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The Question

(Submitted April 03, 1998)

Within the next 50 years will it be possible to travel to other stars within our own galaxy? ...outside our galaxy? ...ignoring money, what are the major limiting technologies? Thanks for whatever information you can supply!!

The Answer

It will not be possible to send people to other stars within 50 years. The nearest star to the Sun is about 4.3 light years away, so even if we had a spaceship which could travel at a tenth of the speed of light, we would have to leave in the next seven years in order to get there in time. Right now, we don't even have a space ship which could get to the Moon.

In 50 years, if we work hard, we might be able to build robotic probes which can get to the nearest stars a few decades later. One suggested probe is StarWisp http://wwwssl.msfc.nasa.gov/newhome/headlines/prop08apr99_1.htm

which weighs about half an ounce--not much room for a passenger and life support.

The main problem is that of propulsion. Even using hydrogen fusion, we would need hundreds or thousands of times as much fuel as payload in order to get up to a few percent of lightspeed. Compared to that, the problems of maintaining a life-support system for the decades that the trip will take are trivial engineering details.

As for intergalactic travel, even the over-optimistic Star Trek: Voyager using hyperdrive requires a lifetime of travel just to get from the far side of the galaxy to here. The Magellanic Clouds are only 160,000 light years away, but the nearest big galaxy, in Andromeda, is a couple of million light years away.

Without major breakthroughs in physics, interstellar travel will always require heroic efforts over decades or centuries.

More information is available at http://www.lerc.nasa.gov/WWW/PAO/warp.htm

David Palmer
for Ask an Astrophysicist

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