Ever wonder if the light goes out when you close the fridge door? Or what it’s like to ride a spacecraft as it burns up in the Earth’s atmosphere? The fridge may remain an eternal mystery, but ESA plans to answer the latter question when its unmanned Automated Transfer Vehicle (ATV)-5 Georges Lemaître completes its six-month mission to the International Space Station (ISS). The space agency has developed a “black box” camera system designed to record the dramatic event and transmit the images back to Earth after the craft breaks up.
If on some clear night you see an unusually spectacular meteor flash across the sky giving off sparks as it goes, odds are that it’s an old satellite burning up as it re-enters the atmosphere. If you happen to be in the emptier parts of the South Pacific, you might even see one of the cargo ships used to resupply the ISS breaking up in a fireworks display at the end of its mission. It’s become a familiar sight over the past 50 years, but ESA plans to go one better by mounting European, American, and Japanese recorders inside the ATV-5 to beam back images of the last ATV freighter’s final seconds.
According the ESA, its infrared Break-Up Camera (BUC) will be bolted to a rack inside the spacecraft along with a JAXA i-Ball camera and a NASA Re-entry Break-up Recorder to provide a complete record of the event. The BUC, along with its Reentry SatCom capsule that works like a black box recorder, was designed, built, and tested in only nine months and is designed to record the break-up of ATV-5 and send the images back to mission control by means of an Iridium satellite link.
The idea is that as the ATV-5 hits the Earth’s atmosphere at 17,000 mph (27,000 km/h), it will start to burn up. As it does so, the superhot gases heated to 1,500ºC (2,700ºF) enveloping the craft will become an electrically-charged plasma, which will black out communications.
Meanwhile, the Reentry SatCom will record the final 20 seconds from the BUC as ATV-5 breaks apart somewhere over the Pacific Ocean. The spherical SatCom capsule has its own ceramic heat shield and is built to (hopefully) survive the break-up, after which it will begin transmission.
"The Reentry SatCom has an antenna, so that once ATV breaks up it begins transmitting the data to any Iridium communication satellites in line of sight," says Neil Murray, ESA project leader. "The break-up will occur at about 80 - 70 km (50 - 44 mi) altitude, leaving the SatCom falling at 6 - 7 km/s (21,000 - 25,000 km/h, 13,000 - 15,000 mph). The fall will generate high-temperature plasma around it, but signals from its omnidirectional antenna should be able to make it through any gap in the plasma to the rear."
Murray went on to say that as the capsule drops below 40 km (25 mi), it will slow down enough for plasma to stop forming, so the recorder can transmit its data clearly to the satellite.