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'''RELIKT-1''' (sometimes '''RELICT-1''' from {{lang-ru|РЕЛИКТ-1}}) was a [[Soviet Union|Soviet]] [[cosmic microwave background]] [[anisotropy]] experiment on board the [[Prognoz 9]] satellite (launched 1 July 1983). It was the first CMB satellite, and gave upper limits on large-scale anisotropy.
'''RELIKT-1''' (sometimes '''RELICT-1''' from {{lang-ru|РЕЛИКТ-1}}) was a [[Soviet Union|Soviet]] [[cosmic microwave background]] [[anisotropy]] experiment launched on board the [[Prognoz 9]] satellite on 1 July 1983. It operated until February 1984. It was the first CMB satellite (followed by the [[Cosmic Background Explorer]] in 1989) and measured the CMB dipole, the Galactic plane, and gave upper limits on the [[quadrupole moment]].

A follow-up, '''RELIKT-2''', would have been launched around 1993, but never took place due to the [[dissolution of the Soviet Union]].


== Concept and construction ==
== Concept and construction ==
⚫
This experiment was prepared by the Space Research Institute of the [[USSR Academy of Sciences]] and supervised by Dr. [[Igor Strukov]].{{fact}}
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⚫
This experiment was prepared by the Space Research Institute of the [[USSR Academy of Sciences]] and supervised by Dr. [[Igor Strukov]].
The experiment weight {{convert|30|kg|lb}}, and consumed 50W of power.<ref name="Strukov1984" />


== Launch and observations ==
== 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 1,000km and apogee around 750,000km, and an orbital period of 26 days.<ref name="Klypin1992" />
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 1,000km and apogee around 750,000km, and an orbital period of 26 days.<ref name="Klypin1992" />


RELIKT-1 observed at 37&nbsp;GHz (8&nbsp;mm), with a bandwidth of 0.4GHz 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. The signal was sampled twice a second, and the noise was correlated between samples.<ref name="Klypin1992" />
RELIKT-1 observed at 37&nbsp;GHz (8&nbsp;mm), with a bandwidth of 0.4GHz and an angular resolution of 5.8°. It used a superheterodyne, or [[Dicke-type modulation radiometer]]<ref name="lambda" /> with an automatic balancer for the two input levels with a 30 second time constant. The noise in 1 second was 31mK,ref name="Klypin1992" /> with a system temperature of 300K, and a receiver temperature of 110K.<ref name="Strukov1984" /> The signal was sampled twice a second, and the noise was correlated between samples.<ref name="Klypin1992" />


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.<ref name="Klypin1992" />
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.<ref name="Klypin1992" />


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, and the in-flight system temperatures were measured to vary by 4% on a weekly basis.<ref name="Klypin1992" />
The radiometer was calibrated to 5% accuracy before launch, as was an internal noise source (which was used every four days during observations). <ref name="Klypin1992" />Additionally the moon was used as a calibrator, as it was observed twice a month,<ref name="Strukov1984" /> and the in-flight system temperatures were measured to vary by 4% on a weekly basis.<ref name="Klypin1992" />


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. 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.<ref name="Klypin1992" />
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.<ref name="Klypin1992" /> The signal was recorded onto a tape recorder, and transmitted to Earth every four days.<ref name="scienceUSSR" /> 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,<ref name="Klypin1992" /> after collecting 15 million measurements.<ref name="lambda" />


== Results ==
== Results ==
It measured the CMB dipole, the Galactic plane, and constrained the [[quadrupole moment]].<ref name="Klypin1992" />
It measured the CMB dipole, the Galactic plane,<ref name="lambda" /> and reported constraints on the quadrupole moment.<ref name="Klypin1992" />


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.<ref name="Strukov1984" />
⚫
A 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 <math>(\Delta T/T)_{quad} = 1.5 \times 10^{-5}</math> with a 95% confidence level, assuming a [[Harrison-Zeldovich spectrum]], or <math><3.0\times10^{-5}</math> without assuming a model. The results were close to those measured by the [[Cosmic Background Explorer]].<ref name="Klypin1992" />


A reanalysis of the data by Strukov et al. in 1992 found a quadrupole <math>(\Delta T/T)_{quad}</math> between <math>6\times10^{-6}</math> and <mat>3.3\times10^{-5}</math> at 90% confidence level, and also reported a negative anomaly at l=150°, b=-70° at a 99% confidence level,<ref name="Strukov1992" /><ref name="Strukov1993" />
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A reanalysis of the data in the later years claimed a confident blackbody form and anisotropy of the cosmic microwave background radiation. Results have been reported in January 1992 at the All-Moscow Astronomy Seminar held at [[Sternberg Astronomical Institute]], and published, for example, in issue 4/1992 of the "Science in USSR" journal<ref>http://epizodsspace.airbase.ru/bibl/nauka-v-ussr/1992/vzglad.html</ref> and in [[Soviet Astronomy Letters]] in May–June 1992.<ref>{{cite journal|authors= Strukov, I. A., Brukhanov, A. A., Skulachev, D. P., & Sazhin, M. V. |title=Anisotropy of the microwave background radiation |journal= Soviet Astronomy Letters |year=1992 |volume=18 |issue=5 |pages= 153–156 |bibcode=1992SvAL...18..153S}}</ref> Nevertheless, the Nobel Prize in Physics for 2006 was awarded to a team of American scientists, who announced the fact on April 23, 1992 based on data taken by the [[Cosmic Background Explorer|COBE]] spacecraft.


⚫
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 <math>(\Delta T/T)_{quad} = 1.5 \times 10^{-5}</math> with a 95% confidence level, assuming a [[Harrison-Zeldovich spectrum]], or <math><3.0\times10^{-5}</math> without assuming a model. The results were close to those measured by the [[Cosmic Background Explorer]].<ref name="Klypin1992" />
The heat radiation map of the Universe served as the emblem of the 1989 international conference "The Cosmic Wave Background: 25 Years Later" in L'Aquila, Italy.

The discovery of anisotropy by the RELIKT-1 spacecraft was first reported officially in January 1992 at the All-Moscow Astronomy Seminar held at [[Sternberg Astronomical Institute]].


== RELIKT-2 ==
== 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 193GHz (1.6mm). 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.<ref name="Klypin1992" /> 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]] on a [[Molniya]] rocket.<ref name="scienceUSSR" /> The spacecraft was scheduled to launch in 1993-1994, but the launch never took place because of the [[Dissolution of the Soviet Union|Soviet Union's break-up]] and lack of funding.
As a follow-up to RELIKT-1, it was decided in 1986 to study the anisotropy of CMB as part of the '''Relikt-2''' project.

⚫
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 193GHz (1.6mm). 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.<ref name="Klypin1992" /> The spacecraft was scheduled to launch in 1993-1994, but the launch never took place because of the [[Soviet Union's break-up]] and lack of funding.


== References ==
== References ==
{{Reflist | refs=
{{Reflist | refs=
<ref name="Klypin1992">{{Cite Q|Q68552080}}</ref>
<ref name="Klypin1992">{{Cite Q|Q68552080}}</ref>
<ref name="Strukov1992">{{cite journal|authors= Strukov, I. A., Brukhanov, A. A., Skulachev, D. P., & Sazhin, M. V. |title=Anisotropy of the microwave background radiation |journal= Soviet Astronomy Letters |year=1992 |volume=18 |issue=5 |pages= 153–156 |bibcode=1992SvAL...18..153S}}</ref>
<ref name="scienceUSSR">{{cite web |title=Взгляд в прошлое Вселенной ("A glimpse into the past of the universe", "Science in the USSR" 1992 #4) |url=http://epizodsspace.airbase.ru/bibl/nauka-v-ussr/1992/vzglad.html |website=epizodsspace.airbase.ru |access-date=26 April 2021|lang=ru}}</ref>
<ref name="lambda">{{cite web |title=LAMBDA - Relikt Overview |url=https://lambda.gsfc.nasa.gov/product/relikt/ |website=lambda.gsfc.nasa.gov |access-date=26 April 2021}}</ref>
<ref name="Strukov1984">{{cite journal |last1=Strukov |first1=I. A. |last2=Skulachev |first2=D. P. |title=Deep-Space Measurements of the Microwave Background Anisotropy - First Results of the Relikt Experiment |journal=Soviet Astronomy Letters |date=1984 |volume=10 |pages=1–4 |url=https://ui.adsabs.harvard.edu/abs/1984SvAL...10....1S/abstract}}</ref>
<ref name="Strukov1993">{{cite journal |last1=Strukov |first1=I. A. |last2=Brukhanov |first2=A. A. |last3=Skulachev |first3=D. P. |last4=Sazhin |first4=M. V. |title=Anisotropy of relic radiation in the RELICT-1 experiment and parameters of grand unification |journal=Physics Letters B |date=1 September 1993 |volume=315 |pages=198–202 |doi=10.1016/0370-2693(93)90180-P |url=https://ui.adsabs.harvard.edu/abs/1993PhLB..315..198S/abstract |issn=0370-2693}}</ref>
}}
}}

==References==
* Strukov, I. A.; Skulachev, D. P. Deep-Space Measurements of the Microwave Background Anisotropy - First Results of the Relikt Experiment. 1984
* Strukov, I. A.; Brukhanov, A. A.; Skulachev, D. P.; Sazhin, M. V. Anisotropy of relic radiation in the RELICT-1 experiment and parameters of grand unification. Physics Letters B, Volume 315, Issue 1-2, p.&nbsp;198-202. 09/1993

==External links==
* [http://lambda.gsfc.nasa.gov/product/relikt/ The Relikt Experiment] at NASA's LAMBDA


{{CMB experiments}}
{{CMB experiments}}

Revision as of 19:00, 26 April 2021

RELIKT-1
Part ofPrognoz 9 Edit this on Wikidata
OrganizationAcademy of Sciences of the Soviet Union Edit this on Wikidata
Wavelength37 GHz (8.1 mm)
First light1 July 1983 Edit this on Wikidata
DecommissionedFebruary 1984 Edit this on Wikidata
Telescope stylecosmic microwave background experiment
artificial satellite of the Earth Edit this on Wikidata
Angular resolution5.8 degree Edit this on Wikidata
[edit on Wikidata]

RELIKT-1 (sometimes RELICT-1 from Template:Lang-ru) was a Soviet cosmic microwave background anisotropy experiment launched on board the Prognoz 9 satellite on 1 July 1983. It operated until February 1984. It was the first CMB satellite (followed by the Cosmic Background Explorer in 1989) and measured the CMB dipole, the Galactic plane, and gave upper limits on the quadrupole moment.

A follow-up, RELIKT-2, would have been launched around 1993, but never took place due to the dissolution of the Soviet Union.

Concept and construction

This experiment was prepared by the Space Research Institute of the USSR Academy of Sciences and supervised by Dr. Igor Strukov.[citation needed]

The experiment weight 30 kilograms (66 lb), and consumed 50W of power.[1]

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 1,000km and apogee around 750,000km, and an orbital period of 26 days.[2]

RELIKT-1 observed at 37 GHz (8 mm), with a bandwidth of 0.4GHz and an angular resolution of 5.8°. It used a superheterodyne, or Dicke-type modulation radiometer[3] with an automatic balancer for the two input levels with a 30 second time constant. The noise in 1 second was 31mK,ref name="Klypin1992" /> with a system temperature of 300K, and a receiver temperature of 110K.[1] The signal was sampled twice a second, and the noise was correlated between samples.[2]

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.[2]

The radiometer was calibrated to 5% accuracy before launch, as was an internal noise source (which was used every four days during observations). [2]Additionally the moon was used as a calibrator, as it was observed twice a month,[1] and the in-flight system temperatures were measured to vary by 4% on a weekly basis.[2]

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.[2] The signal was recorded onto a tape recorder, and transmitted to Earth every four days.[4] 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,[2] after collecting 15 million measurements.[3]

Results

It measured the CMB dipole, the Galactic plane,[3] and reported constraints on the quadrupole moment.[2]

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.[1]

A reanalysis of the data by Strukov et al. in 1992 found a quadrupole between and <mat>3.3\times10^{-5}</math> at 90% confidence level, and also reported a negative anomaly at l=150°, b=-70° at a 99% confidence level,[5][6]

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 with a 95% confidence level, assuming a Harrison-Zeldovich spectrum, or without assuming a model. The results were close to those measured by the Cosmic Background Explorer.[2]

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 193GHz (1.6mm). 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.[2] 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 on a Molniya rocket.[4] The spacecraft was scheduled to launch in 1993-1994, but the launch never took place because of the Soviet Union's break-up and lack of funding.

References

  1. ^ a b c d Strukov, I. A.; Skulachev, D. P. (1984). "Deep-Space Measurements of the Microwave Background Anisotropy - First Results of the Relikt Experiment". Soviet Astronomy Letters. 10: 1–4.
  2. ^ a b c d e f g h i j Klypin A. A.; Strukov I. A.; Skulachev D. P. (1992). "The Relikt missions : results and prospects for detection of the microwave background anisotropy". Monthly Notices of the Royal Astronomical Society. 258: 71–81. Bibcode:1992MNRAS.258...71K. doi:10.1093/MNRAS/258.1.71. ISSN 0035-8711. Wikidata Q68552080.
  3. ^ a b c "LAMBDA - Relikt Overview". lambda.gsfc.nasa.gov. Retrieved 26 April 2021.
  4. ^ a b "Взгляд в прошлое Вселенной ("A glimpse into the past of the universe", "Science in the USSR" 1992 #4)". epizodsspace.airbase.ru (in Russian). Retrieved 26 April 2021.
  5. ^ "Anisotropy of the microwave background radiation". Soviet Astronomy Letters. 18 (5): 153–156. 1992. Bibcode:1992SvAL...18..153S. {{cite journal}}: Unknown parameter |authors= ignored (help)
  6. ^ Strukov, I. A.; Brukhanov, A. A.; Skulachev, D. P.; Sazhin, M. V. (1 September 1993). "Anisotropy of relic radiation in the RELICT-1 experiment and parameters of grand unification". Physics Letters B. 315: 198–202. doi:10.1016/0370-2693(93)90180-P. ISSN 0370-2693.
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