NASA is refining plans for a second SUV-sized Curiosity rover mission to Mars in 2020 that would search for evidence of past biological activity, a potential international enterprise whose results may address the prospects for life elsewhere in the solar system and perhaps beyond.
A 19-member Science Definition Team selected by NASA earlier this year to study such a robotic mission outlined the strategy in a 200 page report unveiled earlier this week.
Later this year, the space agency intends to seek proposals for mission science instruments. Fashioned around the Curiosity rover that landed successfully in Gale Crater on Mars in August, Curiosity 2 would be designed to carefully select and drill 31 core samples from Martian rock once it landed and cache them on the new rover until they could be retrieved and brought back to Earth by either a follow on robotic mission or possibly U. S. astronauts.
“I would not rule out that perhaps human explorers would retrieve the cache 20 plus years from now,” John Grunsfeld, NASA’s associate administrator for science, told a news briefing. “That is an eventual goal — to put planetary geologists and scientists on Mars.”
Three years ago, President Obama directed NASA to plan for a human expedition to the Martian environs in the mid 2030s, with an intermediate mission to an asteroid. The National Research Council, an arm of the congressionally chartered National Academy of Sciences, placed a high priority on a Mars sample return mission in a 2011 decadel survey, declaring it the best means of placing Martian soil and rock under the scrutiny of the world’s top researchers and most advanced analytic instrumentation.
Experts would be looking for “biomarkers,” or physical evidence of past biological activity.
By duplicating much of the design effort that went into the $2.5 billion Curiosity mission, NASA should be able to prepare a second mission for about $1.5 billion, exclusive of the launch vehicle expense, according to Jim Green, director of NASA’s Planetary Sciences Division. The cost of the science instrument suite is estimated at $80 to $100 million, he said.
Within months of its dramatic landing, Curiosity was able to establish that Mars once had an environment at least suitable for microbial life.
Studies at a site calledYellowknife Bay suggest a neutral form of water — not too acidic and not too alkaline — flowed through the rocks and soil before Mars turned cold and dry. Those conditions would have been just for life to emerge. But did it?
Curiosity’s next assignment is to determine when and for how long Mars was habitable. The rover is currently headed toward the base of Mount Sharp, a 3.4 mile high rise comprised of sedimentary layers. Curiosity is equipped to study the layering for the remainder of its two year mission. Gale, itself, is a near 100 mile wide depression created when Mars was struck by a space object more than three billion years ago.
The U. S. plans its next Mars mission launch in November. MAVEN, an orbiter, is designed to study the Martian upper atmosphere to characterize the environmental forces that depleted it over time. InSight, a NASA mission scheduled for a 2016 launch, features a stationary lander that will probe the Martian underground for a better understanding of geologic processes.
While those missions are under way, the European Space Agency intends to mount new Mars missions as well, withRussia as a partner. ExoMars, which NASA was forced to withdraw from because of budget issues, will also attempt to lay the ground work for the return of Martian soil and rock samples. NASA with participate modestly through the contribution of science instruments.
“The action is still on the soil of Mars,” said Grunsfeld, as he outlined the Science Definition Team strategy. “We need to go back to the surface and do the next steps — find out about the potential for past life.”
As envisioned, Curiosity 2 may accomplish much more than address that question for Mars alone.
The entire solar system evolved with organics, the carbon-based chemistry that forms the building blocks for life. The chemistry is evident in the comets that swirl around the solar system in a cloud. Other stars in the “local group of stars” that share our region of the Milky Way formed from the same processes.
“We have literally shared spit with the material in our whole local group and the outer parts of our solar system,” said Green. “Consequently, the question of how life originated in our solar system will address some of the same basic questions that will be important and relevant for each of the stars in our local group and therefore throughout the galaxy. It’s a huge leap we are making. Our first step within our solar system of understanding if life existed elsewhere beyond our Earth is indeed an extremely important one.”