Destination Mars

by Rod Pyle

  But, of course, there was. The results were nothing short of amazing.

  “The final thing that was totally astounding and unexpected was the chemistry experiment identifying a chemical called perchlorate. Now, I am personally not a chemist, and I didn't know much about perchlorate, so my first thought was that it was a bleach, chlorine bleach, and I thought, ‘My god, the soils of Mars are filled with bleach, we're never going to find life here!’ I mean, that's how you clean the microbes out of your drinking water, right? But it turns out that the chlorine in the perchlorate form is very stable, very soluble in water, and has four interesting properties. One is that it lowers the freezing point of water, so if you concentrate perchlorate, you get a very low freezing point in brines, and life could survive in those brines. Second, there are microbes on Earth that live on perchlorate. They use it as a food source, an energy source. Third, perchlorate is used in solid rocket fuel, so it could be a resource for astronauts. The fourth property is that in high concentrations it is toxic to humans—future astronauts will need to be prepared to protect themselves. It was all very exciting.”

  The best was yet to come. Phoenix went on to not only be the first mission to successfully land on the polar regions of Mars, but one of the more successful static landers overall, despite its short life.

  When asked to reflect on his accomplishments, Smith leans back in his chair. The answer is not what one might expect from one of America's top planetary explorers: “It's simple. I'm a lucky man: lucky to be able to work with some of the best scientists and engineers in the world. Together we accomplish great deeds.”

  It's more than luck, as anyone involved who has observed his hard work knows. But don't tell Peter Smith…he's busy designing instruments for NASA's new asteroid-rendezvous mission. And he is likely hoping for luck on that one too.

  If Pathfinder's Sojourner rover was a remote-controlled toy and the Mars Exploration Rovers were ATVs, then NASA's new Mars Science Laboratory (MSL) rover is an SUV. The mammoth mobile science platform is the newest Mars effort, launched on November 26, 2011. And it's a doozy.

  Not since the Viking landers has anything so large and complex been sent to the surface of Mars. Nuclear-powered and better-equipped than any of its predecessors, MSL is set to redefine Mars-surface exploration in a big way. Just the numbers alone are impressive:

  Where the MER rover weighed about four hundred pounds, MSL weighs two thousand.

  MER's instrument package weighed less than fifteen pounds, MSL's weighs 276.

  The Spirit and Opportunity rovers were just over five feet long, MSL is over ten.

  MSL can surmount obstacles almost a yard high, well over double that of MER.

  MSL has a minimum expected travel range of over twelve miles during its two-year mission, far longer than the initially expected range of MER.

  MSL's heat shield is the largest ever flown, larger than the Apollo heat shield of the 1960s.

  MSL is powered by a plutonium heating element, one of NASA's last,1 generating five times the power of MER's solar panels, and it will not suffer the power reduction that Sojourner and MER suffered during periods of reduced illumination on their solar panels, with a life of over fourteen years.

  MSL will not bounce to a generally defined landing zone within a cocoon of airbags as previous rovers have. The craft needs to make a pinpoint landing. This rover, the size of a Mini Cooper® automobile, is also far too large and heavy for the beach-ball method, and herein lies one of the biggest headaches of the mission. It will come into the Martian atmosphere much as other landers have—at high speed, surfing on its heat shield. But once it nears the surface and ejects its protective coverings, and after being slowed by the usual parachute (albeit a far larger one), eight rocket motors will brake the spacecraft to a hover, and the rover will be winched down from an array of cables from which it will dangle. Once the rover itself reaches the surface, the cables (also known as “bridles”) will be cut with pyrotechnic charges, and the descent stage will drift away to crash nearby.

  The system is known as Skycrane, and that's how it's supposed to work.

  It is easily the most complex system ever devised for a Mars landing, and with that comes exponential amounts of complication and many grueling tests. Even the atmospheric-entry phase is more complex, and the targeting for this landing is far more demanding and tightly aimed than its predecessors. As it enters the upper atmosphere, the brain of MSL will compute the amount of deviation between its proposed course and its actual location in the air. By throwing off small amounts of ballast during this high-speed entry phase, the spacecraft will be able to steer through the Martian skies, resulting—hopefully—in a relatively pinpoint landing. Again, it's a white-knuckler. But that, as has been said, is the Mars-exploration business.

  Testing has been the key to success with the Mars landers, and MSL is no exception. In fact, the testing regimen for this mission may be the most involved yet. One example is the landing radar software. A mock-up of the computer onboard MSL was placed in an F-18 fighter jet and lofted above the Mojave Desert in Southern California. The aircraft climbed to forty thousand feet and began a series of dives at angles ranging from forty to ninety degrees. Each time, the jet pulled out of the dive at about five thousand feet. During the dives, the computer checked against the radar, allowing for a simulation of the mid-altitude descent of MSL through the Martian atmosphere. This allowed the designers and programmers to fine-tune the package to provide the most accurate landing they can.

  The rover's given name is Curiosity, selected from thousands of submissions from schoolchildren nationwide, and it carries the largest and most complex scientific investigative package ever landed on another world—including the Apollo lunar missions.

  Investigative goals include examining the geology and climate of the region it surveys as well as continuing the search for life compatible environs and organic compounds, if any exist. And of course, the rover will search out possible evidence of past—and with luck, present—water.

  The rover has a mast with cameras at the top, as all Mars rovers have had. The cameras are capable of high-resolution stereo (3-D) stills, as well as HD video, a first. And, in another first for rover cameras, the Mastcam has a ten-power zoom lens. The cameras for this mission are being built by a private company, Malin Space Science Systems, which has traditionally built orbiter cameras. Along with the usual engineers and scientists on the team, movie director James Cameron was brought into the mix for his creative and technical abilities.

  Another camera, the creatively named Mars Hand Lens Imager (MAHLI), will be mounted on the robotic arm (also a staple of all rovers) to take microscopic images of the rocks being investigated. It has both white- and UV-light sources to see differing aspects of the rocks.

  A descent imager, the Mars Descent Imager (MARDI), capable of saving four thousand rapid-fire images, will document the trip down to the surface. This will allow for mapping the area in which the rover lands in great detail as it approaches, not unlike the Ranger moon missions of yore (but hopefully with a softer landing!).

  The amazing ChemCam is a suite of instruments that includes the first laser-induced breakdown spectroscopy device, which can target a rock from about twenty feet and vaporize a sample, collecting a spectral sample as it does so. The laser used is a 10-megawatt beast that is perfect for vaporizing bits of rock and sand, but would not be friendly to any Martians nearby (we should be so lucky!). This instrument is a combined effort of the United States and France.

  Like Sojourner and the MER mission before it, Curiosity will carry an alpha proton X-ray spectrometer (APXS), which hails from a consortium of Canadian and US universities. This instrument can identify other minerals in the targeted sample.

  A unique experiment called Sample Analysis at Mars (SAM) is an echo of the Viking life-science lab and can investigate samples both externally and in internal containers à la Viking and Phoenix. It uses a mass spectrometer, a gas chromatograph, and a
tunable laser spectrometer to seek organic compounds. The latter instrument can, unlike Viking, differentiate between organic and inorganic substances. If a lucky moment occurs, this may settle quite a few arguments about the nature of Martian soil and its constituents, while inevitably raising new questions. This is another US/France collaboration.

  The Russian Federation has supplied the Dynamic Albedo of Neutrons device (DAN), which will seek to indentify hydrogen, ice, and water at the surface. Another device, the Radiation Assessment Detector (RAD) will investigate near-surface radiation levels in an effort to determine necessary protection for future human explorers of Mars. To gain a better understanding of the weather such explorers might face is the Rover Environmental Monitoring Station (REMS), a meteorological suite designed to measure Martian weather.

  Another suite of devices will measure the environment the lander passes through during its descent and is called the MSL Entry Descent and Landing Instrumentation (MEDLI). Finally, the obligatory navigation and hazard-avoidance cameras will adorn the corners of the rover, identifying formations to be avoided and building 3-D maps for autonomous navigation across the Martian surface.

  Coordinating and commanding the instruments and the rover itself is the onboard computer, once again the Power PC© chips used on so many preceding craft. Two of the RAD750 chips will power the computer, one assisting the other. The computer is a vast leap over those used in previous probes in terms of memory capabilities, and it is over ten times faster. The main computer is assisted by an inertial navigation unit. This is not unlike that used in the Apollo program, and is again similar to the accelerometers and related measurement system used in today's iPhones®.2 It allows the rover to measure its current location by comparing speed and direction changes since its last known location.

  After years of debate and consideration, a region known as Gale Crater was chosen as the landing site from about fifty other possible sites. The crater is almost one hundred miles wide, with a central mountainous peak rising about three miles from its center. The twelve-mile-wide landing zone places Curiosity near this peak. The rocks in the region are of a different appearance than those investigated by other rovers. Much of what will be found there should be rocks that have tumbled down from the crater wall as well as from the central peak. Additionally, as with other craters, there will be a bonanza of outcrops and strata visible to the rover in the walls of the crater, exposing many millions of years of geology. Add this to Curiosity's ability to use its laser spectrometer to do remote sampling of rocks, and it's easy to see that this mission should be one for the record books.

  Near the base of the central peak is an area that has been identified from orbit as rich in clay and sulfates, both formed in the presence of water. As always, this is a prime target for investigation—but especially so in Curiosity's case, as it will have the ability to sniff out organic compounds. When Curiosity does find a desirable sample, controllers have many choices of how to proceed. The sampling arm, over five feet long, has a full complement of collection options available. In an evolution over the MER sampling techniques, this rover has a small rock drill, which will allow it to grind powder from rocks. The drill has an interchangeable bit on the end; if a bit becomes dull or stuck in a rock, Curiosity can simply eject it and pick up another drill bit from a collection it will carry onboard. It also has a rotary brush for cleaning rock surfaces, similar to the RAT on MER.

  Also positioned at the end of the sample arm are collection sieves and containers. The samples, whether they be sand, drillgenerated powders, or other materials, can be sifted into a scoop on the end of the arm and then delivered to the onboard lab for analysis. And the rock drill itself actually has the capability to transport the powders it generates along the drill, up out of the hole, and into the sample container.

  MSL has not come cheap. The overall cost of the mission is expected to be about $2.5 billion over the life of the mission. This includes massive cost overages across the last few years, and there will probably be more by the time the extended missions are complete. But there is more to this story than overall cost.

  For one thing, all space missions, especially the manned ones, tend to be underestimated at the outset. This is not a lack of foresight or planning on the part of the folks who price-out the mission. Rather, it is a combination on unforeseeable price changes and, more often, the need to quote low in order to get a mission approved. In other words, one must assume the best possible outcomes in terms of cost to pry the funds from an increasingly frugal federal government.

  It should be noted here that JPL's endeavors have almost always returned many, many times what has been promised. Orbiters designed to last a year or two routinely continue operations for five or even ten years. Landers and rovers expected to operate for a few months end up running for years and years—and in MER's case, often covering ten times or more than the expected territory. And this is not due to deliberately lowered expectations on the part of mission planners. The mission objectives are specified by NASA headquarters, and it is expected that each effort will meet these minimum requirements. After that, the rest is frosting on the cake. And JPL's missions traditionally produce a lot of frosting; it's like finding thirty pounds of buttercream on a cupcake.

  Curiosity is scheduled to land on Mars in August 2012. Standby.

  M arried to another JPL scientist, Joy Crisp can be found on off hours at her Princeton home quietly immersed in a science fiction book, often a David Brin title. She has been at work on the Mars Science Laboratory for years, acting as the deputy project scientist, but her path to Mars was not a simple one.

  “I was a volcanologist, so I studied volcanoes on the Earth. I was doing a postdoc at UCLA, and a friend of mine said ‘I think there are people at JPL that are volcanologists, and there might be a postdoc position open there.’ I had no idea! I thought JPL was just a place where they studied space. I talked to them and sure enough they were using thermal infrared sensors to look at Hawaii. I started to do research at JPL with a group of people, and then Pathfinder came along and they needed someone who could work on the instruments like the APXS [alpha proton x-ray spectrometer], which measured the chemistry of rocks and minerals, and they said they needed someone that knew about geochemistry. I was one of the few people that had that expertise, so I got involved and it was interesting. I moved to the Mars Exploration Rover project, and now I'm on Mars Science Laboratory. So I transitioned from studying volcanoes on Earth to volcanoes on Mars, and I ended up doing all kinds of projects.”1

  Of those projects, the Mars Science Laboratory is easily the largest to date.

  “This is a very big project, so there's a lot of things to do. We must make sure the science team can carry out their investigations, keep an eye out for the things the engineers are doing that could affect science, and advise a project manager when he has to make decisions.

  “[MSL] really is a stepping-stone beyond missions like Pathfinder and [MER], which were very geology focused and didn't really have any capability for looking at organic compounds and the building blocks for life. [The] Mars Science Laboratory is better equipped.

  “Pathfinder was a technology-demonstration mission. It was a short-lived mission and we confirmed a lot of things we knew about Mars. We did measure some slightly higher silicon composition, so there were some ground truths right at the site where we landed. Spirit and Opportunity were a huge step in understanding because they were more capable, and because they lived so long. Opportunity is still going, and because of that, we've learned a tremendous amount at two very different sites. One thing that those rovers have done is to show us that there is definitely a diversity of geology on the planet and that we can redirect [the rovers] and find evidence of past water. With Opportunity, we found some rock layers where water was even flowing on the surface, depositing the grains, and also secondary water, ground water, was circulating through them, and cementing them, and making those little hematite spheres in them. So there were lot
s of clues.

  “What we will really be able to do much better with Curiosity is to identify the minerals. We were struggling a little bit with Spirit and Opportunity; we could identify iron-bearing minerals with the Mössbauer spectrometer, but with other minerals, we had to guess somewhat. [We took clues] from a thermal infrared spectrometer as to what mineral combinations might be there. So when we get there with our x-ray diffraction spectrometer on Curiosity, we'll have a much better way to say what minerals are present in the soil and in the rocks that we look at.

  “We're also bringing the instrument called SAM, Sample Analysis at Mars; and that one will be able to drill into rocks and find out [if any] organic compounds are present. We haven't tried to do that since Viking days, and when Viking tried to do that, it couldn't find any organics in the soil. We're going to have a more sensitive instrument. We'll be able to heat [the soil] up much higher and be able to look for organics at even a lower level and look at drilled rocks. It's still going to be pretty hard, and it's a remote possibility that we're going to find organic compounds on Mars, but we'll certainly have a better chance of doing it with this rover.”

  The MSL rover is not designed to search for life, though. It will search for the basic elements that can support life: “We're not trying to do what we did with Viking, which was to look for life. [With Viking] after we got the experimental results, we scratched our heads and realized that we could think of a way for an inorganic substance to create those kinds of results. That wasn't the best test, and we realized how hard it would be to devise an experiment to look for life. We don't have an instrument that the science community can [agree on] to go look for life. So we're kind of taking a baby step in that direction, going slower than Viking tried, saying ‘let's try to find the organic compounds and measure those again in a better fashion.’”