New experiments to fly on Europe's last ATV cargo ship
BY STEPHEN CLARK
Posted: June 9, 2014
Nearly ready for a dual mission to deliver cargo to the International Space Station and conduct technological experiments for future space projects, Europe's final automated resupply spacecraft is set for liftoff the last week of July after a previous commercial Ariane 5 rocket launch was postponed by a problem with an Australian telecommunications satellite.
Besides the cargo, the Automated Transfer Vehicle is outfitted with a suite of next-generation infrared and laser ranging sensors to demonstrate the feasibility of future missions approaching out-of-control space junk or dead satellites for repairs or removal from orbit.
At the end of the mission early next year, engineers at the ATV control center in Toulouse, France, will guide the spaceship back into Earth's atmosphere at a shallower angle than any mission before. NASA wants to collect data on the ATV's re-entry to test their computer models as officials plan for the final days of the space station, when the outpost will crash into a remote stretch of the South Pacific Ocean some time in the 2020s.
Technicians are filling ESA's fifth ATV with propellant this week before the bus-sized spaceship is hoisted on top of an Ariane 5 launcher, said Massimo Cislaghi, mission manager for the ATV 5 cargo flight.
ATV 5 is next in Arianespace's launch queue after a commercial Ariane 5 launch was postponed to resolve an issue inside the propulsion system of the Australian Optus 10 communications satellite.
Owned by SingTel Optus, the Optus 10 satellite will be transported from the Ariane 5 launch base in Kourou, French Guiana, back to its Space Systems/Loral manufacturing plant in Palo Alto, Calif., according to John Celli, president of SS/L.
"Following additional testing that could not be performed at the launch site, [Optus 10] will be shipped back at a time coordinated with our customer," Celli wrote in an email to Spaceflight Now.
It is not clear how long Optus 10 will be grounded. Optus 10's co-passenger, the Measat 3b television broadcasting satellite owned by Malaysia's Measat Global, is in storage at the Guiana Space Center in Kourou.
Measat released a statement June 5 stating that Measat 3b's launch had been rescheduled for September. If Optus 10 is unavailable then, Arianespace will have to find another co-passenger to ride into space with Measat 3b or risk a longer delay.
The Ariane 5's lift capability also allows ESA to use the launcher to send supplies to the space station in greater numbers than any other cargo vehicle since the retirement of the space shuttle.
Cislaghi said the ATV 5 mission is slated to deliver 6,561 kilograms, or about 14,464 pounds, of fuel, dry cargo, water, air and oxygen to the space station.
Most of the cargo is already on-board the supply ship, with about 1,185 kilograms, or 2,615 pounds, of "late-load" time-sensitive cargo and last-minute additions due to be placed in the ATV's pressurized module the week of June 30, Cislaghi said Thursday in a telephone interview.
Filling of the ATV with hydrazine and nitrogen tetroxide will be complete June 13, then technicians will configure the spacecraft's pyrotechnic charges and valves before transferring the ship to the Ariane 5's final assembly building for attachment on top of the launcher June 25.
The ATV's "late-load" cargo will all be inside the spacecraft by July 3, beginning final closeouts before workers lower the Ariane 5's payload fairing around the European logistics freighter, Cislaghi said.
Launch is scheduled for July 26 at approximately 0117 GMT (9:17 p.m. EDT on July 25), according to Cislaghi.
The ATV's launch date depends on little or no delay of the launch of a Russian Soyuz rocket from the Guiana Space Center scheduled for July 10. The Soyuz rocket will launch with four broadband communications satellites for O3b Networks.
Arianespace, which manages rocket launches from French Guiana, says it needs nearly two weeks between Soyuz and Ariane 5 missions to reconfigure tracking stations and range assets.
If launch occurs July 25, the ATV will dock with the space station Aug. 12.
The longer cruise to the space station allows time for a planned demonstration of new rendezvous systems designed for future spacecraft that could approach "non-cooperative targets" in orbit, such as dead satellites and space debris.
The ATV's primary rendezvous sensors, a suite of telegoniometers and videometers, have guided the supply ships to four dockings with the space station with help from a GPS navigation system for long-range tracking.
The optical guidance system fires lasers on final approach to the space station, bouncing the light off of specially-located reflectors mounted on the aft end of the outpost's Zvezda service module.
The Laser Infrared Imaging Sensors, or LIRIS, carried on the ATV do not require the reflectors, enabling future missions to rendezvous with nearly any object in orbit.
ESA's ATV contractor Airbus Defence and Space, along with Sodern and Jena-Optronik, proposed flying the new laser and infrared sensors on the ATV 5 mission. The infrared camera was provided by French company Sodern, with German-based Jena-Optronik supplying the laser lidar, according to ESA.
Cislaghi said the ATV will perform a "fly-under" maneuver a few days before docking, approaching within about 5 miles of the space station to demonstrate the infrared camera system.
The laser lidar sensor will be tested during the ATV's final approach on docking day.
At the end of the mission, currently scheduled for January or February, the ATV will undock from the space station's Zvezda service module with trash and waste. Like the previous European cargo ships, the ATV 5 mission will plunge back into the atmosphere over the South Pacific Ocean, destroying itself and the garbage inside, clearing precious room on the space station for fresh experiments and cargo.
The exact timing of the ATV's re-entry is still being discussed, Cislaghi said.
"We'll have to fulfill some special visibility conditions to be able to be seen from above at the ISS and from below by both visual observations and radar tracking means," Cislaghi said.
The ATV will enter the atmosphere at a shallower angle than before. Engineers expect the surviving debris, such as as reinforced propellant tanks and other structures, will fall into the Pacific Ocean along a longer footprint than usual between New Zealand and South America.
"Part of the ongoing study is to determine how to minimize any potential risk to any objects on the ground like planes or boats," Cislaghi said.
Aviation and maritime safety authorities typically issue warnings to airliners and ships in the South Pacific when U.S., European, Japanese or Russian space station resupply vehicles fall into the remote stretch of ocean.
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