The tension as Curiosity rover scientists began their spiel during a news teleconference was palpable. For months of weekly news conferences, reporters had been asking about Curiosity's analyses of atmospheric methane on Mars.
If the rover was finding even one part per billion (ppb) or so of methane, there would be a chance that life -- life on Mars, today -- was producing it.
But no Martians turned up this time.
Christopher Webster of NASA's Jet Propulsion Laboratory in Pasadena, Calif., the instrument lead for the Tunable Laser Spectrometer, Curiosity's atmospheric analyzer, reported that after four analyses he could say only that, with 95 percent confidence, there is between 0 ppb and 5 ppb of martian methane.
That range of concentrations rules out one possible scenario to explain a methane gush astronomers detected in 2003, according to atmospheric modeler Malynda Chizek of New Mexico State University, Las Cruces. (One more whiff of methane was reported in 2006. Nothing since.)
The 2003 gush could have been a once-in-a-century release involving life . . . or not. Or methane on Mars may be down at the few-hundred-parts-per-trillion level, and neither life nor methane-belching volcanoes have anything to do with it.
Curiosity should still be able to settle everyone's questions about methane on Mars. Webster is hoping that concentrating the methane in future Curiosity samples will allow the detection of concentrations as low as 100 parts per trillion. It will just take time, he said, weeks or months of time. Patience. -- ScienceNOW