TopexPoseidon

TOPEX Poseidon, also written TOPEX/Poseidon, was a joint NASA-CNES satellite mission designed to map the height of the global ocean surface and monitor sea level variations. Launched in 1992, the spacecraft operated in a near-polar, sun-synchronous orbit at about 1,300 kilometers altitude, collecting data until 2005. The mission’s core instrument was the TOPEX/POSEIDON radar altimeter, which measured sea surface height by timing radar pulses that bounced off the ocean surface. Data required corrections for atmospheric conditions and orbital geometry to yield accurate sea-surface height, and were complemented by onboard sensors and calibration procedures to ensure long-term consistency.

The primary scientific goal was to produce high-precision, near-global maps of sea surface height, enabling detailed studies of ocean circulation, tides, and variability such as El Niño and La Niña. The mission provided a continuous record of ocean topography for more than a decade, supporting climate research, weather prediction, and global oceanography. TOPEX/Poseidon also established a baseline for successor altimetry missions, notably the Jason series, and helped advance multi-satellite oceanography.

Legacy and data stewardship: After its retirement in 2005, the TOPEX data archive remained a foundational resource for oceanography. Datasets are maintained by NASA's PO.DAAC and by CNES, with continued integration into later altimetry missions and oceanographic models. TOPEX/Poseidon is widely regarded as a landmark mission in satellite altimetry, demonstrating the value of long-term, high-precision sea level measurements for understanding Earth's oceans.