Before humans sojourn to Mars, there is early need to assess risks to astronauts by possible environmental, chemical, and biological agents on the surface of the planet, a trio of experts told the President's Commission on Moon, Mars and Beyond, on the campus of the Georgia Institute of Technology in Atlanta, Georgia.
Highlighted during a Commission panel session was the report, Safe on Mars: Precursor Measurements Necessary to Support Human Operations on the Martian Surface . That report was completed in May 2002 by the National Research Councils (NRC) Aeronautics and Space Engineering Board and undertaken by a special Space Studies Board group.
Many unknowns
Great care must be taken in scripting the very first human missions to Mars "when the unknowns are the greatest and the steps taken must be the most cautious," said former shuttle astronaut Frederick Hauck, now President & CEO, of AXA, a space insurance firm. Hauck also led the NRCs Safe on Mars study.
"The greatest threats to the safe movement of humans and critical equipment on the surface of Mars will likely be degradation of mobility, instability that could result in the toppling of a human or robot, collision of human and robot, or robot-with-robot and mechanical failures of critical components," Hauck told Commission members.
Returning soil and or airborne dust samples to Earth to evaluate and quantify these risks prior to the first mission may be necessary, Hauck said. These samples could help engineers design filtration hardware that might deal with hazardous materials on Mars.
Chemical villain in the soil
The truth is we dont know how dangerous Mars is, said Harry McSween, Jr. of the University of Tennessee. He is also a Mars Exploration Rover scientist, working with the results of the Spirit and Opportunity robots now wheeling about on the red planet.
One toxic metal that appears to be worrisome, McSween said, is hexavalent chromium. "It was the chemical villain in the movie Erin Brockovich," he said. This is the most carcinogenic substance known and causes cancer in lowest concentration of any material yet seen, he added.
There are some reasons to think that Mars soil may indeed contain hexavalent chromium, McSween said. He noted that he personally believes that defining the dangers lurking in the martian soil likely demands bringing samples back to Earth for analysis within terrestrial laboratories.
The NRC study found that, while small amounts of certain metals may not affect the astronauts immediately, they could have long-term effects, such as cancer. Robotic sampling of soil and airborne dust could determine the presence and extent of any harmful organisms or compounds. If certain experiments, such as testing for chromium, cannot be conducted on the Mars surface, a sample must be returned to the Earth for evaluation.
No trespass zones
McSween said that NASA should consider a tactic for green-lighting where astronauts should land on Mars. That is, adopt "zones" that are less risky to astronauts in terms of chemical or biological risks.
These zones would be operational areas on the martian surface determined to the maximum extent practical to be devoid of life or to contain only life forms that are not hazardous to humans or to the Earths biosphere, McSween advised.
"We dont know how dangerous this place [Mars] is," McSween said, "but there is the potential from both the chemical and a biological point of view that could be significant risks. We need to find out sooner rather than later what those risks are so that we can mitigate them."
Irony at work
Pre-qualifying where astronauts should trek should take into account both surface and subsurfaceto look ahead of time for bad things. "If none of them pop up then you are safe," McSween said.
"Its a little ironic that the very thing that makes Mars a very interesting place to explore may be the most dangerous thing to humans on the planet. And that is the possibility of some life form," McSween emphasized.
While flagging the issues of astronaut safety, McSween said that he anticipated a human mission to Mars as "medium risk" proposition. "The risk is probably more from the problems in dealing with microgravity and radiation than it will be from the martian environment," he concluded.
Radiation exposure
Ronald Turner, Principal Physicist, for the ANSER Corporation, pointed to unknowns concerning radiation doses reaching Mars surface. "Radiation exposure will be a significant and serious hazard during any human expedition to Mars," he said.
Turner said that NASA has implemented an Earth-based ground program to characterize radiation risks. However, radiation measurements taken right on the red planets surface is a priority to ensure the safety of the first human mission to Mars, he added.
Both Spirit and Opportunity Mars rovers do not carry radiation detectors, Turner said.
advertisement
