Lately I’ve noticed that, if I look almost due East in the evenings, I can see Mars rising. There’s something about Mars. Although Venus is the closer neighbor, it’s also closer to the Sun. And a lot less hospitable, although Mars ain’t exactly friendly to human life either. Maybe it’s because Mars seems like the next obvious step in space exploration. We’ve been to the Moon, and I keep hoping we’ll go back, but Mars is waiting. The trouble is I know we’ve got some pretty big hurdles to get over. In his book Centauri Dreams Paul Gilster makes a case for a long-term space mission–an unmanned one–to some of our closest stellar neighbors. He compares it to cathedral building which, even at its medieval peak, took decades–even centuries. The problem, of course, is that scientists haven’t yet developed what’s really needed: a spacecraft that can travel at one-tenth the speed of light, or approximately 18,600 miles per second.
If scientists could develop a spacecraft that could travel at that speed–and if it were safe for humans–we could make the trip to Mars at its most distant point in a matter of minutes*.
The trip to the Alpha Centauri system that Gilster describes, by the way, would take more than forty years. That’s why he compares it to cathedral-building. Some of the people involved in the building and launching of such a spacecraft likely wouldn’t live to see the project’s outcome, since, if the radio signals beamed back to Earth travelled at the speed of light, it would still be years before the information about our stellar neighbors reaches us. He also suggests Barnard’s star, although at almost 6 light years it would take even longer, while Epison Eridani, at 10.7 light years, would take even longer.
A spacecraft travelling even at one-tenth the speed of light would make Mars a day trip, but would probably flatten any human passengers, which just reminds me of the biggest obstacle to reaching Mars: gravity. It’s not just that the spacecraft carrying human passengers would need a tremendous amount of fuel for both the takeoff from Earth and the return from Mars. The trip would also take years, and in zero gravity muscles atrophy while bones disintegrate. Gilster doesn’t even think about human beings in his equations so he doesn’t worry about gravity, but it’s a huge problem for space travelers. In most science fiction the problem’s solved with artificial gravity. If we could manipulate gravity it would solve a lot of problems.
Imagine this: if we could manipulate gravity we wouldn’t just be able to create one-G environments inside spaceships. Potentially we could create zero-G environments outside of spaceships, making it possible to launch a ship using only a small amount of fuel. And maybe we could even alter it so that the ship could travel at incredible speed–say, one-tenth the speed of light–while the ship’s passengers would be comfortable in a one-G environment inside the ship.
The problem is that, while Gilster offers some practical solutions to the problem of reaching the closest star (after the Sun), including antimatter and solar sails, as well as a ground-based laser system that would propel the craft from Earth. Okay, they’re not exactly practical, but at least they’re theoretically possible. As far as I know there’s not even a theoretical model for an artificial gravity device, but I hope someone’s working on it. Sending unmanned spacecraft to the stars is an intriguing idea, but I really want to go to other places. Even if I can’t go myself I find the thought of a human footprint–even a permanent human presence–on Mars more exciting than sending unmanned spacecraft to the stars.
*Please feel free to check my math on this, especially since it doesn’t sound at all right. Mars at its most distant is 250 million miles from Earth. I divided that by 18,600 and got 13,440 units, which, divided by 60, comes out to 224 seconds–or a little over 3.7 minutes. But I think it’s safe to say that even if my math is way off at that speed Mars could still be a day trip.