Packing for Mars: The Curious Science of Life in the Void

by Mary Roach

The term “zero gravity” is misleading when applied to most rocket flights. Astronauts orbiting Earth remain well within the pull of the planet’s gravitational field. Spacecraft like the International Space Station orbit at an altitude of around 250 miles, where the Earth’s gravitational pull is only 10 percent weaker than it is on the planet’s surface.

When you launch something into orbit, whether it’s a spacecraft or a communications satellite or Timothy Leary’s remains, you have launched it, via rocket thrust, so powerfully fast and high and far that when gravity’s pull finally slows the object’s forward progress enough that it starts to fall back down, it misses the Earth. It keeps on falling around the Earth rather than to it. As it falls, the Earth’s gravity keeps up its tug, so it’s both constantly falling and constantly being pulled earthward. The resulting path is a repeating loop around the planet.

The tougher question is not “Is Mars possible?” but “Is Mars worth it?” An outside estimate of the cost of a manned mission to Mars is roughly the cost of the Iraq war to date: $500 billion. Is it similarly hard to justify? What good will come of sending humans to Mars, especially when robotic landers can do a lot of the science just as well, if not as fast? I could parrot the NASA Public Affairs Office and spit out a long list of products and technologies* spawned by aerospace innovations over the decades. Instead, I defer to the sentiments of Benjamin Franklin. Upon the occasion of history’s first manned flights—in the 1780s, aboard the Montgolfier brothers’ hot-air balloons—someone asked Franklin what use he saw in such frivolity. “What use,” he replied, “is a newborn baby?”

The nobility of the human spirit grows harder for me to believe in. War, zealotry, greed, malls, narcissism. I see a backhanded nobility in excessive, impractical outlays of cash prompted by nothing loftier than a species joining hands and saying “I bet we can do this.” Yes, the money could be better spent on Earth. But would it? Since when has money saved by government red-lining been spent on education and cancer research? It is always squandered. Let’s squander some on Mars. Let’s go out and play.