A history-making robotic rescue mission scheduled to launch next year will fly on a rocket dropped from a plane.
In September, NASA announced that it has chosen Arizona company Katalyst Space Technologies to boost the altitude of its Neil Gehrels Swift Observatory, a space telescope whose orbit has gotten dangerously low since its November 2004 launch.
Today (Nov. 19), we learned how Katalyst’s spacecraft will get off the ground — aboard Pegasus, an air-launched rocket built by aerospace giant Northrop Grumman.
The $500 million Swift observatory was built by Orbital Sciences, a company that in 2014 became Orbital ATK, which was then acquired by Northrop Grumman in 2018. The space telescope has been studying gamma-ray bursts — the most powerful explosions in the universe since the Big Bang — from low Earth orbit (LEO) for two decades.
But that orbit has decayed considerably over the years, from an initial 373 miles (600 kilometers) to about 249 miles (400 km) today. As Swift gets lower and lower, it encounters more frictional drag from Earth’s atmosphere, so its descent is accelerating — and the observatory has no thrusters to counteract the process.
If nothing changes, Swift will likely crash back to Earth by the end of 2026, and there’s no replacement mission in the works. So NASA decided to fund a rescue effort, leveraging the capabilities of private industry to meet a tight timeline.
Katalyst won that contract. And the company has decided that Pegasus — which fires up its solid rocket motors after being dropped by Northrop Grumman’s L-1011 Stargazer aircraft at an elevation of about 39,000 feet (12,000 meters) — is the right launcher for the job.
“It’s the only launch vehicle that can meet the orbit, the schedule and the cost to achieve something unprecedented with emerging technology,” Katalyst CEO Ghonhee Lee said in a statement today.
Pegasus is capable of hauling about 1,000 pounds (454 kilograms) of payload to LEO. The rocket debuted in 1990 and has 45 missions under its belt to date, 40 of them fully successful. Pegasus flew most recently in June 2021, when it lofted a “space domain awareness” satellite for the U.S. Space Force.
Northrop Grumman already had the rocket hardware for this coming mission pretty much ready to go, according to Kurt Eberly, director of space launch for the company.
“We have to do some final integration and test, and we have to develop the trajectory and the guidance for the RAAN [right ascension of the ascending node] steering and software, but that’s really it,” Eberly told Space.com.
Katalyst’s mission will fly on a Pegasus XL, a slightly longer and more massive version of the air-launched rocket. Terms of the deal were not disclosed, but the total budget of the Swift rescue mission is $30 million, including launch.
The Pegasus XL will launch in June 2026, if all goes according to plan. And there’s not much wiggle room in that target, considering how quickly Swift is coming down.
“We are treating this launch date as a firm commitment,” Kieran Wilson, vice president of technology at Katalyst, told Space.com. “We’ll kind of continuously evaluate where Swift stands in its orbital decay and figure out what sort of adaptations we might need to pursue, whether it’s launching to a different altitude, whether it’s targeting slightly different insertions.”
The Katalyst spacecraft will head to an orbit similar to that of Swift, then spend two to three weeks closing in on the observatory. The boost vehicle will inspect its target “from reasonable standoff distances, to allow us to get high-resolution imagery and understand the current state,” Wilson said.
Once that state is understood, the rescuer — which is about 4.9 feet (1.5 m) tall and weighs 770 pounds (350 kg) — will close in and capture Swift using its three robotic arms.
This will be challenging, as the NASA observatory was not designed to be serviced. And Swift has super-sensitive optics, which cannot be pointed toward the sun, Earth or moon without potentially incurring damage.
So Katalyst has been poring over old prelaunch photos of Swift and consulting with teams from NASA and Northrop Grumman to figure out the best and safest way to grab the observatory.
“There’s a lot of really fun detective work going on behind the scenes, in order to determine what points on the spacecraft we can actually capture and what the states are going to be,” Wilson said.
That work has revealed a primary capture point as well as a few promising backups, he added.
After a successful capture, the Katalyst spacecraft will haul Swift back up to its initial altitude of 373 miles (600 km) or so, if all goes to plan.
“That lasted it 22 years the first time,” Wilson said. “We expect [the boost] to provide a similar amount of on-orbit longevity this time around.”
A successful boost would be historic, marking the first-ever capture of an uncrewed U.S. government satellite by a private spacecraft. (It would not be the first-ever servicing mission to a NASA space telescope, however; astronauts repaired and upgraded the Hubble Space Telescope five times between 1993 and 2009. But Hubble was designed to be serviced.)
Katalyst already has spaceflight experience; in 2024, the company launched two spacecraft to LEO on SpaceX’s Transporter 10 rideshare mission. Those satellites demonstrated many of the core systems that the Swift-boosting craft will employ, Wilson said.
But the Swift mission marks a step up in difficulty, especially given how quickly everything must come together: A June 2026 launch will come just eight or nine months after Katalyst scored the NASA contract.
Saving Swift could therefore serve as a blueprint of sorts, paving the way for similar, and perhaps even more ambitious, feats down the road, according to Wilson.
“If we’re able to do this for NASA in just eight months, I do think that opens up a new set of responsive missions in the future,” he said, noting that servicing missions have historically taken multiple years to develop and launch.
Katalyst plans to operate some of those future missions itself. For example, in 2027, the company aims to launch its first mission to geostationary orbit, which lies 22,236 miles (35,786 km) above Earth. That flight will mark the debut of Katalyst’s larger Nexus spacecraft, “a multi-mission robotic platform to serve both government and commercial customers for life extension and space domain awareness services,” Wilson said.