"Mars was a lot different 3-1/2 billion years ago. It was more like Earth with liquid water. Maybe life existed back then. Maybe it has persisted, which is possible given the fact that we've found life in every extreme environment here on Earth. If life existed on Mars, maybe it adapted very much like life adapted here."
NASA Goddard scientist Jennifer Eigenbrode developed the test of a rock sample to determine whether the sample-preparation method preserved the sample's molecular structure. Her testing methodolgy proved successful, ultimately leading to the experiment’s inclusion in the Sample Analysis at Mars (SAM) instrument on a mobile NASA laboratory that will land on Mars in 2012. The newly added experiment will enhance SAM's ability to analyze large carbon molecules if the mission is fortunate enough to find any.
The mission, NASA's Mars Science Laboratory, will be checking whether a carefully chosen area of Mars has ever had an environment favorable for the development of life and preservation of evidence about life. The mission's car-sized rover will analyze dozens of samples scooped from soil and drilled from rocks.
None of the rover's 10 instruments is designed to identify past or present life, but SAM has a key role of checking for carbon-containing compounds that potentially can be ingredients or markers of life. Most environments on Mars may not have enabled preservation of these organic molecules, but if any did, that could be evidence of conditions favorable for life.
In particular, Eigenbrode's experiment will provide far more details about the evolution of large organic molecules that are made up of smaller molecules such as carbohydrates, lipids, proteins, and nucleic acids.
"Our experiment preserves information on how these molecules formed," she said. "What we'll get are key observations that tell us about organic carbon sources and processing on Mars — shedding light on the planet's carbon cycle.
SAM is considered one of the most complicated instruments ever to land on the surface of another planet. Equipped with a gas chromatograph, a quadruple mass spectrometer, and a tunable laser spectrometer, SAM will carry out the initial search for organic compounds when the Mars Science Laboratory lands in 2012. To identify organic compounds, however, the instrument will have to prepare soil and rock samples before it can obtain measurements.
As planned, the rover's robotic arm will scoop up the soil and drill rock samples and a separate mechanism will deliver the samples to SAM's sample-manipulation system, a carousel-like device that contains two concentric rings holding 74 tiny tubes. Once the tubes are filled with the fine-grained samples, the carousel will rotate and insert the tube inside a pyrolysis oven. As the oven heats, the hermetically sealed sample will begin to break down, releasing gases that SAM's instrument will then analyze for potential biomarkers.
In her quest to find techniques to prep the samples to prevent fragmentation from heat that breaks carbon bonds and obtain more details, Eigenbrode investigated methods that would give a robotic laboratory operating millions of miles from home the same flexibility and capability of an Earth-based organic geochemistry laboratory.
"Sample preparation is the forgotten science in Mars exploration," Eigenbrode said. "An instrument is only as good as the sample, and there is no single method for identifying all molecular components."
In 2009, she tested rocks similar to those found on the red planet, prepping the sample with a small amount of tetramethylammonium hydroxide in methanol (TMAH), a chemical mixture used in laboratories for studying organic compounds. She then heated the sample to determine whether the TMAH not only preserved the sample's molecular structure, but also could survive the higher levels of radiation found on Mars. The testing proved successful.
Source: The Daily Galaxy - NASA's Goddard Space Flight Center.