A possible mission to Mars in 2007 would scrutinize the martian atmosphere for any chemical traces of life, or even environments supportive of life, anywhere on the planet.
An international team led by Dr. Mark Allen, an atmospheric chemist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., developed the mission proposal named Mars Volcanic Emission and Life Scout, or Marvel. Today, NASA announced that Marvel is one of four finalists in competition for the first Mars Scout Mission for the 2007 launch opportunity. Final selection by the NASA associate administrator for space science, Dr. Edward Weiler, will be made by late next summer.
"One of the most exciting questions people ask is whether life exists elsewhere," Allen said. "A lot of us on this team think that if life ever existed on Mars, there is a good chance life still exists if there is any place warm and wet."
Scientists in recent years have been developing strategies for how life on planets around other stars might be detected from what's in a planet's atmosphere. Allen's team turned that thinking toward Mars.
For example, many types of microbes, including those living in cows' guts, produce methane. "Marvel will have such great sensitivity that if you had just three cows anywhere on Mars, we would be able to detect the amount of methane added to the atmosphere," he said.
The mission would equip a Mars orbiter with two types of instruments that have proven useful in studying Earth's atmosphere from Earth orbit. One, an infrared solar occultation spectrometer, would look sideways through Mars' atmosphere toward the setting or rising Sun for an extremely sensitive reading of what chemicals are in the thin air that the sunlight passes through before hitting the instrument. The other, a submillimeter spectrometer, would look through any dust in the atmosphere to seek localized atmospheric concentrations of the chemicals of interest.
"By the end of this decade, Marvel could either detect and localize any existing life and active volcanism on Mars or put extremely stringent limits on their existence," Allen said.
The submillimeter spectrometer would also be used to seek localized concentrations of water vapor in the atmosphere, a strategy to identify places where subsurface water sources are actively venting.
As one novel feature of the mission, the submillimeter spectrometer could be re-tuned from Earth to enable detection of interesting substances that the occultation spectrometer discovers in trace amounts. The instrument would then map the occurrences of the substance globally.
JPL would manage the Marvel mission and would build both spectrometers. A third instrument, a camera for showing the context of cloud conditions during the atmospheric measurements, would be supplied by the Canadian Space Agency. Lockheed Martin Astronautics, Denver, Colo., would build and operate the spacecraft. Designs for the mission, the spacecraft and operations draw heavily from the successful 2001 Mars Odyssey mission, now in orbit at Mars. A 20-member international science team has worked with Allen to plan how to achieve the research goals.
If selected as NASA's first Mars Scout mission, Marvel would launch in the third quarter of 2007, arrive at Mars about a year later, use aerobraking to achieve the best shape for its polar orbit pattern, then begin its primary science mission in October 2008 to examine Mars for a full 22-month martian year.
The other three Mars Scout mission concepts selected and their principal investigators are: Sample Collection for Investigation of Mars, led by Professor Laurie Leshin of Arizona State University, Tempe; the Aerial Regional-scale Environmental Survey, led by Dr. Joel Levine, NASA Langley Research Center, Hampton, Va.; and Phoenix, led by Dr. Peter Smith of the University of Arizona, Tucson.
JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Scout Program for the NASA Office of Space Science, Washington, D.C.