Gallery: Images of Mars from the Curiosity rover
A much-hyped discovery by Mars rover Curiosity flamed out like Evil Knievel over the Snake River as scientists Monday said they didn't actually find the chemicals needed to support life.
Martian soil scooped up by the Jet Propulsion Laboratory managed robot contained traces of water, but no carbon-based chemicals, scientists speaking at a conference in San Francisco said.
The latest findings were highly anticipated after Curiosity project scientist John Grotzinger remarked last month that the result would be "one for the history books," though JPL later clarified he was speaking about the mission as a whole.
"What I've learned from this is you have to be careful what you say, and even more careful about how you say it," Grotzinger said Monday.
In fact, there won't be a single "Hallelujah" moment during a mission that includes findings from a wide range of scientific instruments, Grotzinger said, which makes it difficult for the JPL team to operate in a news environment that travels at the speed of Instagram.
"Curiosity's middle name is patience, and we all have to have a healthy dose of that," he said.
Curiosity's Sample Analysis at Mars instruments detected perchlorates in its recent soil tests, which broke down into "simple" carbon-containing compounds.
He listed several possible explanations, including traces of carbon carried by Curiosity itself and the carbon dioxide known to exist at Mars' polar ice caps.
However, scientists suspect some of their test results have been contaminated by Earthlings.
The few chlorinated hydrocarbons detected by Curiosity break down into chlorine and oxygen, but "we have to be very careful to make sure both the carbon and the chlorine are coming from Mars," Mahaffy said.
The rover also discovered water and sulfur contained in the fine-grained soil, which it gathered from a sandy, windblown area called Rocknest in about a month and a half. Scientists specifically chose the location because it was unlikely to yield any unusual results.
"It's not unexpected that this sandpile would not be rich in organics," Mahaffy said. "It's been exposed to the harsh Martian environment."
Perchlorates have also been found by previous Mars missions, including the Phoenix Mars Lander.
Curiosity, also known as the Mars Science Laboratory, is the first mission with the right tools to search for organic compounds, which are its primary focus during a two-year mission in Mars' Gale Crater. Finding organics could be a major clue that the planet's environment could have once supported life.
The rover has nevertheless already made some big findings, such as the fact that it landed in an ancient, flowing riverbed and that properly equipped astronauts could survive Mars' radiation.
Curiosity has since moved on to an area called Point Lake, overlooking lower terrain, where JPL scientists hope to use its rock-sampling drill for the first time.
The rover's ultimate destination is Mount Sharp, in the center of the crater, where layered rock provides a good chance to find organic material.