It's time to blitz Mars with six small probes that could directly test for microbial life, says a group of planetary scientists.
The Biological Oxidant and Life Detection initiative, nicknamed BOLD, is a direct follow-on to NASA's foundational 1976 Mars Viking life-detection experiments.
"We have much better technology that we could use," BOLD lead scientist Dirk Schulze-Makuch, with Washington State University, told Discovery News. "Our idea is to make a relatively cheap mission and go more directly to characterize and solve the big question about the soil properties on Mars and life detection."
The Viking experiments left behind a mystery about why the Martian soil was so reactive, particularly in an experiment designed to detect microbial life.
Most scientists point to geology as the explanation of the reactive soil, a finding bolstered in 2008 by the discovery of highly oxidizing perchlorates in the soil by NASA's Phoenix lander.
But a handful of holdouts argue biology was behind the mysterious reading. They claim that a sister experiment to look for organics in the soil may not have been as sensitive as scientists originally believed.
"When they found no organics that was kind of the killer blow," retired Viking scientist Patricia Straat, co-investigator of the key life-detection experiment, told Discovery News.
To resolve the mystery, Schulze-Makuch and colleagues propose flying a set of six pyramid-shaped probes that would crash land, pointy end down, so they penetrate four- to 8 inches into the soil. The battery powered spacecraft would then automatically run through six major experiments designed to chemically analyze the soil and detect life.
The science instruments include a sensor that can detect a single molecule of DNA or other nucleotide.
The spacecraft would use an existing Mars orbiter for communicating their results back to Earth. Mission costs would be no more than about $300 million, a fraction of traditional NASA flagship missions, and what the spacecraft lack in robustness, they would make up for in numbers.
"If the probability of landing success for each probe is 50 percent, the chance that at least one of the probes will succeed is greater than 98 percent," Schulze-Makuch and colleagues write in a paper published in Planetary and Space Science.
NASA's next Mars mission, the Curiosity science laboratory, is to due to land in August for a detailed assessment of an area known as Gale Crater, which sports a three-mile high mountain of what is believed to be sediment rising from the crater floor. The goal of the mission is to look for habitats that could have supported life.
"Whether there is life on Mars is what the public is most interested in. Why not do it more directly and go after that?," Schulze-Makuch said. "Given the budget, let's go for a question that we really want to know."
The Obama administration wants to pull out of a planned follow-on European-led initiative called ExoMars to return soil samples to Earth. The project would take three missions and billions of dollars. First launch is slated for 2016.
Schulze-Makuch said BOLD could be ready to fly in 2018.