Image: NASA |
Most planets in the solar system, including our own, have a remarkably effective shield against solar radiation: the magnetosphere. Indeed, without the protection of this magnetic bubble, solar winds and solar flares might render Earth as barren as Mars or the moon, both if which are bubble-less. Intriguingly, the magnetosphere also acts as a kind of sail. Although Earth is far too massive to be blown around like a boat, some scientists wondered whether enveloping a far smaller object, like a spacecraft, with a magnetic bubble might enable it to ride solar winds, protected all the while against cosmic rays and solar flares. The idea of using mini-magnetospheres in propulsion originated a couple of years ago. Now, far-fetched though it might seem, researchers from NASA and the University of Washington have just completed the first round of lab tests.
Marshall Space Flight Center physicist Dennis Gallagher and his colleagues built a suitable bubble with the help of a special ingredient: ionized gas, or plasma; hence they named the project Mini-Magnetosphere Plasma Propulsion (M2P2). "We were able to completely fill the vacuum chamber with a magnetic bubble," Gallagher reports. "The only thing that stopped the expansion was the presence of the chamber walls." He further notes that conducting this same experiment in space might yield a 15-kilometer-wide mini-magnetosphere."If we launched a space probe now equipped with such a bubble it would easily overtake Voyager and become the first spacecrafct from Earth to cross the boundary into interstellar space," Gallagher remarks. "I like to think of M2P2 as the first externally powered fusion engine. The engine is the sun itself¿M2P2 bubbles just ride along on the exhaust." The second round of tests, slated for 2001, should shed more light on the feasibility of using magnetic bubbles to surf the solar winds.
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