Risky mission to save NASA’s falling observatory faces issues of its own - CNN

A daring mission to rescue one of NASA’s crucial space observatories from falling to Earth has encountered issues of its own — but there may still be hope for both spacecraft to beat the odds.

The Neil Gehrels Swift Observatory has served as an astrophysics multitool in low-Earth orbit since it launched nearly 22 years ago, acting as NASA’s first responder in space when celestial objects flare with activity, according to mission scientists.

But atmospheric drag intensified by solar activity exerted its forces on the observatory. Without any intervention, Swift is likely to reenter our planet’s atmosphere this fall once it sinks below an optimal altitude of about 185 miles (300 kilometers) above Earth, according to NASA’s predictions.

The agency selected Arizona-based Katalyst Space Technologies to design, build, test and launch — all in the span of just nine months — a spacecraft capable of rendezvousing with Swift and boosting its orbit.

The robotic satellite, named LINK, launched on July 3. It lifted off on a Northrop Grumman Pegasus XL rocket, which was released midair by the company’s modified L-1011 aircraft, Stargazer.

Everything appeared to go according to plan until LINK began to spin in space around July 25, causing a temporary loss of communications, Katalyst and NASA said on July 28.

While LINK’s spin now appears to be largely under control, the satellite’s rendezvous with Swift is facing a delay. Now, it remains unclear whether LINK will reach the observatory in time.

“I think one of the difficult things to convey is how amazing it is that we’ve gotten this far,” said Shawn Domagal-Goldman, division director of astrophysics at NASA, during a June 17 news conference. “Even if everyone does everything perfectly, there still might be risks that we cannot control ahead of us. I’m just deeply thankful that we’re even giving this a go.”

Here’s everything that has happened so far.

A tumble in the timeline

After LINK’s successful launch into orbit, Katalyst’s mission operations team confirmed it was in communication with the satellite.

Katalyst’s original plan included a few weeks of health checks for LINK’s navigation and sensors in space.

Both Katalyst and NASA reported about a week after launch that commissioning was going according to plan. The satellite had deployed its solar arrays and was firing its thrusters.

Katalyst said on July 13 that LINK was halfway through the activation phase. Two days later, NASA posted a similar update but also said the team had run into some issues.

“The Katalyst team also quickly addressed early communications and attitude control issues seen during flight operations, including an issue with one of the spacecraft’s three reaction wheels,” according to NASA’s post on July 15. “After identifying the cause, they implemented flight software patches and operational updates that restored reliable communications and stable attitude control.”

‘Big Bang fix’ could be buying more time for the farthest spacecraft from Earth

Katalyst said over a week later that the team was validating LINK’s performance, and the spacecraft was preparing for its upcoming rendezvous with Swift. Part of the process included increasing the duration of the satellite’s thruster burns to get ready for the multi-hour firings needed while grappling the observatory.

But on July 28, the company said LINK had been in a multi-axis spin for three days.

“Preliminary investigation shows that two of LINK’s three reaction wheels currently are not operable, and there is some loss of functionality in its cold gas thruster system,” NASA shared in a post that day, adding that Katalyst had a plan to reduce the spin and would reassess any plans related to Swift.

Two days later, Katalyst provided an update that the team had reduced LINK’s spin rate from about 9 degrees per second to 4 degrees per second using a series of thruster burns.

“Teams also further evaluated LINK’s functionality and determined there are still potential paths forward for a boost,” NASA shared in a post on July 31. “NASA is working closely with Katalyst to consider revised, innovative approaches.”

Now, Katalyst has confirmed it is making progress with LINK to restore its original mission to save Swift. The mission team has curbed the spacecraft’s spin rate to 1.47 degrees per second. LINK will maintain this rotation speed while the team prepares for its next steps, the company said on Wednesday.