JPL BLOGS
Inside Views on Outer Space
Hear from scientists, engineers and other experts as they offer a fascinating look at JPL missions, science and history.
Hear from scientists, engineers and other experts as they offer a fascinating look at JPL missions, science and history.
JPL | April 2, 2009
Oceans Up Close - From Space
Not all oceanographers spend their time out on the seas. As a project scientist for the Physical Oceanography Distributed Active Archive Center here at JPL , I study the world's ocean from my computer, using data from a series of NASA satellites that orbit Earth. These data measure everything from how the ocean changes during an El Nino to how such climatic changes affect local regions like California's coast.
This kind of precise data was impossible 100 years ago. In fact, scientific and technological advances over the last century have revolutionized the field of oceanography. Today, we gather data both from instruments in the ocean and from satellites in space. These satellite data measure changes in sea surface topography (the ocean surface has changes in elevation, just like the land), ocean surface winds, sea surface temperature and water pressure at the bottom of the ocean. The satellites view the ocean from 700 to 1,300 kilometers (440 to 800 miles) above Earth. Current advanced technologies allow scientists to combine data from different satellites to view ocean conditions in near-real time, only 6 to 12 hours from when the satellite acquires the data. This information can then be sent to researchers and decision makers for use in improving forecasts for hurricanes to the regional and local impacts of ocean phenomena like El Nino and La Nina.
Examples of satellite data can be seen in these images. The view on the left shows temperatures off the coast of California in September of 1997 (El Nino). On the right, sea surface temperatures from September of 2008 (normal conditions). Notice the warmer temperatures (seen in red) resulting from the 1997-1998 El Nino event. Such temperature changes have direct impacts on local climate and fisheries. These data are leading to a new understanding of how hurricanes get their energy from the ocean. These satellite data also help forecast regional ocean temperatures, which affect local weather.
As technology improves, along with the availability of these data in real time, new opportunities will continue to expand to better understand our planet and its impacts on our lives.
TAGS: EARTH, OCEAN, EL NINIO, TEMPERATURES
JPL | March 9, 2009
Almost There
The Kepler mission, which will look for Earth-like planets, is nearing its scheduled March 6 launch date.
At our flight readiness review on February 4th, our deputy principal investigator, David Koch, took a few minutes to talk about the history of Johannes Kepler, the project's namesake. Koch recapped Kepler's tremendous contributions to the realm of astronomy 400 years ago, and reminded us all why our mission is so appropriately named for that great scientist. He also touched on the more recent history of the mission, reminding us how our science principal investigator, William Borucki, wrote his first paper on the possibility of detecting planets using the transit method back in the '80s, and then in 1992 first proposed the mission that would later become Kepler. While I already knew most of those details, there was something special about hearing them again during that milestone review just one month away from launch. It gave a deeper, richer context to what we were all doing and made me even more excited about seeing this mission succeed. (If you are reading this David, thanks so much for doing that!)
Now here we are, less than a week away from launch. The entire team has been working so hard these last several weeks. The assembly, test and launch operations team has run the final major checkouts on the spacecraft at the Kennedy Space (I don't think it's Spaceflight) Center in Florida, and the spacecraft is now all buttoned up on top of the Delta II launch vehicle.
The operations team has completed the final, full-up operational readiness test to rehearse the launch and early operations period. We've also completed the last pre-launch ground segment integration test and the commissioning operational readiness tests, which together validated the tools and procedures that we will use during that roughly two months of checkout after launch. We're now in the home stretch: signing off the last few test reports, closing out the final action items -- dotting and crossing those proverbial i's and t's.
And so we are nearly ready to go. In just a few days I will head off to Boulder, Colo., where I will join the part of the team located at the mission operations center to support launch and commissioning operations. We're gearing up for an exciting campaign; I can hardly wait for this new phase to begin!
TAGS: SOLAR SYSTEM, KEPLER, EXOPLANETS
JPL | February 24, 2009
Thoughts After Launch
A few hours ago I had the privilege to watch the Orbiting Carbon Observatory launch from Vandenberg Air Force Base. The creativity, effort and dedication of many, many people were sitting on the launch pad. Many of the people who had worked so hard to get the mission to the pad were in attendance with family and friends there to share in the excitement. The weather was perfect. Cold enough to make the stars seems to be just out of reach, still enough to be pleasant to stand outside waiting for the main event. As it got closer, hundreds of voices followed along the magic of the countdown - "10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 - Liftoff!". The rocket cleared the pad - rising on a column of intense white light. At our distance, it seemed to rise forever before the roar finally reached us. In the dark, clear sky we could watch the various stages burn out, fall back and be replaced by the ignition of the next state. Everything seemed to be going perfectly.
We got on the buses to leave the viewing area, excited by what we witnessed and excited by the mission to come. Both feelings did not last long. Soon text messages and phone calls started to disturb the darkened buses. Within a few minutes, it was clear that the launch had not gone as well as we thought. By the time we got off the buses, it looked grim. In the next couple of hours, it became clear that the rocket failed and we never achieved orbit.
Oddly, hearing that the spacecraft hit the ocean near Antarctica made it worse. I had this vision of the system orbiting the Earth - dead and mute - like a modern day Flying Dutchman. Knowing that the hardware I helped design and build had been destroyed on impact made the loss real.
Almost 10 years ago, I was working with a scientist who was also supporting the Mars lander that was lost in 1999. The day after it failed, she told me to always try to enjoy the intellectual challenge of designing a mission and the hardware to make it possible. At the end of the day, that might be all you get. Since then, she has been involved in the incredibly successful Mars Exploration Rovers and the Phoenix lander. She is working to prepare the Mars Science Laboratory for its 2011 launch.
I hope that her past is my prologue. I hope that the next 10 years bring a productive series of missions to advance our understanding of the carbon cycle - much as the recent Mars missions have advanced our understanding of our solar system's history.
TAGS: SOLAR SYSTEM, EARTH, OCO,
JPL | February 20, 2009
Counting Carbon
Imagine if you could scoop exactly one million molecules out of the air in front of you (while being careful not to grab any water vapor). Now, start sorting these molecules into different piles. Start with the two most common molecules and you've sorted 99 percent of your sample -- the nitrogen pile will have about 780,000 molecules, and oxygen pile will have about 210,000 molecules. Working on the third most common molecule, argon, gets you a new pile with about 9,000 molecules. Congratulations, you've sorted 99.9 percent of the molecules into just three piles. The remaining 1,000 molecules are called "trace gases." The most famous and the most common trace gas is carbon dioxide, or CO2. Out of the million you had at the beginning, you'll count about 385 CO2 molecules.
Now, imagine repeating this experiment 12 times per second while flying over Earth at more than 16,000 miles per hour. Each of those counts needs to be accurate enough to note the addition or subtraction of one molecule of CO2 per one million of air. This is the experiment that a group of scientists and engineers at NASA's Jet Propulsion Laboratory conceived almost 10 years ago. We call it the Orbiting Carbon Observatory, and it is now at the launch pad waiting for its ride into space.
The heart of the mission is a very accurate instrument -- called a "spectrometer" -- tuned to sense the presence of CO2. A spectrometer is a type of camera that splits incoming light into hundreds of different colors and then measures the amount of light in each of these colors. In the case of this mission, the spectrometer measures sunlight that has passed through the atmosphere twice: once on the way down to the surface, and then again on the way up to the orbiting spacecraft. When the light passes through air containing CO2, certain colors are absorbed. The spectrometer creates an image with dark bands where the sunlight is partially or completely missing. This image looks similar to a barcode. Encoded in that barcode is the information to infer how many CO2 molecules the sunlight encountered on its way to the spacecraft.
I joined the project in early 2001 as the lead engineer for the spectrometer. In the eight years that have followed, we've gone from an idea to a fully built and tested system sitting on top of a rocket, ready for launch. Along the way, a group of talented people has put in countless hours designing, building, and testing the system. When doing something for the first time, there are always issues that come up -- some of which look insurmountable at the time. It's been a challenge, but the hard work and creativity of our team saw us through all of them.
Now we are waiting for the payoff -- the first data from space. We've done everything we can to be ready. Now, launch awaits ...
TAGS: SOLAR SYSTEM, EARTH, CARBON, OCO, CO2
JPL | February 2, 2009
How We See Dark Matter
Planets, stars, buildings, cars, you and I, we are all made of the same basic stuff - atoms, the building blocks of matter. The late Carl Sagan famously said "we are star stuff," as the heavy elements in our bodies were all forged in supernovas, the explosions of dying stars. In a real scientific sense, we are one with everything we see in the night sky.
We have since learned that everything we see is awash in another kind of matter, a "dark" matter, made of particles yet to be discovered. Dark matter is all around us, but we cannot see it. Some estimate that a billion dark matter particles whiz through your body every second, but you cannot feel them. We now believe that the universe contains five times more dark matter than ordinary matter. While we all may be made of star stuff, we find that the universe is mostly made of something very different.
Why do we believe that dark matter exists? How can we study something that we cannot see or even feel? And how can we unravel the universe's greatest mystery - what is this dark matter?
The idea of dark matter was born at Caltech in 1933. (Just three years later, JPL would be born there as the "rocket boys" began their first launch experiments.) In observations of a nearby cluster of galaxies named the Coma cluster, Fritz Zwicky calculated that the collective mass of the galaxies was not nearly enough to hold them together in their orbits. He postulated that some other form of matter was present but undetected to account for this "missing mass." Later, in the 1970's and '80's, Vera Rubin similarly found that the arms of spiral galaxies should fly off their cores as they are orbiting much too quickly.
Today dark matter is a widely accepted theory, which explains many of our observations. My colleagues and I at JPL are among those working to reveal and map out dark matter structures. Dark matter is invisible. But astronomers can "see" it in a way and you can too, if you know what to look for! For instance, if you have a wineglass on a table and you look through the glass, the images behind it are distorted. So too when we look through a dense clump of dark matter, we see distorted and even multiple images of galaxies more distant. Matter bends space according to Einstein's Theory of General Relativity, and light follows these bends to produce the distorted images. By studying these "lensed" images, we can reconstruct the shape of the lens, or in our case, the amount and distribution of dark matter in our gravitational lens.
Our observations of dark matter in outer space force particle physicists to revise their theories to explain what we see. Hopefully through their efforts, physicists will soon produce dark matter in the lab, catch and identify a small fraction of that which passes through us, and ultimately explain the relationship between dark matter and "star stuff."
TAGS: SOLAR SYSTEM, SUPERNOVAS, DARK MATTER, PARTICLES
JPL | November 5, 2008
Exciting Times for Cassini
It's an exciting time in Cassini-land these days! We are well into the Equinox Mission, an extension to Cassini's mission that includes seven flybys of the Saturnian moon Enceladus, discovered in July 2005 to be geologically active. Prior to the prime mission, we knew that Enceladus was interesting and unique, and thus planned and executed three targeted flybys for the prime mission. With the tremendous discovery of water plumes at the south pole of this small icy moon (which happened on the second targeted flyby), we planned a more in-depth investigation for the Equinox Mission. And we are well into it! Our first Enceladus flyby of the Equinox Mission was in August, and we had two in October.
My job on Cassini is two-fold: I am on the science planning team, helping to plan out the science activities that occur during each icy moon encounter, and I am on the team for the ultraviolet imaging spectrograph instrument, studying ultraviolet data of the surfaces of these icy moons. So it’s really fantastic to be involved in planning each encounter, and then analyzing data to understand the moons.
In order to learn as much as we can about crazy Enceladus (it's so small and icy -- yet it's got these geysers!), we want to let all of the instruments make measurements, and it isn't possible to simultaneously get measurements from all instruments. (That's just the way the spacecraft is built.) We know that the cameras will tell us a lot about the current and historical geology of the surface, the ultraviolet and infrared imagers will tell us about the surface composition, and the long-wavelength infrared instrument will reveal surface temperatures. These four "remote-sensing" instruments can take data simultaneously. But if we want to get the best data from the "in situ" instruments (like the ion and neutral mass spectrometer and cosmic dust analyzer), we need to orient the spacecraft such that it's nearly impossible to get remote sensing data. So we divide up the flybys and allow many instruments the opportunity to get data. The period around the closest approach during the August flyby (called "E4") was allocated to the remote-sensing instruments -- and this resulted in the highest-resolution images of the active "tiger stripes" ever! (See one of these images here: http://photojournal.jpl.nasa.gov/catalog/PIA11113) The closest approach of the next Enceladus flyby - called "E5," on October 9 -- took the spacecraft deeper into the south polar plume than ever before. Here the priority was given to the in situ instruments, which obtained great, high-signal data of the plume, telling us about the composition of both the gaseous and particle components. And the October 31 flyby - called "E6" -- was again dedicated to remote-sensing, for a last look at the south pole before it heads mostly into seasonal darkness.
It’s so fortunate that Cassini has multiple opportunities to execute close encounters of an object as dynamic as Enceladus. The Voyager spacecraft had just one shot as they flew through the Saturn system, but Cassini, as an orbiter, gives us the chance to analyze our data, figure out what we’ve learned, and make thoughtful decisions on what experiments we need to make to follow up on those discoveries.
Things aren’t completely within our control, however! For instance, southern summer in the Saturn system is coming to a close, limiting the amount of sunlight illuminating the fascinating south polar region of Enceladus. But there’s plenty of important science to do in the dark with the in situ instruments, as well as the composite infrared spectrometer and radar, which is great. Who knows — we’ll see what the equinox season (and hopefully the following solstice) has in store for us! We may get some surprises!
TAGS: SATURN, SOLAR SYSTEM, CASSINI, ENCELADUS, MOON
JPL | October 22, 2008
Shakeout for Southern California
For those of us living in southern California, the risk of earthquakes is a constant fact of life. In fact, small earthquakes occur daily, we simply may not notice them. It’s the larger, more damaging earthquakes that are cause for concern. The infamous San Andreas fault twists its way through much of California, posing significant risk to southern and northern California both-- and as many scientists have said, it’s not a question of if, it’s a question of when, a large earthquake will occur.
Even though the risk of earthquakes is always present, I am sure most people are not thinking about this on the way to work, or as they are watching TV at night, or just generally going about their daily lives. Establishing an earthquake preparedness plan probably doesn’t even come to mind, except possibly when there is a major earthquake elsewhere, or a minor earthquake nearby.
We here at JPL are working on ways to extend our ability to forecast earthquakes. We are combining the state of the art in high performance computing resources and modeling software with satellite observations made from space of small scale motion on Earth. This will enhance our understanding of the fundamental earthquake processes. With projects like NASA/JPL’s QuakeSim, which aims to improve our ability to forecast earthquakes, much as we do the weather, we will also be able to help prepare ourselves for the inevitable.
Unfortunately, should a large earthquake catch us unprepared-- and remember, it's not a question of if, it's a question of when-- this could have disastrous consequences. According to FEMA, the annualized loss due to earthquakes is $5.3 billion per year, with 66% ($3.5 billion) concentrated in the state of California alone. A moderate-sized earthquake in the metropolitan Los Angeles region could lead to loss of vital infrastructure-- water via the aqueduct, freeways, possibly even the ports or the airports, rendering us isolated and without resources for not days, but possibly months.
We are told to be prepared in case of an earthquake with 72 hours’ worth of water and food and other necessary emergency provisions. That will certainly see us through the first few days, but if the vital infrastructural resources like our water distribution, sewers, freeways, and other pipelines are taken out, we could be looking at much more than 72 hours without proper services, especially water and power. Are you prepared for such a circumstance?
On November 13, 2008, the United States Geological Survey will lead a disaster preparedness scenario called "The Great Southern California Shakeout." It will be based on a magnitude 7.8 earthquake along the southern San Andreas fault. Shaking from an earthquake of this size is projected to last up to two minutes, and the modeling that they have done has predicted that sediments in the various basins around the Los Angeles area will trap and magnify seismic waves, amplifying ground motions, much like what occurred in the Northridge earthquake. (To learn more about the "Great Shakeout," please visit: www.shakeout.org)
This earthquake scenario will also be the basis for the statewide emergency response exercise, Golden Guardian 2008. These complementary exercises are meant to demonstrate our ability to deal with an earthquake scenario in which there would be 1800 deaths, 50,000 injuries, and $200 billion in damage. An earthquake of this magnitude could produce destruction on the scale of the recent Gulf Coast hurricanes or worse.
One thing to keep in mind, though, is that we need to be proactive, rather than simply reactive. That way, when the inevitable moderate to large earthquake does hit, we will be as ready as we can be to deal with it. Exercises like the ShakeOut certainly help to keep the community more aware of the ever-present risk of earthquakes, but we as individuals also need to take the time to make sure that we are disaster prepared as well. That way we can be not only prepared, but resilient.
TAGS: EARTH, EARTHQUAKE, QUAKESIM, SHAKEOUT
JPL | October 6, 2008
On the Road Again
The Mars Exploration Rovers, Spirit and Opportunity, have been exploring the geology of Mars for nearly five years - well beyond their expected lifetime of three to six months. In that time they have made amazing discoveries, most importantly finding proof that Mars was once a much wetter planet that may have been capable of supporting life. Spirit has been exploring a region around a small mountain range that seems to have once had hot water or steam, the very kind of place life might have originated on Earth. Opportunity has been investigating craters in the plains that provide views deep underground and show evidence of flowing water in the ancient past.
I am a roboticist at JPL, and just one member of the large team of people who work together to enable Spirit and Opportunity to explore. My work focuses on getting robots to do things intelligently, both by developing software for robot autonomy and by operating our two spacecraft on the surface of Mars. Spirit and Opportunity have become like old friends to the operations team. Every day we are anxious to hear the latest news and see the snapshots taken from the new places they are visiting. Working with the rovers never gets routine as each new location brings new circumstances and new problems to solve.
The challenges of operating Spirit and Opportunity have continued to grow and change as they age, and we have had to develop new ways of driving and operating the robotic arm as capabilities decrease. We are discovering how to operate these rovers in ways for which they were never designed. The discovery process requires a lot of imagination and a lot of practice, both on Earth with our engineering rover and on Mars. It’s this kind of completely new and unanticipated problem that is the most fun for engineers like myself to solve.
Both rovers are now starting to show their old age of 4¾ years (that’s at least 300 in rover-years!), and some parts do not function quite as well as they used to. Spirit has to drive more slowly and constantly monitor her progress to make sure she is staying on the right path to compensate for a broken right front wheel that tends to dig into the soil. Opportunity has limited reach with her instrument arm due to a failed shoulder joint, and has to approach science targets in a very precise way. Despite these limitations, both rovers are now about to embark on difficult journeys which will require them to set new milestones and we will need to learn new ways of driving yet again.
After surviving a very difficult winter, Spirit is soon going to be heading south toward some interesting geological features: a hill called von Braun and a depression called Goddard. Scientists hope investigating these unique features will provide insights into the Martian past. They are looking for additional evidence of hot springs or steam vents that have been hinted at by other observations in this region. Based on comparisons to similar locations on Earth (like deep sea vents), this could be an ideal place for life. Reaching these exciting features requires a long drive through sandy terrain in a very short period of time before next winter arrives. This will mean pushing Spirit to new levels of performance.
Opportunity is finishing up her observations of the 800-meter Victoria crater and then will begin a 12-kilometer, two-year odyssey toward a huge crater (about 22 kilometers across) to the southeast. As this means more than doubling the total distance Opportunity has driven in her lifetime, we are excited to be developing new methods to make record distance drives safely. This will require relying on the rover’s onboard autonomy to keep her safe more than ever before as we drive each day well past what we can see.
Spirit and Opportunity’s story of continued exploration - boldly striking out after one new goal after another, far beyond their design lifetimes - is a genuinely inspiring one. It’s as if Magellan circumnavigated the Earth, then paused and said, ‘You know, that’s not good enough. Let’s go to the moon, too.’
TAGS: MARS, ROBOTICS, ROVERS, SPIRIT, OPPORTUNITY, CURIOSITY
JPL | September 29, 2008
Big Wheeling for Extreme Science - The Mars Science Laboratory
Mars Science Laboratory is a mission to create and send to Mars the largest, most capable and most exciting rover that has been sent to another planet to date. It will be a remote robotic scientist that will help us investigate our most Earth-like neighbor in the solar system. It is literally a mobile laboratory -- the size of a car, with a wide array of science instruments that will help us determine whether Mars has the capability to support life, both in the past and in the present.
Most of my work at JPL has been in the area of research robotics, small projects with very focused goals, such as the Urban Robot project, the Spiderbot, and many others. These robots were created using a small team of engineers who each covered a wide area of responsibility such as mechanical, electrical, and different areas of computer science for perception and navigation.
At times, to get one of these robots working right we would “hack” together a solution, and get it implemented in a very short amount of time! By throwing our energy and ideas into each project, we could push the cutting edge of different technologies and robotic capability that could then be used by future projects and researchers.
In contrast I’m now working on the motor control system of the Mars Science Laboratory mission, which as opposed to research is a “flight project” (it’s going to fly!). This is quite a different experience than the research area - the mission is kind of like taking the goal or purpose of the robot, breaking it down into a million pieces, and putting every piece under a microscope to make sure everything will work absolutely perfectly. Instead of 10 or fewer engineers each working on the different subsystems of the robot, we have hundreds of engineers and scientists who are planning, designing, developing, manufacturing, testing and in general creating a very complicated remote-sensing system.
Sending a robot of any kind to another planet is a completely different story than running any such thing on Earth. For one thing, the robot must operate within very extreme temperatures and handle harsh exposure to the sun’s rays. Future robots may have to deal with steep or challenging terrain, or even a lack of a solid surface such as on Titan, Saturn’s largest moon. And throughout all this, the robot has to work perfectly and stay in communication with Earth. There is no control-alt-delete button to handle software crashes, and no technician around who can run out to push the big red reset button. In other words, if you’re going to run a robot on another planet, it has to land unharmed, work the first time, and run correctly every time you command it to do something, so that you’re guaranteed to get back the vital science data you’re after.
TAGS: MARS, MARS ROVERS, CURIOSITY, ROBOT
JPL | September 23, 2008
From the Edge
Winds of charged particles race outwards from the sun at 300,000 miles per hour. They are so faint that, here on the outer edge of the solar system, they would be undetectable if it were not for the very sensitive instruments carried by spacecraft.
From this distant, dark void, the sun is 100 times farther away than it is from Earth. Even so, our star is a million times brighter than Sirius, the brightest star seen from Earth. All around is a near-perfect vacuum, with only the most capable of instruments able to detect an ambient magnetic field that is 200,000 times weaker than the field back on Earth. To top off the loneliness factor, nothing from Earth has ever journeyed this far from home.
This remote zone is the domain now for Voyager 1 and 2. After 31 years of exploration, the twin spacecraft are the elder statesmen of space exploration, robotic envoys in the most distant reaches of our solar system. Voyager 1 is now 107 times farther from the sun than Earth is; Voyager 2 is 87 times farther. It takes about 15 hours for a signal leaving Earth to reach Voyager 1. (By contrast, it takes a little more than 20 minutes for a signal to go to Mars, even when the red planet is farthest from Earth.)
The twin spacecraft do not rest on the laurels of their discoveries at Jupiter, Saturn, Uranus and Neptune - the planets they flew by between 1977 and 1989. In fact, their findings at our solar system’s edge are changing scientists’ theories about what happens “way out there” and how interstellar space affects our solar system.
The Voyagers have shown that the heliosphere - the sun’s protective bubble surrounding our solar system — is not smooth and symmetric, as was originally thought. The robotic team discovered that this bubble is being pushed in and deformed by the pressure from the interstellar magnetic field outside our solar system. Another surprise came when the spacecraft passed an important milestone near the edge of the solar system, called the termination shock. The energy released from the sudden slowing of the sun’s supersonic wind had an unexpected outcome - it was absorbed not by the wind itself, but by ionized atoms that had come from outside our solar system. And inevitably, as theories are shattered in the wind, more questions arise. There are cosmic rays we know come from this distant region, for example, but their origin is yet to be found and explained.
After all this time, Voyager’s discoveries continue to do what they have always done - take us to new places we have never been, and shed light on the how our solar system interacts and interconnects with the surrounding regions of the Milky Way.
Both Voyagers have enough power to run until 2025. Voyager 1 will probably cross into interstellar space by about 2015. At that moment, Voyager 1 will become Earth’s first interstellar spacecraft, leaving the sun behind as it enters the interstellar wind produced by the supernova explosions of other stars.
Until their final transmissions — hopefully many years in the future — the Voyagers still have a long way to go and lots to tell us.
TAGS: UNIVERS, SOLAR SYSTEM, HELIPSPHERE, VOYAGER
