Parts of this article (those related to the launch, which has been postponed indefinitely on 24 June 2022) need to be updated. Please help update this article to reflect recent events or newly available information. (June 2022)

Janus spacecraft.jpg
Mission typeAsteroids flyby
OperatorUniversity of Colorado Boulder, NASA
COSPAR ID Edit this at Wikidata
Mission duration4 years (planned)
Spacecraft properties
SpacecraftJanus Serenity and Mayhem
ManufacturerLockheed Martin
Launch mass36 kg (×2)[1]
Power2 solar arrays and batteries[2]
Start of mission
Launch dateNo earlier than 20 September 2022[3]
RocketFalcon Heavy[2]
Launch siteKennedy Space Center, LC-39A
Small Innovative Missions for Planetary Exploration (SIMPLEx) Program

Janus is a planned dual space probe, called Serenity and Mayhem,[4] that will each visit asteroids that would be chosen prior to launch date. The mission is expected to be launched in September 2022 as a secondary payload on Falcon Heavy together with the Psyche spacecraft.[3] On 3 September 2020, Janus successfully passed Key Decision Point-C and was approved for the final design of hardware. The mission budget is limited to US$55 million.[5]


The two small 36 kg spacecraft —which fall under the 180 kg mass limit for SIMPLEx missions — will conduct stand-alone planetary science missions. They will launch together on a Falcon Heavy as secondary payloads alongside NASA's Psyche spacecraft. The spacecraft is jointly developed by two teams, based at the University of Colorado Boulder (lead by Daniel Scheeres) and at Lockheed Martin (lead by Josh Wood). The two spacecraft, Janus A and B, also go by Serenity and Mayhem.[4][6]


The Janus team plans to image the two asteroids in visible and infrared light, using the ECAM-M50 (visible) and ECAM-IR3a (infrared) cameras. These cameras were developed by Malin Space Science Systems and successfully used on the OSIRIS-REx asteroid sample return mission.[7]


Initial plan

In 2020 NASA gave approval for the Janus mission to proceed to the next phase of development.[5] The mission is managed by the Planetary Missions Program Office at NASA's Marshall Space Flight Center in Huntsville, Alabama, as part of the Solar System Exploration Program at NASA Headquarters in Washington, D.C. The program conducts space science investigations in the Planetary Science Division of NASA's Science Mission Directorate at NASA Headquarters, guided by NASA's agency priorities and the Decadal Survey process of the National Academy of Sciences. Janus is led by the University of Colorado Boulder, where the principal investigator (PI) is based, which will also undertake the scientific analysis for the mission. Lockheed Martin will manage, build and operate the spacecraft.

After riding along with the launch of NASA's Psyche mission in September 2022, the Janus twins will separate and complete an orbit around the Sun, before heading back toward Earth for a gravity assisted sling-shot into space in 2025, each going their separate ways to the two asteroids, (175706) 1996 FG3 and (35107) 1991 VH.[5]

Delay and new targets

Because Psyche's launch date was moved from August 2022 to late September, new targets have to be chosen as Janus would be unable to visit the initially chosen asteroids (175706) 1996 FG3 and (35107) 1991 VH.[8] Psyche's launch was again delayed on June 24, 2022 to an unspecified date after the end of 2022.[9][10] The new targets and trajectories for Janus were not announced at that time.


  1. ^ "NASA - NSSDCA - Spacecraft - Details".
  2. ^ a b "Janus A, B (SIMPLEx 3)". Gunter's Space Page. Retrieved 30 April 2022.
  3. ^ a b Clark, Stephen (23 May 2022). "Launch of NASA's Psyche asteroid mission delayed to late September". Spaceflight Now. Retrieved 24 May 2022.
  4. ^ a b;topic=50260.0;attach=2070175;sess=0
  5. ^ a b c "New SIMPLEx Mission to Send SmallSats on Longest Deep Space Journey to Date". NASA. 10 September 2020. Retrieved 1 January 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  6. ^ "NASA - NSSDCA - Spacecraft - Details". Retrieved 3 June 2022.
  7. ^ Tomaswick, Andy (23 September 2020). "NASA's Janus Mission is Going to Visit Two Binary Asteroids". Universe Today. Retrieved 17 June 2022.
  8. ^ "The delay in the launch of Psyche led to a revision of the objectives of the Janus mission". The Universemagazine Space Tech. 10 June 2022. Retrieved 15 June 2022.
  9. ^ Potter, Sean (24 June 2022). "NASA Announces Launch Delay for Psyche Asteroid Mission". NASA. Retrieved 24 June 2022.
  10. ^ "Psyche launch delay forcing revamp of rideshare mission". SpaceNews. 9 June 2022. Retrieved 30 June 2022.