by Roger Wiens
Although our Mars laser prospects did not look all that bright, an opportunity arose that almost got me to Mars on a completely different kind of mission—the first sample return from the Red Planet. In February 2002, I picked up a phone call from Laurie Leshin, a young professor at Arizona State University. I knew Laurie from my Caltech days; she had been a graduate student doing research in my building while I was working there. Laurie wanted to talk about Mars.
NASA had announced the previous year that there would be a new competition for Mars missions and was looking for innovative concepts. The program was to be patterned after the Discovery mission program, of which Genesis was a part. The similarities to a decade ago were remarkable. As with the start of the Discovery program, there was a beauty contest for “Mars Scout” concepts. The contest location was again in Southern California. A large number of people presented their favorite ideas for Mars exploration. The schemes ranged from the ridiculous to the eminently feasible. And as in the Discovery contest, there were ten concepts selected for further study.
I had attended the Mars contest, this time on teams for two different missions sporting our LIBS instrument, but neither one ended up winning. I remember spending time at the bar afterward with Laurie and several other friends. Laurie was one of the very few people who, like me, had studied the Mars atmosphere trapped in Martian meteorites for her PhD thesis. She had a strong interest in getting a sample of Mars back to Earth. The concept she had championed was a daring one: send a spacecraft zipping through the Mars atmosphere, flying low enough to collect dust during one of the planet’s frequent global storms, and bring the material back to Earth.
The dust collection could be done with aerogel, the same ghostly material the Stardust mission was using to collect comet particles. Aerogel is a super-low-density, filamentary, sponge-like material so full of nothing that one can easily see through inch-thick pieces as if they were not even there. The Stardust mission used it to slow the impacting comet particles gently enough that they didn’t disintegrate. Nobody knew if such an idea would work for Mars dust, but everyone was fascinated by this new idea. Laurie’s concept ended up taking first place at the contest, and her team went off, money in hand, to see if they could make her fabulous but wild idea work.
Many concepts, especially ideas this interesting, end up proving too risky for NASA to bet its money on. I had not heard much about the Mars dust-collection concept until the phone call from Laurie. Her team was near the end of its one-year feasibility study. Miraculously, it sounded like Laurie’s concept really was workable. The main issues—whether the spacecraft could go low enough in the Mars atmosphere to collect a sufficient amount of dust, and whether the dust collectors could survive the hot atmospheric entry—turned out to be solvable. Making the spacecraft bullet-shaped would allow it to dip down to within 8 miles of the highest mountains on Mars. If the aerogel collectors were recessed behind small inlets along the side of the “bullet,” they could be kept cool enough to survive. This was exciting news.
But there was one area Laurie and her team had not yet tackled. They also wanted to collect a sample of the Martian atmosphere. Bringing such a sample back to Earth would allow ultra-precise measurements to be taken of its isotope ratios. Just as Genesis had measured the ratio of isotopes in the Sun, Laurie’s team wanted to measure the ratio of isotopes in Mars’ atmosphere. If they succeeded, their data would go a long way in revealing details of Mars’ long-term climate history. It would indicate whether volcanism had replenished certain atmospheric gases over timescales from hundreds of millions to thousands of years. The gas sample would also tell us a lot about current trends on Mars, such as whether icecaps were stable or slowly melting away on a scale of recent centuries. These details would not be revealed by other Mars missions in the foreseeable future. So far, however, there was no one on her team to lead this effort. But I couldn’t believe my ears: Laurie was asking me to design and lead the Mars atmospheric sample collection. This would complement the work I had done in graduate school studying the atmospheric gases trapped in meteorites from Mars.
The idea of returning a sample of Mars was not new. Ever since the Apollo program, people had dreamed of going to Mars as the next logical step after the Moon. Even without prospects for a manned mission, scientists longed for the possibility of getting a robotic spacecraft to accomplish this feat. The problem was that a conventional mission to land on the surface, scoop up a sample, and blast off again for Earth was just too complicated and expensive. It had been studied a number of times, but each time it was put off in favor of less expensive missions. Finally, at the turn of the twenty-first century, it appeared that a Mars sample return was actually going to happen.
Starting in the mid-1990s, NASA’s Office of Solar System Exploration made Mars a focus of its missions. Almost every two years, the Earth passes Mars in its orbit, making for an easy transit between the two planets. NASA declared that it would send spacecraft to Mars at every such opportunity in a program that would build in sophistication. In Daniel Goldin’s era of “faster, better, cheaper,” NASA was convinced that a sample-return mission could be carried out at a much lower cost than had been previously estimated. With this lower cost, and with help from international partners, the sample return could fit within the budget.
The purported discovery of microfossils in a Mars meteorite in 1996, while it strengthened the Mars program in general, it specifically made returning a sample the main goal of the program. After the huge success of the Mars Pathfinder, a tiny rover flown in 1996, NASA had made plans to fly a lander in 1998 to explore the polar regions and to fly larger rovers in 2001 and 2003. It would use the Mars close-approach of 2005 to test some of the sample-return hardware, and then mount the main expedition in 2007. One of the rovers would bring the desired samples to a location where they could be launched off the surface. The 2007 mission would carry a small rocket, less than 8 feet tall, which would blast the Mars sample into orbit. There it would rendezvous with a French return spacecraft, which would ferry the precious cargo back to Earth.
As hardware was being built for the intervening missions, the plans and designs were drawn up for each aspect of the penultimate sample-return mission. The longest-range planning was needed for those aspects requiring new technology development, such as the small rocket, called the Mars Ascent Vehicle (MAV), which was to loft the samples into orbit around Mars. How would the samples be collected and inserted into the little rocket? How would the MAV be launched into the correct orbit? And how would the Earth return vehicle and the MAV find each other and transfer the samples? Designs covering each of these details were developed and discussed. The whole endeavor appeared to be taking shape.
Unfortunately, these plans came to a crashing halt in the fall of 1998 with the failure of two separate Mars missions—one orbiter and one lander. NASA was becoming too careless with the way it ran its projects. It was pinching the penny too hard, trying to accomplish too many missions with a very limited budget for the unmanned program, less than a tenth that of the shuttle program. Too many mistakes were being made, and whole missions were being lost. The era of “faster, better, cheaper” was over. NASA began to put more money into each mission, adding redundancy to the hardware and bringing in more managers to oversee various aspects of each project. The Mars Exploration Rovers, Spirit and Opportunity, were conceived during this period, with the idea of flying two in case one failed. But with these more conservative practices, the projected cost of the Mars sample-return program once again ballooned out of reach, back into the range of several billion dollars. There would be no sample return in the near future.
It was in this milieu that the Mars Scout program was announced in early 2001. With the recent cancellation of the sample return as a backdrop, it was no wonder that Laurie’s Mars dust-return mission captured the imagination of the review panel. Laurie had a real knack for public relations. As a young female scientist, she held everyone’s attention with her boundless e
nthusiasm. The NASA culture is keen on public relations, and Laurie rose to the challenge. Her mission concept became known by a catchy acronym: Sample Collection for Investigation of Mars—SCIM—perfectly describing in a single short word (“skim”) what it would do at Mars.
For the next several days after Laurie’s call, all I could think about was how we could collect Mars gas. I couldn’t concentrate on my other work. How could we ensure that we got a big enough sample? Would the spacecraft be too high and the air too thin? The Mars atmosphere was already very thin at ground level—less than 1 percent of the Earth’s. Would the transit be too fast? What about contamination from the hot surfaces of the bullet-shaped aeroshell? It was known that some of the surface material would be vaporized. We didn’t want to collect those contaminants. And how does one collect gas in a vehicle traveling at Mach 29, similar to the space shuttle during reentry?
My immediate thought was to find out if this had been done before. I contacted two astronauts whom I knew. No, I was told, neither of them had ever heard of collecting atmospheric samples from the space shuttle. It sounded like this Mach 29 gas sampling would be something completely novel.
The closest thing to this that had already been done was the collection of upper atmospheric samples from small suborbital sounding-rocket flights. The sounding rockets went up about 60 miles, collected their gas, and parachuted back to Earth. But these suborbital flights only went about one-sixth the velocity planned for SCIM and lasted only a few minutes. With such short durations, these experiments could use simpler equipment than we would have to use. Still, sounding-rocket sampling was the closest thing.
We decided to all meet in San Diego, home of Mark Thiemens, a veteran of sounding-rocket gas collection who was already on the SCIM team. Mark was a dean at the University of California, and he was familiar with NASA’s Moon rock and meteorite collection programs. Within three weeks of getting the call from Laurie, I was on my way to San Diego with our best design engineer.
We arrived on the campus of the University of California at San Diego (UCSD) on a Saturday morning in early spring 2002. The place was nearly deserted except for the few excited SCIM team members, who greeted us with hugs and warm handshakes before settling down to discussions. I was overjoyed to find that the SCIM team consisted of many of the best team members from Stardust and Genesis. In addition, aerodynamic modelers had already been added to help the team understand aspects of the dust collection. These experts would soon give us their calculations showing that gas sampling was entirely feasible on SCIM. Although the gas-collection aspects were way behind the rest of the effort, we were rapidly catching up.
Much to my surprise, detail after detail fell into place. We found hardware components designed for other purposes that could be used in our apparatus. These were rugged, inexpensive, mass-produced items that would need minimal new development or modification in order to be used in our gas-collection device. It was exactly what we needed, as there was obviously no time to develop and test new equipment from the ground up. We ended up with a design that was fail-safe. It provided redundancy in case of the failure of one or two components, and it would provide for the collection of much more gas than we needed—an engineer’s dream.
Our plans called for a gas inlet right at the nose of the bullet-shaped aeroshell—the only place where contamination from ablative material could be completely avoided. This also happened to be where the highest gas pressure was, allowing us to maximize the amount of sample collected. The material around the inlet, which we called the nose plug, would have to be made of the highest-temperature, most inert metal in existence so that it would not melt or react with the hot gas. But this had been researched before in the development of rocket-engine nozzles. So I got in touch with a company down the road from JPL that had carried out research on new high-performance nozzles just a few years earlier. They were intrigued by our application and quickly gave us the advice we needed, as well as demonstration samples to eventually show to the review panel.
From the inlet, our design called for two tubes to lead down to two gas-collection tanks. The dual tubes and tanks would provide redundancy. One side would be completely simple, with just a valve to close off the tank once the collection was completed. On the other side we proposed a fancier apparatus with a miniature, ultra-cold refrigerator to freeze a large amount of gas, concentrating it by a factor of ten. This would also maximize our return, something NASA is always interested in doing. The valves had to be high-conductance, allowing rapid flow, not like laboratory valves, where one can wait minutes for small amounts of gas to equilibrate. Here again we would go to the well-established rocket-engine industry and use propulsion valves. Our contacts at one company in particular shared their valve leak-rate data with us, showing that their product could be used as is, although we could still modify the valve seat if needed.
We had gone from nothing to a viable design with absolutely no development work. In the end, the reviewers found almost no fault with our design. The SCIM proposal was submitted in July 2002 along with twenty-some other hopefuls. Like the Discovery missions, NASA would pick several Scout proposals for final study before selecting the one lucky winner. Now the long waiting period began. We expected to hear the results around the end of the year.
Sure enough, when December rolled around, we got the call that we had been waiting for: SCIM was one of the three finalists. We were elated. To top it off, when we heard the encouragement from the top NASA officials, it seemed like SCIM was the leading contender. This might be the mission to make history with the first round-trip to Mars and back.
All of us on the SCIM project threw ourselves into the work as if there was no tomorrow. We had to go from a rough design to a highly refined plan. The details came together amazingly well for the atmospheric collection portion of the project that I headed up. The excitement over this mission made it easy to recruit people, and experts with just the right talents popped out of the woodwork. Within a couple of weeks, we had computer modelers, gas-flow experimentalists, design engineers, and technicians who had been diverted from their other work to jump on the Mars sample return. More details were added to the early designs and calculations, and models were built and tested. The project went through some of the usual hiccups when it came to refiguring the cost, which seems to inevitably rise for large efforts like space missions. Fortunately, the estimated cost for SCIM stayed within the mandated boundaries.
However, in the middle of our feasibility study, something happened in another part of the space program that was to have a greater impact on SCIM than we realized. Having stayed up late working on a Friday night, I slept in the next morning, February 1, 2003. As I was rousing myself, Carson, my ten-year-old, came bounding up the stairs to my room. “Daddy, Daddy, they said on TV that the space shuttle exploded!” I was wide awake in an instant. I ran downstairs. The TV networks had interrupted their programs to cover the terrible disaster. On its way back from orbit, the space shuttle Columbia, after passing almost directly over our town, had disappeared from radar and radio contact. There were reports of debris falling out of the sky in eastern Texas and near the Louisiana state line. Over the next hours and days, the story unfolded of what must have happened. A dent near the leading edge of the wing, caused during launch, had been unable to withstand the searing heat of reentry. The resulting failure of the shuttle’s wing led to destruction of the vehicle and its passengers.
The only other shuttle disaster had happened seventeen years earlier, when Challenger had exploded shortly after launch. I had watched that fateful launch on TV as a young graduate student, and I had been at Johnson Space Center in Houston when President Reagan and the other dignitaries arrived for the memorial service.
Those of us on SCIM realized that the shuttle Columbia had been traveling at about the same speed and in the same pressure regime to be encountered by the bullet-shaped aeroshell in the Mars atmosphere. We did the best we could to make sure that our mission would not su
ffer the same fate. We restudied various aspects of the aeropass, but nothing was found that could lead to the loss of the vehicle. So we went on with our plans.
The day finally came for our presentation to the review panel. We found ourselves back in the same room where Jim Martin had pounded his fist on the table, and where we had won Genesis the next time around. As the elevator door opened on the floor of the presentation room, the reviewers were greeted with an impressive array of hardware as well as working models of various portions of the mission: a full-size model of the dust-collection mechanism and return capsule, the prototype of the gas-collection system, a life-size plastic model of the gas inlet, and high-temperature metal pieces from the company we had selected to build the inlet.
Our SCIM presentation went flawlessly. We felt that this mission was bound to happen. After congratulatory hugs and handshakes, we all went home to eagerly await the official decision.
NASA had given everyone a good idea of when they expected to make the announcement. A meeting was scheduled to brief NASA’s head of Solar System Exploration, and the announcement was scheduled for after that meeting, on the first Friday in August 2003. Mars was already in the limelight that summer, as the MER missions had just launched successfully a few weeks earlier, taking advantage of a special close approach of the Red Planet. National Public Radio gave a lengthy report in the Friday morning news on the upcoming Mars selection, interviewing the leads of the various teams, including Laurie, who shone as usual. Then, after a silence of several hours, we all received a mysterious e-mail from the Mars program office saying that the selection would not be announced that day. No explanation was given. Whatever had happened, it didn’t seem good.