University of Washington
An artist's conception shows a space station, at left, firing a stream of magnetized ions at a transport spacecraft with Jupiter in the background.
By Alan Boyle Science editor
updated 10/19/2004 8:41:03 PM ET 2004-10-20T00:41:03

A novel propulsion system, involving a beam of magnetized ions, could reduce the round-trip travel time for a trip to Mars from more than two years to as little as 90 days, the project's leader says.

The "mag-beam" concept, advanced by a team at the University of Washington, envisions establishing beam-generating space stations near Earth and Mars. At the start of the trip, the Earth station would focus its particle beam on the magnetic sail of a Mars-bound space taxi, pushing it to speeds of tens of thousands of miles an hour. During the approach to Mars, the Red Planet station would fire its own beam to decelerate the spacecraft.

"We're trying to get to Mars and back in 90 days. Our philosophy is that, if it's going to take two and a half years, the chances of a successful mission are pretty low," said Robert Winglee, an Earth and space sciences professor who is leading the university's project.

Two and a half years or so is the standard estimate for the length of a human mission to Mars — but that time frame raises concerns about the health effects of long-duration spaceflight, such as bone loss, muscle loss, radiation exposure and psychological isolation. Anything that can reduce the travel time would make Mars missions much more doable.

The mag-beam system would eliminate the need for a transit vehicle to carry its own interplanetary propulsion system. "Rather than a spacecraft having to carry these big powerful propulsion units, you can have much smaller payloads," Winglee said.

The space stations themselves would have to carry megawatt-scale beam generators, however. "It can be nuclear-powered, or it could be solar electric with some fuel cells attached," Winglee told me.

The concept is a spin-off of an earlier scheme Winglee was investigating, known as mini-magnetosphere plasma propulsion, or M2P2. The earlier concept called for creating a magnetic bubble around the transit spacecraft, which would then be pushed outward by the solar wind.

The mag-beam idea is an improvement, Winglee said, because M2P2 "was considered too passive, and it was problematic as to how you could provide a test in the laboratory that you could easily scale."

Winglee said mag-beams would work better than light-based space-sail systems because of the issue of beam divergence over the vast distances of space. "What mag-beam offers, compared with the other methods, is an amount of self-focusing," he said. The space station's emitter would be magnetically linked to the space taxi's sail, providing a built-in guide for the ion beam.

If it works, the mag-beam approach would open up "a lot of new trajectories," and could make quick trips to other parts of the solar system routine, Winglee said. Mag-beam units could be installed on space probes going to deep-space destinations for other purposes — for example, the Jupiter Icy Moons Orbiter . Those probes could then serve as the remote robotic space stations for the first wave of taxi-borne explorers.

The mag-beam system is one of 12 proposals that has just received a $75,000, six-month grant from the NASA Institute for Advanced Concepts, or NIAC. If the idea is validated at the end of those six months, the team could receive as much as $400,000 more over two years.

Winglee said the first outer-space tests of a mag-beam system could be conducted within five years, using suborbital sounding rockets. But what about Mars? NASA officials have said the first humans could be sent to the Red Planet in 20 or 30 years . Winglee says the mag-beam can be ready by then.

"We could easily do it by 2020, if we were continuously funded," he said.

This report originally appeared as a Cosmic Log item on Oct. 15, 2004.

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