The first men and women to set foot on Mars will not be the first to peer closely at the planet—only the first to visit in person.

Long before the first boot steps on it, the red dirt there will have been baked in teleoperated rover ovens, dissolved in remote-control chemical labs and probably examined with electron microscopes in Earthbound laboratories.

The inhabitants of the first Mars base will have detailed maps to guide them as they explore their surroundings, and they may even be under orders to avoid certain areas because life—or the conditions that would support it—may be present.

“The planning of human missions, including the base site location and mission objectives, must be based on detailed local site information from precursor robotic evaluation and sample return missions,” a NASA workshop on planetary protection recommended a decade ago.

No one wants to discover life on Mars only to find out that it dies when exposed to Earthly microbes, or that it is descended from something that arrived on one of the Viking landers or even on those first boots on the ground.

NASA already is building two of the vehicles that may someday deliver the first human explorers to the surface of Mars (see page 41), robots have been making the trip for decades and they will continue to do so to pave the way for that human landing in the 2030s or later. Human space exploration with today’s technology is simply impossible without robotic scouting, but just as explorers in the age of sail used hand-held telescopes to survey newfound landfalls, the hand that drives the robot is human.

“There is no such thing as a pure robotic mission,” says John Grunsfeld, associate NASA administrator for science. “Robots do not discover anything. Humans do. The Hubble Space Telescope does not discover anything. We are getting the results on the ground, so it is very much a partnership.”

Grunsfeld is an astronomer who gained plenty of hands-on experience in space as a shuttle mission specialist servicing the Hubble on three separate visits. In his desk job at NASA headquarters, he oversees the fleet of probes the agency has dispersed across the Solar System to learn as much as possible without actually sending human scientists to do the job.

On Mars now, two rovers—Curiosity and Opportunity—are operating on the surface, and three orbiters—Mars Reconnaissance Orbiter, Mars Odyssey and Europe’s Mars Express—circle the planet. India’s first Mars orbiter—Mangalyaan, with a suite of atmospheric and surface-observation instruments—is due to arrive in September, as is a new NASA orbiter. Called Maven, for Mars Atmosphere and Volatile Evolution, the latest U.S. spacecraft is designed to study the planet’s upper atmosphere to learn what happened to the water that once flowed on the surface (AW&ST
Aug. 26, 2013, p. 40). Maven may be able to work with the Indian spacecraft to make complementary measurements.

Curiosity already has achieved one of its primary missions—finding evidence that Mars was once habitable. Its radioisotope thermoelectric generator could keep it operating for years as it climbs through the sedimentary layers of the mountain at the center of Gale Crater, using its onboard chemistry lab and other sophisticated instruments to pry more data out of the dusty, dry stones it encounters.

Bringing home some of those stones—or at least material ground out of them—remains the top priority of planetary scientists, as gauged by the U.S. National Research Council in its decadal survey of the undertaking. The European Space Agency’s ExoMars rover, set for launch in 2018, is scheduled to collect samples to cache for eventual return to Earth, and the reprise of the Curiosity rover that NASA is developing for a 2020 launch probably will do that task, too. The agencies initially collaborated on the project, but NASA dropped out for budget reasons (AW&ST May 14, 2012, p. 27).

Planetary scientists want to outfit both rovers with drills that can reach about 2 meters (6.5 ft.) below the surface to collect sample material unaffected by the solar radiation that bathes the surface of Mars and unimpeded by the magnetic fields that protect Earth. While Curiosity and other surface missions have found the chemical building blocks of life in the material they examined, life itself probably cannot survive the radiation.

“The ExoMars 18 mission is actually that leap to the subsurface we’ve all been waiting for, to get below the depth where the ionizing radiation, the galactic cosmic radiation, will modify the chemistry,” says Jim Garvin, chief scientist at NASA’s Goddard Space Flight Center.

Neither Europe’s ExoMars 18, nor NASA’s Mars 2020 rover, will be equipped to deliver the cached samples they collect all the way back to Earth. That task will fall to undefined follow-on missions that probably will use another rover to pick up the samples and a solid-propellant ascent vehicle to deliver them to Mars orbit or send them on an Earthward trajectory.

Just how the samples will reach Earth’s surface remains an open question, given planetary-protection concerns about “back contamination” of the home planet with Martian microbes. One concept under consideration is using the Orion crew vehicle to collect specimins, perhaps in lunar orbit, and return them in an external “vault” designed to isolate them from the Orion crew and the Earth environment (see concept on cover). That would also allow use of the Orion thermal protection system to shield samples (Martian, lunar or other) from the heat of reentry, instead of requiring development of a special sample-entry vehicle, in keeping with the concept of reusing modular “extensible” technology to hold down costs (see page 44).

“You would still have to have multiple layers of encapsulation and protection for it, but you would not have to have a heat shield necessarily,” says Josh Hopkins, the space exploration architect at Lockheed Martin, which is building Orion for NASA.

Scientists are eager to examine pristine Martian particles on Earth because the laboratory equipment that is available, or presumably will be in the future, far surpasses anything that can be stuffed into a rover and teleoperated. While the search for evidence of extraterrestrial life is a prime motivation for bringing back samples, so is the hunt for resources that human explorers can exploit to survive on Mars or perhaps even convert into propellant for the trip home.

NASA’s Mars 2020 rover will include an in-situ resource utilization (ISRU) experiment that will allow engineers to begin working on ISRU processes in the Martian environment. Close analysis of samples on the ground could raise interesting ISRU possibilities, so the next U.S. robot on Mars will be a prospector as well as a scientist, looking for samples to take back to the
21st-century equivalent of the gold-field assay office for analysis.

“Space exploration is risky; it isn’t like Star Trek,” James L. Green, director of NASA’s Planetary Science Div., likes to emphasize. “We won’t ‘boldly go where no man has gone before.’ Before humans are sent out into the Solar System, we have to know every aspect of the environment that we possibly can to reduce the risk. And it is our robotic explorers that are going there first.”