[Jeff Foust] NASA, Advanced Space team up for CAPSTONE follow-on mission

[threelonmusketeers@sh.itjust.works]

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Jeff Foust

6–7 minutes

A NASA-industry team is embarking on a follow-up to a cubesat mission to the moon by developing a pair of smallsats that will test rendezvous and proximity operations there.

NASA announced July 24 it is working with Advanced Space on the CAPSTONE 02 mission, scheduled to launch in late 2027. It will feature two spacecraft built by Terran Orbital that will operate in a highly elliptical lunar orbit. The mission completed its critical design review earlier this month.

The project is a successor to the original CAPSTONE, or Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, which launched in 2022. It was a single cubesat testing operations in near-rectilinear halo orbit (NRHO) around the moon, intended to inform plans for NASA’s lunar Gateway. That mission also was led by Advanced Space using a Terran Orbital bus.

CAPSTONE 02 builds upon that earlier mission, which Brad Cheetham, chief executive of Colorado-based Advanced Space, now calls CAPSTONE Classic. “We realized that there are other technical challenges and technology demonstrations that we needed to do that we just couldn’t get to with CAPSTONE Classic,” he said in an interview.

Key among them is demonstrating rendezvous and proximity operations (RPO) in the vicinity of the moon, particularly in orbits where the gravity of both the Earth and moon influence trajectories. Another is testing autonomous flight operations around the moon and beyond.

NASA also intends to use the mission to measure the radiation environment in cislunar space to inform future crewed missions. “It’s going to be very helpful for us as we have crews out around the moon and on the moon for much longer,” said Sean Fuller, NASA’s CAPSTONE manager.

While Advanced Space and NASA had been talking about a follow-on to CAPSTONE for a year and a half, NASA’s announcement in March that it will develop a lunar base, requiring dozens of missions, helped crystallize plans for CAPSTONE 02. “All of us are going to have different spacecraft maneuvering in orbits around the moon, in close proximity sometimes,” Fuller said.

CAPSTONE 02 features both similarities to and differences with the original CAPSTONE. The biggest difference is the spacecraft: while CAPSTONE used a single cubesat weighing 25 kilograms, CAPSTONE 02 will use twin spacecraft each weighing 400 kilograms.

The much larger spacecraft, Cheetham said, are needed to accommodate both the payloads and propellant needed for the mission. Advanced Space is also able to leverage an existing production line of similar buses at Terran Orbital. “We’re able to benefit from some economies of scale from other programs, where we’re able to buy a common, well-established, flight-proven platform.”

Among the payloads that larger spacecraft bus will host is a new communications system from the Space Dynamics Laboratory (SDL), an updated version of the Iris radio flown on CAPSTONE.

“A lot of what Advanced Space was asking for on CAPSTONE 02 fit perfectly with several of the new technologies and features that we were working to add to version three of the radio,” said Tim Neilsen, head of the spacecraft missions and technologies branch for civil space at SDL. That includes improved precision navigation and timing capabilities and the ability to support additional crosslinks.

The two spacecraft will launch on a low-energy ballistic lunar transfer trajectory, heading out more than 1 million kilometers from Earth before returning to enter orbit around the moon in three to four months. Advanced Space plans to use that extended cruise to test autonomous navigation technologies.

Once at the moon, the CAPSTONE 02 spacecraft will go into NRHO. While NASA is no longer pursuing that orbit for the Gateway or other Artemis operations, Cheetham said it provides an opportunity to demonstrate RPO activities between the spacecraft in different parts of that highly elliptical orbit.

“NRHO itself gives us a test bed that allows us a bunch of different analogous conditions for where we might be doing these operations in the future,” he said.

“We can refine the techniques with the propellant used on CAPSTONE 02 so that we’re better prepared for the Orion missions like Artemis 4, 5 and much beyond,” Fuller added.

CAPSTONE 02 will cost NASA “just under” $100 million, Fuller said, a figure that does not include launch. He said NASA is working on launch arrangements that will combine CAPSTONE 02 with other missions related to its lunar base plans.

Both NASA and Advanced Space expect to incorporate lessons for operations into early Artemis missions even before CAPSTONE 02 launches. “A tremendous amount of the lessons learned and the risk reduction actually happens before we ever launch,” Cheetham said, citing the experience of CAPSTONE Classic.

He noted that CAPSTONE 02 is sharing information with the Orion and Human Landing System programs and the broader Moon Base effort at the agency. “We are learning before launch a tremendous amount technologically, and that is being shared in real time with all those other programs.”

CAPSTONE 02 is designed for a two-year prime mission, but Advanced Space is keeping open options for extended missions. CAPSTONE Classic remains operational today, with Advanced Space using it for testing after NASA wrapped up its use of the spacecraft in June.

“We’re absolutely going to do interesting stuff with them, and we’ve got a lot of ideas,” Cheetham said, but emphasized the company is focused on carrying out the prime CAPSTONE 02 mission first. “We’re orbit nerds, and when orbit nerds design missions, we never run out of fuel.”

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