Preventing biological contamination will be one of the key elements in a series of missions to Mars slated for the next two decades, particularly when samples of Martian soil come back to Earth around 2014, said scientists at the American Geophysicists Union conference, which is taking place here this week.
"We don't want to be finding out that there are Mars microbes after we get people on the planet," said John Rummel, planetary protection officer at NASA headquarters. Conversely, equipment from Earth has to be sterilized with hydrogen peroxide and oven heating so that scientists "don't detect life forms from Florida on Mars."
Thanks in part to the success of the Mars Rover program, presidential directives and a longtime fascination with our closest neighbor, NASA has obtained the wherewithal to plan for several voyages to the Red Planet.
The next voyage to Mars occurs toward the middle of next year, when the Mars Reconnaissance Orbiter launches. The 4,800-pound craft is equipped with a high-resolution camera that will be capable of scanning the surface of the planet and identifying items about the size of a dinner plate. Current orbiters can capture clear images of features that are table-size.
Then, in 2007, comes the Phoenix, which will explore the polar ice caps and drill for samples, according to Karen Buxbaum, Mars program planetary projection manager from the Jet Propulsion Laboratory. The ice caps are believed to contain organic compounds, which, in turn, could help answer the question of whether life existed--or exists--on Mars.
This will be followed in 2009 with the ambitious Mars Science Laboratory, the first vehicle that will be able to guide itself over the surface of the planet and take samples with a wide variety of probes, drills and cameras.
By 2014, the Astrobiology Field Lab, a surface robot, will launch rockets of its own to return soil samples back to Earth. In 2018, the Deep Drill Lander--for digging holes deeper than a few feet--will land.
During years when robotic rovers and labs aren't landing on the surface, NASA plans to launch reconnaissance scouts to capture images and relay information from surface vehicles, Buxbaum said.
"A Mars sample return is on the horizon," she added.
The complexity of cleanliness, however, grows with each mission. A sock made of Kevlar and Mylar, for instance, is being designed for the probe arm of Phoenix to prevent contamination from Earth to Mars. Techniques also have to be devised for sterilizing hardware, which sometimes can be hurt in high-heat sterilization, and for breaking any biological links between the two planets.
When samples of Martian soil hit Earth in self-propelled metal containers in 2014, scientists want to make sure that the inside samples are active but that the exterior skin of the craft is clean. The return rocket will likely be programmed to land somewhere in the desert. Conceptually, the research in bio-isolation will pave the way for humans to land on the surface.
The issue of Earth inadvertently contaminating other planets was first raised in the 1950s. An outer-space treaty in 1967 then made it U.S. policy to try to prevent infections.
The idea of infecting other planets, however, became a more distinct possibility seven months after the launch of the Mars Viking probe in 1975, Rummel said. It was then that scientists discovered deep-sea hydrothermal vents, which teem with microorganisms.
"It illustrated our ignorance of the planet," Rummel said. Since then, microbes have been studied in caves, dry deserts and volcanoes.
"At Mount St. Helens, even when the rocks are too hot to handle, they are covered with microbes," he said.
