PROCYON (Proximate Object Close flyby with Optical Navigation) is an asteroid flyby probe that was launched together with Hayabusa 2 on 4 December 2014 13:22:04 (JST). It was developed by University of Tokyo and JAXA.
It is a small (approx. 60 cm cube), low cost (¥500 million) spacecraft.[1]
It was intended to flyby the asteroid 2000 DP107 in 2016,[2] but the plan was abandoned due to the malfunction of the ion thruster.[1]
Mission overview
PROCYON was launched as secondary payload together with the Hayabusa 2 asteroid landing probe. After separation from the carrier rocket, PROCYON was left on a heliocentric orbit. On February 22 2015, the ion engine was started, with the intention of adjusting the orbit so that an Earth flyby in December 2015 would direct the probe towards asteroid 2000DP107[3]. Initial results were favourable - the engine delivered 330µN of thrust rather than the designed 250µN - but unfortunately the engine failed on March 10 and could not be restarted; PROCYON flew past Earth on December 3 2015, but was unable to make a controlled orbit change.
The 70kg spacecraft has a specific impulse of 1000 seconds, for a delta-V budget of about 500ms-1; the intention was to use 20% of the xenon propellant for the initial orbit correction, and the rest of the propellant between the Earth flyby and the asteroid flyby to ensure a controlled flyby distance of 30km.[4]
A novel subsystem tested by PROCYON involved feeding both the main ion engine and the eight cold-gas attitude control thrusters from the same tank (containing 2.5kg of xenon at launch)
Instruments
Small telescope for near-asteroid navigation and data acquisition.
Lyman-alpha imaging camera to observe geocorona[5]
^超小型探査機「PROCYON」 二重小惑星を目指して航行中 [Very Small Probe PROCYON Cruising Toward a Binary Asteroid]. Space Elevator News. 7 April 2015. Retrieved 7 April 2015.
^PROCYON development team. 超小型深宇宙探査機 PROCYON（プロキオン）(PDF) (in Japanese). Retrieved 14 May 2015. {{cite web}}: Invalid |script-title=: missing prefix (help)
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
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