NASA to Dump Junk in Space

July 19, 2007 — It's not the politically correct way to dispose of trash, but NASA says it has no better option than to dump from the International Space Station a refrigerator-sized container holding ammonia and a 200-pound camera stand.

Station flight engineer Clay Anderson will do the deed during a spacewalk planned for Monday.

"We agonized over this for a very long time before we came to this decision," space station deputy manager Kirk Shireman said in an interview. "It sounds bad."

NASA is not as concerned about its image as it is about the potential damage the ammonia container, which weighs more than 1,400 pounds, could do after it falls from orbit in about a year. Pieces as big as 39 pounds could survive re-entry and crash on Earth.

The U.S. space agency calculates the odds of the debris hurting or killing a person at one in 5000. That sounds high, but consider that engines flown on the country's heavy-lift Delta and Atlas rockets have a one in 1,000 chance of affecting a person.

The objects are so big that military radars will have no problem keeping track of them in orbit and will be able to pinpoint their fall through the atmosphere up to about two hours prior to re-entry, said Johnson Space Center spokeswoman Lynnette Madison.

That should allow ample warning if the debris seems headed for a populated area. The remains most likely will end up in the ocean, said space station flight director Bob Dempsey.

NASA originally planned to return the equipment aboard a space shuttle, but with only 14 flights to the outpost remaining before the fleet is retired there's no room to fly the carriers that would be needed to transport the gear in the cargo bay, Dempsey said.

Engineers are more concerned with the immediate effects of tossing away such large pieces of equipment. To make sure the items don't hit the outpost during their first few orbits as free-flying objects, NASA plans to boost the station's orbit a few hours after the equipment is jettisoned. Several other altitude adjustments may be necessary over the coming months.

The ammonia container is too bulky for Anderson to do much more than just push it away. He will be anchored to the station's robot arm during the jettison and the station will be flying backwards to give the departing wares a bit more momentum.

NASA has shed objects in space before, including a large solar array wing on the Hubble Space Telescope that could not be folded up to be brought back home in the shuttle's cargo bay.

More recently, some sun shields that were protecting equipment on the space station were tossed away, but they were lightweight and were easily incinerated as they were pulled through the atmosphere.

NASA launched the ammonia container in 2001 to replenish coolant in the station's first thermal control system, which has since been replaced. It was designed to withstand the space environment for five years. NASA reassessed the device and gave it another year in space before deeming it at risk of structural disintegration, which could pose a danger to the station and its crew.

The camera stand, which weighs about 212 pounds, is expected to be completely destroyed during re-entry. The device is no longer needed and is taking up valuable space on a stowage platform intended for other equipment.