Taking Out the Trash in Space

July 23, 2007 — -- NASA astronauts at the International Space Station literally took out the trash today when they got rid of two pieces of old equipment by hurling them it into space.

Astronaut Clay Anderson, who took care of the hoisting, told Mission Control, "I will be sending my bill in the mail — space trash disposal." Anderson is on the first spacewalk of his career and he clearly had a blast tossing first an unwanted 212-pound camera mount, then a 1,300-pound ammonia tank.

Perched on the end of the space station's fully extended robot arm, Anderson tossed the unwanted equipment into space as the station orbited 220 miles above the south Atlantic Ocean.

Wind Up the Arm

NASA tries to avoid throwing out space junk, but it doesn't have a lot of options — especially with the larger piece.

That item is a coolant storage unit on the outside of the space station -- an EAS, short for early ammonia servicing unit. It's now been replaced by a more powerful system, and the old unit is in the way. It is heavy and big — big enough that no one at NASA takes the decision to toss it overboard lightly.

Kirk Shireman, deputy space station program manager, said there are several questions to ask before deciding to toss something overboard: "Is it safe for the International Space Station? Is it safe for any other orbiting vehicle? Is it safe for people on Earth? Does it make sense from an overall problematic risk standpoint?"

Anderson and Russian cosmonaut Fyodor Yurchikhin went outside in their pressure suits, and Anderson held onto the EAS, while his partner undid the bolts that held it in place.

Anderson had his boots locked into footholds at the end of the station's robot arm, operated by cosmonaut Oleg Kotov, who was inside the space station.

Then, when the robot arm was fully extended, Anderson gave the EAS a good shove — enough, engineers hope, that it goes tumbling away from the station at a speed of about 3 feet per second.

NASA's Shireman said the goal is to put it into an orbit so that it won't collide with the space station. "Picture grabbing hold of a refrigerator," he said. "What is important is the initial velocity with which he throws it."

Shireman added, "I've played baseball with Clay Anderson, and I've seen him pitch. He can do this."

Space Junk Common

The numbers are staggering: 13,000 pieces of junk, each of them more than 30 feet long, are orbiting in space.

There are at least an additional 100,000 hunks of junk that measure between one and 10 centimeters — roughly one half to 4 inches. The number of pieces smaller than one centimeter orbiting Earth is in the millions.

It's a mess up there.

Why does NASA care so much about all the space junk? Because it only takes one tiny object, flying at thousands of miles an hour, to punch a catastrophic hole in the International Space Station or a space shuttle.

SuitSat

Space station crew members have a colorful history of shoving items into orbit. Perhaps their biggest hit was SuitSat 1 in 2006, an old Russian spacesuit stuffed with trash from the station and equipped with a battery-powered transmitter.

A cosmonaut tossed it overboard during a spacewalk and watched it tumble slowly away, looking ominously like a lost colleague. It sent weak radio signals that enthusiasts tracked from the ground and it orbited for several months. SuitSat was so popular the Russian Space Agency is considering doing it again.

Cosmonaut Panel Vinogradov hit a gold ball into orbit Thanksgiving Day as a publicity stunt for a golf club manufacturer. The golf ball stayed in orbit for only a few days.

Most space junk burns up in the atmosphere without ever reaching the ground. Occasionally, parts of larger objects survive re-entry, though most of it falls harmlessly into the ocean or onto unpopulated land. NASA knows of only one person ever hit by space junk — a woman in Oklahoma who felt a tap on the shoulder from a piece of rocket insulation, wafting to the ground.

The EAS may be large enough for parts to reach Earth, though NASA said it's not terribly concerned.

How long will it take for the EAS to lose enough altitude that it finally breaks up in Earth's atmosphere? Shireman said probably months.

Where might any remains end up? That's anyone's guess.