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MARS TRAVEL HAZARDS
By Sean Henahan, Access Excellence
Washington, D.C. (1/20/97)
The discovery of what appear to be ancient bacterial fossils on a Martian
meteorite may be leading NASA to reconsider the idea of a manned mission
to the red planet. But such a trip won't be possible unless scientists first
determine a way to protect the astronauts from the radiation hazards associated
with such a trip, according to a new study from the National Research Council.
Cancer and brain damage are two potential risks associated
with long-term exposure to the kind of high-energy galactic cosmic rays
interplanetary astronauts would encounter. The problem is, very little research
has been done on the degree of danger this radiation poses or on what kind
of protective shielding would be needed. And it is not likely that such
research will ever be done unless $10 billion or more can be budgeted to
the project, the NRC panel says.
Conducting the needed physical and biological research
will require significant access to ground-based particle accelerator facilities
that can generate high-energy particles like those that will bombard a craft
in deep space. Even if adequate facilities, staff, and funding were devoted
immediately to this research, it would probably take more than a decade
to answer questions about health risks and the needed protective shielding.
At NASA's current rate of research in this area, more than
20 years will be needed to provide adequate data. This could delay a Mars
mission beyond the next quarter century, or may result in use of excess
shielding and therefore higher costs than necessary.
The NRC report suggests NASA explore a number of possibilities
for increasing the time that is allotted to the needed research at appropriate
particle accelerator facilities. These options include reserving more time
at a currently operating facility, expanding existing facilities, building
a new accelerator dedicated to this research, or collaborating on international
studies conducted at overseas accelerator facilities.
Wherever the research is done, a number of important questions
need to be answered, the report says. These include:
- What are the cancer risks of exposure to the protons
and high-energy nuclei of galactic cosmic rays?
- How do the thickness and composition of shielding affect
the rate of cell death and chromosome aberrations induced by this radiation?
- Estimates of human genetic risk are based on studies
of radiation-induced genetic alterations in rodents. Can studies be conducted
that will increase confidence in these estimations?
- Is there a risk to the central nervous system from exposure
to heavy ions at the level that would occur during long missions in deep
space?
- How do the selection and design of the space vehicle
affect the radiation environment in which the crew has to survive?
The study was funded by NASA. The National Research Council
is the principal operating agency of the National Academy of Sciences and
the National Academy of Engineering. It is a private, non-profit institution
that provides science and technology advice under a congressional charter.
A task-group roster follows.
Copies of "RADIATION HAZARDS TO CREWS OF INTERPLANETARY
MISSIONS: BIOLOGICAL ISSUES AND RESEARCH STRATEGIES" will be available
in February 1997 from the National Academy Press; tel. (202) 334-3313 or
1-800-624-6242.
Related information on the Internet
NASA:
Human Space Flight
National Academy
of Sciences
AE:
Exobiology Interview with Dr. Stanley Miller
AE: 8/96 Life On Mars?
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