This morning, the crew of the International Space Station will say goodbye to Orbital ATK’s Cygnus cargo capsule, which has been docked to the orbiting lab for the past two and a half months. To prep the vehicle’s departure, the station's Canadian robotic arm grabbed hold of the Cygnus earlier and undocked the capsule from the Unity module. The robotic arm will hold the capsule away from the station, and release the spacecraft at 9:30AM ET. The Cygnus — which has been filled up with around 3,000 pounds of station trash — will remain in orbit around Earth for about a week before it eventually burns up in the planet’s atmosphere.
But NASA isn't done with the vehicle quite yet
Just because the capsule is leaving the station doesn’t mean NASA is done with the vehicle quite yet. About five hours after the Cygnus departs the ISS — and gets far enough away — a large blaze will ignite inside the capsule’s belly. It’s all part of an experiment called Saffire-I meant to study how fire behaves in microgravity. A cotton-fiberglass material measuring more than 3 feet long and 1 foot wide will burn for 15 to 20 minutes inside Cygnus, creating the largest controlled fire ever in space. A suite of onboard sensors and cameras will collect data about the blaze and relay that information to NASA over the next week. That info will help the space agency come up with better ways to detect fires in space, as well as figure out how to control flames in zero G.
Apart from housing this science experiment, Cygnus is also responsible for deploying a couple satellites after it leaves ISS. On June 20th, the capsule will let go of five Lemur-2 satellites, manufactured by satellite-maker Spire Global. These satellites will help track ships traveling in remote areas of the world’s oceans, as well as monitor weather.
As for the Cygnus capsule, NASA will destroy it on June 22nd. That’s when the vehicle’s engines will fire twice, taking the spacecraft out of orbit and triggering its descent toward Earth. Cygnus will then burn up somewhere over the Pacific Ocean, effectively getting rid of all the trash it has on board. Those items include broken hardware from ISS, food containers, dirty laundry, and astronaut waste, according to Holly Vavrin, the flight lead for the current Cygnus mission.
NASA will also be using the capsule’s fiery death plunge as an opportunity to study how vehicles break up during atmospheric reentry. Another payload onboard Cygnus, called the ReEntry Breakup Recorder, will be taking super quick measurements of the capsule’s temperature, speed, acoustics, and more as it falls to Earth. The recorder will then help rapidly relay that data to NASA scientists on the ground before it also burns up. This should help NASA understand how spacecraft enter Earth’s atmosphere, which could be useful when designing future vehicles.
Live coverage of the Cygnus departure begins at 9AM ET.
Update June 14th 9:57AM ET: The article has been updated to indicate the new date of deployment for the Spire Global satellites.