Scientists say that there are at least 68 potentially life-supporting planets to explore. [© kazeyan - Fotolia.com]
In 1998, NASA established its virtual Astrobiology Institute (NAI) to develop the field and provide a scientific framework for flight missions. Astrobiology encompasses the search for habitable environments in “our Solar System and on planets around other stars; the search for evidence of prebiotic chemistry or life on Solar System bodies such as Mars, Jupiter’s moon Europa, and Saturn’s moon Titan; and research into the origin, early evolution, and diversity of life on Earth,” according to NASA.
European countries have also combined scientific and financial resources to form the 18-nation European Space Agency (ESA), which has some collaborative initiatives with NASA focused on astrobiology. For example, in 2016, they expect to launch the NASA/ESA ExoMars/Trace Gas Orbiter (EMTGO) mission, part of the ExoMars Rover Project.
The primary objective is to characterize the chemical composition of the Martian atmosphere, particularly trace species that may be signatures of extant biological and/or geological processes and its variability in space and time. These measurements, along with a good understanding of the contemporaneous atmospheric state, may allow localization of the surface source(s) of “exotic” trace gases.
But how on Mars can scientists detect and analyze life with equipment designed for earth-like conditions? Many collaborative efforts are aimed at developing the specialized equipment required to detect and analyze extraterrestrial samples for signs of life. These will involve developing relatively cheap, compact, rugged instruments that can survive and function in unearth-like environments.
Mass Spec for Mars
The next generation of Mars rovers will most likely use mass spectrometers to search for signs of life, such as amino acids. Current devices, however, are large, consume a lot of energy, and are complex to operate. Scientists at the U.S. Department of Energy’s Idaho National Laboratory (INL) reported that it may have gotten around one complexity by developing a new way to generate electric fields.
Called total ion control (TIC), the method makes it easier to direct ions along specified paths. Most current mass spectrometers rely heavily on airflow to guide ionized soil samples through an inlet, down a channel, and into a trap for analysis. These systems are less than ideal for Martian conditions since they require airflow maintained by heavy, energy-gobbling pumps.
The ExoMars Rover will be powered by solar energy. Hence all its instrument components will have to be very low-power. INL’s new technology guides ions using versatile, complex electric fields that reduce the need for pumps. It could potentially make ExoMars’ life-detecting tools cheaper and more sensitive.
TIC-based inlets weigh less than an ounce, making them much smaller and lighter than other types, inventors say. Relatively small mass is critical for space missions, since it currently costs about $10,000 to put one pound of payload into Earth’s orbit and much more to move it to Mars.
Alien Genome Detection
Back on earth, a team of researchers at Harvard and MIT have initiated a project to study whether life on Earth might have descended from Martian organisms carried here by flying objects like meteors. Called the Search for Extraterrestrial Genomes (SETG), the project is based on evidence that viable microbes could have been transferred between the two planets.
As an example of the adaptability of microbial organisms, the team pointed to the discovery of the first known organism that can thrive and reproduce using arsenic instead of phosphorus in its cells. Last December, a NASA team isolated the bacteria from Mono Lake, CA, chosen because of its high salinity, alkalinity, and arsenic levels.
The NASA investigators said their data showed evidence for arsenate in macromolecules that normally contain phosphate, “most notably nucleic acids and proteins.” Such studies are changing our perception of what chemicals are needed for life and thus also our perception of what chemicals to look for on and around other planets.
The Harvard/MIT project will look for DNA and RNA through in situ analysis of Martian soil and ice samples. The team intends to use molecular biology approaches including PCR and to develop an instrument that can isolate, amplify, detect, and classify any extant DNA- or RNA-based organism, even at extremely low abundance.
Gary Ruvkun, Ph.D., professor of genetics, Harvard Medical School, explained in the team’s proposal that the group intends to develop an instrument that is “less than 5 kg and requires less than 10 Watts during any experimental run. We also propose to explore contamination-reduction protocols and to expand the DNA probes used to explore the boundaries of detectable life on Earth to maximize our chances of detecting life that is divergent from life on Earth.”
Where's the Money?
And as great strides in planetary exploration continue, why stop at Mars? “We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone—a region where liquid water could exist on a planet’s surface,” William Borucki of NASA’s Ames Research Center has noted.
Some candidates could even have moons with liquid water. “Five of the planetary candidates are both near Earth-size and orbit in the habitable zone of their parent stars,” he added.
But sustaining a viable astrobiology program without adequate funding to accomplish its stated programmatic goals may be mission impossible. Astrobiology at NASA has been hit hard by budget cuts; as the Mono Lake findings were announced, NASA astrobiology funding had declined 50% over the prior two years, with no expectation of quick restoration. During this same period, other NASA programs saw a 15% budget reduction.
Some relief came in 2007 when approximately $4 million was added back to the program from NASA’s Science Mission Directorate (SMD) discretionary funds and a reallocation of resources within SMD’s Planetary Science Division. In 2008, NASA awarded five-year grants averaging $7 million each to 10 research teams from across the country.
Nevertheless, the current expectation is that NASA’s astrobiology budget will remain at approximately the FY2007 level with annual corrections for inflation. With at least 68 new potentially life-supporting worlds to explore, one can only hope that in troubled financial times, astrobiology finds a funded future.