Wide Field Infrared Explorer
Encyclopedia
The Wide Field Infrared Explorer (WIRE) was a satellite
launched on 5 March 1999 on the Pegasus XL rocket into a polar orbit
between 409 km and 426 km above the Earth's surface. WIRE was intended to be a four-month infrared
survey of the entire sky at 21-27 micrometres and 9-15 micrometres, specifically focusing on starburst galaxies
and luminous protogalaxies
.
The science team was based at the Infrared Processing and Analysis Center in Pasadena, California. Flight operations, integration, and testing were from Goddard Space Flight Center
in Maryland. The telescope was built by Space Dynamics Laboratories in Utah.
Premature ejection of the spacecraft aperture cover led to depletion of the solid hydrogen cryogen shortly after launch, ending the primary science mission. The onboard star tracker remained functional, and has been used for long-term precision photometric monitoring of bright stars in support of an asteroseismology
program.
On May 10, 2011 (around 07:00 GMT) WIRE reentered Earth's atmosphere, according to the mission website.
In order to salvage some functionality from the spacecraft, operations were redirected after the failure of the cryogen system to an alternate science mission using the undamaged onboard star tracker for long-term monitoring of bright stars in support of an asteroseismology
program. This technique aims to measure oscillations in nearby stars to probe their structure. While the star tracker has poor spatial resolution, having been designed primarily for a wide field of view and detection of the brightest stars, it is above the atmosphere and thus avoids scintillation, enabling high-precision photometry.
As a secondary experiment, one solar array includes a section with reflectors, to test a concentrator system.
The original science goals of WIRE may finally be achieved by the Wide-field Infrared Survey Explorer (WISE)
mission which was successfully launched into orbit on December 14, 2009 and began observations on January 14, 2010.
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....
launched on 5 March 1999 on the Pegasus XL rocket into a polar orbit
Polar orbit
A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator...
between 409 km and 426 km above the Earth's surface. WIRE was intended to be a four-month infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
survey of the entire sky at 21-27 micrometres and 9-15 micrometres, specifically focusing on starburst galaxies
Starburst galaxy
A starburst galaxy is a galaxy in the process of an exceptionally high rate of star formation, compared to the usual star formation rate seen in most galaxies. Galaxies are often observed to have a burst of star formation after a collision or close encounter between two galaxies...
and luminous protogalaxies
Protogalaxy
In physical cosmology, a protogalaxy, which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation, during this period of galactic evolution, will determine whether a galaxy is a spiral or elliptical galaxy; a...
.
The science team was based at the Infrared Processing and Analysis Center in Pasadena, California. Flight operations, integration, and testing were from Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...
in Maryland. The telescope was built by Space Dynamics Laboratories in Utah.
Premature ejection of the spacecraft aperture cover led to depletion of the solid hydrogen cryogen shortly after launch, ending the primary science mission. The onboard star tracker remained functional, and has been used for long-term precision photometric monitoring of bright stars in support of an asteroseismology
Asteroseismology
Asteroseismology also known as stellar seismology is the science that studies the internal structure of pulsating stars by the interpretation of their frequency spectra. Different oscillation modes penetrate to different depths inside the star...
program.
On May 10, 2011 (around 07:00 GMT) WIRE reentered Earth's atmosphere, according to the mission website.
Mission
A design flaw in the spacecraft control electronics caused the telescope dust cover to eject prematurely in its first few hours on-orbit, exposing the telescope to the Earth. In normal operations the telescope would avoid pointing at the Earth as well as the Sun because the heat load was too high for the cryogenic cooling. At this early stage in the mission, the telescope was deliberately pointed at the Earth for safety under the assumption that the dust cover was present. The influx of power into the telescope caused the solid hydrogen cryostat to boil off all of its cryogen. As a result, the cryostat vent, now expelling gas at rates orders of magnitude higher than designed, acted as a tiny thruster rocket overwhelming the attitude control system and ultimately spinning the spacecraft up as high as 60 rpm. After the hydrogen was exhausted, spacecraft engineers were able to re-establish attitude control. However, with the cryogen gone, the science instrument was no longer functional and the original science mission ended.In order to salvage some functionality from the spacecraft, operations were redirected after the failure of the cryogen system to an alternate science mission using the undamaged onboard star tracker for long-term monitoring of bright stars in support of an asteroseismology
Asteroseismology
Asteroseismology also known as stellar seismology is the science that studies the internal structure of pulsating stars by the interpretation of their frequency spectra. Different oscillation modes penetrate to different depths inside the star...
program. This technique aims to measure oscillations in nearby stars to probe their structure. While the star tracker has poor spatial resolution, having been designed primarily for a wide field of view and detection of the brightest stars, it is above the atmosphere and thus avoids scintillation, enabling high-precision photometry.
As a secondary experiment, one solar array includes a section with reflectors, to test a concentrator system.
The original science goals of WIRE may finally be achieved by the Wide-field Infrared Survey Explorer (WISE)
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer is a NASA infrared-wavelength astronomical space telescope launched on December 14, 2009, and decommissioned/hibernated on February 17, 2011 when its transmitter was turned off...
mission which was successfully launched into orbit on December 14, 2009 and began observations on January 14, 2010.
External links
- http://www.ipac.caltech.edu/wire/