by Roger Wiens
While in France we solved another problem: what to call the instrument. We had been batting around silly acronyms for several years without coming up with anything that really worked. Having decided to add an imager that would provide visual contexts for our chemical measurements, one of our team members suggested we split the name and call it “ChemCam,” short for “Chemistry and Camera Instruments.” The MERs had a set of imagers called “Pancam.” We thought “ChemCam” would sound faintly familiar and yet innovative to the people who might review our proposal. The name stuck.
On the French side, the prototype laser and telescope were being tested, while on our side, the spectrometer passed its tests, and in our laser lab Dave was putting out important analytical results and making impressive holes in rocks zapped by the laser. The proposal was coming together. Our international team could work around the clock, given the eight hours of time difference between Los Alamos and France.
The last day of proofreading finally came and went, and we sent the ChemCam proposal to the printers, breathing a sigh of relief. We had given it our best shot, and no one could be ashamed of our attempt. But we knew that, competing against instruments that had already flown, our chances were extremely slim. In the end, nearly fifty proposals were submitted. Only a handful would be chosen to fly to Mars.
chapter
twelve
TICKET TO MARS
I WAS READY TO CLEAN UP MY OFFICE, WHICH HAD BECOME A real mess during the long hours we spent writing the proposal, and to turn my attention to other things. But then came a bombshell. On July 15, 2004, the day the MSL proposals arrived in Washington, there was an accident in our laser lab. A student intern, who was working at the lab for the summer, had accidently glanced into a laser beam without wearing protective goggles. The result was permanent eye damage.
There had been a series of security incidents involving classified information in another part of the lab complex in the months leading up to this, and the laser accident was the last straw. The laboratory director announced the suspension of all work at the whole complex until investigations could be completed and retraining could be assigned. The stand-down affected all ten thousand workers. All were to report to work, but we could only clean our offices and reread our safety training materials. The suspension happened on a Friday—the first day I took off from work in many months. I realized that if this whole series of events had happened just a few days earlier, we could not have submitted our proposal.
The picture suddenly looked very bleak for getting ChemCam to another planet. Would our laser lab end up being closed for good? Perhaps our administrators would decide not to support our proposal. I approached my supervisor to ask what we could do to reassure NASA that we could still carry out the work. He suggested that I should withdraw the proposal—this kind of work was too dangerous! That mindset was pervasive following the security and safety incidents. Instead of taking his advice, however, I consulted with others at the lab. Ultimately, we put a letter on a public website explaining that we didn’t believe the accident would jeopardize our proposal. And we sat and waited.
I tried not to think about all the competition among the fifty proposals: first of all, there was the experienced team that had courted us for a time. They had likely proposed more advanced cameras along with another thermal emission spectrometer similar to ones on the MERs. These spectrometers observed the Mars surface in the wavelength range from 5 to 30 microns, yielding information on illumination, mineral, and thermal properties. That team alone was likely blowing us out of the water in the reviews, perhaps by adding new innovations. And if the referees preferred shorter wavelength infrared sensors, they would pick Diana Blaney’s spectrometer, to be built by JPL. Or, if NASA was short on money, they could pick the infrared spectrometer being proposed by a completely French team. To be built with Euros, it wouldn’t cost NASA anything. These infrared devices could spot different minerals based on their characteristic absorption and emission caused by different vibrations of the crystal structures—assuming the rocks weren’t covered by dust, which was ChemCam’s ace in the hole.
There were other ways to observe these mineral phases. Raman spectroscopy was based on the same minute crystal vibrations that infrared and thermal spectrometers detected, but rather than depending upon sunlight and the surrounding temperature to excite the crystals, this technique, discovered in India in the 1920s, used a laser.* The beam excited crystals in the rocks, causing some of the returning light to be modified, either to higher or lower wavelengths, by the energy of the crystal vibrations. A Raman spectrometer had been selected to go on the arm of the MERs, but the instrument had been canceled before it was even started. Dr. Alian Wang of Washington University in St. Louis, its champion, was still a part of the MER team, and she was absolutely determined to get her instrument on board the next flight to Mars. She had lots of experience working with MER, and having partnered with JPL, she had a strong NASA ally.
Then there were our collaborators on another project, from the University of Hawaii. Shiv Sharma, one of the world’s leading experts at Raman spectroscopy, had ingeniously demonstrated that this technique could work at a long distance, just like LIBS. In fact, we were working with him and his assistant to develop a combined instrument to do both LIBS and Raman spectroscopy, but that was a step too far for this proposal. We were both going it on our own in this round. We hoped we could partner with them on a future mission, but we didn’t want to be beaten by them now. In addition to the Hawaiians, there were rumors of at least one other Raman spectrometer proposal.
Those were a few of the competitors we knew about, but it was clear that they were only the tip of the iceberg. The mission’s main thrust was actually the “mobile laboratory” that would sit inside the rover. The instruments within the mobile lab might include mass spectrometers of all kinds, x-ray diffraction instruments, neutron and gamma-ray spectrometers, and whatever else people could think up. In addition to US proposals, there were German, Russian, Spanish, Canadian, and French entries, and probably more.
The review panel would have their hands full trying to decide on the best combination of instruments and teams. Many different aspects come into play in the selection of a winning proposal. An excellent instrument with an inexperienced team would be a waste of scientific resources. But a good combination of team expertise and instrument capabilities would still be rejected if the cost was too high or if the instrument was too big and heavy. And credibility is a major factor. Could the reviewers believe the claims made in the proposals? An independent cost-estimating team was on hand to second-guess instrument costs and rate each proposal’s cost credibility. Technical reviewers performed the same function for claims about instrument performance. There was no wiggle room—everything would be scrutinized in fine detail.
Back in Los Alamos, our laser lab remained closed. When the incident investigation was complete a couple of months later, the task of cleaning up the facility began. Since the laser lab belonged to a different division from the space instrumentation division that I was in, I was not notified when the cleanup got under way. But the lab was still contracted by NASA to do laser studies, and eventually it became clear that the lab hoped to carry out this work. The management, however, was in no hurry to reauthorize the use of lasers.
In October, I got a request from NASA asking for a small bit of paperwork missing from the proposal. In addition, the French space agency rated the six proposals they were involved with at that time, and surprisingly, ours got the top billing. We tried to advertise this fact to NASA, but in the end we knew it had almost no bearing on NASA’s decision.
When the selections were delayed by over a month, I eventually called the payload manager at JPL to politely ask what was going on. He explained the delays and assured me that I would be hearing from him soon. “Hearing from him soon?” I wasn’t sure whether to take that as a positive sign or a negative one. I didn’t think he would be the one to make the announcement, as those
usually came out of Washington. I had politely refrained from asking what he might know. But he did seem to know something, and he seemed ever so slightly encouraging. Did it mean something?
Finally, on an unusually cold morning in December, I arrived at the office to find a voice message from the head of NASA’s Mars program with a request to call back. Before I could do that, a press release popped up on my e-mail announcing that the MSL rover instrument selections had been made. As I started to read it, the phone rang again, the voice on the other end congratulating me on being selected! A wire from our senator’s office followed shortly after. I quickly made a joyful call to Sylvestre in France, who was incredulous. The next several days until Christmas were a flurry of announcements, correspondence with team members, and interviews with reporters.
We were on board! We had been selected in spite of being burned out of our field test, in spite of being dropped by the veteran instrument team, in spite of our lab being shut down, and in spite of being told to withdraw the proposal. It was against all odds. We had a ticket to Mars!
After the initial excitement faded a little, I cast an eye on the other instrument selections. The selection team had been good to new technology—there would be a lot of novel gadgets on board. The primary mobile laboratory instrument, called Sample Analysis on Mars (SAM), would have an oven and a tiny gas chromatograph. These had been used for over half a century to separate large organic molecules in the lab, but none had ever flown. In addition, SAM would have a tunable laser spectrometer, a type of spectrometer that was designed to determine the isotope ratios of gases. This was very new technology. Even Earth-bound versions of the tunable laser spectrometer were just coming into their own. The rover body would also contain an x-ray diffractometer (XRD) for identifying minerals on the Red Planet. Though frequently used in the laboratory, the XRD was new to space instrumentation. The science cameras selected for MSL were to sport zoom lenses, also a new feature. There would be a radiation monitor, a Spanish weather station, and a novel Russian neutron experiment. The only instruments that could be considered repeats of ones sent on previous missions were the hand lens camera and an alpha particle x-ray spectrometer (APXS), both improved versions of instruments on the MERs.
These gadgets would be ChemCam’s bedfellows, fellow sailors on its journey to the Red Planet. On a ship’s crew, the sailors’ skills should complement one another. For MSL, the overall selection seemed reasonably balanced. We had remote sensing instruments—Mastcam and ChemCam—to act as sentries for the vehicle. There were environmental detectors to understand weather and radiation and look for water (using neutrons). The mobile laboratory package was a good pick. And the arm instruments (APXS and the hand lens) would be useful whenever the arm was deployed. The APXS would complement ChemCam nicely. It worked by bombarding samples with x-rays and alpha particles. Both interactions produced x-rays characteristic of the elements in the top few micrometers of the sample, which could be read out from a detector to yield the elemental abundances of the target. Having been refined over several missions, and made for deployment directly onto the samples, it provided somewhat better accuracy than ChemCam. However, because our instrument would not require an arm deployment, or close proximity of samples to the rover, ChemCam would be able to make many more measurements than APXS.
I also thought about the instruments that were not picked. There would be no thermal, infrared, or Raman spectroscopy. The function of identifying sample composition would be handled by ChemCam at a distance and by APXS and the XRD instrument for samples at arm’s reach or fed into the rover.
The proposed budget for the payload had been $75 million, which was only marginally higher than the budget for the MERs’ payloads when adjusted for inflation. But with twice as many instruments and far greater complexity we were not sure how this would work. A number of other space missions had payload budgets three or four times as much. The instrument teams felt a little shortchanged. We knew we would have to work very hard if we were to stay within the budget.
*Originally using a different light source, this technique did not come into widespread use until after the development of the laser in the 1960s.
chapter
thirteen
NEW-INSTRUMENT STRUGGLES
IN THE WORLD OF NASA, WHEN INSTRUMENTS AND CONCEPTS are selected for flight, it does not mean they are ready to be built. Selection is only the beginning of a long process leading eventually to construction of the flight units. The winning team must go through a number of intermediate and final design stages as well as two major reviews. Usually a prototype, or “engineering model,” is built and tested before any metal is cut on the flight instrument. And once the flight unit is built, it goes through an equally long period of testing, first as a solo instrument and again after being bolted on the rover.
Why build separate engineering and flight models? Ideally, the prototype undergoes the full range of environmental and performance tests. Whatever parts don’t work are redesigned for the flight unit. Often the engineering unit is handled much more roughly than the flight model, experiencing harsher test conditions than one would risk on the flight instrument. The engineering model doesn’t have to come out looking pretty. Holes can be redrilled if they were misplaced on the first try, new parts might get strapped on—and in the end the engineering model is often much less flightworthy than desired. One always does a better job on the second try. On MSL, the engineering model was to be delivered to JPL to be installed on a prototype rover, which would allow the software developers responsible for the rover-to-instrument interfaces to get to work. After launch, the engineering model doesn’t necessarily go to waste, either; one can continue to perform tests on it with new kinds of samples.
Every flight project progresses through different stages. During the initial part of development, the instrument teams go through a getting-acquainted process with the rover team and with each other. The proposal phase only involves a few people. After selection, the full teams of engineers are brought in. The concept of throwing a bunch of engineers together on a project is slightly akin to stranding a group of complete strangers on a desert island. Things don’t necessarily start out smoothly. There are a range of personalities and styles—so many different ways of doing things. Everyone has a lot to get used to; each institution has its own culture; people have different priorities. Team members are too busy with their own thing to listen to others and what they might require for a given part or interface. But eventually the need to survive and make progress impels people to work together, which calls for listening to each other and collectively working out various issues.
This was my second major flight project. I had some ideas about what to expect, but ChemCam’s was a much bigger team than my team on Genesis, with half of the team members belonging to a different culture across the Atlantic. And the rover was a brand new beast with so many competing priorities. Never before had a rover been built to house ten different instruments. It would be a challenge to keep the project on track through the early part of the development.
One of the greatest challenges our team encountered in the beginning was the interface with the rover. We had designed ChemCam in two parts. The telescope, which projected the laser beam, would have to be pointed at targets to do the sampling. The rover’s mast could do the pointing for us. So we designed the telescope and laser to be on the mast, up above the body of the rover. But our device was too large for the whole thing to be perched up there. We didn’t consider that to be a problem. In the lab we used optical fibers to bring the light from the telescope to the spectrometers, which were located nearby. Many people know about optical fibers from their use in fiberoptic lamps, where the light is sent from a bulb hidden inside to the outer ends of the fibers, making a pattern that glows with various colors. Optical fibers are used heavily in industry, most notably for phone and Internet communication cables. Of course, these fibers can be used to carry light for optical instruments as well. So for ChemCam,
we envisioned optical fibers carrying light from the telescope on the rover’s mast to spectrometers in the body of the vehicle. That was how we had done it for the COTS prototype on the K-9 rover four years earlier. JPL was to be responsible for all the cables between different parts of the rover, including our optical fiber cable. At first we thought this was a good thing—they would do all of the development of the fiber. But we eventually realized that the rover engineers were oversubscribed, with ten instruments to deal with, and they did not understand optical fibers or how we needed them to be used for ChemCam.
The distance between the mast and body sections of our instrument was only about 4 feet. In our proposal, the plan was to use a cable about 6 feet long to cover this distance with length to spare, based on our K-9 experience. We explained to the engineers that we wanted the fiber to be as short as possible, as some of the light is lost along the fiber. Our calculations indicated that our detectors did not have a lot of signal to spare. However, within a few months of our selection, the rover designers had positioned our spectrometers as far away from the mast as possible in the rover body. We were told that other things had priority.
In addition, the optical fiber cable, along with all of the other cables to the mast, had to be routed past several moving joints, including one to rotate the mast from side to side (azimuth) and one to point the mast up or down (elevation). Our idea for getting past these joints was simply to hang the cables out far enough from the joints so they wouldn’t get tangled. We could provide enough slack so the mast could move any way it needed to. But we had not thought this through well enough. Everything, even short lengths of cable, had to be securely fastened down during launch. The rover engineers wanted to use a twist cap to solve this problem. At the rotation joint, the cable would be wound loosely around a cylinder three times. When the mast rotated in one direction, the cable would become more tightly wound, and when the mast rotated the other way, it would become looser. Unfortunately, these windings would add a lot of length to the cable, especially since there were to be two such units—one around each joint. If we used this method, our fiber cable would end up being more than 25 feet long, many times the original estimate!