NASA Scrubs Janus Asteroid Smallsat Mission

NASA has canceled its Janus mission that aimed to send two smallsats to binary asteroids. The spacecraft will be stored for a potential future mission. This decision was made due to problems with the Psyche asteroid mission that delayed the launch of Janus.

The Janus Mission

Janus was a mission selected as part of NASA's Small, Innovative Missions for Planetary Exploration (SIMPLEx) program. The mission was designed to send two identical smallsats to fly by different pairs of binary asteroids. The spacecraft were nearly complete when NASA decided to cancel the mission.

An artist's depiction of the twin Janus probes in space. (Image credit: Lockheed Martin)

Delayed Launch

The Janus mission was delayed due to problems with the Psyche asteroid mission. Janus was a rideshare payload on the Psyche mission. However, the rescheduled launch of Psyche in 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.

Alternative Missions

NASA allowed the Janus project to study alternative missions using the spacecraft after removing it from the Psyche launch. The project examined several options, including flybys of binary or triple asteroids. These options would allow the mission to perform science similar to the original mission.

One of 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. The redirected Janus spacecraft would be able to visit Apophis before the flyby and gather valuable data.

One of two Space Dynamics Laboratory-built Iris Radios, shown in this July 28, 2020, photo at SDL in North Logan, Utah, is equipped to provide communications for dual Lockheed Martin small spacecraft being built for NASA's deep-space mission called Janus, to visit near-Earth asteroids. (Credit: Kelden Peterson/Space Dynamics Laboratory).

Budget Constraints

In a June 28 memo, NASA's planetary science division 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 spacecraft," a portion of the memo 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.

Lessons Learned

Attendees at the Small Bodies Assessment Group (SBAG) meeting expressed frustration with the fate of Janus being tied to problems with another mission, Psyche, beyond its control. "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," Statler added.

NASA's decision to cancel the Janus mission was due to problems with the Psyche asteroid mission that delayed the launch of Janus. Although the Janus project studied alternative missions, budget constraints prevented NASA from pursuing them. The two nearly completed spacecraft will be placed into long-term storage for a potential future mission. The incidents with Janus and Psyche highlight the risks inherent in the SIMPLEx program and provide valuable lessons for future smallsat missions.