NASA's IMP-6 (Explorer 43) was launched on 14 March 1971 into an elliptical orbit to monitor cosmic rays, solar wind, radio waves, and magnetic fields in space. Its gamma-ray monitor recorded spectra from six gamma-ray bursts, helping confirm their hard X-ray and gamma-ray nature, before the spacecraft re-entered on 2 October 1974.
Alerts for directly linked future launches and major activity.