The Problem: Cosmic Storms
Earth’s atmosphere and magnetic field protect us from the constant stream of harmful solar radiation and other occasional deadly particles from deep space. Venturing beyond Earth’s protection is a gamble. But how dangerous is it?
Nuclear accidents and attacks show that short, severe exposure to radiation is deadly for humans. During solar storms, space-farers hunker in shielded areas of their stations akin to tornado or bomb shelters. But scientists still don’t know how the human body will react to sustained low-level doses of radiation inherent in space travel. There are few ethical ways to find out, however: An accidental decades-long exposure in Taiwan suggests it’s not as simple as “more radiation is bad.” When 1,700 apartment buildings were unintentionally exposed to radiation from 1983 until 2005, residents actually had lower rates of cancer and birth defects.
The Solution: Gimme Shelter
Scientists still don’t have a solution for shielding interplanetary astronauts from radiation. But a space station in equatorial low-Earth orbit (ELEO) would sit inside Earth’s magnetic field. It would receive most of the benefits of radiation shielding that ground-dwellers enjoy. Al Globus, a researcher with San Jose State University and NASA Ames Research Center, has put a lot of thought into such a dwelling. “ELEO is the best place for [safe] radiation by a large margin,” he says.
For people who want to travel beyond Earth’s magnetic field, the only other safe and long-term option might be underground. Hiding some 15 feet under the surface of Mars or the moon would provide all the radiation shielding of home.
Both those worlds also have natural caves. Ancient underground lava flows have carved tube-like caves that can stretch up to 1,000 yards wide and extend for many miles. Occasionally, parts of the cave ceiling can collapse, creating a large skylight opening. By securing these natural skylights with thick glass, the vast interior spaces could be pumped full of air and used as a pre-fab home. “You can imagine setting up a large mirror farm on the surface to bounce light into the tunnel,” says Jeff Greason, CEO of Agile Aero and an aerospace expert. Such a setup would bring sunlight to living or green spaces. Humanity’s future could look much like our past in Earth’s caves.