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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.