Ota Lutz is a STEM elementary and secondary education specialist at NASA’s Jet Propulsion Laboratory. When she’s not writing new lessons or teaching, she’s probably cooking something delicious, volunteering in the community, or dreaming about where she will travel next.
In The News
This week, we celebrate the 80th anniversary of the Jet Propulsion Laboratory. JPL was founded long before it became NASA’s premier center for robotic exploration of the solar system – and even before the agency existed. In fact, JPL started as the test-bed for some of the earliest rocketry experiments (thus the name “Jet Propulsion Laboratory”). There were a number of factors that conspired to change JPL’s focus from rocketry to space exploration. The Space Race and the resulting formation of NASA were two major factors. But also, with its growing expertise in launching rockets to new heights, JPL was anxious to take its experiments even farther. So in 1957, when the Soviet Union won the first leg of the Space Race by placing Sputnik, the first artificial satellite, into Earth orbit, JPL was called into action. A few months later, NASA launched the JPL-built Explorer 1, which became the first U.S. satellite.
Soon, the challenge was to land on the moon – and JPL was once again called to the task. Landing on another planetary body had never been accomplished so, understandably, it took a few tries to get things right. JPL’s first attempts at a moon landing with Rangers 1 through 6 all failed for various reasons. Some of the spacecraft flew very near the moon only to miss it by a few hundred kilometers; others met their mark only to have onboard cameras fail. Ranger 7 was the first mission to successfully land on the moon and transmit data, capturing images 1,000-times better than those obtained by ground-based telescopes. It wasn’t a particularly soft landing; rather it was a purposeful crash landing, capturing images along the way. But everyone at JPL was thrilled to have hit their target and returned usable data. These data, and those collected by subsequent missions, made possible NASA’s later human missions to the moon.
At the same time it was launching the Ranger lunar missions, JPL had also set its sights on venturing even farther into space and began launching a series of missions called Mariner to Venus, Mercury and Mars. It wasn’t long before JPL’s specialty became creating robotic spacecraft to go not just to the moon, but also where no one had gone before.
Learn more about the history of JPL and the U.S. space program in the video series below. And explore the interactive timeline.
How They Did It
What’s often not known is that all the early rocket experiments and later missions to the moon and beyond wouldn’t have been possible without a team at JPL known as the human “computers.” Most of these human computers were women who either had degrees in mathematics or were simply very good at mathematics. Over the course of time, these women not only performed hundreds of thousands of mathematical calculations crucial to the U.S. space program, but also eventually became some of the first computer programmers at NASA.
In the early days of space exploration, the best mechanical computers were large (the size of a room) and not particularly powerful. Human capabilities were much more powerful for many tasks, including the rapid calculations needed for trajectory analysis and verification, as well as the graphing of data points on trajectories, which made a spacecraft’s path easy to see.
One of the human computers’ main tasks was computing the planned trajectories, or paths, for a spacecraft based on the vehicle weight, lift capacity of the rocket, and the orbital dynamics of the planets.
When a spacecraft is launched, it begins sending telemetry signals back to Earth. These signals tell engineers information about the spacecraft’s location and health. But this information isn’t perfectly straightforward. It arrives as a bunch of numbers that need to be combined in formulas along with other constantly changing parameters (such as velocity, vehicle mass and the effect of gravity from nearby bodies) in order to reveal the spacecraft’s actual location. Before there were computers (as we know them today) to do these calculations, human computers would feverishly calculate the exact location of the spacecraft as the telemetry came in and compare that to the planned trajectories. Their calculations would reveal whether the spacecraft was on target.
Doing the calculations required to get Explorer 1 into orbit was no small task. Calculating the trajectory for a Ranger crash landing or a Surveyor soft landing on the moon was even more challenging. Once humans were destined to be on board for the Apollo missions, the stakes were even higher. Fortunately, JPL had set the stage developing the techniques – and calculations – necessary to land a robotic spacecraft safely on the moon.
Why It’s Important
Today, JPL continues setting the pace for exploration of the solar system using robots to go where humans hope to venture one day, such as Mars. Though trajectory computations are now done using modern day computers, humans are still required to do trajectory analysis and mission planning. Every mission is different, and with new techniques comes new simulation equations that must be developed and computations that must be performed during actual mission events to ensure success. But even now, nothing is fail-proof. Lots of variables can and do influence spaceflight. Arriving safely on another planet millions of miles away isn’t easy or taken for granted, but when things go right and we achieve a safe landing, it is definitely cause for celebration.
When launching to another planet, we want to take the most efficient route, using the least amount of rocket fuel possible. The early human computers quickly discovered that launching when two planets are closest and using a lot of rocket fuel for the job isn’t the best plan.
Use this fascinating bit of history as a real world, advanced algebra and physics lesson with students in this standards-aligned activity that has grades 9-12 calculate the next launch window to Mars!
- Meet JPL engineer Sue Finley – Finley started at JPL in 1958 as a human computer and still works at the laboratory.
- Women at JPL website
- JPL History
- JPL 80th Anniversary Article
- JPL Timeline
- JPL 80th Anniversary Video Playlist
- JPL 80th Anniversary Printable Calendar
- Mars in a Minute Video Series
- Stomp Rockets Activity
- Basics of Space Flight Tutorial
In the NewsYou didn’t need to check social media, read the newspaper or watch the local news to know that California wildfires were making headlines this summer. Simply looking up at a smoke-filled sky was enough for millions of people in all parts of the state to know there was a fire nearby.
Fueled by high temperatures, low humidity, high winds and five years of vegetation-drying drought, more than 4,800 fires have engulfed 275,000-plus acres across California already this year. And the traditional fire season – the time of year when fires are more likely to start, spread and consume resources – has only just begun.
With wildfires starting earlier in the year and continuing to ignite throughout all seasons, fire season is now a year-round affair not just in California, but also around the world. In fact, the U.S. Forest Service found that fire seasons have grown longer in 25 percent of Earth's vegetation-covered areas.
For NASA's Jet Propulsion Laboratory, which is located in Southern California, the fires cropping up near and far are a constant reminder that its efforts to study wildfires around the world from space, the air and on the ground are as important as ever.
JPL uses a suite of Earth satellites and airborne instruments to help better understand fires and aide in fire management and mitigation. By looking at multiple images and types of data from these instruments, scientists compare what a region looked like before, during and after a fire, as well as how long the area takes to recover.
While the fire is burning, scientists watch its behavior from an aerial perspective to get a big-picture view of the fire itself and the air pollution it is generating in the form of smoke filled with carbon monoxide and carbon dioxide.
Natasha Stavros, a wildfire expert at JPL, joined Zach Tane with the U.S. Forest Service during a Facebook Live event (viewable below) to discuss some of these technologies and how they're used to understand wildfire behavior and improve wildfire recovery.
This animation shows how FireSat would use a network of satellites around the Earth to detect fires faster than ever before.
Additionally, JPL is working with a startup in San Francisco called Quadra Pi R2E to develop FireSat, a global network of satellites designed to detect wildfires and alert firefighting crews faster. When completed in June 2018, the network's array of more than 200 satellites will use infrared sensors to detect fires around the world much faster than is possible today. Working 24 hours a day, the satellites will be able to automatically detect fires as small as 35 to 50 feet wide within 15 minutes of when they begin. And within three minutes of a fire being detected, the FireSat network will notify emergency responders in the area.
Using these technologies, NASA scientists are gaining a broader understanding of fires and their impacts.
Why It's Important
One of the ways we often hear wildfires classified is by how much area they have burned. Though this is certainly of some importance, of greater significance to fire scientists is the severity of the fire. Wildfires are classified as burning at different levels of severity: low, medium, and high. Severity is a function of intensity, or how hot the fire was, and its spread rate, or the speed at which it travels. A high-severity fire is going to do some real damage. (Severity is measured by the damage left after the fire, but can be estimated during a fire event by calculating spread rate and measuring flame height which indicates intensity.)
The impacts of wildfires range from the immediate and tangible to the delayed and less obvious. The potential for loss of life, property and natural areas is one of the first threats that wildfires pose. From a financial standpoint, fires can lead to a downturn in local economies due to loss of tourism and business, high costs related to infrastructure restoration, and impacts to federal and state budgets.
The release of greenhouse gases like carbon dioxide and carbon monoxide is also an important consideration when thinking about the impacts of wildfires. Using NASA satellite data, researchers at the University of California, Berkeley, determined that between 2001 and 2010, California wildfires emitted about 46 million tons of carbon, around five to seven percent of all carbon emitted by the state during that time period.
In California and the western United States, longer fire seasons are linked to changes in spring rains, vapor pressure and snowmelt – all of which have been connected to climate change. Wildfires serve as a climate feedback loop, meaning certain effects of wildfires – the release of CO2 and CO – contribute to climate change, thereby enhancing the factors that contribute to longer and stronger fire seasons.
While this may seem like a grim outlook, it’s worth noting that California forests still act as carbon sinks – natural environments that are capable of absorbing carbon dioxide from the atmosphere. In certain parts of the state, each hectare of redwood forest is able to store the annual greenhouse gas output of 500 Americans.
Studying and managing wildfires is important for maintaining resources, protecting people, properties and ecosystems, and reducing air pollution, which is why JPL, NASA and other agencies are continuing their study of these threats and developing technologies to better understand them.
Have your students try their hands at solving some of the same fire-science problems that NASA scientists do with these two lessons that get students in grades 3 through 12 using NASA data, algebra and geometry to approximate burn areas, fire-spread rate and fire intensity:
- Fired Up Over Math: Studying Wildfires from Space - In this activity, younger students use arithmetic, scale, and math tiles; middle school students employ rate and partial polygon area formulas; and high school students use Google Earth software embedded with recent NASA wildfire data to make inferences about fire severity.
- Pixels on Fire – In this technology-based lesson, students detect mock fires using mobile devices and study NASA data visualizations to determine when actual California wildfires started.
- NASA/JPL FireSat Press Release
- SciJinks: Can Meteorologists Help Fight Wildfires?
- Soberanes Fire: Image Captured by NASA's Terra Spacecraft
- Let's Clear the Air: The Danger of Forest Fire Smoke to Firefighters
Lyle Tavernier was a co-author on this feature.
In the News
History was made recently as the last-existing, flight-qualified external fuel tank for NASA's Space Shuttle Program made a 16.5-mile crawl through the streets of Los Angeles to its new home at the California Science Center. On May 21, 2016, the tank, a nearly 154-foot long, more than 65,000-pound behemoth dubbed ET-94, was towed from the port in Marina del Rey (where it arrived after another epic voyage) to the science center. Eventually, it will be displayed with the space shuttle Endeavour and two solid rocket boosters in launch configuration – looking like it's ready to blast into space.
How They Did It
› Larger image | › Interactive Google Map
Transporting a large object such as the external tank is no small job. Shuttle external tanks were routinely transferred from their manufacture and assembly point at NASA's Michoud Assembly Facility in New Orleans to the Kennedy Space Center in Florida by way of barge. However, the trip to California is a bit more involved.
In April, ET-94 boarded a barge as usual, but this time traveled west, through the Panama Canal to Marina del Rey in Los Angeles. On May 18, the tank arrived, and three days later, was towed through the streets of Los Angeles – streets that were not designed to accommodate a giant rocket fuel tank!
Los Angeles has some experience with this sort of challenge as the space shuttle orbiter Endeavour traveled a similar route from Los Angeles International Airport to the California Science Center in October 2012. Though Endeavour is wider, taller and heavier, ET-94 is longer. Resting on its side, the tank is half the length of a football field. So it presents a different set of navigational challenges – which, coincidentally, make for some great math problems.
As does this bit of external fuel tank history ...
A Slice of History
Most people will recognize the external tank as the giant orange structure that was attached to the shuttle to supply fuel to the shuttle's main engines during liftoff. Space shuttle external tanks carried freezing cold liquid hydrogen and liquid oxygen and were the only non-reusable part of what was called the Space Transportation System, or STS. But the tanks weren't always orange.
During the first shuttle missions, engineers were worried that the sun's ultraviolet radiation might damage the insulating foam, so the tanks were painted white. Because the white latex paint had to cover such a large surface area, it added a whopping 600 pounds to the already hefty tanks, which in their earliest iteration were called standard-weight tanks, or SWTs, and made of aluminum alloy 2219 welded via tungsten arc welding and coated with an inch-thick layer of polyisocyanurate foam. They weighed 77,086 empty and fuel added an extra 1,589,577 pounds!
After the first two STS missions, engineers agreed that the sun's ultraviolet radiation merely caused the insulating foam to change color from its original tan to the familiar dark orange and did not pose a structural risk, so the use of white paint was discontinued. The saved poundage allowed subsequent space shuttle missions to carry an additional 600 pounds of science experiments.
Ever striving to lighten the load of the STS to make room for more science payloads, engineers developed the next iteration of external tanks, called lightweight tanks, or LWTs, using weight-shedding techniques including eliminating portions of stringers (structural stiffeners running the length of the hydrogen tank), using fewer stiffener rings, and modifying major frames in the hydrogen tank. This new tank provided a 6,426-pound reduction in specification weight that further evolved to an actual weight of 65,081 pounds for ET-94.
The final iteration of the external tank, called a super lightweight tank, or SLWT, shed an amazing 18,586 pounds from the very first specifications by using a new aluminum-lithium alloy (Al-Li 2195) and some new welding techniques.
Why It's Important
In 2003, disaster struck space shuttle Columbia during the STS-107 mission. The shuttle was fueled by ET-94's sister tank, ET-93, and as the only remaining lightweight tank in existence, ET-94 was heavily analyzed to examine the role played in the incident by the tank's external insulating foam. Several chunks of foam were removed from the tank during the analysis, necessitating future repair work to return it to its original appearance.
After analysis was complete, the tank resided at the Michoud Assembly Facility, awaiting an opportunity to fly to space that never came, as it could not compete with the svelteness of the new super-lightweight tanks and would require some weighty upgrades to meet new safety standards. Eventually, NASA donated ET-94 to the California Science Center for public display. When finalized, the display will be the only complete stack of STS flight hardware in existence.
Help your students apply their math problem-solving skills to this history-making event. While considering the challenges encountered in moving a giant fuel tank through the streets of Los Angeles, younger students can practice their number sense skills and older students can solve problems using formulas – plus use mapping technology to help ET-94 find its way to the California Science Center!
- Website: NASA Space Shuttle Program
- Feature: History of NASA's External Tank
- Website: NASA Michoud Assembly Facility
- Interactive: The Shuttle
- California Science Center: Endeavour Exhibit
- Feature: JPL-built instruments and experiments that flew on Endeavour
In the News
“Sea level rise” – we hear that phrase, but what does it mean, really? How does it affect us? Do I have to be concerned about it in my lifetime? These are all great questions!
Sea level rise is the increasing of the average global sea level. It doesn’t mean that seas are higher by the same amount everywhere. In fact, in some areas, such as the west coast of the US, sea level has actually dropped slightly … for now. But before we get into that, let’s understand the main contributors to sea level rise:
- Melting mountain glaciers - Glaciers are bodies of ice on land that are constantly moving, carving paths through mountains and rock. As glaciers melt, the runoff flows into the oceans, raising their levels.
- Melting polar ice caps - Think of our north and south polar regions. At both locations, we have ice on land (“land ice”) and ice floating in the ocean (“sea ice”). Melting sea ice, much like ice cubes melting in a drink, does not affect the level of the oceans. Melting land ice, however, contributes to about one third of sea level rise.
- Thermal expansion of water - Consider that our oceans absorb over 90 percent of the heat trapped by greenhouse gasses in Earth’s atmosphere. When water heats up, its molecules become more energetic, causing the water to expand and take up more room, so that accounts for about a third of sea level rise.
Let’s take a closer look at global sea levels. Sea level is not constant everywhere. This is because it can be affected by ocean currents and natural cycles, such as the Pacific Decadal Oscillation, or PDO, a 20- to 30-year cyclical fluctuation in the Pacific Ocean’s surface temperature. Because of the PDO, right now the Eastern Pacific has higher sea levels than usual, while the Western Pacific has lower sea levels than usual. However, the global average of 3 millimeters of sea level rise per year is increasing and the rate that it’s increasing is speeding up. That means that sea level is rising, and it’s rising faster and faster. Take a look at this video for some great visuals and further explanation of how phenomena such as the Gulf Stream affect local sea level heights.
Why It's Important
You may be asking yourself, how do we know sea levels are rising? Well, a couple of ways. First, for the past 23 years we have been using data from several NASA satellites to constantly measure sea surface height around the globe. Data from these ocean altimeters is integrated to refine and calibrate measurements. Additionally, we have tide gauges on Earth to ground-truth (locally validate) our satellite measurements. As for historical data, we use sediment cores -- drillings into Earth that yield the oldest layers on the bottom and the youngest layers on top -- to examine where oceans once reached thousands of years ago.
Locally, folks are making observations – and already seeing the impacts of sea level rise on their communities. Places such as Miami are now experiencing regular flooding in downtown city streets at high tide. The South Pacific island nation of Kiribati saw a 2.6 millimeter rise in sea level between 1992 and 2010. That may not seem like much, but when you consider that the land only sits about 2 meters above sea level, that’s a big deal; some villages have already had to relocate to escape the rising tides. Residents of China's Yellow River delta are swamped by sea level rise of more than 25 centimeters (9 inches) a year. Even NASA is concerned about some of its facilities that are located in low-lying areas.
Besides wiping out dry land, encroaching salt water can pollute our fresh water supplies and damage fresh-water dependent ecosystems. It’s not just fresh water rivers and lakes that are at risk – our aquifers, or natural underground water storage, are at risk of filling with salt water as the ocean encroaches on the land above them.
Clearly, sea level rise is something that is already affecting people and will continue to do so. All three contributors to sea level rise can be attributed to the warming of the Earth system. Warming temperatures cause mountain glaciers and polar ice caps to melt, thereby increasing the volume of water in the oceans. At the same time, our oceans are getting warmer and expanding in volume as a result of this heat (thermal expansion). Since 1880, global sea level has risen 20 centimeters (8 inches); by 2100, it is projected to rise another 30 to 122 centimeters (1 to 4 feet). Watch this video for some illustrations of these facts:
Also check out the Climate Time Machine for Sea Level to see what impact a 1 meter to 6 meter rise in sea level will have on the coastal US and other areas of the world.
If we can control our contributions to the rise in greenhouse gases in Earth’s atmosphere, we can perhaps level out the warming of the Earth system and eventually stabilize our sea levels. In the meantime, we need to be prepared for the impact encroaching seas will have on our coastal communities and water supplies.
To engage your students in analyzing real climate data and drawing their own conclusions, have them try these Next Generation Science Standards and Common Core Mathematics aligned problems.
Have students use these two satellite data graphs to answer the questions below. (To obtain exact data points, place your mouse on the section of the graph you would like to examine.)
- What is the source of the data for each graph?
- Which years are covered by each graph?
- Is one graph a better representation of global sea levels than the other? Why or why not?
- By approximately how many millimeters did sea level rise between:
A) 1910 and 1930?
55 mm – 45 mm = 10 mm (approx.)B) 1930 and 1950?
120 mm – 55 mm = 65 mm (approx.)
- What is the approximate average rate of increase of sea level rise between 1870 and 2000?
Note: students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find the slope of the line of best fit. The correct answer is approximately 1.5 mm per year.
- By how many millimeters did sea level rise between the first measurement obtained in January 1993 and the first measurement obtained in January 2013?
(55.69)-(-16.56) = 72.25 mm
- What is the approximate rate of sea level rise between January 1993 and present?
Note: The answer for this problem is directly stated at the top of the graph, 3.21 mm per year. Students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find slope of the line of best fit.
- By how much did the average global temperature change, and did it increase or decrease between 1910 and 1930? How about between 1930 and 1950?
A) (-0.12)-(-0.46) = 0.34 (increase by 0.34 degrees C)
B) (-0.19)-(-0.12) = -0.07 (decrease by 0.07 degrees C)
- Compare your answers to question number 8 with your answers to question number 4. Can you offer an explanation for the correlation or lack thereof?
Encourage students to critically examine the graph, noting the temperature increase that occurred between 1930 and 1944, preceding the temperature decrease between 1944 and 1950. Students familiar with heat capacity should include this concept in their discussion.
- What is the approximate average global temperature rise per year from the first measurement taken in 1880 to present?
Note: students of various math abilities may approach and solve this problem within their capabilities. The most sophisticated approach is to find slope of the line of best fit. The most conservative answer is 0.007°C per year, the best-fit answer is closer to 0.01°C.
Have students examine this line graph for average global temperature and use it to answer the questions below.
Now, what can you do to be kind to Earth and do your part to control greenhouse gases in our atmosphere?
- First, watch this video to learn more about our changing climate:
- Next, check out this interactive feature to see what others around the globe are doing and add your ideas.
News and Resources
- Earth Right Now Blog
- Article: "Warming Seas and Melting Ice Sheets"
- Article: "The Fingerprints of Sea Level Rise"
- NASA’s Climate Change website
- NASA Earth Missions