A version of this article appears in the August 11/18 double issue of Aviation Week & Space Technology.

Controllers are in final preparations for the Sept. 21 red planet arrival of NASA’s Mars Atmosphere and Volatile -Evolution Mission (Maven), an orbiter designed to help scientists figure out where the planet’s early atmosphere went, and with it the water that once flowed on its surface. As the Maven team gears up to take data, the winners in an international competition to place instruments on the U.S. space agency’s next Mars rover are hard at work on the imagers and spectrometers that will look for signs that the water once supported life.

The Mars 2020 rover missions will be a reprise of the Curiosity Mars rover’s ongoing expedition, which found evidence the planet’s ancient water was drinkable. Its $130 million instrument suite, announced July 31 (AW&ST Aug. 4, p. 12), is not intended to find extant life, but only the biosignatures of ancient life.

“If something hops in front of the camera, or there are some molecules—if you find a long-chain fatty acid—you would say ‘that’s really hard to do,’” says Michael Meyer, lead scientist for NASA’s Mars exploration program.

No one really considers that -scenario likely. The surface of Mars is bathed with ultraviolet light and blasted with cosmic radiation that would break up the complex molecules that typify life fairly quickly. The 2020 rover will have a mechanism on its robotic arm that can pull sample cores about 10 cm (4 in.) deep; but under current plans, promising cores would be cached to return to Earth—somehow, some day—for deeper analysis with mass spectrometers and other equipment much too large to send to Mars.

That isn’t soon enough for some astrobiologists, who remain intrigued by experiments on the two Viking landers that tested for living microorganisms. Most consider the results inconclusive, but believe that is no reason not to keep looking. As NASA announced its Mars 2020 instrument suite, a grass-roots advocacy group—ExploreMars.org—kicked off a project it calls “ExoLance” that will adapt military bunker-busting technology to place life-detection gear deep enough below the surface that any life there might survive the radiation.

ExploreMars has turned to Aerojet Rocketdyne to update the Deep Space 2 penetrator mission, which rode piggyback to Mars on the 1999 Mars Polar Lander but never established radio contact after its two penetrators hit the ground. The group sponsors the annual Humans to Mars symposium in Washington (AW&ST May 8, p. 22), where a discussion prompted board member Joseph Cassady, an Aerojet Rocketdyne executive, to ask if there might be another use for the military hardware his company develops to hit buried targets.

In the resulting concept, a penetrator dispenser would be integrated into a lander mission such as Mars 2020 or Europe’s ExoMars. After the heat shield separates high in the atmosphere for parachute deployment by the primary payload, the dispenser would fall freely, using the kinetic energy remaining from the interplanetary cruise to send several tungsten-tipped penetrators 1-2 meters (3.3-6.6 ft.) into Mars. Each penetrator would relay its findings back to Earth via Mars orbiters just as the Curiosity and Opportunity Mars rovers do today, transmitting with an antenna on the surface connected to the instruments with a data umbilical.

ExploreMars has established a crowdsourcing site at indiegogo.com/projects/exolance, with an initial goal of $250,000 to fund development of a penetrator prototype for terrestrial testing. ExploreMars Executive Director Chris Carberry says members have held informal talks with NASA counterparts about a piggyback ride on Mars 2020, which Cassady notes could take the place of the ballast that flew on the Curiosity entry vehicle.

Ultimately ExploreMars hopes to form public-private partnerships with space agencies for multiple penetrator missions. Developing the sensors will not be easy, both because of the hardening necessary for them to survive an impact with the surface, and the complexity—addressed in the Mars 2020 instrument suite—required to distinguish biosignatures.

“The suite of instruments allows you to try to attack as many of those non-biological mechanisms as you can,” says NASA Chief Scientist Ellen Stofan.

Any instruments would be looking for the signatures of Earthlike life, on the hypothesis that Earth and Mars share the same organic chemistry. Confirming that would disappoint many astrobiologists, particularly as astronomers discover evidence there are millions of planets orbiting other stars.

“It would be more exciting to find something different; because if we did, it would tell us that life is common in the universe,” says Chris Carr, an astrobiologist at the Massachusetts Institute of Technology. “If it’s just the same origin that’s shared between Earth and Mars, then, well, maybe it happened only once in our Solar System, and it was just a lucky event. So we can’t really use that to gain any statistical leverage.”