1) Advance Microwave Radiometer – measures signal delay caused by water vapor. 2) GPS antennas – ensure knowledge of precise orbit path. 3) Poseidon-3 altimeter – measures sea level. 4) Doris antenna – tracking and positioning control. 5) Laser Retroreflector Array (LRA) – tracks and calibrates measurements.
Jason-1 and -2 are joint CNES (French space agency) and JPL (Jet Propulsion Laboratory) missions that follow on from the highly successful TOPEX/Poseidon and form part of NASA's EOS (Earth Observing System).
The satellite series is named after Jason of Greek mythology – an adventurer fascinated by the ocean. As global warming continues to increase, the polar icecaps will lose more and more of their mass to the oceans, adding volumes of seawater potentially great enough to swallow islands and permanently flood coastal areas.
Jason-1, launched on 7 December 2001, on the same Delta rocket as TIMED, is collecting data on ocean circulation which are intended to enable better climate predictions and understanding of events such as El Niño. It will improve upon TOPEX/Poseidon's topographic resolution to about 2.5 vertical cm, and also record direct measurements of surface temperatures using a radiometer.
Jason-2, launched on 20 June 2008, will provide a topographic map of 95% of Earth's ice-free oceans every 10 days. It has the capability to resolve global sea-level variations as small as one mm per year. The data it gathers will give better insight into the mass movement of water around the globe and thus help weather and climate agencies to make better forecasts.
Jason-2 has an on-orbit mass of 525 kg (1,155 lb), a height of 3 m (9 ft 8 in), and a power generation capacity of 511 W. It orbits at a mean altitude of 1,338 km (831 mi).