WASHINGTON — A reflector that enables Europe’s Automated Transfer Vehicle (ATV) to perform its unpiloted approach to the international space station (ISS) may have been damaged last month when a hobbled Russian cargo ship docked with the station, a NASA spokesman said May 6.
The Progress cargo ship that reached ISS April 26 had to dock without the benefit of a communications antenna used by the craft’s Ukrainian-built Kurs automated docking system. The antenna failed to extend after launch, possibly leaving its undeployed bulk in the path of the laser radar reflector ATV uses as a navigation aid during its own automated rendezvous.
Ground controllers in Moscow elected to proceed with the Progress docking despite the stuck antenna, uploading a software patch to help with proximity operations and bringing the freighter toward the station’s Zvezda service module at reduced speed.
“The stowed antenna is folded up toward the lip of the docking ring on the forward end of the Progress,” NASA spokesman Josh Byerly wrote in a May 7 email. “That is the part that touches the station and also in the vicinity of the navigation aids that ATV uses when it lines up for docking.”
While the damage — if any — has not been confirmed, concern on the ground about the laser radar reflector is great enough that officials have decided to take a closer look, William Gerstenmaier, associate administrator for NASA’s Human Exploration and Operations Mission Directorate, told SpaceNews.
“We could use the camera on Soyuz, [or] astronauts could do it,” Gerstenmaier said May 6.
The first opportunity for a Soyuz to scan for damage will be May 13, when a capsule docked with the space station is scheduled to return astronauts Tom Marshburn and Chris Hadfield and cosmonaut Roman Romanenko to Earth.
The next Russian spacewalk is not scheduled until June 22, Byerly said.
Gerstenmaier declined to speculate about how long it might take to repair or replace the laser radar reflector, if it is indeed damaged. Any fix would have to be carried out by spacewalking astronauts.
European Space Agency spokesman Pal Hvistendahl did not respond to a request for comment by press time.
Just in case the laser radar reflector unit now installed on the Zvezda module is unsalvageable, “we’re talking about flying a replacement up on the next Soyuz flight,” Gerstenmaier said. The next crewed Soyuz launch from the Baikonur Cosmodrome in Kazakhstan is slated for May 28.
If the reflector does have to be replaced, it will mark the second swap out this year. The unit that might have been damaged April 26 had only been on the space station about a week. Spacewalking cosmonauts installed the device April 19 following concern on the ground that the old reflector was in poor condition.
Meanwhile, the fourth ATV is scheduled to launch June 6. The vehicle was fueled at Europe’s Kourou spaceport in French Guiana and is now awaiting integration with its Ariane 5 launcher. The ATV scheduled to launch next month is the penultimate vehicle in Europe’s ATV program. The fifth and final ATV is nominally scheduled to launch in April 2014.