The joint NASA/French Space Agency oceanography satellite Jason 1 has reached its operational orbit and begun six months of instrument calibrations with its sister spacecraft, Topex/Poseidon. Mission flight controllers at France’s Centre National d’Etudes Spatiales’ (CNES) Satellite Control Center, Toulouse, France, and NASA’s Jet Propulsion Laboratory, Pasadena, Calif., last week commanded Jason 1 to fire its thrusters and lower itself into its operational orbit of 1,337 kilometers (830 miles). Jason 1 is now approximately one minute (approximately 370 kilometers or 230 miles) ahead of the Topex/Poseidon satellite, on an identical ground track. Launched December 7, 2001 from Vandenberg Air Force Base, Calif., Jason 1 was initially inserted into a 1,327 kilometer (823 mile) orbit 10 kilometers (6 miles) below Topex/Poseidon. A series of thruster maneuvers over the past five weeks gradually placed Jason 1 into its current orbit. Checkout of the spacecraft and its instrument payload is now complete. All instrument and spacecraft functions and the operations systems at the French space agency and JPL are functioning nominally.