This week the New York Times is carrying an Op-Ed piece by Seth Shostak, an astronomer with the SETI institute, about how we will never make it out of our own solar system. I find it greatly amusing that someone who works for SETI - possibly the single most heedlessly optimistic science program operating in the world today - is the one to throw down the wet blanket on dreams of interstellar travel.
Shostak, the little buzzkill, points out the obvious: given the technology currently at hand, interstellar travel is simply not feasible.
"[…] such sci-fi crafts would get embarrassingly bad mileage. The energy required to reach even the nearest stars in a decade or less with a very modest-size starship (say, the tonnage of the 17th-century Mayflower) equals the total energy consumed in the United States last year. At 10 cents per kilowatt-hour, that's a fuel bill of $5 trillion."
Blah blah blah! YES OKAY, if you do the math, interstellar travel is not actually possible today, or in the near future. Although I find it interesting that Shostak does not do the math on ram scoop designs, since it's my understanding that these are the most plausible of the current space travel offerings.
Instead, Shostak posits that the most likely way to journey to the stars is with very small robots, which send their signals back to Earth. (That sound you hear is me, giggling with delight that of course this is what a SETI guy would posit.) Our telepresence technology is robust and developing quickly, and micro-robots would be considerably easier to ship outside the solar system. Tiny robots are far easier to ship, requiring little in the way of atmosphere, fuel, or gravity - unlike human travelers.
One interesting point about this argument which Shostak didn't address is that micro-robots would make for a far more egalitarian exploration of the universe. When we watch science fiction, we always imagine ourselves being there with the crew. The truth is that 99.999% of humanity is left behind on Earth, while the remaining .001% gets to travel into space. ("A new life awaits you in the Off-world colonies" not withstanding.)
Statistically, none of us would be the ones out there exploring the new frontier and pooping into bags. However, if micro-robots explored and reported back with a vast array of sensory data, all of us could see it at the same time. Only a tiny handful of people visit the Maldives every year, but we can all look at them with Google Earth.
The second point that can be made from Shostak's argument (which is probably correct, sad as I am to say it) is that we will not be finding and inhabiting new planets any time soon. If we're lucky and very very smart, we'll get Mars into semi-habitable shape within the next 100 years. (Kim Stanley Robinson's Mars Trilogy spanned almost 200 years, from dusty red planet to watery oasis.)
I think a lot of science fiction fans are secretly hoping that interstellar travel and colonization will be the end solution to all of our problems here on Earth. But, as Shostak points out, that's just not going to happen. (I wonder if the polar bears would like Europa?)