Small Scale Cooler

 
The driving requirements for the cryogenics subsystem are the volume, mass and consumption of relatively high temperature (T>77K) coolers for many missions:

• Planetary or interplanetary probes carrying multiple instruments that need some compact and low cost cooling for small NIR-TIR, Ge or X-ray detectors (e.g. VIR on Rosetta/Venus Express, Chemin/SSL, NOMAD on ExoMars)
• Constellations of operational microsatellites (e.g. Spirale)

Currently, these missions have to rely on tactical micro-coolers (typically Ricor’s K508) to cool the detectors and have to cope with a military standard lifetime specification of 8000 hours, which is insufficient for typical space applications.

Objectives
To develop, manufacture and test a Cryocooler with the following characteristics: Cooling power: 0.75W@77K with less than 25W input power ; Mass: less than 1kg ; Lifetime: more than 50000 hours

Achievements and status
A first prototype was manufactured with good performances: Cooling power: 500mW @77K with 22W input power ; Mass: 620g (145mm x 70mm x 60mm) ; Lifetime > 50000 hours (by design). The technology has been licensed by RAL to Honeywell Hymatic who is industrialising such a cooler for terrestrial applications.

Benefits
The cooler is currently less cryogenically performant than required but is more compact and lighter with higher lifetime  which is of interest for operational missions. The fact that it is industrialized for terrestrial application by Honeywell Hymatic guarantees market, know-how and is expected to reduce the overall cost.

Next Steps
Exploring the possibility of optimize design (1W@77K) + lifetime test.