Aug 22, 2008 07:00 AM
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According to the scientists who attended this year's Joint Propulsion Conference in Hartford, Connecticut, humans may never be able to achieve interstellar travel. Aerospace experts from NASA to MIT claim that finding the amount of energy and time we'd need to cross the huge distances involved is out of the realm of possibility. In a recent article, Wired Magazine's Robert Lemos suggested that the JPC's frustrating findings meant humans would never reach the stars. But don't add "space adventure" to your list of unlikely futures for the human species just yet — here are four reasons why.
1. We are likely to develop new propulsion methods.
True, we have not yet reached as far as the Sun, which is only a mere 8 light-minutes away (okay, that's also 150 million kilometers). There are quite a few good reasons for that, but concern about the necessary propulsion for the journey is a main one. Physics dictates that in the vacuum of space, travelers must create their own forward momentum. Rocket propulsion, as MIT professor Ian A. Waitz (now the Head of the Department of Aeronautics and Astronautics) explained to this young engineering student and future io9 correspondent, is not unlike jellyfish propulsion. In order to go far forward, you'd better have a lot of mass to squelch out your back — and at a high velocity, too, because there aren't any helpful water currents in space. As Lemos correctly tells it, we're not quite ready for that yet:
... Using the best rocket engines Earth currently has to offer, it would take 50,000 years to travel the 4.3 light years to Alpha Centauri, our solar system's nearest neighbor. Even the most theoretically efficient type of propulsion, an imaginary engine powered by antimatter, would still require decades to reach Alpha Centauri, according to Robert Frisbee, group leader in the Advanced Propulsion Technology Group within NASA's Jet Propulsion Laboratory.
All right, that is quite a pickle, but a hundred years ago we didn't even know what lift was, and now we have the 110,000-kilogram Boeing 787-8 Dreamliner, which will be carrying almost 300 people over 15,200 kilometers on each of its flights when it enters service in 2009. In 1957 the launch of Sputnik amazed everyone, but by the end of 1969 two men had walked on the moon. The limitations of our current propulsion methods won't necessarily block our star exploration forever.
2. Humans could figure out ways to endure long space journeys.
Why do we keep perpetuating this idea that the voyage to a distant star must somehow fit inside the confines of a current human lifetime? That's not strictly necessary. In the past two thousand years, the expected lifespan of an average human has doubled, and with luck and medical advancement, it might not take that long to double again.
Plus, that suspended animation you saw in Alien or 2001: A Space Odyssey will probably be medically possible for humans, and soon. In 2005, scientists at the University of Pittsburgh found a way to revive dogs after the animals had been clinically dead for three hours, and a group at the Fred Hutchinson Cancer Research Center in Seattle successfully induced suspended animation in mice for up to six hours. Hasan Alam, a trauma surgeon at the Massachusetts General Hospital, led a group that achieved suspended animation in pigs — and the pigs suffered no damage after the process over 90 percent of the time. Alam is now working on clinical trials of suspended animation for humans.
3. Earth is not the only source of fuel.
Lemos presents yet another problem in his article, and this one should sound quite familiar to anyone who gawked at gas prices today:
It would take at least the current energy output of the entire world to send a probe to the nearest star, according to Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute. That's a generous figure: More likely, Cassenti says, it would be as much as 100 times that."We just can't extract the resources from the Earth," Cassenti said during his presentation. "They just don't exist. We would need to mine the outer planets."
Well, as it turns out, the outer planets are a lot closer than the outer stars. Even Neptune is only 0.0004 light-years away from the Earth; a hefty figure when you consider that it's also 4 billion kilometers, but certainly a good deal closer than Alpha Centauri. We still have quite a lot of exploring left to do in our own solar system, and we can probably do that without needing to solve every obstacle of interstellar travel. A new energy resource might just present itself somewhere — and if we don't discover life on any of the planets around the Sun, it's probable nobody will mind if we do a little drilling.
4. We may yet discover a way to achieve faster-than-light travel.
Lemos quotes Frisbee again as saying "any time you try to get something up to the speed of light, Newton is still God." That's probably true — though some Baylor University scientists might beg to differ — but there is quite a lot of knowledge yet to come for human beings, and it could be right here in our solar system. No matter how much information we think we have today, nobody can accurately predict what course space exploration might take after tomorrow's flabbergasting revelation.
So you may not be hitching a ride to Alpha Centauri tomorrow, and your kid might not ever get to do it, either, but let's not jump the gun and rule it out for every human.
According to NASA's Robert Frisbee:
It's always science fiction until someone goes out and does it.
That's the spirit!
Rocket Scientists Say We'll Never Reach the Stars [Wired Magazine]
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