ESA's ATV space ferry goes out in a blaze of glory
Sen—At 13:42 UTC on Feb. 14, 2015, ESA's fifth and final Automated Transfer Vehicle (ATV-5), also known as Georges Lemaître, kissed goodbye to the International Space Station (ISS) and was sent on a path down to Earth in a controlled re-entry.
The spacecraft broke up in the atmosphere, marking the end of seven years of service by ESA's remarkable ATV vehicles, which so impressed NASA that their technology will help drive the agency's new Orion spaceship.
ESA astronaut Samantha Cristoforetti and Roscosmos cosmonaut Sasha Samokutyaev monitored ATV-5's departure from the moment it pulled away from the ISS yesterday, joined by ground teams from ESA and the French space agency CNES based at the ATV Control Centre in Toulouse, France.
Today's re-entry activities for the operations teams kicked off at 11:29 UTC, and two deorbit burns (DEO) started the re-entry procedure.
Timelapse made up of images taken by astronauts on board the ISS of ATV-5 undocking and moving away towards Earth yesterday. Video credit: NASA
DEO1 was carried out at 14:29 UTC as the ATV fired its thrusters for almost 14 minutes, reducing its speed by 186 km/h and lowering its altitude by 150 km. ATV-5's final orbit across the globe then began at 17:14 UTC and was visible in the twilight sky over parts of eastern Europe.
As DEO2 started at 17:26 UTC over the Caspian Sea, the control room in Toulouse became more crowded as scientists and engineers involved in the ATV project started to gather to witness its final moments. The manoeuvre, which lasted approxmately 23 minutes, reduced the spacecraft's speed by almost 323 km/h.
At 17:53 UTC, the last command from the Control Centre was sent to ATV-5, getting it to briefly fire its thrusters to allow Earth's atmosphere to grab the spacecraft as it reached an alititude of approximately 200 km. The spacecraft was brought into a tumbling freefall safely above the Pacific ocean in what the ATV team termed "The Big Dive". Contact was finally lost at 18:11 UTC, marking the end of an era for all involved.
What made this standard ATV re-entry unique, apart from being the last of this generation, was the special infrared camera that was installed by Christoforetti to capture front-seat views of the space ferry's interior as it broke apart.
"The battery-powered camera will be trained on the Automated Transfer Vehicle’s forward hatch, and will record the shifting temperatures of the scene before it," project leader Neil Murray explained in a statement on the ESA website last week.
"Recording at 10 frames per second, it should show us the last 10 seconds or so of the ATV. We don’t know exactly what we might see—might there be gradual deformations appearing as the spacecraft comes under strain, or will everything come apart extremely quickly.
"Whatever results we get back will be shared by our teams, and should tell us a lot about the eventual re-entry of the International Space Station as well as spacecraft re-entry in general."
The camera planted inside will not have survived the re-entry; however, it was linked to a "SatCom" sphere enveloped in a ceramic thermal protection system that offers shielding against extreme temperatures of up to 1500°C as it hurtled through the atmosphere at speed.
In this way, the SatCom acts as the "black box" of the ATV, transmitting all of its stored data to nearby Iridium communication satellites once it separates away from the disintegrating spacecraft.
ATV-1 Jules Verne burning up as it undergoes a planned re-entry into the atmosphere of our planet. On Sept.29 2008, the supply vehicle broke up 75km above the Earth's surface at 14:58 CEST, with the remaining fragments falling into an uninhabited area of the Pacific ocean some 12 minutes later. Credit: ESA/NASA
Some signal loss is to be expected from the camera feed when it is examined due to intereference from the hot atmospheric plasma blocking radio signals. It is hoped that the omnidirectional antenna attached to the SatCom was able to exploit any gap in the intereference to continue transmission, but if not the signal will have been picked up again after the plasma had cleared—expected to occur at an altitude below 40 km.
All ATVs, built by Airbus Defence & Space, have ended their supply missions the same way—by being filled with waste from the ISS and sent to be destroyed over an uninhabited area of the Pacific ocean.
Not only did Misson Control in Houston and Moscow follow the events as they happened via TV monitor, but NASA will also be showing hats-off appreciation for the years of reliable service from ESA's ATVs by incorporating the spacecraft's advanced and intelligent electronics system into the Orion module, ensuring that the legacy of this space station supply ferry lives on.