Renowned theoretical physicist Stephen Hawking caused a bit of a stir this week when he suggested during a talk in Hong Kong that humans need to get off the earth and colonize space.
“It is important for the human race to spread out into space for the survival of the species,” Hawking said. “Life on Earth is at the ever-increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers we have not yet thought of.”
He predicted we will colonize the moon within 20 years and Mars within 40 years, assuming we don’t self-destruct in the meantime.
Reactions to Hawking’s rather off-the-cuff remarks have been mixed. Advocates of human space exploration predictably loved the media coverage, while more pessimistic types scoffed at the notion.
Actually, Hawking’s notions are not original or even ground-breaking. Even Pres. George W. Bush, in a lame imitation of JFK’s famous 1962 challenge to land a man on the moon by the end of the decade, has made human missions to the moon and Mars as a goal of the US space program. NASA developed — on paper anyway — lunar colonies back in the 60s and orbiting space colonies in the 70s. And of course science fiction writers have been kicking around the idea for more than 100 years.
So, is Hawking off his rocker, or is there some merit in putting humans in space?
We have the technology, to be sure. We have sent men to the moon and brought them back safely. We have placed people in orbit, sometimes for months at a time, with relatively few fatalities. We understand the dangers of space flight and the health risks of longterm exposure to “zero-g” conditions.
The question is do we have the will, and willingness to spend the necessary funds to attempt such an expansion of humankind into space? And more importantly, can we manage to avoid ruining our habitations “out there” the way we are destroying our home world right now? (Imagine food wrappers on the lunar surface.)
While we have the technology, setting up habitats on the moon and Mars present many challenges. Living on the moon or on Mars would make living in Antarctica look like a picnic in the park.
The moon is logical stepping stone to Space, and a handy proving ground for a martian colony. As Hawking noted, it is nowhere near as hospitable as Earth.
It has one-sixth our gravity, so a 240-pound person would weigh only 40 pounds there. It has no atmosphere, and thus no ozone layer, no weather. Daytime and nightime each last about 14 Earth days, as the moon actually rotates just as fast as it revolves around Earth.
So, moon colonists would need to adjust their normal patterns of motion and physical exertion, since the lower gravity would throw off their normal reactions and coordination, and tempt them to lift heavy objects faster than would be wise. (Objects still retain their mass and their inertia. Imagine lifting a barbell fast enough off the ground to have it in turn lift you off the floor!) They would also need to adapt somehow to two weeks of daylight followed by two weeks of night.
They would risk overexposure to ultraviolet radiation from the sun and ionizing radiation from space in general, necessitating suitable protection and/or limitations on time spent on the surface. Habitats would need to be built partially underground to provide adequate shielding.
Pitching a tent and digging a hole in the ground will just not work, however. Habitats would have to be “trucked in,” requiring either one very large spacecraft or several smaller ones. The actual building materials for everything (ships and habitats) would have to be hauled out of the earth’s substantial gravity well. In short, that part will be really, really expensive, given our current launch technologies.
The moon’s crust is rich in aluminum and titanium, and with nearly limitless access to solar energy (clear skies for two weeks at a time), we could conceivably smelt and fabricate building materials in situ, given enough time to create the necessary infrastructure.
Bigger issues are water and oxygen. Satellite reconnaissance of the moon suggests there may be water ice in the shadows of some craters near the poles, raising hopes of similar formations under the surface. Oxygen is contained in the surface, chemically bound to other elements, so producing enough oxygen may not be a major problem.
So, if we as a species manage to commit the trillions of dollars necessary to create a moon colony, it is certainly possible to have one in place within 20 years, as Hawking suggests.
Mars’ surface gravity is about half Earth’s. So that 240 pound astronaut would weigh about 120 pounds. Mars has an atmosphere, though it is very thin and not at all breathable. Martian astronauts would still need space suits and air tanks, and end up bouncing around a lot like their lunar compatriots.
Mars has weather, principally wind and duststorms. The tenuous atmosphere does a poor job of blocking radiation, necessitating suitable protection, and a poor job of retaining any solar heat. A warm day on Mars is a comfortable -20 C (well, if you’re from Siberia). Night time lows are below the freezing point of carbon dioxide. Brr. Bring a scarf.
Whether Mars has enough native water and bound oxygen are still big questions, though the evidence supports the notion that Mars had both liquid water and probably gaseous oxygen billions of years ago. Getting to the water and oxygen may be about as difficult as it will be on the moon.
The clincher, though, is the distance involved. The moon is a mere 384,000 km (240,000 miles) away; getting there takes a matter of days. Mars, however, is millions of kilometers away; getting there will take at least several months using the most advantageous trajectory.
[Mars missions will probably coast on the way to their destination, using a booster burn and the earth’s greater orbital speed to sling them toward Mars. So, a Mars-bound ship will follow a long curved path, a transfer orbit (see also the Interplanetary Transfer Network), between the two planets.]
So, a Mars colony is two, two, two missions in one. The first part involves building a ship large enough to hold a complement of hardy astronauts, enough food, water and air to sustain them for at least two years, and enough fuel to get them to Mars and hopefully back home again. The second
mission is to obtain a foothold on the martian surface, and to do so without the expectation that help from home will be on its way in a few days’ time. It will be a sink-or-swim deal.
If colonizing the moon will take trillions of dollars, getting humans to Mars and back will be even more expensive. It can still be done. It does not require exotic technology. It just requires the will and the willingness to spend a crapload of money.
Neither project will be popular so long as there are people on the earth who are poor, ill fed and in bad health. The oldest objection to human space exploration has been that it diverts resources away from more pressing human needs (and so-called “legitimate” scientific exploration using robot probes). Humans are unable to see the longterm advantages of human habitation of space — such as Hawking’s preserving the species — while counting pennies.
The more visionary among us, however, see human exploration of space as just another chapter, albeit a formidable one, in the expansion of human habitation across our homeworld. There are potentially lucrative projects in space as well, so commercial interests may get there before
government agencies do.
Hawking, now 64, has not lost his youthful wonder about nature, and space, I guess. Maybe some stodgier science types are now too caught up in their research projects and grant proposals to remember those “gee whiz” days of yore. For them, Hawking is a space cadet.
For me, he’s a wing commander. Like the Russian rocket scientist Konstantin Tsiolkovsky, Hawking perhaps realizes that “Earth is the cradle of humanity, but one cannot remain in the cradle forever.”
To space … and beyond, Dr. Hawking!