Janus: A NASA SmallSat Mission to Explore Binary Asteroids

Janus is a two-spacecraft SmallSat mission to fly by two different pairs of binary near Earth asteroids, the C-type (175706) 1996 FG3 and the S-type (35107) 1991 VH. During the encounters, the spacecraft will return high resolution visible and infra-red images to study the structure and evolution of rubble pile asteroids. The two identical Janus spacecraft were scheduled to launch during a launch period opening 1 August 2022 as secondary payloads with the NASA Psyche mission on a SpaceX Falcon Heavy launch vehicle. However, a few months before launch the Psyche primary mission was delayed until at least 2023, and the impacts to both Psyche and Janus are still being determined. Janus is led by principal investigator Dr. Dan Scheeres at the University of Colorado Boulder and managed, built, and operated by Lockheed Martin. Although these spacecraft are small, they share many challenges similar to larger deep space missions: Janus must execute maneuvers to achieve hundreds of meters per second ΔV to reach its destinations, close a telecommunication link at ranges up to 2.4 AU, autonomously manage a telecommunications blackout during solar conjunction, operate at a maximum Sun range of 1.62 AU, and survive for approximately four years in interplanetary space before encountering the target asteroids. In getting Janus ready to launch, the implementation team successfully managed an aggressive mission schedule despite COVID-19 related supply chain impacts and work environments, all while remaining on target for the SIMPLEx-2 cost cap. Janus is a pathfinder for achievable and affordable planetary SmallSat science missions and for multi-spacecraft asteroid scout missions.