ESA tests new rendezvous system as ATV-5 docks at Space Station
By David Szondy
August 12, 2014
ESA’s last Automated Transfer Vehicle (ATV)-5, Georges Lemaître, has arrived at the International Space Station (ISS). In what the space agency describes as a "flawless demonstration of technology and skill," the unmanned cargo ship autonomously docked itself while supervised by mission control in Toulouse, France and by ESA astronaut Alexander Gerst and Russian cosmonaut Alexander Skvortsov inside the space station.
The fifth and final mission of the European ATV program, ATV-5 approached the ISS in a series of steps over several hours as ESA, NASA, and the station crew carried out a series of safety checks before clearing the spacecraft to proceed. Operating under full automatic control, ATV-5 docked on the aft section of the Russian Zvezda module at 13:30 GMT (3:30 pm CEST) today.
"From 39 km (34 mi) to just 250 m (820 ft) from the Station, ATV navigated itself using relative satnav signals, in which both the Station and ATV compare their positions using GPS," says Jean-Michel Bois, leader of the ESA operations team at the ATV Control Centre in Toulouse, France. "For the final 250 m, ATV navigated using a ‘videometer’ and ‘telegoniometer’, which use laser pulses to calculate the distance and orientation to the Station."
Once it made a "soft" docking with the space station, ATV-5 was latched onto with hooks that sealed it firmly to the module. These will later be joined by electrical and data connections, and the hatch is scheduled to be opened tomorrow, when a fan will be installed to circulate air into the pressurized cargo compartment stuffed with 6,602 kg (14,554) of food, clothing, drinking water, propellants, breathable gases, science experiments, and spare parts.
This docking is also significant because it marked the first flight of ESA’s Laser InfraRed Imaging Sensors (LIRIS) demonstrator. This system, which uses infrared lasers instead of radar beams, is designed to test technology that may one day allow spacecraft to rendezvous with "uncooperative" targets. That is, objects like space debris or a Mars sample capsule that may be tumbling. According ESA, the LIRIS is designed to scan objects in space using lasers and onboard computers produce a map to aid navigation and control.
Before docking, ATV-5 made several passes under the station and scanned it in a simulated rendezvous. In practice, LIRIS would use infrared cameras while 30 km (18.6 mi) from the target and when it reached 3.5 km (2.1 mi), it would switch to lidar for final approach. During today’s docking, LIRIS only observed the operation, but took no active part
Launched on 29 July from Europe’s Spaceport in Kourou, French Guiana, ATV-5 Georges Lemaître is named after the Belgian priest and scientist who first formulated the Big Bang Theory. During its six-month stay at the ISS, the cargo ship will be used to reboost the station into a higher orbit. ESA says that the thrusters will be tested on Thursday. When ATV-5 completes its mission, it will burn up on re-entry while ESA and NASA instruments record the event.
"While this is the last of the ATV flights, the know-how and technology will soon fly again as early as 2017." says Gerst. "NASA’s Orion spacecraft with the European Service Module are paving the way for the next generation of space exploration."
The video below shows highlights of ATV-5 docking.