Curiosity

by Rod Pyle

  The landers contained mini life-science labs that were miracles of miniaturization. This was more of a feat than it might at first seem. In that day and age, such instrumentation usually filled a large room. The Viking lander's laboratories were about the size of a dishwasher. Inside were four experiments: three designed to look for microbial life and the fourth to perform basic atmospheric and soil analysis. But it was the biology experiments that ultimately caused such consternation.

  Scientists come in many stripes, but among the prominent ones there is a tendency to have an equally prominent set of beliefs. Of course, the very basis of scientific inquiry requires a mind open to the results of experimentation and an acceptance of the results. But this does not preclude a strong attachment to hypotheses, and in this the Viking crew were divided roughly into two camps. One was the “I doubt we will find anything, but let's load some soil into a container, expose it to some carbon-14, pump out the air, burn the dirt, and look at what comes out of it” camp; the idea was that living things would metabolize the 14C and the instrument could then measure it.

  The other camp also started with a soil sample but then added a nutrient “broth” to it, thought to be something Martian microbes would eat as readily as earthly ones would. This was the “grab the dirt, feed it, and see what shows up” crowd. Once wetted, the sample would be monitored to see if it gave off methane or any other by-products of metabolization.

  There were two other soil experiments: another form of feeding the dirt (and anything within) to measure resulting gasses, and yet another that would look at untreated soil samples that were heated. But it was the first two that caused the controversy—the two men in charge simply could not agree on much. The “I doubt we will find anything” group was led by Dr. Norman Horowitz of Caltech. The “Let's feed it and see” camp followed Dr. Gilbert Levin. The opposing results of their respective experiments would fuel a multidecade controversy and affect the design of Mars landers and future experiment packages heading off to Mars for decades.

  The landers set down on opposite sides of the planet in 1976, Viking 1 on July 20 and Viking 2 on September 9. Each soon deployed an arm and scoop to gather soil samples, which they then deposited in small, onboard receivers. Each of the experiments mentioned got a bit of sample material and went about their tasks. In general, they created differing conditions within the samples and then looked at the results to see if there were any positive indications of microbial activity. When the first samples were ingested and processed, three of the instruments indicated readings consistent with sterile soil—no life found. The fourth, however, demonstrated a rapid spiking of what could have been metabolic activities, then declined just as quickly. Researchers were excited but then puzzled by the odd readings; they should not have declined so precipitously. In the end, the general consensus was that it had been a mere chemical reaction in the soil with no microbes in sight. A small faction, however, continued to interpret the reading as indicative of biology at work. The debate has quietly raged ever since.

  Fig. 4.3. SUCCESS: The first image successfully transmitted from the surface of Mars: in 1976, the Viking 1 lander sent this image back to a gleeful JPL. It shows the footpad firmly planted on Mars, assuring nervous flight controllers that the lander was level and safe. Image from NASA/JPL-Caltech.

  In the meantime, the thirty-foot-wide Viking orbiters wheeled overhead, snapping images of the entirety of the planet. Between them, the two orbiters returned tens of thousands of images of the Martian landscape, mapping its geological complexity in exquisite (for the time) detail. Mariner 9's discovery of massive erosional forces that had at one time been at work below were confirmed and scrutinized in detail. Where all that water had gone was still a mystery, but hundreds of gullies, gorges, buttes, and deltas had been formed by something vast, violent, and wet in the ancient past. Future spacecraft would unravel the mysteries catalogued by the long-serving Vikings.

  One by one, the orbiters and landers shut down, with Viking 1 being the last to succumb in November 1982. It was not a victim of the harsh environment but of an erroneous command that caused the radio dish to rotate away from Earth.

  That day in November would be the last time a signal would be heard from the surface of Mars until 1997.

  We're taking a break from the history lesson that leads us to MSL and the Curiosity rover. After that first memorable expedition to Death Valley, I was invited for a second visit, but this one would place me within a few hundred yards of my car at all times. I could hardly complain. The activity was some sand-dune testing of a variant of the Curiosity rover specifically designed for driving tests on Earth. They called it the Scarecrow.

  The Scarecrow was a smaller, lighter version of Curiosity. The resemblance to the real thing was vague, but functionally it was identical, at least so far as driving on Mars was concerned. Its lithe design, just a framework, some motors, and six wheels, was designed to mimic the way Curiosity would handle driving in the 0.38 of Earth gravity that it would face on Mars; Scarecrow weighed only 38 percent of what the real rover did and should interact with the sandy terrain in a way similar to what Curiosity would experience on Mars.

  Oh, and the computer is off-board, connected by a cable. That's why they call it the Scarecrow—it has no brain. Get it? I guess that would make John Grotzinger the wizard, but he might not see it that way.

  I should mention here that although I have referred to Grotzinger as “the Big Kahuna” and as a wizard, John himself would assuredly defer any kudos to the team of scientists, engineers, technicians, and support people that make up the MSL mission. JPL’ers are team driven, and few will take single-source credit for an invention or an accomplishment. So whether you are talking to Grotzinger about the mission science, to Manning about the engineering, or to Vasavada about planning and execution, they are likely to remind you that it is a team effort and that they just happen to be in charge of all or part of that particular team. And it's true. But we civilians tend to seek out a person in charge of some part of the mission, a personality with whom we can identify, a leader with which we can share a moment of glory. Blame it on centuries of training by organized religion and, more recently, supermarket tabloids. But for the individuals whom I spoke of and others profiled in this book, I'm sure that they would have me remind you one more time: it's a team effort.

  Back to our tale.

  It was still months before the launch, and this was a chance to see the hardware at work. I drove out with John Beck-Hoffman, the JPL videographer who had joined us for the Death Valley adventure, and we discussed video production and space exploration during the multihour drive. It was fun to get another perspective. “I've worked at JPL for over twenty years,” he told me, “and still learn new stuff all the time.” We discussed his now-famous “7 Minutes of Terror” video, which he wrote, shot, edited, and even scored. The man is irritatingly talented. He has since left the lab, surely a loss to their media efforts. As Grotzinger once commented, “That video is the gift that just keeps on giving. I cannot give [a] public presentation without showing that thing. When I look at that, it brings a tear to my eye and for the audience it's just another hooting and hollering moment.” NASA can use all the hootin’ and hollerin’ moments it can get.

  Fig. 5.1. IF I ONLY HAD A BRAIN: The Scarecrow, a stripped-down version of Curiosity for use in mass-equivalent (i.e., simulated Mars gravity) testing, is to the right. Mike Malin, creator of Curiosity's camera systems, is being interviewed to the left. Image from NASA/JPL-Caltech.

  Everyone loves an audience. Beck-Hoffman got one, many millions strong. It was a spectacular piece of outreach.

  When we arrived at the test area near the west entrance to Death Valley, the Scarecrow was already up and running. There was a tarp-covered spot of shade where a few young engineers operated the rig from a laptop. Grotzinger was here, then over there, then back again, making sure that the rover would work in the way it was expected to.

  A gentleman named Mike Ma
lin was there too, working off the tailgate of a truck, testing some bits of camera equipment. Middle-aged, bearded, and not slim, he could pass on a quick glance as my brother. An area where nobody would confuse us would be in intellect. I get by fine, but Malin has a MacArthur Foundation award under his belt and owns a mind of that caliber. You find a lot of that around Caltech and JPL. He speaks expressively but does not dwell on himself—it's hard to tell if it is modesty or simply that the subject at hand is more important. I suspect, in his mind, it's some of both.

  Watching him tinker with the cameras that day, it was pretty clear that he is always working on something, often a new invention to enhance planetary photography. Talking to him makes it clear that (a) he is a genius and (b) he does not suffer fools, or the press, gladly. Fortunately, Grotzinger was kind enough to make an introduction and that won me an enjoyable conversation. “Rod's one of the good guys…” he said, and I heartily agreed. I was on the right side of the angels that day.

  I asked Mike what he was doing out there in the windblown sand and scorching sun. “We've been out here all week doing a field test of the mobility system on the rover to determine how well it will handle navigating on sand. We're just finishing up a couple of tests looking at intermediate slopes and intermediate compaction of the sand.” As you might imagine, sand comes in all sorts of conditions on Mars (steep dunes, shallow dunes, fields, pits, mounds, etc.), as well as in varying levels of compaction (soft, hard, medium, etc.). And on Mars, with only 38 percent of Earth's gravity, the slopes are at different grades and the sand can behave differently. Testing is paramount.

  “We got through the extremes yesterday. We did some testing in a flat area with the sand all churned up, and then went to steeper grades to see how well it could handle steep slopes of sand. Today's test is in between those extremes to get some transition information, and then the last thing we will do today is to try to drive it up a dune over here and see how far it goes before it stalls.” The dune is not terribly steep for a human walking in one gravity, but for a machine like Curiosity, in Martian gravity, it could be a different story.

  Clearly this is more than just work—Malin is here for more than the technology: “I'm out here for a couple of reasons. First, this is fun for me, I am a geologist, so this is my natural environment and habitat. Most of the time I'm sitting in an office banging away at a computer, so to sit outside and actually feel the wind on my face and watch the sand blowing is very soothing. Generally I'm here to advise the engineers on how and where to test the rover, but this is really vacation for me.”

  I then see Malin's associate fiddling with a couple of off-the-shelf digital SLR cameras connected via a cable to a computer rig, and query Malin about them. “This is a Mastcam simulator.” Mastcam is the imaging system atop the camera mast on Curiosity that Malin built. “It's a consumer-level version of what we flew to Mars, so it's very inexpensive to build. It has two cameras, each with 35 mm and 100 mm lenses. The whole assembly is secured to a mount which we got from a telescope and which is controlled by this Mac mini. We write sequences that look like the ones we send to the cameras on Mars, and we interpret those using this consumer-based camera by having it do the same process.”

  His assistant had rigged the Mac mini in a drink cooler with ice to keep it from overheating. Smart—I could have used one of those on my first Death Valley excursion, for my head. Mike continued: “As with most engineering you want to take it outside where you will be working in the real environment to test it. Sometimes it might not work all that well. We intend to test it in other environments later this summer and into the fall. We are using it to simulate what we will be getting from Mars as a training tool, then when we get to Mars we will use it to take similar pictures so that we can compare what we see on Mars to what we see on Earth, and we then learn from those comparisons.”

  I thought the rig was pretty ingenious. When we hear of space missions that cost $2.5 billion, we tend to think of all the work as being conducted the same way that Apollo was—with expensive, top-drawer, custom technology, all work done in clean rooms. In reality, the only way to keep a mission like this as inexpensive as $2.5 billion is for people like Malin, who has probably contributed double the time than he has charged for, to work with off-the-shelf components doing clever tests like this one.

  After this chat, and a closer look at his impressive rig, I wandered over to where the Scarecrow was doing its thing. The machine was slowly working its way up a sand dune, moving at a glacial crawl, which is Curiosity's usual speed of transport. It's slower than you think: quicker than the minute hand of a clock but possibly more sluggish than the second hand.

  Along its route were set up a couple dozen still cameras on tripods. The Scarecrow had four large, white, foam balls spaced across its top, one on each corner. They were being used in the same way that movie visual-effects practitioners use Ping-Pong balls on actors in front of green-screen setups to track the motion of the subject, in this case the Scarecrow. This documentation aided in motion studies and tracking any slip in the sand. Slipping is more critical than it might at first seem, for reasons we will learn soon.

  Based on experience gained from the Mars Exploration Rovers (MERs), especially Spirit, sand dunes and sand traps are a big concern on Mars. Spirit got bogged down a couple of times, despite its own exhaustive testing. This was exacerbated by the malfunctioning of two of its six wheels. The last sand trap was fatal, and Spirit died in a grainy bog. It was a lesson well learned, so extensive studies were being conducted across a range of sand-related questions: How steep a slope can you assault before the machine begins to slip? Under what conditions will it become bogged down? What is the optimum speed for it to travel on different surfaces? Are there specific kinds of sand environments that it should avoid altogether?

  While the engineers were working out their troubles, I had just discovered a few of my own. My video camera was acting up, probably due to its being made of black plastic and the hot sun beating down on us; it had become a twelve-pound heat-sink and was quite hot to the touch. I covered it, and once it cooled it ran fine, but then I discovered another, more-insidious problem. There had been a light breeze all day, which felt wonderful in the hot weather. But that breeze, upon closer inspection, also carried a fine, almost-invisible cloud of sandy dust that, weirdly, stopped at about shoulder level. I hadn't really noticed it. But when I went to twist the camera's focus ring in midafternoon, I heard—and felt—a gruuuunch! sound. Sand had gotten into the lens mechanism. Fine, sharp grains of sand and optics don't mix well, and the proceeds from this assignment would be more than devoured by the trip to the repair depot the camera would be making.

  Oh well, keep shooting. It's all for the space program. And to be honest, I was having a lot of fun—it was a space geek's delight.

  Toward the end of the afternoon, I got together with Grotzinger for an interview. By this time I had not only shaded my camera but also had wrapped it protectively in a plaid shirt (the shirt was wretchedly ugly; I was glad to put it to one more use before I tossed it). This engendered a couple of odd looks from the press corps, but I figured they would eat crow when they got home and later found their own optics going gruuuunch! So much for camaraderie in journalism.

  Too soon, the press interview drew to a close and we were shooed-off to allow the JPL folks to get some work done. Beck-Hoffman and I drove back to LA. He would soon be off to work for National Geographic TV and other outlets, and I had a book to write.

  Scarecrow continued to work for the rest of the week. Alas, it never found a brain, but did lay a solid foundation for Curiosity's upcoming travels.

  The first rover to Mars arrived in a somewhat-undignified fashion. After a mad dash from Earth, it smashed into the thin atmosphere, cut a scorching swath across the sky, popped a parachute, fired some braking rockets, and then bounced. Quite high, and again and again, because it was designed to do so. But even if it was inelegant, it worked.

  The landing o
f Pathfinder was exciting and arrested the attention of the public. This plucky little machine, developed quietly and on a limited budget, became the darling of the Internet. JPL's servers crashed on the first day from the millions of hits. This was the first machine on Mars since 1976's Viking landers, and it thrilled the world for the next three months.

  But, prior to launch, Pathfinder had been a touch-and-go mission. Many inside the space agency had opined over the years that rovers were too complicated, were too risky, and would be too expensive and too hard to land. But by the early 1990s, technology had progressed sufficiently so far downstream since the Vikings landed on Mars that it was clearly time to reconsider. A small team in JPL came up with a new approach, that would ultimately become the first wheeled vehicle on Mars, a tiny precursor to Curiosity. And the public loved it.

  It was a right-sized mission for the time. NASA's new administrator, Daniel Goldin, had decided that the agency needed to stop building large, heavy, and multipurpose spacecraft like Galileo (Jupiter) and Cassini (Saturn). The school-bus-sized behemoths were expensive to produce, launch, and operate. And a single failure, as almost happened when Galileo's antenna failed to deploy fully, could mean a billion-dollar loss. In the financial climate of the day, the continuation of these flagship missions was not high on the list of preferred projects.

  Enter the Discovery Program. Goldin's mantra was to make space projects “faster, better, and cheaper.” It was a tall order, for in space exploration (and technology in general), those three things do not often play well together. If asked, many JPL engineers would have told him, “Sure, pick any two.” But in this era of lean budgets (not unlike today), if you wanted to fly a spacecraft, especially if it was “interesting” (read “risky”), then the Discovery Program was the way to go. The idea was to design and build Pathfinder as a mission costing less than $150 million; all Discovery Program missions would have constrained budgets.