Which observatory/satellite was launched into space first, Hakucho or Chandra X-ray Observatory?
Hakucho Hakucho (also known as CORSA-b before launch) was Japan's first X-ray astronomy satellite, developed by the Institute of Space and Aeronautical Science (then a division of the University of Tokyo). It was launched by the ISAS M-3C-4 rocket on February 21, 1979 and reentered the atmosphere on April 16, 1985 .
LEGRI The Low Energy Gamma-Ray Imager (LEGRI) was a payload for the first mission of the Spanish MINISAT platform, and active from 1997 to 2002. The objective of LEGRI was to demonstrate the viability of HgI detectors for space astronomy, providing imaging and spectroscopical capabilities in the 10-100 keV range.