Chandra is designed to observe X-rays from high-energy regions of the universe, such as the remnants of exploded stars.

GLAST (to be launched in 2007) is a high-energy gamma-ray observatory designed for making observations of celestial gamma-ray sources, such as merging neutron stars and supermassive black holes.

RXTE probes the physics of cosmic X-ray sources by making sensitive measurements of their variability over time scales ranging from milliseconds to years. How these sources behave over time is a source of important information about processes and structures in white-dwarf stars, X-ray binaries, neutron stars, pulsars, and black holes.

Suzaku (formerly Astro-E2) is an X-ray telescope that is currently in operation. This mission is a collaboration between Japan and the United States.

Swift, a NASA mission with international participation, studies Gamma Ray Bursts, the most powerful explosions in the Universe.

WMAP measured the fluctuations in the microwave background of the universe to make the first detailed full-sky map of the oldest light in the universe, i.e., a "baby picture" of the universe. In doing so, it gave us the age of our Universe (13.7 billion years) and the geometry of our Universe.

XMM-Newton is a joint NASA-European Space Agency (ESA) orbiting observatory designed to observe high energy X-rays emitted from exotic astronomical objects such as pulsars, black holes, and active galaxies.