EXOSAT

EXOSAT (European X-ray Observatory Satellite) was an X-ray observatory developed by the European Space Agency (ESA) for the purpose of studying cosmic X-ray sources within and beyond our Milky Way galaxy. Launched on May 26, 1983, EXOSAT was operational until April 1986, providing valuable data on X-ray emissions from stars, galaxies, and other celestial bodies. Its mission marked a significant advancement in the field of astronomy and contributed to the understanding of the universe's high-energy processes.

Mission Overview

EXOSAT was designed to observe X-ray emissions that are absorbed by the Earth's atmosphere and, therefore, inaccessible to ground-based observatories. The satellite operated in a highly eccentric orbit, which allowed for long, uninterrupted observations of celestial objects. This unique orbit enabled EXOSAT to observe its targets for up to 76 hours, significantly longer than its predecessors.

Instruments

The satellite was equipped with three main instruments:

• A low-energy imaging telescope (LEIT) that provided images and spectra of X-ray sources.
• A medium-energy detector array (ME) that measured the energy distribution of X-ray photons.
• A gas scintillation proportional counter (GSPC) that offered high-resolution spectral observations.

These instruments allowed EXOSAT to cover a wide range of X-ray energies, from 0.05 to 50 keV, making it a versatile observatory for various scientific investigations.

Scientific Achievements

EXOSAT made several important contributions to the field of X-ray astronomy:

• It conducted detailed studies of X-ray binaries, shedding light on the nature of compact objects such as neutron stars and black holes.
• The satellite observed the X-ray emissions from active galactic nuclei (AGN), contributing to the understanding of supermassive black holes at the centers of galaxies.
• EXOSAT's observations of stellar coronae provided insights into the magnetic activity of stars other than the Sun.
• The mission also detected X-ray pulsations from isolated neutron stars, offering clues about the structure and evolution of these dense objects.

Legacy

Although the mission ended in 1986, the data collected by EXOSAT continue to be valuable to researchers. The mission paved the way for subsequent X-ray observatories, such as XMM-Newton and Chandra X-ray Observatory, by demonstrating the importance of space-based X-ray astronomy. EXOSAT's success underscored the need for international collaboration in space research and set a precedent for future missions by the European Space Agency.

See Also

• X-ray astronomy
• European Space Agency
• XMM-Newton
• Chandra X-ray Observatory