A Canadian CubeSat is currently falling out of the sky – but that's all part of the plan. After spending seven months tracking aircraft, the shoebox-sized satellite CanX-7 has started the second phase of its mission, deploying four drag sails to help it fall to Earth faster. The system is designed to demonstrate ways that spacecraft could dispose of themselves when their mission is over, helping to curb the growing space junk problem.

Wherever humans go you can be sure trash will soon follow, and space is no exception. About 15,000 pieces of space debris are currently being tracked in Earth's orbit, and it's increasingly posing a threat to satellites and spacecraft. To help manage the problem, the Inter-Agency Space Debris Coordination Committee (IADC) has set up guidelines that recommend that satellites deorbit within 25 years of their mission wrapping up.

But for small satellites with short missions, like CubeSats, space and weight is too tight to include the usual deorbit instruments you'd find on a bigger satellite. Designed by the University of Toronto's Space Flight Laboratory (SFL), CanX-7 was designed to showcase just how such a system could be stashed inside a small device, without interfering with its primary mission.

"We want our drag sail technology to be compact and non-intrusive to a satellite's main mission," says Robert Zee, Director of SFL. "This will ensure wide acceptance and easy adoption by future microsatellite missions."

Launched in September 2016, CanX-7 measures 34 x 10 x 10 cm (13.4 x 3.9 x 3.9 in) and weighs just 3.5 kg (7.7 lb). For the first seven months of its life, the nanosatellite used its Automatic Dependent Surveillance Broadcast (ADS-B) receiver to track aircraft and collect data on them, but now it's moved on to phase two.

Last week, CanX-7 deployed its four drag sails, each with a surface area of around 1 m2 (10.8 sq ft). As these sails slow the satellite down, it should cause the craft's orbit to decay much faster than normal, eventually leading to the burn-up of CanX-7 as it reenters Earth's atmosphere. This might still take a few years, but that's better than the projected timeline of centuries for it to happen naturally.

According to the team, the sails were deployed without a hitch, and the SFL team will keep an eye on the slowly-crashing craft to determine how closely reality lines up with their predictions. The end goal is to demonstrate how effective the technology might be in making future nanosatellite missions adhere to space junk protocols.

"With SFL's innovative drag sail technology verified on orbit, the door is opened to using this technology on future missions where compliance to IADC guidelines would not otherwise be possible," says Zee. "Such compliance is essential to ensuring that space debris is mitigated for the world. It is also a critical component in satisfying regulatory bodies so that small satellite missions may proceed uninhibited."