A private rescue spacecraft is having troubles of its own in Earth orbit.
LINK, a satellite built and operated by the Arizona company Katalyst Space Technologies, launched July 3 on a daring and unprecedented mission: Rendezvous with NASA's Swift space telescope and boost the observatory to a higher orbit before it falls out of the sky.
About three weeks after launch, however, LINK started spinning at an unexpected rate, a problem that caused a temporary communications dropout and a reset of its satellite platform. And two of LINK's three orientation-controlling reaction wheels stopped working.
Spacecraft operators always work hard to fix such problems when they crop up, but there's a special urgency where LINK is concerned. It needs to reach Swift soon, or atmospheric drag will pull the observatory — which possesses no thrusters of its own — down past a point of no return. NASA thinks this boundary lies at around 186 miles (300 kilometers) above Earth, an altitude that Swift is expected to reach by October.
So the original plan called for LINK to meet up with Swift in early August, just a month after launch — pretty much as soon as commissioning work on the rescue craft wrapped up. That's not going to happen at this point, but mission teams haven't given up on the rescue attempt. Indeed, they're making progress on getting LINK back up to speed, as a new update relates.
"LINK originally was in a multi-axis spin rotating at about 9 degrees per second, which resulted in sporadic communications and impeded LINK’s progress toward Swift," NASA officials wrote in the update, which the agency posted on Thursday (Aug. 6).
"Using a series of burns from one of LINK’s electric propulsion thrusters, the Katalyst team now has slowed that spin to about 1.47 degrees per second," they added. "Katalyst plans to keep LINK at that spin rate as it proceeds with next steps for the mission."
Those next steps include uploading flight software updates "with new attitude controllers designed to maintain LINK’s stability in its current configuration," NASA officials wrote. "These updates would allow LINK to begin maneuvering to align with Swift’s orbit."
The updates are expected to be beamed up to LINK "in the coming days," according to the update.
Swift — officially known as the Neil Gehrels Swift Observatory, launched in 2004 to study gamma-ray bursts, the most energetic events in the universe.
The $250 million telescope's initial altitude was about 375 miles (600 km). But it has fallen considerably since then, and the descent is accelerating: The lower Swift goes, the more atmosphere it encounters and the greater the force of frictional drag becomes.
Swift is still working just fine, which explains why NASA wants to save it. Last September, the agency awarded Katalyst $30 million to build LINK — a refrigerator-sized spacecraft with three robotic arms — and fly its rescue mission.
That's a very tight timeline, but Katalyst hit it, getting LINK ready by its launch date and checking off a number of commissioning milestones before running into trouble. The company has experience delivering under pressure, so maybe it can pull off the rescue craft's rescue before it's too late.
