Full Analysis of Martian Soil Detects Simple Organics

After much speculation about a huge discovery on Mars, NASA finally announced the results of the soil tests performed by Curiosity's Sample Analysis at Mars (SAM) instrument Monday.

The findings are a letdown, revealing that the rover has not made any definitive detection of Martian organics in the initial phase of the experiments, after analyzing soil from a sand dune located at a site called "Rocknest".

SAM is used to detect organic molecules in Martian soil samples. When the instrument analyzed the gases released by the dusty sand when it was heated in an oven, there was no sign of carbon compounds, which are organics essential for life, NASA said.

"We have no definitive detection of Martian organics at this point, but we will keep looking in the diverse environments of Gale Crater," said SAM principal investigator Paul Mahaffy of NASA's Goddard Space Flight Center in Greenbelt, Md.

But the rover detected simple organics like water and sulfur and chlorine-containing substances, among other ingredients in the samples. Water seen by SAM does not mean that Rocknest was wet, NASA scientists said.

When SAM analyzed different isotopes of the Martian water vapor, it found that the vapor contains deuterium (heavy hydrogen) five times than that found in Earth water. It means that the Martian water vapor is heavier, reported BBC.

NASA notes, "Water molecules bound to grains of sand or dust are not unusual, but the quantity seen was higher than anticipated."

Rover also detected chlorinated methane compounds (one-carbon organics) that formed when there were reactions with other chemicals heated in the SAM instrument. NASA scientists suggest that the chlorine could be from Mars, but the carbon might be from Earth, carried by Curiosity to the red planet.

The car-sized rover landed on Martian soil in early August, to detect if the environmental conditions could have ever supported microbial life. Curiosity has been pursuing various experiments, including testing Martian rocks and soil samples, and also measuring the planet's atmospheric composition to identify signs of life.

A few weeks ago, the rover hinted at the presence of methane in the atmosphere of Mars, raising hopes about a habitable environment. But when scientists double-checked the finding, they noticed that there was no presence of methane. They explained that the first signal was probably because of a contamination in the Martian soil, the Los Angeles Times reported.

Although the new discovery is seen as a disappointment, NASA scientists note it is a milestone in their mission, as the on-board laboratory worked well and will collect more data over the next two years.

"We used almost every part of our science payload examining this drift," said Curiosity Project Scientist John Grotzinger of the California Institute of Technology in Pasadena. "The synergies of the instruments and richness of the data sets give us great promise for using them at the mission's main science destination on Mount Sharp."

The results were presented at the fall meeting of the American Geophysical Union in San Francisco.