ESA's ATV-3 departs the ISS. Photo Credit: NASA TV
The European Space Agency's third Automated Transfer Vehicle departed the International Space Station late Sept. 28 with a final assignment: relay the destructive events surrounding its controlled plunge into the Earth's atmosphere over the Pacific Ocean to an Aerospace Corp. research team.
Re-entry is set for late Oct. 2.
Data gathered and relayed to researchers by the Re-entry Breakup Recorder installed by the station's crew aboard the ATV-3 Eduardo Amaldi before the re-supply craft pushed away could influence the design of future orbital spacecraft to address the mounting orbital debris problem.
Efforts to discard the trash-filled freighter on Sept. 25 were delayed by an error in the command link between the station’s Russian segment and the ATV-3, then by concerns that two pieces of orbital debris would pass close enough to the outpost and its three-member crew to require an avoidance maneuver.
By facilitating breakups that won't rain dangerous debris all the way to the Earth's surface, design changes could encourage greater reliance on random breakups to slow the growing accumulation of debris from aging satellites and spent rocket bodies circling the planet.
"We have a number of large object re-entries every year," William Ailor, REBR's Aerospace principal investigator, explained on NASA Television earlier this week. "And these objects that come in randomly can be large enough to cause hazards on the ground. That is one reason we want to know how things break up, to assess that hazard."
NASA's Upper Atmospheric Research Satellite, a 21-year-old decommissioned environmental spacecraft, carried out a widely reported uncontrolled re-entry on Sept. 24, 2012, without causing harm. With hardly any fanfare, five rocket and satellite fragments, some launched as long ago as 1978, have plunged back to Earth in a similar fashion since Aug. 1, according to an Aerospace Corp. count that illustrates uncontrolled re-entries are common.
William Ailor, Aerospace Corp principal investigator, with REBR. Photo Credit: NASA
As part of the REBR experiment, researchers are using the carefully controlled re-entries of larger European as well as Japanese ISS re-supply craft as test beds to study the breakup process. If there are lessons that can be applied to spacecraft lacking the costly propulsion systems of the Japanese and European freighters, the expense of re-entry to reduce the orbital debris problem drops substantially, Ailor explained.
The ATV-3's nine pound REBR package, placed near the crew access hatch, is essentially a cell phone with a heat shield surrounded by a copper shell.
As the ATV-3 re-enters, REBR will begin to log accelerations and attitude rates as well as temperature and pressure changes. Once it breaks free of the disintegrating capsule, the cell phone transmits the data through the Iridium satellite constellation so that it can be formatted on a web page.
REBR is two for three, successfully transmitting data as Japan's HTV-3 and HTV-2 ISS re-supply ships re-entered on Sept. 14 and March 30, 2011. Data was not captured as ESA's ATV-2 re-entered on June 11, 2011.
The ATV-3 undocked from the station's Russian segment at 5:44 p.m., ending a six-month stay.
Launched on March 23 from the European spaceport in Kourou, French Guiana, the unpiloted ATV-3 docked five days later, delivering over seven tons of cargo.