HYDRA, the multi-headed star tracker

Sodern, a French company which specialises in space instrumentation and optics, was one of the first suppliers of compact autonomous star trackers, taking advantage of state-of-the-art Active Pixel Sensor, or APS, detector technology. Didier Vilaire, Director of Space Programs at Sodern, says, “With HYDRA, the company is offering a multi-head design which separates the optical head from the centralized processing unit. This eases the thermal control of the optical heads and allows continuous attitude measurement, whether the satellite is facing Earth, Sun or other bright objects.”



The generic HYDRA with four heads
Photo credit: Sodern

 With support of ESA, under ARTES 3-4, and CNES, Sodern developed a version of HYDRA tailored for the geostationary telecommunication satellite market (HYDRA-TC). Because price-competiveness is critical in this market segment, the company simplified the electronics to drive only two optical heads, thereby significantly reducing costs, as well as mass and power consumption.

The unit was ground qualified in 2013, leading to a number of sales. The first commercial flight will be on the forthcoming DirectTV-15 mission, based on the Eurostar 3000 platform of Airbus Defense and Space, which will be launched in December 2014. It will also be deployed on ESA's EDRS-A mission whose launch is planned in 2015.

“With this version of HYDRA, Sodern will continue to maintain its position as a leading supplier in this key market,” says ESA technical officer Steeve Kowaltschek.

The new Hydra-TC electrical unit, internally redundant and able to pilot two optical heads
Photo credit: Sodern


Published 04 July 2014
Last updated at 05 November 2014 - 11:10