When astronauts sent back to Earth the iconic Blue Marble image in 1972, the picture galvanized the nascent environmental movement, demonstrating to the public how "tiny, vulnerable, and incredibly lonely" our planet is.
Ironically, a society capable of taking that photo is also one that is capable of grave environmental damage. As engineer Laurent Pambaguian put it to me, we're "living at a time when life is comfortable and we have not destroyed the planet yet.” That time may not be long.
Not your average, terrestrial environmentalist, Pambaguian is part of the European Space Agency’s Clean Space Initiative, which claims that “reaching for the sky leaves footprints on the ground.” It seeks to understand the environmental impact of space exploration, then find ways to reduce it.
“Before, we didn’t take too much care. ‘There is plenty of room in space,’ we thought. Then we realized the room was very crowded,” says Pambaguian. NASA claims that more than 500,000 pieces of debris, ranging from the size of a marble to eight tons, are in orbit. These scattered fragments travel at speeds up to 17,500 mph. In the forthcoming movie Gravity, a piece of satellite debris destroys a shuttle, but even much smaller objects such as chips of paint could damage a satellite, space station, or a spacecraft carrying astronauts.
Left uncollected, the debris stands to collide, creating clouds of fragments that would lead to an irreversible pollution problem. A 2009 study performed by all the major space agencies—including ESA, NASA, and Roscosmos—revealed that even if no further space launches occur, the amount of orbital debris will continue to increase. More than simply littering Earth’s low orbits, we would be hindering our ability to safely travel beyond it.
The only way to preserve key orbits is to remove the debris, like picking up scraps of refuse blowing down a highway. Debris experts recommend removing at least five objects every year for the next 50 years. The approach shouldn’t leave debris behind as it cleans up the sky.
“It’s an extremely challenging mission,” says Luisa Innocenti, the head of the Clean Space Office. “Getting close to the debris is dangerous because you need to maneuver around the uncontrolled object.”
This means developing a guidance and navigation control system where chasers stay close to the targeted debris. A capturing mechanism—a big net, a harpoon, a robotic arm, or a giant tentacle that, amid the stars, would clamp down on the object—would collect the debris and return it to Earth. The goal is to have a mission in 2022.
Innocenti also emphasizes the need to design satellites that won’t become debris once they reach the end of their expected five-to-10 year life spans. Most satellites are equipped with collision avoidance maneuvers—until the last bead of propellant burns away and their uncontrolled orbits begin. The Clean Space Initiative is developing technology for satellites to return to the Earth’s atmosphere where they can safely burn down (called Design for Demise).