FEATURE
New Experiment Enhances Ability to Find Life on Mars
Goddard scientist Jennifer Eigenbrode never dreamed that an experiment she developed for analyzing large organic molecules on an alien world would find a berth so quickly on a spaceflight mission. But that’s exactly what has happened.
Her experiment has been incorporated into the Goddard-developed Sample Analysis at Mars (SAM) instrument, one of 10 flying on the Mars Science Laboratory. The car-sized rover will launch in 2011 to analyze dozens of samples scooped from the soil and drilled from rocks to assess whether Mars now or ever sustained life.
“Mars was a lot different 3-1/2 billion years ago. It was more like Earth with liquid water,” Eigenbrode said. “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.”
Experiment to Reveal More Details About Evolution of Life
Should the mission find large organic molecules — potential precursors or artifacts of life that are made up of smaller molecules such as carbohydrates, lipids, proteins, and nucleic acids — Eigenbrode’s experiment will reveal far more details about their evolution. “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. Even if we don’t detect signs of life, we might learn why not.”
Eigenbrode secured the flight opportunity after successfully proving in a series of R&D-funded tests earlier this year that thermochemolysis — the combination of heat and a specific chemical — would significantly enhance SAM’s ability to analyze large carbon molecules if they are discovered on Mars.
Complex Instrument
Complicated Instrument
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.
There is a catch, however. Although SAM will be effective at identifying organic compounds, heat breaks carbon bonds, resulting in fragmentation and the loss of molecular information. What was needed, Eigenbrode believed, were other ways to prep the samples to prevent fragmentation.
In her quest to find these techniques, Eigenbrode used Internal Research and Development funds to investigate 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 FY 2009, she tested rocks similar to those found on the red plant, prepping the sample with a small amount of tetramethylammonium hydroxide in methanol (TMAH), a derivatization 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.
| Seeing the benefit of adding Eigenbrode’s sample-preparation method to the overall SAM mission, Principal Investigator Paul Mahaffy and scientists Daniel Glavin (see related story below) and Jason Dworkin agreed to donate two of the 10 cups for her experiment. Just a few weeks ago, the SAM team added and sealed the TMAH chemical inside the two cups.
“When I began working on my concept earlier this year, I thought it might be suitable for a future Mars mission, perhaps in 2016,” Eigenbrode said. “I never thought that it would fly so soon on SAM. I believe we have really enhanced the capabilities of SAM should it find organic material. What I really want now is to find macromolecules on Mars.” |
As part of R&D-funded research, scientist Jennifer Eigenbrode injected a chemical into a rock sample and then heated the test tube to determine whether the sample-preparation method preserved the sample’s molecular structure. Her testing proved successful, ultimately leading to the experiment’s inclusion on the Sample Analysis at Mars instrument.
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No Technology Hurdles
The tests also proved that the addition of her experiment on SAM posed no technical challenges. Ten of the 74 carousel cups already were reserved for a “wet chemistry” derivatization experiment effective for analyzing free amino acids, the building blocks of proteins.
Seeing the benefit of adding Eigenbrode’s sample-preparation method to the overall SAM mission, Principal Investigator Paul Mahaffy and scientists Daniel Glavin (see related story below) and Jason Dworkin agreed to donate two of the 10 cups for her experiment. Just a few weeks ago, the SAM team added and sealed the TMAH chemical inside the two cups.
“When I began working on my concept earlier this year, I thought it might be suitable for a future Mars mission, perhaps in 2016,” Eigenbrode said. “I never thought that it would fly so soon on SAM. I believe we have really enhanced the capabilities of SAM should it find organic material. What I really want now is to find macromolecules on Mars.”
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