RELIKT-1
   HOME

TheInfoList



OR:

RELIKT-1 (sometimes RELICT-1 from russian: РЕЛИКТ-1) was a
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
cosmic microwave background In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all spac ...
anisotropy Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...
experiment launched on board the
Prognoz 9 Prognoz 9 was a Soviet satellite. It was designed to investigate residual radiation from the Big Bang and gamma flares in deep space. Mission The mission was of Investigation of residual radiation from the Big Bang and gamma flares in deep spa ...
satellite on 1 July 1983. It operated until February 1984. It was the first CMB satellite (followed by the
Cosmic Background Explorer The Cosmic Background Explorer (COBE ), also referred to as Explorer 66, was a NASA satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation (CMB or CMBR) of th ...
in 1989) and measured the CMB dipole, the Galactic plane, and gave upper limits on the
quadrupole moment A quadrupole or quadrapole is one of a sequence of configurations of things like electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure refl ...
. A follow-up, RELIKT-2, would have been launched around 1993, and a RELIKT-3 was proposed, but neither took place due to the
dissolution of the Soviet Union The dissolution of the Soviet Union, also negatively connoted as rus, Разва́л Сове́тского Сою́за, r=Razvál Sovétskogo Soyúza, ''Ruining of the Soviet Union''. was the process of internal disintegration within the Sov ...
.


Launch and observations

RELIKT-1 was launched on board the Prognoz-9 satellite on 1 January 1983. The satellite was in a highly eccentric orbit, with perigee around 1,000 km and apogee around 750,000 km, and an orbital period of 26 days. RELIKT-1 observed at 37 GHz (8 mm), with a bandwidth of 0.4 GHz and an angular resolution of 5.8°. It used a superheterodyne, or Dicke-type modulation radiometer with an automatic balancer for the two input levels with a 30-second time constant. The noise in 1 second was 31mK, with a system temperature of 300K, and a receiver temperature of 110K. The signal was sampled twice a second, and the noise was correlated between samples. The receiver used two corrugated horn antennas, one pointing parallel to the spacecraft spin axis, the other pointing at a parabolic antenna to point at 90° from the spin axis. The satellite rotated every 120 seconds. The experiment weight , and consumed 50W of power. The radiometer was calibrated to 5% accuracy before launch, as was an internal noise source (which was used every four days during observations). Additionally the moon was used as a calibrator, as it was observed twice a month, and the in-flight system temperatures were measured to vary by 4% on a weekly basis. The satellite rotation axis was kept constant for a week, giving 5040 scans of a great circle, after which it was changed to a new axis. The signal was recorded onto a tape recorder, and transmitted to Earth every four days. It observed for 6 months, giving 31 different scans that covered the whole sky, all of which intersected at the ecliptic poles. The experiment ceased observations in February 1984, after collecting 15 million measurements.


Results

It measured the CMB dipole, the Galactic plane, and reported constraints on the quadrupole moment. The first dipole measurement was reported in 1984, while the telescope was still observing, at 2.1±0.5mK, and upper limits on the quadrupole of 0.2mK. It also detected brighter-than-expected Galactic plane emission from compact HII regions. A reanalysis of the data by Strukov et al. in 1992 found a quadrupole (\Delta T/T)_ between 6\times10^ and 3.3\times10^ at 90% confidence level, and also reported a negative anomaly at l=150°, b=-70° at a 99% confidence level, Another reanalysis of the data by Klypin, Stukov and Skulachev in 1992 found a dipole of 3.15±0.12mK, with a direction of 11h17m±10m and -7.5°±2.5°. It placed a limit on the CMB quadrupole of (\Delta T/T)_ = 1.5 \times 10^ with a 95% confidence level, assuming a Harrison-Zeldovich spectrum, or <3.0\times10^ without assuming a model. The results were close to those measured by the
Cosmic Background Explorer The Cosmic Background Explorer (COBE ), also referred to as Explorer 66, was a NASA satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation (CMB or CMBR) of th ...
and the
Tenerife Experiment The Tenerife Experiment was a Cosmic Microwave Background (CMB) experiment built by Jodrell Bank (then known as the Nuffield Radio Astronomy Laboratories) of the University of Manchester in collaboration with the Instituto de Astrofisica de Canar ...
.


RELIKT-2

The second RELIKT satellite would have been launched in mid-1993. It would have had five channels to observe at 21.7 (13.8), 24.5 (8.7), 59.0 (5.1), 83.0 (3.6) and 193 GHz (1.6mm), using degenerated paramps. It would have had corrugated horns to give a resolution of 7°, and a more distant orbit to avoid contamination from the Moon and Sun, with a mission duration around 2 years, to give a better sensitivity than COBE. It would have been cooled to 100K. It was constructed, and was undergoing tests in 1992. It would have been launched as the
Libris satellite LIBRIS (Library Information System) is a Swedish national union catalogue maintained by the National Library of Sweden in Stockholm. It is possible to freely search about 6.5 million titles nationwide. In addition to bibliographic records, one fo ...
on a
Molniya Molniya (Russian for ''lightning'') may refer to: * Molniya (satellite), a Soviet military communications satellite ** Molniya orbit * Molniya (explosive trap), a KGB explosive device * Molniya (rocket), a variation of the Soyuz launch vehicle * OKB ...
rocket. The launch was put back to 1996, with expanded plans to observe with 1.5-3° resolution from two spacecraft in 1995, but ultimately never took place because of the Soviet Union's break-up and lack of funding. A RELIKT-3 was also planned, which would have observed at 34–90 GHz with a resolution around 1°.


References

{{Space observatories 1983 in spaceflight 1983 in the Soviet Union Cosmic microwave background experiments Space telescopes Soviet space observatories Spacecraft launched in 1983