interact with the atmosphere, creating auroras. Knowing how Earth’s magnetic field shifts and how particles interact with the field can help keep satellites in safe orbits. In Force Field, students use pi to calculate how much force a hydrogen atom would experience at different points along Earth’s magnetic field.

### Teach It

Pi Day is a fun and engaging way to get students thinking like NASA scientists and engineers. By solving the NASA Pi Day Challenge problems below, reading about other ways NASA uses pi, and doing the related activities, students can see first hand how math is an important part of STEM.

#### Pi Day Resources

Plus, join the conversation using the hashtag #NASAPiDayChallenge on Facebook, Twitter, and Instagram.

#### Related Activities for Students

TAGS: Pi, Pi Day, NASA Pi Day Challenge, Math, Mars, Perseverance, Ingenuity, Mars Helicopter, OSIRIS-REx, Bennu, Asteroid, Auroras, Earth, Magnetic Field, DSOC, Light Waves, DSN, Deep Space Network, Space Communications