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Launched in 2011, HY-2A is a Chinese oceanography satellite with CNES’s DORIS instrument on board, thanks to which its orbit can be determined with centimetre accuracy.

HaiYang means ‘ocean’ in Chinese, which explains the ‘HY’ in HY-2A, a Chinese satellite dedicated to studying sea-surface height, temperature and wind velocity. Launched on 15 August 2011, HY-2A complements the HY-1A and HY-1B satellites that acquired ocean colour measurements for ocean biology studies.

To determine sea-surface height, HY-2A uses a radar altimeter that measures the satellite’s distance or ‘range’ to the ocean surface and a DORIS instrument developed and supplied by CNES. Operating in combination with a laser retroreflector and GPS receiver, DORIS enables the satellite’s orbital position to be determined with centimetre accuracy. CNES also provides support for orbit determination operations.

HY-2A was initially planned to fly a 3-year mission, 2 years in an altimetry orbit and then 1 year in a geodetic orbit, but it is still operating and the change of orbit is now not scheduled until 2016.