NASA’s Mars Odyssey spacecraft has confirmed suspicions that the radiation on Mars is so intense that it could endanger astronauts sent to explore the Red Planet, scientists said Thursday.
THE HIGH RADIATION levels measured by the robotic probe also suggest any extraterrestrial life that might call the planet home would have little chance of surviving unless it were shielded beneath the planet’s dusty, cold surface, said Cary Zeitlin of the National Space Biomedical Research Institute in Houston.
“It would have to be pretty robust against all kinds of environmental horrors,” said Zeitlin, one of the scientists working on the project.
The conclusions stemmed from new data released by scientists at NASA’s Jet Propulsion Laboratory from the first year of scientific results from the $300 million mission.
ODYSSEY’S SCIENTIFIC FINDINGS
Scientists also presented information on the minerals and elements that make up the planet’s surface.
Arizona State University’s Philip Christensen, principal investigator for Odyssey’s thermal imager, said layers of a mineral called olivine in the Martian super-canyon known as Valles Marineris indicate that it’s been billions of years since water flowed there.
Some scientists have speculated that ancient Mars was warmer and wetter than it is today, but Christensen said, “Maybe it’s been a cold, wet climate. ... It’s been a cold, wet planet for much of its history.”
Measurements indicate that Mars’ northern hemisphere is richer in water than its southern half. Near the planet’s north pole, frozen water makes up as much as 75 percent, by volume, of the top 3 feet (1 meter) or so of soil, said the University of Arizona’s William Boynton, who heads the team behind Odyssey’s gamma ray spectrometer.
“We’re talking ice with a little bit of dirt mixed in it, and not the other way around,” Boynton said.
CONCERN ABOUT HUMAN MISSIONS
NASA talks vaguely of future human missions to Mars, where astronauts could use that ice for drinking water, fuel and oxygen to breathe. The new radiation findings suggest such a mission would be risky.
Even so, possible accidents involving the spacecraft that would take astronauts to and from Mars pose a far greater risk, Robert Zubrin, president of the pro-exploration Mars Society, said in a telephone interview.
“The idea (radiation) represents this incredible, forbidding obstacle to Mars exploration just isn’t so,” Zubrin said.
Mars is continuously bombarded by radiation from the galaxy at large, as well as by periodic bursts from the sun. The radiation would expose astronauts in orbit to an effective dose 2.5 times greater than that received by humans in low Earth orbit aboard the international space station, Zeitlin said.
A three-year mission would expose astronauts to the radiation limit considered safe by NASA over the career of an astronaut, he added.
The radiation environment on the surface of Mars is unknown but probably poses a similar risk, even though the planet’s tenuous atmosphere would provide some shielding.
“It still remains to be seen what the hazards are on the surface,” Odyssey project scientist Jeffrey Plaut said.
SOLAR STORMS
InsertArt(1822248)The main worry for astronauts on Mars would be the periodic bursts of charged particles that stream outward from the sun. On Earth, a global magnetic field and a substantial atmosphere protect against that radiation.
Observations made last year show bombardments of solar radiation can last more than a week. Presumably, astronauts on Mars would have to remain confined in some sort of shelter during such blasts of radiation, Zeitlin said.
“They’re manageable, as long as the spacecraft has these refuge areas,” Zeitlin said.
Unsafe levels of radiation exposure would lead to a significantly higher incidence of cancer.
Mars Odyssey’s science mission is expected to last 1½ more years but probably will be extended. The spacecraft has been thrifty enough with its fuel to enable it to stay in orbit 20 more years, Plaut said.
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MSNBC’s Alan Boyle contributed to this story.