Discovery Space: Next Generation

NASA-JPL is a Hotbed of Student Activity

About 300 students at all levels, from high school through graduate school, have been working at NASA's Jet Propulsion Laboratory in Pasadena, California over the summer. And the 25 different programs that the lab offers for students are not just summer work -- about half of them are academic-year positions.

And they span the gamut, from engineering to data analysis to planetary science.

These are amazing opportunities for anyone interested in working in space science of any kind. Here's just a few examples of the work students have been doing at what is certainly the world's premier center for designing and operating planetary exploration missions. (No offense to Ames, which is NASA's other principal planetary research center, but which doesn't actually build and operate as many robotic missions).

-- Yuri Carillo, 18, is a sophomore in electrical engineering Cal Poly who has been working there this summer. She actually put in her first stint working at JPL while she was still in high school. She's worked on a gadget to help a Mars robot change drill bits, and on batteries for a future rover. "Before I came I thought it was going to be very serious and uptight, and then I realized it's more like a college campus," she says.

-- Brandon Jones, at 28, is a bit farther along -- he's a PhD student in aerospace engineering at the University of Colorado who has been working on satellite navigation systems, tracking the positions of the GPS satellites that are used to track everything else. He spent a previous summer working at Johnson Space Center in Houston, so he's really racking up his mileage at NASA.

-- It's not just hard-core technology types who can find a niche at JPL. Take Erin Edkins: She's a 28-year old student who spent time as a personal fitness trainer and a restaurant manager before deciding to go back to school in planetary science at  UC Santa Barbara. Now a senior there, she's putting in her second summer at JPL. She works on planetary atmospheres and is analyzing the swirling storm systems on Jupiter.

As part of that job, she enjoys being often the first person to see new planetary images that arrive from a distant planet. Her advice to other students is to just go ahead and apply for a JPL internship, as she did.

"Go for it," she says. "Definitely the worst thing that could happen is you could contact someone to work with at JPL and they say no. Then you're in the same position you started in."

You can read up on JPL's student opportunities on their web site. There's something for just about anybody who's interested in doing space-related work. Go ahead, give it a try!

photos: top, Yuri Carillo. bottom, Erin Edkins. photos courtesy of NASA/JPL.

To My Martian Readers

Today's post is a special message to my Martian readers.

No, you probably don't know who you are. But I'm willing to bet that at least one of you, reading this blog right now, will end up being among the first humans to spend time on the surface of Mars -- in other words, you are going to be one of the first Martians. At least, unless you want to count the microbes that I suspect are probably already living there. But I'll come back to that.

Current plans call for US astronauts to return to the moon about a decade from now -- about 50 years after the first human landings there, and about 45 years from the last time human feet walked there. China hopes to send its first astronauts (they call them "Taikonauts") to the moon somewhere around the same time. The European Space Agency, Japan, and others have talked about going there too.

And then, after people gain a bit more experience in staying alive a very long way from home, Mars is clearly the next destination people will be hankering for. In fact, some of us have had that hankering for a long time now.

So, maybe about 20 years from now -- maybe sooner, if people really start trying, maybe later if there are some setbacks -- the first humans will arrive on Mars. They'll probably stay for a few months, maybe even a year or two. And then there will be more. By 30 or 40 years from now, I'd be surprised if there isn't some kind of a permanently inhabited outpost there. No, I'm not talking colonies -- for a long time, it will be more like the research stations in Antarctica, I suspect, although in the longer term Mars has much better prospects than Antarctica, in fact than anyplace else in the solar system, to sustain self-supporting colonies.

So, people who are probably in college right now -- in other words, the people for whom I'm writing this blog -- will be among that first group of astronauts who make the initial landings on Mars, and somebody who is in college right now may well be among the very first permanent settlers there. Maybe it's you!

That's what I hope. And I hope that this blog, over the coming days, months and years, will be a valuable tool to help get you there. I aim to make this a useful resource full of tips about opportunities for doing research, field work and hands-on projects that will help to lay the groundwork for future space exploration -- and that will add the kind of cutting-edge work experiences to your resume that may help to get you into the astronaut corps, off into space, and on to other worlds.

So why do I keep talking about Mars all the time? No, it's not the only interesting place out there. I'm fascinated by the prospects for exploring Jupiter's moon Europa, which has a vast, global frozen-over ocean of liquid water, and quite possibly will turn out to be the first place where we will discover proof of an independently-evolved form of life -- which will be perhaps the most epochal discovery in the history of human science. I'm very interested in Saturn's moon Titan, the only other place in the solar system that presently has a cycle of evaporation and precipitation, with rivers and lakes on its surface (even if they are made of petrochemicals). And I know that landing on, exploring, and harnessing the resources of an asteroid may be the most practical near-term exploration goal for many reasons. But still, there's just noplace like Mars.

In a nutshell, it's the one place where humans stand a chance, perhaps within our lifetimes, of really setting up housekeeping. It has soil that can grow crops, air that could be concentrated and enhanced inside inflatable structures to support people, and abundant supplies of frozen water -- maybe even liquid water not far underground -- that can be harnessed for drinking, and split to make oxygen to breathe and hydrogen for fuel. In short, it's the only place where we stand a realistic shot at establishing something approaching self-sufficiency. It's almost certain to be the first real home-away-from-home for us inhabitants of Earth.

But let's get back to those microbes for a minute. Bugs on Mars are, in a way, one of the most compelling reasons for going there -- a place where we may learn things about the nature and history of life that we couldn't find anywhere else. But, if they exist, they are also the one thing that might seriously slow down our human exploration of the red planet.

I'm pretty sure microbes do live there, and that's a topic I've written about many times, and will continue to offer my thoughts on, including in this space (some examples here, here and here). In a nutshell: The Viking life-detection experiments in 1976 produced a series of results that met the criteria that all the scientists had agreed on as indicating a positive detection. Although many of the scientists on the team doubted that interpretation, and insisted the data were indicating some kind of exotic chemical reaction instead, the guy who actually designed and built the experiment that produced the most dramatic and compelling results, the Labeled Release (LR) test, Dr. Gilbert Levin, is quite convinced that the LR test really did provide strong evidence for the existence of living microbes on Mars right now.

And I think he's very likely right about that.

But it may take some time before it gets proved, one way or the other. There are no life detection tests on Phoenix, which is scraping away there now, or on any upcoming Mars mission in the next few years. But Phoenix does have a shot at completely demolishing the argument that the skeptics on the Viking team made to explain why the LR results shouldn't be seen as evidence for life.

The argument was that a separate instrument on Viking failed to detect any organic molecules. And no organics, no life. Case closed.

Except – recent tests have shown the Viking instrument could actually have missed huge amounts of organic material. And now, for the first time, we have a chance to find out. Maybe within the next few days, Phoenix could start detecting organics in the ice and frozen soil of Mars' polar region. And if it turns out there really are organics there, that throws the Viking results into a whole new light. Maybe we really did discover alien life 32 years ago, and it's just taking a while for people to accept it.

I can hardly wait to see those new results, and of course Levin is watching with great interest and anticipation.

So, why did I say that Martian life might slow down our exploration? Well, if there really are living microbes there now, that will become one of the most important subjects imaginable for biological research. If they turn out to be close relatives, made from regular DNA, as I suspect is the case – rocks have been hurtling back and  forth between the Earth and Mars for billions of years, and it would be sort of surprising if there hadn't been some cross-fertilization – then they may reveal important clues about our own origins. And if they're not related, then they could teach us fundamentally new things about the nature of life, and what is essential and what variations are possible.

So, the last thing we'd want to do is contaminate the whole planet and screw up that research. Any human missions would likely be delayed, or minimized, because it's virtually impossible to design vehicles and spacesuits that wouldn't spread bits of terrestrial biology in just the places where we'd want to be looking for the alien bits. It would slow things down, but it wouldn't stop us. I'm convinced that, in the long run, the human settlement of Mars is absolutely inevitable.

And you, reading this now, may be one of the first people to do it. A member of the first generation of sentient, tool-building, world-changing Martians. I certainly hope so. And I hope I can help in some small ways to get you there, by providing information, tips, and maybe a bit of inspiration.

When you get to Mars, maybe I'll be standing there next to you. I hope so. But if not, I hope you'll remember me and give me an interplanetary call. I'll be waiting.

Good luck to you, my future-Martian readers!

(Photos: College students in the Atacama desert, Chile, one of the most Mars-like places on Earth, doing research with a team of NASA scientists to help develop and interpret life-detection tests for Mars. Photos by me, David L. Chandler, copyright 2006)

A Texas Semester on Mars

The coolest place to be this summer is the polar plains of Mars, where the Phoenix spacecraft is scraping away at a layer of ice and looking for signs of organic chemistry. This is the most exciting thing to happen in planetary science since the amazing Mars rovers-that-will-not-die that landed more than four years ago.

And I practically feel like I've had a chance to be there and be part of it thanks to some wonderfully detailed firsthand accounts (another one here) by some college students who have been lucky enough to get into positions working on the mission.

As I've mentioned, this is the first time a mission to another planet has had its mission control center on a university campus. The University of Arizona, home of Phoenix chief scientist Peter Smith, is the place where the mission is run, and several students from around the country are having the experience of a lifetime working on various science and engineering teams there.

This week, we get to hear from a student from Texas A&M University. She's Keri Bean, a junior meteorology major from Schertz, Texas. Here's what she had to say about her lucky job:

"I've been interested in the space program for only a few years now. My first passion was with the weather. A severe storm passed over my preschool, and I came home that day and said "Mommy, I want to be a meteorologist when I grow up!" My mother patted my head and said "Sure thing, dear" thinking the next day it'd be a nurse, or a firefighter, etc. I never once flinched from this goal.

Space-wise, I've always had the typical Wal-mart telescope, but around 2002 I got a Meade ETX-70. I still was more focused on weather, but I was starting to pay attention more to astronomy. In 2005 I just happened to be in Florida during the week of the return to flight space shuttle launch, STS-114. I was about 7 miles away from the launch, and pulled over there on that side of the highway, I knew that I wanted to be doing that one day.

A year before I started at Texas A&M, I attended an event called Aggieland Saturday. The meteorology professor there noticed my interest in space exploration and told me to talk to a professor in the department, Dr. Mark Lemmon, the co-investigator of the Surface Stereo Imager (SSI). I sent him an e-mail the summer before I started, and I met with him every week since school started in the fall. He had me listen to Spirit & Opportunity planning teleconferences, and I did a small research project with some data from Spirit right before winter break. When I got back, he asked me if I wanted to work on Phoenix over the summer, I quickly agreed. He sent me to the Lunar and Planetary Science Conference (LPSC) over spring break (it proves I'm a nerd that I would give up my spring break to attend a science conference), and while I was overwhelmed at first, it was a great learning experience for me. After that, I helped Dr. Lemmon prepare programs for use on Phoenix, and I arrived at the Science Operations Center (SOC) in Tucson, AZ a week before landing.

My title on Phoenix is SSI IDA, or Surface Stereo Imager instrument downlink analyst. I do a bunch of different jobs. While at the SOC, I operated a huge computer screen in the downlink room, and as the images were coming down, I would put the important ones up on the screen. Things like deliveries to TEGA or WCL, images of the trenches, the first set of microsope images, etc. would be put up on the screen. I also keep track of the time of day the mission success panorama images were taken, and which ones were partial. On landing day, my job was to take the images and put them up on the projector screens so everyone in the downlink room could see them. I was on a flexible time schedule, so my shifts would be anywhere from 5 to 10 hours long, depending on the number of images, how many projects I was doing, and the meetings taking place. Now that I'm back at Texas A&M taking classes, I don't do as much, but I still keep up with the mission and keep track of the panorama.

One of the other interesting tasks I do is maintain the Phoenix Facebook profile. I made one for Spirit & Opportunity many months ago as a joke, and now it seems nearly every NASA satellite, telescope, etc. has a Facebook profile.

Most of the other students are either documentarians, work for the atmospheric science theme group, or work on the SSI as engineers. I think most of the SSI team is comparatively young to the other science or instrument groups, which means we're getting the opportunity of a lifetime to work with these images and on some days, be the first to see these images from Mars. I can't think of a more awesome job.

One of the greatest aspects of this job, in my opinion, is simply meeting the scientists and engineers. I was so used to seeing these guys on documentaries or reading their papers that it was a bit of shock to not just meet them, but get to be on a first name basis or have them depend on your work that day.

I honestly still can't really believe I'm doing this job. If someone would have told me at this time last year what I'd be doing this summer, I would've laughed and told you to stop teasing me. It's a dream come true to be involved in such a historic mission. Back in the day, I always wanted to be Dr. Greg Forbes on the Weather Channel because he was the expert on everything, but now I can't imagine doing anything else. When I met NASA administrator Mike Griffin at the LPSC, I told him I was working on the rovers and soon Phoenix, but my eventual goal was to study the Martian atmosphere from the surface of Mars myself. He smiled and said he'd have to see what he could do about that. So here's to hoping!

I watched the landing at the SOC with the atmospheric science team. When they announced touchdown, I leaped out of my chair and one of my friends hugged me hard enough to lift me up off the ground. I ran around the room hugging all the friends I'd made in just my first week there. I met my professor's family and ate quickly at the banquet. The celebration was over quickly because my shift started about an hour after landing.

My family back in Texas and many friends watched the landing and first downlink footage. I was really visible during downlink, because when the camera turned on in the SOC, I was right below it, working on getting the images up on the projector screens. My mom said that her head and her heart knew that was me on NASA TV, but she still simply couldn't believe it. My friends think it's pretty cool that I'm so young and have been given this great opportunity. While I was in Tucson, a friend of mine met astronaut Sunita Williams (I'm a big fan of hers) and when my friend told Sunita that I'd be there if it weren't for me working on Phoenix, Sunita thought it was quite awesome that someone so young was working the mission. It's cool to know I have a fan in the astronaut corps!"

(Photos. Top, Clayton Chu and and Keri Bean in the PIT with the test model of Phoenix. middle right: Keri Bean working. Middle left:  Bean operating the computer screen at the SOC with scientists around. Professor Mark Lemmon is behind her, second from right. Bottom: Engineer Rob Manning and Bean in the PIT. Photos courtsey of Keri Bean)

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Another Semester on Mars

The most exciting thing going on this summer in the planetary sciences is the ongoing mission of the Phoenix Mars lander. It's been scraping and baking the sheets of ice just under the soil there for a month and a half, and is about to begin baking another batch. This might be the one that reveals whether there are organic molecules in the Mars soil, which would be a very exciting new result.

As I've mentioned before, Phoenix is bringing not only a bonanza of data for our understanding of the Martian environment, but in chances for college students to be involved right on the front lines of the greatest space mission going. Because Phoenix is the first planetary mission to be controlled from a college campus, the opportunities for hands-on involvement by undergraduate and graduate students has never been greater.

I've highlighted some of those student experiences before. Here is another look from the inside at what it's like to be virtually sitting on the surface of Mars this year, digging and scraping into its hidden secrets. There are also some good lessons in these accounts about how students have managed to work their way into positions that space scientists used to only dream of. Many thanks to those of you who have written in about your experiences. And if you're reading this and you've been working on Phoenix or any other space or astronomy first-hand project this summer, please write to me about it. Or you can post comments below.

Before, we heard from students at Washington University of St. Louis, thanks to the very central involvement of Ray Arvidsen, a savvy veteran of many planetary missions. This time, it's an aerospace engineering student right at University of Arizona, Clayton Chu, who is spending this summer working as a Surface Stereo Imager Downlink Engineer.

Here's what Clayton had to say about the job:

"This is (hopefully not) a once-in-a-lifetime experience for me! It has always been my dream to work for NASA since I was a child, so to be actually doing it is just astounding to me. I pretty much love space and engineering, so any combination of two will get me excited.

"I am originally from Gilbert, Arizona. I have always been interested in the space program since I could remember, and one of the main reasons I went to the UA in the first place was because of the Phoenix mission. It was basically pure luck that I became a part of the mission.

"Last summer, I was sent an application from the UA/NASA Space Grant Consortium, a program where undergraduates are granted research internships with various science and engineering labs or companies. I applied and got in, but I did not choose where I could be placed. It was only luck that I was chosen to work for the Mars Lander. I began my internship with the mission last September; in April, I was hired full-time for surface operations. If we get funding for an extended mission, I will be a part of it until about November or December.

"I am an Instrument Downlink Engineer (IDE) for the Stereo Surface Imager (SSI), the primary camera operating on Mars. I am just as important a role as any other IDE for other instruments. I help maintain the health and safety of the instrument; analyze and interpret the data and images that the lander has sent back to Earth; and help investigate anomalies or do other tasks related to the SSI. Some things we look for include if our instrument actually took all the images we told it to take, the  temperatures of the different motors, and what images we received yet were partial.

"When I am off-shift, I am usually writing data analysis programs to assist in interpreting the downlink. The information about our instrument is contained in giant documents sent by the lander that contain info about all instruments, so it gets very difficult to review and determine in a timely manner our health and if all the images were wanted were actually executed. The analysis process used to take a few hours; now it takes 15 minutes on a nominal day. If everything ran smoothly, we can focus on analyzing our images and not worry about our instrument; if there were anomalies or other problems, the tools give us organized-enough information that we can quickly find issues. My tools have been used several times in both operations simulations and surface operations to detect anomalous results in the data.

"I am a full-time employee, so I am officially working  40 (but more like 50-60) hours a week. The IDE shift is 8.5 hours long, and it's pretty intense.

"There are two other undergraduates working with me on the SSI; one goes to Texas A&M, the other is a senior here at the UA. She has been my partner throughout both the Space Grant internship and now. The SSI team also has two graduate students and two just-graduated engineers. So the SSI is for the most part student-run, in a sense. "Other undergraduates work in education/public outreach or systems engineering and support."

Clayton even got to take part during the anxiety-filled landing on Mars, close enough to be part of the collective excitement. I was lucky enough to be at JPL for the last three successful Mars landings, so I was very sad to miss this one. Here's what Clayton had to say about being there:

"I was on-shift for landing day, so of course I watched the landing live! It was quite the experience as well; very emotional and exciting. I was shaking uncontrollably from the shock and awe of it all. A lot of us just got together and yelled for a good few minutes. Others were shaking hands, and some were crying. Our lead engineer for the day didn't do any of that, and just booked it straight to the SSI office to prepare for the incoming images.

"This job has definitely opened doors and allowed me to make connections to JPL and NASA. I thought it just a dream previously to be a mission manager or someone of importance working on a NASA mission; now I can see that with some work, it's entirely possible. One of the mission managers for Phoenix was actually a UA graduate, and even participated in the NASA Space Grant internship (after being rejected twice!), so it's very encouraging.

"My family are friends are extremely impressed and proud of me, of course. My parents can't stop talking about how cool it is that their son works for NASA; my friends believe I'm their ticket into flying into space. It's a great feeling."

Thanks Clayton, for sharing the experience with us. I will have another firsthand account from the Phoenix frontlines next week. Keep tuned to this space. And let's hear from some more of you!

(photos: top, NASA/JPL/UAZ; bottom, NASA)

First Proof of a Watery Moon

A team of scientists from Brown University in Rhode Island, including a graduate student there, have just published the first evidence that proves the existence of some water in the moon's composition. That could be very good news for the prospects for eventual permanent human bases there.
There has long been speculation that some deposits of water ice might exist on the moon, hidden in deep craters near its poles -- the only places that never get bathed in sunlight as the moon rotates, and therefore the only place where ice could survive on the surface without melting away (or, technically, subliming away -- that is, turning directly into vapor) over the eons. And there has been some tantalizing evidence, especially readings from the Clementine lunar mission some years ago, which indicated a source of hydrogen -- presumably in ice -- near the south pole. But it's hard to detect for the same reason that may have allowed ice to survive there -- the fact that it would be deeply hidden in craters near the poles, a region invisible from Earth or even from any spacecraft whose path stays within the ecliptic -- the plane of all the planets' orbits.
The new evidence doesn't tell us anything about what's near the poles, or even what is anywhere on the lunar surface. But it does tell us that the moon had water among its constituents when it was born about four billion years ago -- the result of a collision that tore off most of Earth's crust and flung it into space, where much of it clumped together to become the moon.
The new evidence comes from a decades-old source -- a treasure-trove of scientific information whose secrets have barely begun to be extracted: The rocks collected on the moon by the Apollo astronauts, and stored in carefully sealed and guarded vaults at Johnson Space Center in Houston.
Alberto Saal, a professor at Brown, working with fellow professors Reid Cooper and Malcolm Rutherford as well as graduate student Mauro Lo Coscio, did the analysis of some of these rock samples, with help from scientists at Case Western Reserve and the Carnegie Institution.
What they found was that volcanic glasses, formed when lava erupted onto the moon's surface 3 billion years ago, contained traces of water. They used a sophisticated lab technique called secondary mass ion spectrometry, which can detect incredibly minute quantities of elements in the rock. They could have detected as little as five parts per million of water, but were very surprised to find much more -- up to 46 ppm. No previous analysis of any of the Apollo samples had been sensitive enough to detect the water. The new research was published this week in Nature.
By calculating how much of the water content must have been lost into space during the volcanic eruptions -- about 95 percent -- the researchers concluded that the moon originally contained about as much water as the Earth did. And that makes it much more likely that there is indeed some water left there, frozen in those polar craters.
That's good news indeed for would-be moon settlers. Ice could be mined as a local source of drinking water, as well as split into oxygen for breathing, and hydrogen as fuel for rockets and rovers. Every ton of material that has to be brought up from Earth adds hugely to the cost of doing anything useful on the moon, so if there are local sources of basic essential materials that opens up enormous new possibilities for long-term work there. It's not exactly living off the land, but it's a step in that direction.
But that still doesn't prove that there's ice on the surface in quantities that could be useful. The final answers to that question could come later this year, when NASA's Lunar Reconnaissance Orbiter will start circling the moon to make a detailed study. Then, finally, we may have proof that the moon is indeed equipped with a potential highway service station -- a source for a refreshing drink, a breath of fresh air, and a fillup for your rocket's gas tank. Come on down!

Summer Semester on Mars

The Phoenix lander on the icy northern plans of Mars, as I mentioned before, is the first planetary mission ever to be controlled from a university campus instead of from a space-agency center. Mission control for Phoenix is located on the University of Arizona campus in Tucson, but it turns out that's not the only campus whose students are getting to play significant roles in the mission.
One of the others is Washington University in St. Louis, where Prof. Ray Arvidson, head of the Earth and Planetary Sciences department there and who heads some of the Phoenix science teams, has managed to get some of his undergraduate students to play important roles in the mission.
Arvidson and his students led the selection of the landing site for Phoenix, and are now working with the robotic arm to gather soil and water-ice samples, taking images with the robotic arm camera and interpreting and archiving the data.

One of those students, Kirsten Siebach, just finished her freshman year, and last year already had a chance to work with Arvidson on the Mars rover mission. This is what Kirsten had to say about her work on the Phoenix:

"This experience has been amazing for me. I watched the landing with the Science team at the University of Arizona Science Operations Center, and it was very suspenseful and so exciting when it landed safely. I didn't realize how personally interested I would be in this mission until the landing, but since that first day, I have been more interested and involved in every success and setback for Phoenix than I ever expected.

"Professor Arvidson invited me to join him working on Phoenix in the spring when I was deciding where I would work this summer, and I began working on the project during the last month of school, then came out to Tucson a few days before landing and trained for about two weeks before I started working as a documentarian.

"About half of the time I am at work, I have an official role as a Strategic Documentarian. As strategic doc, I keep spreadsheets that track the major activities we have done and will do each sol (Mars day), track completion of mission objectives, and track the names of surfaces in the workspace as they change because of our digging and sampling activities. I also take notes during the strategic meetings and help make sure our strategic plans make sense with our objectives and requirements. When I have time, I work with the Geology theme group on interpreting and analyzing the data we get back from Phoenix. I generally focus on analyzing the properties of the Martian soil like the cohesion and the angle of internal friction from pictures and calculations of forces required for the digging movements of the robotic arm, but I also help out with other analyses.

"I have not declared my major yet, but will most likely major in Earth and Planetary Science. My friends and family have been supportive, and although its hard to be away all summer and working on Mars time, I have been able to keep in touch with them on email and on the phone, and I got to take a short trip home this past week."

What a great way to spend the summer! Congratulations to Kirsten and her fellow students working on the mission. I'm green with envy about their work on the red planet!

(Photos: top, Phoenix lander with its digging scoop, courtesy of NASA/JPL-Caltech/University of Arizona; middle, Kirsten Siebach; Bottom, three of the WUSTL students working on the mission, with Prof. Ray Arvidson at right. Photo courtesy of WUSTL.) 

The Solar System's Greatest Hits

The biggest wallop ever suffered by any planet during the violent, turbulent early days of the solar system was when something as big as Mars slammed into the Earth with such force that the entire crust melted and splattered off into space. Some of it fell back, and much of the rest globbed together and became the moon. That's something scientists only managed to figure out after analyzing the rocks brought back from the moon by the Apollo astronauts.

The second biggest hit, it seems, was one suffered by Mars, when it got clobbered by something bigger than Pluto. That idea, which has been kicking around since the mid-80s, was not taken very seriously until this week, but now suddenly gets catapulted into being the likeliest explanation for the strange lopsided surface of the red planet.

The new evidence for a colossal impact that left a deep gouge on Mars that's bigger than Eurasia  came out in a trio of papers published this week in the journal Nature. One of the papers used recent spacecraft data to reconstruct the outline of the giant basin on Mars -- the largest impact remnant ever seen anywhere. The other two papers used computer modelling to figure out exactly how big the impacting body must have been, and how fast and at what angle it struck Mars.

These are major, significant papers that apparently solve one of the biggest remaining mysteries about our planetary system, the riddle of why Mars has two such radically different hemispheres. These papers, though they will undoubtedly be debated for a few years as is the norm for any significant shift in scientific understanding, will likely stand as among the most important advances in planetary astronomy in recent decades. (See these stories in the New York Times, Christian Science Monitor, Discovery Channel  and National Geographic, for example)

One of those papers, an analysis of the size and direction of arrival of the impacting body, was done by a group at Caltech. And the lead author of the paper, Margarita Marinova, is a graduate student there. Kudos to Marinova for an important and groundbreaking piece of research.

Marinova, a graduate student in Caltech's Division of Geological and Planetary Sciences, found that the impactor must have been between 1,600 and 2,700 km. across, producing a 100 billion gigaton blast. "This size range of impacts only occurred early in solar system history," Marinova says. It all happened about 4 billion years ago, around the same time as the moon-forming crash. Those early days of the solar system were very violent times, when the planetesimals from which the planets were built were still in flux and there was a whole lot of crashing going on.

Sometimes student work in science is thought of, especially by outsiders, as sort of practice work, a kind of second-class level of research. But most scientists know very well that this example, of truly significant new findings, is actually pretty typical. Much of the cutting-edge work in science, in fact, is the product of student research projects.

It's nice to be reminded of that from time to time, as in this case.

By the way, in that same issue of Nature there's a whole package of articles related to impacts on Earth, timed to the fact that this Monday, the 30th, will be the 100th anniversary of the biggest terrestrial impact known to have been witnessed by people -- the Tunguska blast over Siberia in 1908. Among that collection of articles is one that I wrote -- a sort of oral history of how our understanding of near-Earth asteroids and the danger they pose has evolved over the last few decades. It's accompanied by a very clever cartoon, depicting some of the pioneers in that field (who were the subjects of my interviews). I take no credit for the illustration -- the idea came from my friend and Nature's news and features editor, Oliver Morton, and was quite brilliantly executed by the artist David Parkins.

What Color is the Red Planet?

No, seriously.

It may sound like one of those classic dumb questions, like who's buried in Grant's Tomb or what color was the Old Gray Mare. But it's not.

Determining, and reproducing accurately, the true colors of Mars is a surprisingly complicated  thing to do, and sometimes there are no clear-cut "right" answers. But some students from Florida are helping to get us a little closer.

In fact, there have been arguments about how to get the most accurate color balance on  images of Mars ever since the first color images came back from spacecraft in the '70s. Some of the very first images sent back from the surface, by the Viking landers in '76 -- iconic images that have continued to be reproduced ever since -- had a strongly exaggerated orange shade. They just didn't have time to do much color correction before the first image releases, and some of those versions just keep getting reproduced.

But it's not easy to balance those color images to make them as accurate as possible. And exactly what does that mean, anyway?

Color is a surprisingly subjective phenomenon, and reproducing colors requires a lot of judgement calls. That's why Fuji film has a distinctly different look from Kodak film, for instance. (Remember film?) And why things look different in daylight than under incandescent lights, and different again under fluorescents.

And CCDs and other electronic detectors all have their own, distinct color response curves. Most spacecraft images, like those from the Mars rovers Spirit and Opportunity, and from the newly-landed Phoenix, use a set of filters to provide several different wavelength bands. But those filters, and the inherent responses of the detectors, don't actually match the distinctive color responses of the color-detecting cone cells on the human retina.

So how do they go about reconstructing a set of black and white images taken through filters that don't quite match the human eye into an accurate color image -- something that looks more or less the way it would look to you or me if we were standing there on Mars right now?

Very carefully.

Mars has been known as the "red planet" since antiquity. But most of the images you've seen have probably exaggerated the redness of the surface, partly just because that's what meets everyone's expectations. But the way the imaging team goes about adjusting the colors is by using targets.
Basically, the targets consist of little swatches of color -- the kind of thing you'd check out at the  paint store. If there are swatches of color on the spacecraft, and it uses its camera to take pictures of itself through its color filters, then by twiddling the dials in a digital imaging program, you can make the onboard swatches look as close as possible to the identical ones that were left on Earth.
The Mars rovers had very simple swatches, and they still left a lot of room for arguments over the most accurate colors (see some arguments here). Now, thanks to some Florida students and their professors, the Phoenix craft has got a much better set of color targets.
University of Central Florida Physics and Astronomy Professor Dan Britt and two students there, working with University of Florida chemistry professor Randy Duran and his students, developed the new color targets, using the lessons learned from watching the Mars rover targets over the last four years to help guide their improvements.

In coming weeks, we'll see more and more of the color images that will result from the new calibration targets. (The highest-resolution soil image ever sent back from Mars was just released yesterday -- but not in color.)
“It was amazing to provide students with an opportunity to create something that could make history in space,” Duran said, according to a story in the  UF newspaper. (And to be fair, here's one from the UCF paper)

As they continue work on the calibration of the latest images from Mars over the coming weeks, we'll keep checking in on them to see how it's all working. Watch this space.

photos:NASA/JPL/UF