Janus spacecraft illustration
NASA will put the completed Janus spacecraft into long-term storage with the hopes of potentially flying them on a future mission. Credit: Lockheed Martin

WASHINGTON — NASA has canceled a mission to send a pair of smallsats to binary asteroids and will put the nearly completed spacecraft into storage for a potential future opportunity.

NASA announced July 11 that it was concluding the Janus mission and planned to put the spacecraft into long-term storage. The mission, selected as part of the agency’s Small, Innovative Missions for Planetary Exploration, or SIMPLEx, program, had planned to send two identical smallsats to fly by different pairs of binary asteroids.

Janus had been in limbo, though, after problems with the Psyche asteroid mission delayed its planned August 2022 launch. Janus was a rideshare payload on the Psyche mission, and the rescheduled launch of October 2023 would not allow Janus to reach its original targets.

“Once we got taken off of Psyche, we were already pretty much over other than getting the spacecraft into storage,” said Dan Scheeres, principal investigator for Janus at the University of Colorado, during a July 12 meeting of NASA’s Small Bodies Assessment Group (SBAG) advisory committee.

NASA decided last November to remove Janus from the Psyche launch but did allow the project to study alternative missions using the spacecraft. The project examined several options and discussed them with agency officials at a NASA Headquarters meeting June 14.

Among the options included sending the Janus spacecraft to Apophis, a near Earth asteroid that will make a very close flyby of Earth in April 2029. NASA has already approved a proposal to use the OSIRIS-REx spacecraft, after it delivers samples from the asteroid Bennu back to Earth in September, to visit Apophis shortly after the 2029 flyby.

The redirected Janus spacecraft, though, would be able to visit Apophis before the flyby. “If we really want to understand what happens to Apophis when it has its close Earth passage, you really need to have some ‘before’ images and models to compare with the after ones,” Scheeres said.

The Janus team studied several other options, including flybys of binary or triple asteroids, that would allow the mission to perform science similar to the original mission. “There is a pretty rich set of possible targets that exist,” he said.

However, in a June 28 memo, NASA’s planetary science division (PSD) elected not to pursue any of those alternative missions. “At this time the PSD budget does not allow for a commitment to be made for a new mission, even one that would utilize the completed Janus spacecrafts,” a portion of the memo, quoted by Scheeres in his talk, stated.

The two spacecraft, now at a Lockheed Martin facility, will be placed into long-term storage at a NASA center later this year. That will effectively conclude the Janus project, he said.

The spacecraft are effectively complete, he said, with a total cost including closeout activities of less than $49 million. NASA had placed a cost cap of $55 million each on missions selected through that round of the SIMPLEx program, which included Janus as well as the ESCAPADE Mars mission and Lunar Trailblazer.

While the NASA memo left the door open to an alternative mission in the future, there is no formal mechanism to regularly review opportunities for using them, Scheeres said. “We would probably happily repropose something if given the opportunity,” he said. “I think some guidance from NASA would certainly be helpful since this is a situation that doesn’t crop up that often.”

Attendees at the SBAG meeting expressed frustration with the fate of Janus being tied to problems with another mission, Psyche, beyond its control. But an agency official said at the meeting that was one of the risks inherent in the overall SIMPLEx program.

“The point of SIMPLEx was to be able to do these high-risk missions with smallsats, and part of the risk is exactly what we had happen,” said Tom Statler, a program scientist in NASA’s planetary science division. How to recover from that, either for Janus specifically or for other smallsat missions that experience problems with rideshare launches, is an open question. “Having that as a broader discussion as part of the many lessons learned from SIMPLEx will be a helpful thing.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...