After the rocket experiments during the 1960s, the first X-ray Earth-orbiting explorers
were launched in the 1970s (Uhuru, SAS 3, Ariel5) followed in late 1970s early
1980s by larger missions (HEAO-1, Einstein, EXOSAT, and Ginga). Their scientific
outcome, in particular the first X-ray images taken by Einstein, lifted X-ray
astronomy into the mainstream of astronomical research. It is now known that nearly
every astronomical object from nearby comets to
quasars emits X-rays. In the 1990s the ROSAT survey detected more than 100,000 X-ray
objects, the ASCA mission made the first sensitive measurements of the X-ray spectra
from these objects, and RXTE studied their timing properties. The late 1990's launch of
the Chandra and XMM-Newton observatories brought high-resolution imaging and
high-throughput capability to X-ray astronomy. These missions, combined with
Suzaku/Astro-E2, launched in 2005, have opened new and exciting horizons in the
journey of the X-ray astronomy exploration.
SAS 2 and Cos B, launched in the 1970s, made the first surveys of the gamma-ray sky,
followed by the Compton Gamma-ray Observatory in 1990 and more recently by INTEGRAL in 2002.
pulsars, and many unidentified sources in our galaxy are the gamma-ray emitters.
Fermi (formerly GLAST), the latest gamma-ray observatory, is expected to resolve the diffuse emission and
make an all-sky survey with higher angular and energy resolution.
gamma-ray bursts (GRBs) discovered in the late 1960s by the Vela satellite, were
shown to be the most powerful explosions in the Universe and isotropically distributed,
thanks to the rapid response capability of BeppoSAX and the all-sky monitoring of CGRO.
Swift, launched in November 2004, is providing data on the GRBs prompt emission and
their afterglows to allow the most comprehensive study on GRBs and determine their origin.