NASA asks space industry for proposals on using the shelved Janus probes on mission to Apophis

NASA has now put out a request for proposals from the space industry for refitting the two Janus planetary probes, whose asteroid mission was shelved when its launch as a secondary payload was delayed due to problems with the Psyche primary payload, as a mission to the asteroid Apophis in connection with its April 13, 2029 close approach to the Earth.

NASA has been studying this new mission goal since early 2023, but apparently had failed to come up with a plan. It is now asking the private sector for suggestions on getting it done, including finding the funding for any plans.

NASA gives up on finding a new asteroid target for Janus

Without funding for its own launch vehicle, and unable to find a new asteroid target that can be reached by any future planned NASA launch, NASA has decided to shelf the Janus asteroid mission, putting the spacecraft into storage.

Designed to send twin small satellite spacecraft to study two separate binary asteroid systems, Janus was originally a ride-along on the Psyche mission’s scheduled 2022 launch. Psyche’s new October 2023 launch period, however, cannot deliver the two spacecraft to the mission’s original targets, and Janus was subsequently removed from the manifest.

The spacecraft will remain in storage, and might be revived at some point in the future, should another mission’s launch allow it to reach some other asteroid.

The twin asteroid Janus probes, stranded by Psyche delay, might go to Apophis

Apophis' path past the Earth in 2029
A cartoon showing Apophis’s path in 2029

The science team that built the twin Janus spacecraft, designed to fly past an asteroid but stranded when its launch got canceled, are now considering the potentially dangerous asteroid Apophis as a new target.

If the Janus spacecraft can find a ride by early 2028, scientists could use one or both of the spacecraft to scout out the large asteroid Apophis before its super-close approach to Earth in April 2029. (If only one spacecraft visits Apophis, scientists would see only about half of the asteroid but could send the second spacecraft elsewhere; if both spacecraft fly past the same object they can be arranged to reveal the whole surface.)

Initially the entire Janus mission had been designed on the assumption it would launch as a secondary payload when the Psyche mission to the asteroid Psyche launched last fall. When that launch had to be canceled because Psyche was not ready, Janus lost its mission. The science team has since been struggling to find a replacement, handicapped by the fact that it must go as a secondary payload.

There is a serious issue however with arriving ahead of Apophis’s close approach in 2029. The science community has discouraged such missions, because they fear a spacecraft arriving then could shift Apophis’s trajectory and actually increase the chance it will hit the Earth during a later close approach. Instead, all planetary probes presently going to Apophis in 2029 are planning to arrive after the flyby.

The risk is extremely small, but it must be considered before sending Janus to Apophis.

Delay in Psyche launch wrecks smallsat asteroid mission

The two month delay in the launch of NASA’s Psyche asteroid mission because of software issues has apparently wrecked a smallsat asteroid mission that was to launch as a secondary payload on the Falcon Heavy rocket.

Janus, a NASA smallsat mission selected in 2019, will launch two identical spacecraft as secondary payloads on the Falcon Heavy rocket whose primary payload is Psyche. After a series of Earth flybys, each Janus spacecraft was to fly by different binary asteroids, designated 1996 FG3 and 1991 VH.

However, the mission’s principal investigator said June 8 that mission plan is no longer possible. Speaking at a meeting of NASA’s Small Bodies Assessment Group (SBAG), Dan Scheeres of the University of Colorado noted that mission plan assumed Psyche launched in August of this year as previously planned. NASA announced May 23 that the mission’s launch had been delayed to no earlier than Sept. 20 to provide more time for testing the spacecraft’s software.

With the revised launch date, he said it’s no longer possible for the spacecraft to perform those Earth flybys with the existing spacecraft design. “Those flybys were essential for setting up our flybys of our target binaries, 1991 VH and 1996 FG3,” he said.

The Janus team are right now scrambling to see if they can find other asteroids the spacecraft can reach, based on the new launch date. Their work however is badly hampered by the uncertainty of that date, which could still change for many reasons.

The heart of the problem, as Scheeres notes, is its status as a secondary payload.

“We have no ability to influence the launch dates or the targeting of the launch vehicle, and that arises from our status as a rideshare,” he said.

The article also describes two other NASA interplanetary smallsat missions that have been badly hindered because of their status as secondary payloads. All three stories strongly suggest that in the future it will make much more sense to put such missions on its own rocket, as the primary payload. This is what NASA did with its CAPSTONE smallsat mission to the Moon, which will launch on a Rocket Lab Electron rocket sometime before the end of the month.