Polar is an Earth-observing satellite that, together with its sister spacecraft Wind, are NASA's contribution to the International Solar Terrestrial Program (ISTP), an international effort to quantify the effects of solar energy on Earth's magnetic field. Polar is designed to measure the entry, energization, and transport of plasma into the magnetosphere. Data from Polar are correlated with data from ground-based scientific observatories and the other spacecraft in the ISTP program – Wind, Geotail, and SOHO (the Cluster spacecraft would also have participated, but were destroyed during launch) – to better understand the physical effects of solar activity on interplanetary space and Earth's space environment.



launch date Feb 24, 1996
launch vehicle Delta 7925
launch site Vandenberg Air Force Base
orbit 5,554 × 50,423 km × 86.3°
mass 1,300 kg