BeppoSAX
Encyclopedia
BeppoSAX was an Italian
–Dutch
satellite
for X-ray astronomy
which played a crucial role in resolving the origin of gamma-ray bursts (GRBs), the most energetic events known in the universe. It was the first X-ray mission capable of simultaneously observing targets over more than 3 decades of energy, from 0.1 to 300 kiloelectronvolts (keV) with relatively large area, good (for the time) energy resolution and imaging capabilities (with a spatial resolution of 1 arc minute
between 0.1 and 10 keV). BeppoSAX was a major programme of the Italian Space Agency
(ASI) with the participation of the Netherlands Agency for Aerospace Programmes
(NIVR). The prime contractor for the space segment was Alenia
while Nuova Telespazio
led the development of the ground segment. Most of the scientific instruments were developed by the Italian National Research Council
(CNR) while the Wide Field Cameras were developed by the Netherlands Institute for Space Research
(SRON) and the LECS was developed by the astrophysics division of the European Space Agency
's ESTEC
facility.
BeppoSAX was named in honour of the Italian physicist
Giuseppe "Beppo" Occhialini
. SAX stands for "Satellite per Astronomia a raggi X" or "Satellite for X-ray astronomy".
X-ray
observations cannot be performed from ground-based telescope
s, since Earth's atmosphere
blocks most of the incoming radiation.
One of BeppoSAX's main achievements was the identification of numerous gamma ray burst
s with extra-galactic objects. (See the linked article for details.)
Launched by an Atlas-Centaur
on 30 April 1996 into a low inclination
(<4 degree) low-Earth orbit, the expected operating life of two years was extended to April 30, 2002 due to high scientific interest in the mission and the continued good technical status. After this date, the orbit started to decay rapidly and various subsystems were starting to fail making it no longer worthwhile to conduct scientific observations.
On April 29, 2003, the satellite ended its life falling into the Pacific Ocean
.
The first four instruments (often called Narrow Field Instruments or NFI) point to the same direction, and allow observations of an object in a broad energy band of 0.1 to 300 keV (16 to 48,000 attojoule
s (aJ)).
The WFC contained two coded aperture
cameras operating in the 2 to 30 keV (320 to 4,800 aJ) range and each covering a region of 40 x 40 degrees (20 by 20 degrees full width at half maximum) on the sky. The WFC was complemented by the shielding of PDS which had a (nearly) all-sky view in the 100 to 600 keV (16,000 to 96,000 aJ) band, ideal for detecting gamma ray burst
s (GRB).
The PDS shielding has poor angular resolution. In theory, after a GRB was seen in the PDS, the position was refined first with the WFC. However, due to the many spikes in the PDS, in practice a GRB was found using the WFC, often corroborated by a BATSE-signal. The position up to arcminute precision - depending on the signal to noise ratio of the burst - was found using the deconvoluted WFC-image. The coordinates were speedily sent out as an International Astronomical Union
(IAU) and Gamma-ray burst Coordinate Network Circular. After this, immediate follow-up observations with the NFI and optical observatories around the world allowed accurate positioning of the GRB and detailed observations of the X-ray, optical and radio afterglow.
The MECS contained three identical gas scintillation proportional counter
s operating in the 1.3 to 10 keV (208 to 1602 aJ) range. On 06 May 1997 one of the three identical MECS units was lost when a fault developed in the High Voltage power supply.
The LECS was similar to the MECS units, expect that it had a thinner window that allows photons with lower energies down to 0.1 keV (16 aJ) to pass through and operated in a "driftless" mode which is necessary to detect the lowest energy X-rays as these would be lost in the low field regime near the entrance window of aa conventional GSPC. The LECS data above 4 keV (641 aJ) is not usable due to calibration issues probably caused by the driftless design. The LECS and MECS had imaging capability, whereas the high-energy narrow field instruments were non-imaging.
The HPGSPC was also a gas scintillation proportional counter, operating at a high (three atmospheres) pressure. High pressure equals high density, and dense photon-stopping material allowed detection of photons up to 120 keV (19,000 aJ).
The PDS was a crystal (sodium iodide
/ caesium iodide
) scintillator detector capable of absorbing photons up to 300 keV (48,000 aJ). The spectral resolution of the PDS was rather modest when compared to the gas detectors, but the low background counting rate resulting from the low inclination BeppoSAX orbit and good background rejection capabilities meant that the PDS remains one of the most sensitive high-energy instruments flown.
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
–Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
for X-ray astronomy
X-ray astronomy
X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and...
which played a crucial role in resolving the origin of gamma-ray bursts (GRBs), the most energetic events known in the universe. It was the first X-ray mission capable of simultaneously observing targets over more than 3 decades of energy, from 0.1 to 300 kiloelectronvolts (keV) with relatively large area, good (for the time) energy resolution and imaging capabilities (with a spatial resolution of 1 arc minute
Minute of arc
A minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
between 0.1 and 10 keV). BeppoSAX was a major programme of the Italian Space Agency
Italian Space Agency
The Italian Space Agency is a government agency established in 1988 to fund, regulate and coordinate space exploration activities in Italy...
(ASI) with the participation of the Netherlands Agency for Aerospace Programmes
Netherlands Agency for Aerospace Programmes
The Netherlands Agency for Aerospace Programmes was the official space-exploration agency of the Dutch government until 2009....
(NIVR). The prime contractor for the space segment was Alenia
Alenia Aeronautica
Alenia Aeronautica, a Finmeccanica subsidiary, is a European aerospace company from Italy. Its subsidiaries include Alenia Aermacchi and Alenia Aeronavali...
while Nuova Telespazio
Telespazio
Telespazio is a space systems services company, based in Rome, Italy. Telespazio was founded in 1961; however the company as it exists today was formed on July 1 2005 with the merger of the original Telespazio with the space services division of Alcatel...
led the development of the ground segment. Most of the scientific instruments were developed by the Italian National Research Council
Consiglio Nazionale delle Ricerche
The Consiglio Nazionale delle Ricerche or National Research Council, is an Italian public organization set up to support scientific and technological research. Its headquarters are in Rome.-History:The institution was founded in 1923...
(CNR) while the Wide Field Cameras were developed by the Netherlands Institute for Space Research
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 groundbreaking research in space, focusing on astrophysical research, Earth science and planetary research...
(SRON) and the LECS was developed by the astrophysics division of the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
's ESTEC
European Space Research and Technology Centre
The European Space Research and Technology Centre is the European Space Agency's main technology development and test centre for spacecraft and space technology. It is situated in Noordwijk, South Holland, in the western Netherlands....
facility.
BeppoSAX was named in honour of the Italian physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
Giuseppe "Beppo" Occhialini
Giuseppe Occhialini
Giuseppe Paolo Stanislao "Beppo" Occhialini ForMemRS was an Italian physicist, who contributed to the discovery of the pion or pi-meson decay in 1947, with César Lattes and Cecil Frank Powell . At the time of this discovery, they were all working at the H. H...
. SAX stands for "Satellite per Astronomia a raggi X" or "Satellite for X-ray astronomy".
X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
observations cannot be performed from ground-based telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s, since Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
blocks most of the incoming radiation.
One of BeppoSAX's main achievements was the identification of numerous gamma ray burst
Gamma ray burst
Gamma-ray bursts are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the most luminous electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes, although a typical...
s with extra-galactic objects. (See the linked article for details.)
Launched by an Atlas-Centaur
Atlas-Centaur
The Atlas-Centaur was an American expendable launch system designed and built by General Dynamics Convair Division in San Diego, CA. It was derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was used for 61 orbital launches between 1962 and 1983. It was...
on 30 April 1996 into a low inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
(<4 degree) low-Earth orbit, the expected operating life of two years was extended to April 30, 2002 due to high scientific interest in the mission and the continued good technical status. After this date, the orbit started to decay rapidly and various subsystems were starting to fail making it no longer worthwhile to conduct scientific observations.
On April 29, 2003, the satellite ended its life falling into the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
.
Spacecraft characteristics
- Dimensions: 3.6 m high, 2.7 m diameter
- Solar cell power: 3 kW
- Data generated: 1 GBGigabyteThe gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...
each orbit (90 min)
Instrumentation
BeppoSAX contained five science instruments:- Low Energy Concentrator Spectrometer (LECS)
- Medium Energy Concentrator Spectrometer (MECS)
- High Pressure Gas Scintillation Proportional Counter (HPGSPC)
- Phoswich Detector System (PDS)
- Wide Field Camera (WFC)
The first four instruments (often called Narrow Field Instruments or NFI) point to the same direction, and allow observations of an object in a broad energy band of 0.1 to 300 keV (16 to 48,000 attojoule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
s (aJ)).
The WFC contained two coded aperture
Coded aperture
Coded Apertures or Coded-Aperture Masks are grids, gratings, or other patterns of materials opaque to various wavelengths of light. The wavelengths are usually high-energy radiation such as X-rays and gamma rays. By blocking and unblocking light in a known pattern, a coded "shadow" is cast upon a...
cameras operating in the 2 to 30 keV (320 to 4,800 aJ) range and each covering a region of 40 x 40 degrees (20 by 20 degrees full width at half maximum) on the sky. The WFC was complemented by the shielding of PDS which had a (nearly) all-sky view in the 100 to 600 keV (16,000 to 96,000 aJ) band, ideal for detecting gamma ray burst
Gamma ray burst
Gamma-ray bursts are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the most luminous electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes, although a typical...
s (GRB).
The PDS shielding has poor angular resolution. In theory, after a GRB was seen in the PDS, the position was refined first with the WFC. However, due to the many spikes in the PDS, in practice a GRB was found using the WFC, often corroborated by a BATSE-signal. The position up to arcminute precision - depending on the signal to noise ratio of the burst - was found using the deconvoluted WFC-image. The coordinates were speedily sent out as an International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
(IAU) and Gamma-ray burst Coordinate Network Circular. After this, immediate follow-up observations with the NFI and optical observatories around the world allowed accurate positioning of the GRB and detailed observations of the X-ray, optical and radio afterglow.
The MECS contained three identical gas scintillation proportional counter
X-ray astronomy detector
X-ray astronomy detectors are instruments that detect X-rays for use in the study of X-ray astronomy.X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray emission from celestial objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to...
s operating in the 1.3 to 10 keV (208 to 1602 aJ) range. On 06 May 1997 one of the three identical MECS units was lost when a fault developed in the High Voltage power supply.
The LECS was similar to the MECS units, expect that it had a thinner window that allows photons with lower energies down to 0.1 keV (16 aJ) to pass through and operated in a "driftless" mode which is necessary to detect the lowest energy X-rays as these would be lost in the low field regime near the entrance window of aa conventional GSPC. The LECS data above 4 keV (641 aJ) is not usable due to calibration issues probably caused by the driftless design. The LECS and MECS had imaging capability, whereas the high-energy narrow field instruments were non-imaging.
The HPGSPC was also a gas scintillation proportional counter, operating at a high (three atmospheres) pressure. High pressure equals high density, and dense photon-stopping material allowed detection of photons up to 120 keV (19,000 aJ).
The PDS was a crystal (sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
/ caesium iodide
Caesium iodide
Caesium iodide is an ionic compound often used as the input phosphor of an x-ray image intensifier tube found in fluoroscopy equipment....
) scintillator detector capable of absorbing photons up to 300 keV (48,000 aJ). The spectral resolution of the PDS was rather modest when compared to the gas detectors, but the low background counting rate resulting from the low inclination BeppoSAX orbit and good background rejection capabilities meant that the PDS remains one of the most sensitive high-energy instruments flown.