The Astronomical Netherlands Satellite (ANS; also known as Astronomische Nederlandse Satelliet) was a space-based

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

and

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...

. It was launched into

Earth orbit Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi) in a counterclockwise direction as viewed from above the Northern Hemisphere. One complete orbit takes days (1 sidereal year), during which time E ...

on 30 August 1974 at 14:07:39 UTC in a Scout rocket from

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg Sp ...

, United States. The mission ran for 20 months until June 1976, and was jointly funded by the

Netherlands Institute for Space Research SRON Netherlands Institute for Space Research is the Dutch expertise institute for space research. The Institute develops and uses innovative technology for research in space, focusing on astrophysical research, Earth science and planetary resea ...

(NIVR) and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

. ANS was the first Dutch satellite, and the Main Belt asteroid 9996 ANS was named after it. ANS reentered Earth's atmosphere on June 14, 1977. The telescope had an initial orbit with a periapsis of , an apoapsis of , with

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

98.0° and eccentricity 0.064048, giving it a period of 99.2 minutes. The orbit was sun-synchronous, and the attitude of the spacecraft could be controlled through reaction wheels. The momentum stored in the reaction wheels throughout the orbit was regularly dumped via magnetic coils that interacted with the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

. The satellite also had two masses that were released shortly after orbit injection, to remove most of the satellite's

angular momentum In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed syst ...

induced by the launcher. The attitude could be measured by a variety of techniques, including

solar sensor A photodiode is a light-sensitive semiconductor diode. It produces current when it absorbs photons. The package of a photodiode allows light (or infrared or ultraviolet radiation, or X-rays) to reach the sensitive part of the device. The packag ...

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ...

sensors, star sensors and a

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

. ANS could measure

photons in the energy range 2 to 30 keV, with a 60 cm² detector, and was used to find the positions of galactic and extragalactic X-ray sources. It also measured their spectra, and looked at their variations over time. It discovered X-ray bursts, and also detected X-rays from Capella. ANS also observed in the

part of the spectrum, with a 22 cm (260 cm²)

Cassegrain Cassegrain may refer to * Cassegrain reflector, a design used in telescopes * Cassegrain antenna, a type of parabolic antenna * Cassegrain (crater), on the Moon * a Belgian canned vegetables producer now part of Bonduelle S.A. People : * Guillau ...

telescope. The

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

s of the observed photons were between 150 and 330 nm, with the detector split into five channels with central wavelengths of 155, 180, 220, 250 and 330 nm. At these frequencies it took over 18,000 measurements of around 400 objects.

See also

References

Further reading