Mars, and Step on It
When it’s not the journey but the destination that counts.
- By Michael Klesius
- Air & Space magazine, September 2009
(Page 4 of 4)
By contrast, the superconducting magnets corral the power of all that energy and essentially squirt it out the end. “Magnetic fields don’t melt,” says Emrich.
In theory, the engine could unleash a specific impulse of a million seconds. It would need only 1/10th of that to propel a craft to Mars in two weeks. But Emrich notes that to make a fusion-powered spaceship light enough to reach Mars in two weeks, propulsion experts will need a breakthrough in materials science.
“Mars in 30 days?” he says. “That’s getting closer.”
If and when new materials make that possible, Mars may in fact be too close to Earth for a fusion rocket to truly show what it’s got under the hood. A trip to Jupiter, on the other hand, 366 million miles away at its closest approach, would give the crew of a fusion-powered spacecraft almost 183 million miles of acceleration to the journey’s midpoint. By then, a fusion engine delivering about 30,000 seconds of impulse would have gathered a speed of 50 miles per second—about 180,000 miles an hour. After decelerating for the next 90 days, it would slip into orbit around Jupiter; by then, the trip would have lasted 180 days, only six times as long as a one-way trip to Mars, despite covering 10.5 times the distance. True, while the astronauts are exploring Jupiter, Earth wanders farther away than it was at launch time; however, at these speeds, orbital separation between the planets becomes less of a problem.
“The space program began the day humans chose to walk out of their caves,” says Chang Díaz. “By exploring space we are doing nothing less than insuring our own survival.” Chang Díaz believes that humans will either become extinct on Earth or expand into space. If we pull off the latter, he says, our notion of Earth will change forever.
As for Cast Away’s Chuck Noland, he eventually concludes that it would be better to risk it all and die trying to escape his imprisonment than to waste away on the beach. He builds a coarse raft, says good-bye to the island, and rows out to the reef. In a panicky moment when it seems he’s already failed, he barely surmounts crashing walls of surf. Briefly exuberant, he turns for one long, sobering look at the island, its peaks receding on the horizon. Then he turns his back to it, and paddles out to the Pacific in pursuit of his destiny.
Michael Klesius is an associate editor at Air & Space/Smithsonian and a fan of high-speed space travel ideas.