Using fields of force to accomplish goals in space is
a favorite device of science fiction authors. In Larry Niven's award-winning
1970 novel Ringworld,
protection against the harsh environmental hazards of space is provided by a
hybrid system consisting of a General Products hull and the
Slaver stasis field. The
General Products hull is an example of a "passive" or material shielding; the
hull is transparent to visible light and impervious to electromagnetic energy
and matter in any form. The Slaver stasis field creates an area in which time
does not pass; since time stands still, no damage can be done to the material
occupying the space protected by the field.
Former astronaut Jeffery Hoffman is proposing a
different sort of hybrid system to protect future astronauts; on long voyages
through the solar system they will be exposed to lethal doses of radiation from
cosmic rays. He has recieved funding from NASA through NIAC (NASA Institute for
Advanced Concepts) to research the idea of a superconducting magnetic radiation
shielding system to supplement (or replace) traditional passive
shielding.
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Isn't this cozy:
Magnetic fields protect astronauts while supplying
drive.
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The idea of using a magnetic field to shield a craft
from radiation is not new; as Dr. Hoffman points out "the Earth has been doing
it for billions of years!" Using magnetic shielding was proposed in the late
1960's, but not pursued after plans for further space exporation were scrapped.
Two types of radiation need to be addressed,
according to William S. Higgins, an engineering physicist who works on radiation
safety at Fermilab, the particle accelerator near Chicago, IL:
- Solar flare protons (which would come in bursts
following a solar flare)
- Galactic cosmic rays (a continuous background
radiation)
The easiest way to protect
against this radiation is to absorb it. However, such shielding can be massive,
and cosmic rays can interact with the shielding and create secondary charged
particles, worsening the situation. The primary benefit of using magnetic
shielding is to save on the mass required for traditional absorption
technologies. The mass of the spacecraft, which must be lifted off from the
Earth and placed in orbit, directly drives the cost of space systems. Reducing
the amount of mass would make space exploration more affordable and therefore
more sustainable over the long term.
Hoffman believes that the best solution may be a
hybrid system using both a magnetic field and some passive absorbtion shielding.
"That's the way the Earth does it," Hoffman explained, "and there's no reason we
shouldn't be able to do that in space."
A related experiment, the Alpha Magnetic Spectrometer
(AMS), is scheduled to be attached to the outside of the International Space
Station and search for different types of cosmic rays. This experiment will be a
practical test of maintaining the magnetic field strength and the near-absolute
zero temperatures of this kind of system in space.
Phase I research studies the shielding efficiency of
the baseline design, and would begin conceptual systems design. Phase II would
provide a detailed comparison of magnetic shielding with traditional passive
absorption technologies, and detail how to integrate the magnetic shield into a
spacecraft.
Read more at Magnetic Bubble Could Protect
Astronauts and Use of Superconducting Magnet Technology
for Astronaut Radiation Protection (pdf).
(This Science Fiction in the News story used
with permission from Technovelgy.com - where science meets fiction.)
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