Destination Mars (16 page)

It is worth noting that the water masses are, in some areas, projected to be about half a mile deep. But the instrumentation on these orbiters was able to measure only about a yard down, so
anything beyond that is theoretical. However, this deep water-mass projection does come close to resolving the mystery of the missing water on Mars as regards total mass.

One more shock awaited. The MARIE experiment, designed to measure radiation in the Martian orbital environment, presented a surprising picture: the amount of radiation, the kind that might put future astronauts at risk, was at least double that of Earth. As a control, measurements were taken aboard the International Space Station during roughly the same period. The experiment had previously been used on both the station and the shuttle, but this was the first time it had left Earth orbit. MARIE measured both solar radiation and galactic cosmic rays. The result? Astronauts spending extended periods in the Martian orbital environment would need extra protection from radiation. The experiment ended when a spike in solar flares appeared to have overloaded the device.

But Mars Odyssey had one more trick up its sleeve. By the time it had reached its first Martian year of operation—687 Earth days—it had been pressed, as planned, into being a relay station for the newly landed Mars Exploration Rovers. A full 75 percent of the early images from the rover Spirit were relayed through Odyssey, and the orbiter continued to render assistance for the life of Spirit (until it ceased function), as it continues to for the rover Opportunity.

And Mars Odyssey has earned one more distinction. In late 2010, it broke Mars Global Surveyor's record as the longest operational spacecraft at Mars: 3,340 days. It is still going strong and continues to provide data, imaging, and relay capability for other missions.

While it may not look much like the Energizer Bunny
^®
, Mars Odyssey just keeps going, and going, and going…

J
effrey Plaut started his college education studying music composition but was unable to maintain his allegiance to Bach and Beethoven. He can often be found on the porch of his small home at the foothills a few miles east of JPL in Sierra Madre, a small hamlet that resembles Mayberry as much as a Southern Californian suburb. From his back patio, with a view of the nearby San Gabriel Mountains, he is as likely to be listening to Jimi Hendrix as Joseph Hayden. He is not able to spend as much time as he would like with his wife and two young daughters due to his long and rewarding involvement with Mars Odyssey. From his home he recalls those formative college years:

“There were several different things I was interested in, and one of them was music, and I did composition, I played the piano, a whole variety of stuff…and I pursued that, but I always had an interest in math and science, and I sort of kept that going in the background while I was doing my music major. I was taking some math courses and astronomy courses senior year, and I took a class called Planetary Geology. It was a graduate course, so I was somewhat out of my league, having not done any geology up to that point. I managed to make it through the course, and I got kind of excited, I wrote a term paper that my professor enjoyed about the moons of Jupiter and the possibility of life there. So I graduated as a music major, but the geology sort of stuck with me, and after a couple years I decided to look for a career in it and got
into a program at Washington University in St. Louis, and that has one of top programs in planetary geology, and the adviser was tied in with JPL, and that's how I eventually got into JPL.”
¹

Once on the track to JPL, there was no turning back. He had been bitten by the Mars bug.

“I came on as the deputy project scientist, and the guy who I succeeded, Steve Saunders, was something of a mentor for me here at JPL, and I guess he liked having me as his right-hand man, so he brought me onto this project; then he retired and I got moved up to the project scientist position. For the last twelve or thirteen years, I've been focusing mainly on Mars, and I've also worked on two other Mars orbiter projects, [the Mars Reconnaissance Orbiter] and Mars Express.”

But Mars Odyssey was not initially planned as simply an orbiter. It was something far more complex, in the vein of the Viking missions of 1976: “This project actually consisted of both an orbiter and a lander that we were going to fly to Mars. The orbiter was going to land first, and the lander, along with a small rover similar to the Pathfinder rover, was going to land. So the orbiter would have two jobs, one would be to relay the data, as we do now for the Mars Exploration Rovers, and the orbiter would also make measurements around the planet as well as handle the lander's data.

“That mission unfortunately never flew. We were well in development for the lander part of the Mars 2001 mission, and when we had the twin failures on the Mars 1998 project, which were of course the Mars Polar Lander and the Mars Climate Orbiter.

“So, half a step in, they said that the Mars 2001 Lander was extremely similar to the Mars Polar Lander, which failed, so they said, ‘Let's still hold on to that, we still have the orbiter.’ [T]hey understood the problems, and it really wasn't any fundamental problem with the orbiter itself, so, we went on and did the 2001 mission and the lander was put on the shelf…and eventually got
resurrected as the Phoenix Lander. [It had the] exact same hardware, [was the] exact same unit that was supposed to go to 2001, which eventually went to a 2007 mission and was very successful.”

In fact, the Phoenix Lander became the first successful landing above equatorial Mars, and the mission, though brief in comparison to Mars Odyssey, was wildly successful. But that's another story.

One instrument would set Mars Odyssey apart from all previous orbiters, and its name was THEMIS: “It's a unique instrument [that] makes images using infrared vision. Its detector is taken straight out of night-goggle technology, and it sees a part of the spectrum where there are diagnostic spectral signatures of certain minerals that appear on Mars that are not easily detected with other [spectra] on instruments. And another thing unique about it is that it will create global maps of Mars, almost 100 percent coverage of Mars, so basically it makes an image of the planet's temperature. You can see how the surface gets cooled down during the night. [The] rockier areas stay warmer during the night while dusty areas cool down faster, so the camera can really tell us a lot about the terrain on Mars and its texture. The resolution is really incredible, about 100 meters per pixel.”

Odyssey was well equipped to make history. “I think we're already at the point where we can look back and see what's historical and what really this mission has achieved. There are two different areas. First is the discovery and mapping of ice in the soil. The onboard instruments made unequivocal observations and maps of hydrogen in the subsurface of Mars down within the first couple of feet, and we saw both polar regions and down to about sixty degrees north and south latitudes. [This is] what you might call the Arctic of Mars…just shot through with ice in the soil. There really was no way for anybody to make that measurement before, and make the maps, until Odyssey came along. This provided the target for the Phoenix lander, which set down within this arctic circle. Besides the scraping with its robotic arm and
those investigations, the soil was blown away by the descent boosters of the lander, and it uncovered ice right underneath it. So historically speaking, that might be the biggest mark that Odyssey has made and will be remembered for.

“The whole theme of this Mars exploration program is to follow the water and to understand the possibility of life on Mars. Clearly all life that we know of needs water in its cells and its environment to survive. So it's always been the major goal of the mission to understand the role of water in both the history of Mars and also the evolution of Mars today. It's as if to say, ‘where can we find water [and] the ice,’ and to be able to localize a map, and ultimately have it confirmed for the [landing site]. That was a huge step, to follow the water and touch it with the Phoenix lander. We have several other plans to send landing craft to Mars. None of [the others] are going to these icy terrains, but I think, ultimately, we will go back to some of these icy areas, maybe to find a place where there might be a hospitable environment for some kind of little microbe.”

But the Mars Odyssey mission was not all guts and glory: “I think the most difficult period during the mission was about two years after we arrived, which was around October 2003. There was a series of huge solar flares, and that resulted in a kind of radiation or magnetic storm at Mars, and it just clobbered our spacecraft. It actually killed off the MARIE instrument; the sensor just measured this radiation and choked on it. The storm also set Odyssey into a safe mode, which is a good thing if a spacecraft's in trouble. It goes into a safe state, where it's not actually required to do a whole lot, but we did lose contact for a time. When we got it back, we saw that it had been rattled, and we had to improvise, press the reboot button and do a complete hard reset of the computer. That is a bit stressful. But other than that we have been very fortunate.”

So what lies ahead for Mars Odyssey, currently the longest serving spacecraft at Mars? “We are going to go for as long as we
can! We are already way beyond our prime mission. One thing that helps is that we served this relay function, we're continuing to do that for the [Mars] Opportunity Rover, [and] hopefully in a year or so, when the Mars Science Laboratory arrives at Mars. We still have good science with the instruments we have around, [and] as long as we have fuel, we still should be able to continue to operate. We just might have another ten years, if we don't run out of fuel or funding.”

These two factors, fuel and funding, are the great nemeses of robotic exploration of the cosmos. Fuel is a fixed quantity once the craft leaves Earth, but continued funding is something that dedicated explorers like Jeffrey Plaut worry about every day.

I
n the first years of the new millennium, spurred by the success of Mars Odyssey, JPL seemed to regain its institutional confidence. Things were working again, and Mars seemed within reach in a way not seen since Viking.

The next step after the spectacular success of Mars Odyssey, which continued to operate and send back information vital to future mission planning, was a set of dual rovers. These would be an evolution of the Mars Pathfinder mission: similar in design but an exponential leap in scope and ambition. They were the Mars Exploration Rovers (MER).

These twin rovers, which built on knowledge gained from the successes (and limitations) of the Mars Pathfinder rover, Sojourner, were built at JPL. In general terms, the orbiters tended to be built by outside contractors (Lockheed Martin preeminent among them) while the rovers were built at the lab by internal staff. The design and fabrication of Pathfinder had been exemplary; the Mars Exploration Rovers would outshine even that.

Each completed spacecraft would weigh in at about 2,400 pounds, with the rovers themselves tipping the scales at about 408 pounds. Rather than depending on the landing stage as a relay for the radio transmissions back to Earth (as Sojourner did), MER would utilize spacecraft already in orbit around Mars, the Mars Global Surveyor and Mars Odyssey probes. It was an ingenious and carefully planned perfection of the capabilities of JPL assets
on and in orbit around Mars. The rovers were also capable of communicating directly with Earth, but the orbiters offered a superior conduit for communication.

The rovers were both far larger and more robust than Sojourner, but with a similar overall design. These too used solar panels for power, and each would arrive on Mars sitting inside a lander shielded by metal petals. The lander itself would follow a flight profile similar to Pathfinder's, and would employ an almost identical landing scheme, right down to the beach-ball cocoon and the multiple-bounce arrival. Why mess with success?

But while Sojourner had provided a few short weeks of successful operations within sight of its lander, MER would range far and wide over long and active missions. To provide a maximum return on investment, the instrumentation had been beefed up as well.

For starters, the rovers were loaded with cameras. There was a panoramic camera, mounted on a mast about five feet high, to image the surrounding terrain. On the same mast was a navigation camera, with a wider field of view. This one operated in black and white and for driving and navigation purposes. Below this was a mirror for the Thermal Emission Spectrometer, which helps to identify promising rocks and soils for closer investigation. Finally, there were four more black-and-white cameras, two up front and two at the rear, for hazard avoidance. Their sole purpose was to assist in keeping the rovers out of trouble.

One more imager made up the visual complement: the Microscopic Imager, which would take extreme high-resolution close-ups of the rocks and soils being investigated by the arm.

The instruments for scientific investigation took their cue from Sojourner and expanded on this theme. These were mounted on the same robotic arm as the Microscopic Imager, which gave the rover even more reach. There was an Alpha Proton X-Ray Spectrometer (an improved version of the APXS on Pathfinder) that could identify the elements of the rocks that the rover would
stop and “sniff.” Another device was the Mössbauer spectrometer, used to investigate iron-bearing rocks and soils.

Less high-tech but still useful was the oddly named “RAT,” or Rock Abrasion Tool, which would dust off or, if necessary, grind down the surface of rocks to be examined. This allowed for a clean, fresh surface to test with the various devices. And last but not least, there was a collection of magnets, to pick up any ferrous material from the RAT or from the environment at large, which the Mössbauer spectrometer would more closely analyze. This device is particularly adept at identifying iron-bearing minerals that other devices may not be able to “see” when present in small amounts. It can sense the magnetic properties of samples and potentially identify materials formed in hot and wet environments. If there was a downside of this particularly valuable device, it was that a thorough reading took up to twelve hours. But the rovers would have plenty of time.

Altogether, it was a neat and tidy little science package, which owed a lot to the successes of its predecessor, Pathfinder's Sojourner rover.

The landing zone for Spirit, the first rover to descend, had been carefully selected. It would have to be smooth enough that the airbag landing method would work. It had to be low enough in elevation that there would be sufficient atmosphere to pass through for slowing of the heavier rovers to occur. It had to be near the equator, and not so potentially dusty that the solar panels would become disabled. Over 150 candidates were considered; for this first landing, the final choice was a large crater named Gusev.

About fifteen degrees south of the Martian equator, Gusev was named after a nineteenth-century Russian astronomer. It is almost one hundred miles wide and geologically speaking is a transition zone between the ancient highlands to the south and the smoother, younger plains to the north. And entering the crater from the southeast is a 550-mile-long meandering valley
called Ma'adim Vallis, which appeared to have been massively eroded by water at some time in the distant past. The hope was that, since the water appeared to have emptied into the crater, the floor might have layers of sedimentation that could be explored.

It was a cleverly selected site, decided upon by a combination of acquired knowledge, deduction, and detective work. Its promise seemed clear.

Spirit arrived in a fireball on January 3, 2004, entering the Martian atmosphere at over 12,000 mph. Once again, airbags were used to cushion the blow of the high-speed entry, and the machine bounced a couple miles before settling into its final landing spot.

Upon arrival, the craft deflated the airbags, unfolded its petals, and took a preliminary image, again, just as its predecessor Pathfinder had. On the ground in Pasadena, those glued to the monitors were ecstatic. It was just what they had hoped for.

To the untutored eye, the flat expanse with a few rocks would seem desolate. But for a rover control team and the associated scientists, it was heaven. The rover had a perfect-looking surface to traverse, a wide selection of rocks to explore, and an open horizon to seek. And, perhaps most important, it was different than that encountered by either the Viking landers or Pathfinder.

For the first week, the rover sat in place and surveyed its surroundings. Nearby was a depression about thirty feet wide, soon dubbed Sleepy Hollow (features near landing sites never remained anonymous for long). It was either a wind-worn hole or a meteor crater; either way, it offered immediate access to subsurface geology. It was the proverbial hole in one.

But before this would be explored, a number of more symbolic gestures were to be made. First, there was a plaque aboard the rover, which was dedicated to the astronauts lost in the space shuttle
Columbia
accident with a moment of silent observation. Then a DVD, stored atop the spacecraft, was imaged by its camera. It was a funny moment: here was a DVD, with a little Lego
^®
-style
robot printed on it, and all of it held in place by what appeared to be Lego building bricks. It was all part of a sophisticated but seemingly simple effort to reach out to kids, to budding young scientists. This is something that JPL has done exceedingly well, especially since the Pathfinder mission with its huge Internet component. This DVD held the names of
four million
people, part of the “Send Your Name to Mars” outreach project, along with other student messages to future human or alien explorers. But not to forget the science, simple magnets had been attached to the edges of the disk to allow students around the world to study how much ferrous metal was contained in windblown dust. It was clever beyond measure, and fun to boot. Before too many years have passed, the first of these students will be entering careers in space science, many inspired in part by this simple gesture. It was an unusual moment of marketing genius by NASA, and it cost next to nothing to accomplish.

But now, it was time to explore. To the transmitted strains of Bob Marley's “Get Up, Stand Up,” Spirit flexed its robotic muscles and prepared to roll off its platform, a week after arrival. But before it went a-strolling, more images were sent home, these with the infrared spectrometer. After the rousing success of infrared imaging by Mars Odyssey, MER had taken a similar instrument along for the ride. Once again, materials invisible to the naked eye could be seen in the surrounding terrain, but this time, it was at ground level. Besides helping to identify the composition of the rock, the instrument also spotted dusty areas to be steered around. It was the best thing since putting wheels on Mars!

First the front wheels, then the rear ones, were extended. This was a carefully observed process. The suspension of the machine had acquired its DNA from the Sojourner rover, using the same “rocker-bogie” arrangement of swinging arms and six wheels.
¹
Once upright, a cable near the center of the rover had to be cut to allow it to move free of the lander. NASA had long ago learned the danger of plugs and connectors coming loose on spacecraft, so,
since the dawn of the space age, when spacecraft connected by a wire to another craft or the ground needed to separate, this was accomplished with explosives and knifelike guillotines. While this may sound extreme, it works well in practice, and the failure rate has been very low.
Bang
went the pyrotechnic charges, a blade swung and the wires were cut, never to rejoin. Spirit said good-bye to its lander. It was the last of 126 pyrotechnic charges fired since the launch of Spirit almost a year earlier. Nobody said exploring space is simple…or quiet.

Slowly, so very slowly, Spirit embarked on the first step of its long drive to places unknown. Driving on Mars was a slowly evolving science. It had been done only once before, with the Pathfinder mission. And that rover, Sojourner, had gone only a few dozen feet away from the lander that was its link to home. Spirit and Opportunity would range far and wide, communicating (it was hoped) directly with JPL's orbiting spacecraft as they passed overhead every ninety minutes or so. But still, despite the wealth of experience, despite the somewhat-autonomous hazard-avoidance software onboard, and despite a long delay of outgoing radio commands (and a similar delay on verifications from Mars), the rovers needed to be driven by humans on Earth. It was the old mile-long drinking-straw analogy, the item through which mission controllers had to labor to make things work on Mars. It was not as simple as jumping into a car and driving off.

There were many layers in the process and many skills to be learned. First, the surrounding terrain was extensively imaged by Spirit to give the drivers a sense of place and a taste of the road ahead. Then, through communication with the Mars Odyssey orbiter overhead, Spirit got a better fix on its actual location. Finally, via the infrared images, it was possible to map out the difficult terrain and any “sand traps” in the surrounding area.

In the few years prior to the landing, JPL's “rover drivers” had been in a sort of extraterrestrial driver's ed class. Called Field Integrated Design and Operations, or FIDO, it involved taking a
facsimile of the rover out to California's Mojave desert and simulating driving on the rock-strewn Martian plains. Like MER, FIDO moved slowly (less that 1 mph) and sported an onboard hazard-avoidance navigation scheme. The investigative tools were similar to Spirit's as well. As the program evolved, the rover was controlled from JPL just as it would be once on Mars. Commands were relayed via satellite with a built-in time delay to better simulate the Martian mission. In fact, the JPL personnel were not even advised as to where the rover had been dropped off, to better maintain the illusion of being on Mars.

The importance of simulating this mission was obvious. MER was a quantum leap beyond Pathfinder. The new rovers were much more autonomous, and indeed needed to be, for they would be covering up to three hundred feet in a day, which was farther than the Pathfinder rover ever got from home base during its entire mission. And with a planned mission duration of ninety days (and much more was hoped for), it was critical to gain experience with the machine.

While there were some basic differences between MER and FIDO—size, weight, and physical operations among them—they were essentially very similar and lessons learned would be of great value. Getting stuck in a crevasse or tipping over due to an overly ambitious climb were a lot less expensive, not to mention final, on Earth than on Mars. On Earth, someone can wander over and kick the rover (and at times, someone did). On Mars, all one can do is invoke harsh language from afar.

The designers of the simulation had done their best to compress twenty days of Mars operations down to about ten days on Earth. This meant focusing on the most important operations and letting a few others slide. Like the grueling Apollo and Shuttle simulations of previous eras, planners deliberately inserted malfunctions and small emergencies into the program to make sure that the rover drivers back at JPL were on their toes.