Janus A, B (SIMPLEx 3)

Janus [Lockheed Martin]

Janus by the University of Colorado, Boulder, is a mission consisting of two identical spacecrafts designed to fly by two binary asteroids to get images of the objects using both visible and infrared cameras. The mission is aimed at investigating how binary asteroids are formed and evaluating existing theories regarding how these systems evolve.

The Janus mission is led by the University of Colorado, Boulder. Lockheed Martin Space will design and build the spacecraft and provide mission operations after launch, with Malin Space Science Systems providing the instrument suite including visible and infrared cameras. The selected investigations will be managed by the Planetary Missions Program Office at NASA's Marshall Space Flight Center in Huntsville, Alabama.

The targets selected for the two probes are the binary asteroids (175706) 1996 FG3, a rocky S-Type binary asteroid in an excited state and a non-synchronous secondary rotation state and (35107) 1991 VH, a primitive C-type binary asteroid in a long term stable state and a synchonous secondary.

The two spaceprobes was to be launched in 2022 as secondary payloads on a Falcon-Heavy (Block 5)(px) together with the Psyche mission.

Due to delays of the Psyche mission, the Janus probes will not be able to explore the originally selected targets and will explore other asterois instead. In November 2022, they were removed from the Psyche launch to be manifested to fly with another mission.

After considering the opportunities and requirements for alternative missions using the twin spacecraft, and the expected resources available to planetary science in the next few years, NASA has decided in July 2023 to stand down further work on the Janus mission. The project will complete the contracted work remaining on the two spacecraft and then prepare them for storage in the event that future funding may enable an opportunity to utilize the spacecraft.