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Il '''Wilkinson Microwave Anisotropy Probe''' ('''WMAP'''), conosciuto anche come [[sonda spaziale]] per l<nowiki>'</nowiki>[[anisotropia]] delle [[microonde]] ({{en}}: '''Microwave Anisotropy Probe''' ('''MAP''')), e '''Explorer 80''', è un satellite che misura ciò che rimane delle radiazioni dovute al [[Big Bang]], ovvero la [[radiazione cosmica di fondo]]. Diretto dal professore della Johns Hopkins University [[Charles L. Bennett]], si tratta di un progetto che prevede la collaborazione tra il [[Goddard Space Flight Center]] della [[NASA]] e l<nowiki>'</nowiki>[[Università di Princeton]].<ref name="2003PressRelease" /> Il satellite WMAP è stato lanciato il [[30 giugno]] [[2001]], alle ore 19:46 (GDT) dallo stato della [[Florida]]. Il WMAP è l'erede dei satelliti [[COBE]] e [[MIDEX (satellite)|MIDEX]] previsti dal [[programma Explorer]]. Tale satellite è stato così chiamato in onore di [[David Todd Wilkinson]] (1935-2002).<ref name="2003PressRelease" />
=[[en:Bulbous corpuscle]]=
=[[Corpuscolo di Ruffini]]=
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|Didascalia=Terminazioni nervose del corpuscolo di Ruffini
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Il '''corpuscolo di Ruffini''' è una classe di [[meccanorecettore|meccanorecettori]] ad adattamento lento. Si pensa che siano presenti solo nelle zone naturalmente glabre del [[derma]] (dorso della [[mano]], pianta del [[Piede (anatomia)|piede]], [[labbro|labbra]], [[piccole labbra]] e [[glande]]), e nell'[[ipoderma]] umano. Il nome deriva dal medico italiano [[Angelo Ruffini]].
The WMAP's measurements are more accurate than previous measurements; per the [[Lambda-CDM model]] of the universe, the data indicate [[age of the universe|the age of the universe]] is 13.73 ± 0.12 billion years old, with a [[Hubble's law|Hubble constant]] of 70.1 ± 1.3 km·s<sup>-1</sup>·Mpc<sup>-1</sup>, and is composed of 4.6% ordinary [[Baryonic#Baryonic matter|baryonic matter]]; 23% unknown [[dark matter]] that neither emits nor absorbs light; 72% [[dark energy]] that accelerates expansion; and less than 1% neutrinos — all consistent with a [[Shape of the universe|flat geometry]], and the ratio of energy density to the [[critical density]] Ω = 1.02 ± 0.02. These results support the Lambda-CDM model and the [[physical cosmology|cosmologic]] scenarios of [[cosmic inflation]], and evidence of [[cosmic neutrino background]] radiation.<ref name="2008Hinshaw">Hinshaw et al. (2008)</ref>
==Function==
The data contain unexplained features; an anomaly at the greatest angular measurements of the [[quadrupole moment]] and a large [[WMAP cold spot|cold spot]]. Per ''Science'' magazine, the WMAP was the ''Breakthrough of the Year for 2003''.<ref name="2003Seife">Seife (2003)</ref> This mission's results papers were first and second in the "Super Hot Papers in Science Since 2003" list.<ref name="incites">{{cite web | url=http://www.in-cites.com/hotpapers/shp/1-50.html | title="Super Hot" Papers in Science | publisher=in-cites | month=October | year=2005 | accessdate=2008-04-26}}</ref> As of 2008, the WMAP continues working, slated to end in September 2009.
This spindle-shaped receptor is sensitive to skin stretch, and contributes to the kinesthetic sense of and control of finger position and movement.<ref>{{Cita libro|cognome=Mountcastle |nome=Vernon C. |anno=2005 |titolo=The Sensory Hand: Neural Mechanisms of Somatic Sensation |editore=Harvard University Press |p=34}}</ref> It is believed to be useful for monitoring slippage of objects along the surface of the skin, allowing modulation of grip on an object.
Ruffinian endings are located in the deep layers of the skin, and register mechanical deformation within joints, more specifically angle change, with a specificity of up to 2 degrees, as well as continuous pressure states.They also act as a thermoreceptors that respond for a long time, so in case of deep burn there will be no pain as these receptors will be burned off.<ref>{{Cita libro|cognome=Hamilton |nome=Nancy |anno=2008 |titolo=Kinesiology: Scientific Basis of Human Motion |editore=McGraw-Hill |pp=76–7}}</ref>
==Footnotes and references==
== Objectives ==
<references />
[[Image:CMB Timeline75.jpg|thumb|The universe's timeline, from inflation to the WMAP.]]
==External links==
* {{Cita pubblicazione|autore= Paré M, Behets C, Cornu O |titolo= Paucity of presumptive ruffini corpuscles in the index finger pad of humans. |rivista= J Comp Neurol |volume= 456 |numero= 3 |pp= 260–6 |anno= 2003 | pmid = 12528190 | doi = 10.1002/cne.10519}}
<nowiki>
[[Category:Sensory receptors]]
[[cs:Ruffiniho tělísko]]
The WMAP is to measure the temperature differences in the [[Cosmic microwave background radiation|Cosmic Microwave Background (CMB) radiation]]. The anisotropies then are used to measure the universe's [[geometry]], content, and evolution; and to test the Big Bang model, and the [[cosmic inflation]] theory.<ref name="2003Bennett" /> For that, the mission is creating a full-sky map of the CMB, with a 13 [[arcminute]] resolution via multi-frequency observation. The map requires the fewest [[systematic error]]s, no correlated pixel noise, and accurate calibration, to ensure angular-scale accuracy greater than its resolution.<ref name="2003Bennett">Bennett et al. (2003a)</ref> The map contains 3,145,728 pixels, and uses the [[HEALPix]] scheme to pixelize the sphere.<ref name="2003Bennettb" /> The telescope also measures the CMB's E-mode polarization,<ref name="2003Bennett" /> and foreground polarization; <ref name="2008Hinshaw" /> its life is 27 months; 3 to reach the L2 position, 2 years of observation.<ref name="2003Bennett" />
[[de:Ruffini-Körperchen]]
[[es:Corpúsculos de Ruffini]]
== Development ==
[[fr:Corpuscule de Ruffini]]
[[gl:Corpúsculo de Ruffini]]
[[Image:BigBangNoise.jpg|thumb|A comparison of the sensitivity of WMAP with COBE and Penzias and Wilson's telescope. Simulated data.]]
[[he:גופיף רפיני]]
[[pl:Ciałka Ruffiniego]]
The MAP mission was proposed to NASA in 1995, selected for definition study in 1996, and approved for development in 1997.<ref name="news_facts">{{cite web | url=http://map.gsfc.nasa.gov/news/facts.html | title=WMAP News: Facts | publisher=NASA | date=[[22 April]] [[2008]] | accessdate=2008-04-27}}</ref><ref name="news_events">{{cite web | url=http://map.gsfc.nasa.gov/news/events.html | title=WMAP News: Events | publisher=NASA | date=[[17 April]] [[2008]] | accessdate=2008-04-27}}</ref>
[[pt:Corpúsculo de Ruffini]]</nowiki>
The WMAP was preceded by two missions to observe the CMB; (i) the Soviet [[RELIKT-1]] that reported the upper-limit measurements of CMB anisotropies, and (ii) the U.S. [[COBE]] satellite that reported large-scale CMB fluctuations, and the ground-based and balloon experiments measuring the small-scale fluctuations in patches of sky: the [[BOOMERanG experiment|Boomerang]], the [[Cosmic Background Imager]], and the [[Very Small Array]]. The WMAP is 45 times more sensitive, with 33 times the angular resolution of its COBE satellite predecessor.<ref name="2008Limon">Limon et al. (2008)</ref>
==The spacecraft==
[[Image:WMAP spacecraft diagram.jpg|thumb|WMAP spacecraft diagram]]
The telescope's primary reflecting mirrors are a pair of [[Gregorian telescope|Gregorian]] 1.4m x 1.6m dishes (facing opposite directions), that focus the signal onto a pair of 0.9m x 1.0m secondary reflecting mirrors. They are shaped for optimal performance: a [[carbon fibre]] shell upon a [[Korex]] core, thinly-coated with [[aluminium]] and [[silicon oxide]]. The secondary reflectors transmit the signals to the corrugated feedhorns that sit on a [[focal plane]] array box beneath the primary reflectors.<ref name="2003Bennett" />
[[Image:WMAP receivers.png|thumb|Illustration of WMAP's receivers]]
The receivers are differential [[radiometer]]s (sensitive to [[polarization]]) measuring the difference between a two telescope beams. The signal is amplified with [[HEMT]] [[low-noise amplifier]]s. There are 20 feeds, 10 in each direction, from which a radiometer collects a signal; the measure is the difference in the sky signal from opposite directions. The directional separation azimuth is 180 degrees; the total angle is 141 degrees.<ref name="2003Bennett" /> To avoid collecting Milky Way galaxy foreground signals, the WMAP uses five discrete radio frequency bands, from 23GHz to 94GHz.<ref name="2003Bennett" />
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; font-size: 90%;"
|- bgcolor="#B0C4DE" align="center"
|+ Properties of WMAP at different frequencies<ref name="2003Bennett" />
! Property !! K-band !! Ka-band !! Q-band !! V-band !! W-band
|-
| Central [[wavelength]] (mm) || 13 || 9.1 || 7.3 || 4.9 || 3.2
|-
| Central [[frequency]] ([[GHz]]) || 23 || 33 || 41 || 61 || 94
|-
| [[Bandwidth (signal processing)|Bandwidth]] (GHz) || 5.5 || 7.0 || 8.3 || 14.0 || 20.5
|-
| Beam size (arcminutes) || 52.8 || 39.6 || 30.6 || 21 || 13.2
|-
| Number of [[radiometer]]s || 2 || 2 || 4 || 4 || 8
|-
| System temperature ([[Kelvin|K]]) || 29 || 39 || 59 || 92 || 145
|-
| Sensitivity (mK s<math>^{1/2}</math>) || 0.8 || 0.8 || 1.0 || 1.2 || 1.6
|}
The WMAP's base is a 5.0m-diameter [[solar panel]] array that keeps the instruments in shadow during CMB observations, (by keeping the craft constantly angled at 22 degrees, relative to the sun). Upon the array sit a bottom deck (supporting the warm components) and a top deck. The telescope's cold components: the focal-plane array and the mirrors, are separated from the warm components with a cylindrical, 33 cm-long thermal isolation shell atop the deck.<ref name="2003Bennett" />
Passive thermal radiators cool the WMAP to ca. 90 degrees K; they are connected to the low-noise amplifiers. The telescope consumes 419 [[watt|W]] of power. The available telescope heaters are emergency-survival heaters, and there is a transmitter heater, used to warm them when off. The WMAP spacecraft's temperature is monitored with [[platinum resistance thermometer]]s.<ref name="2003Bennett" />
The WMAP's calibration is effected with the CMB dipole and measurements of [[Jupiter]]; the beam patterns are measured against Jupiter. The telescope's data are relayed daily via a 2GHz [[transponder]] providing a 667[[kbit/s]] downlink to a 70m [[Deep Space Network]] telescope. The spacecraft has two transponders, one a redundant back-up; they are minimally active — ca. 40 minutes daily — to minimize [[radio frequency interference]]. The telescope's position is maintained, in its three axes, with three [[reaction wheel]]s, [[gyroscope]]s, two [[star tracker]]s and sun sensors, and is steered with eight [[hydrazine]] thrusters.<ref name="2003Bennett" />
== Launch, trajectory, and orbit ==
[[Image:WMAP trajectory and orbit.jpg|thumb|The WMAP's trajectory and orbit.]]
The WMAP satellite arrived at the Kennedy Space Center on 20 April 2001, was tested for two months, mounted atop a Delta II 7425 rocket, and fired to outer space on 30 June 2001.<ref name="2008Limon" /><ref name="news_facts" /> It began operating on its internal power five minutes before its launching, and so continued operating until the solar panel array deployed. The WMAP was activated and monitored while it cooled. On 2 July, it began working, first with in-flight testing (from launching 'til 17 August), then began constant, formal work.<ref name="2008Limon" /> Afterwards, it effected three Earth-Moon phase loops, measuring its [[sidelobe]]s, then flew by the Moon on 30 July, enroute to the the L2 Sun-Earth [[Lagrangian point]], arriving there on 1 October 2001, becoming, thereby, the first CMB observation mission permanently posted there.<ref name="news_facts" />
[[Image:WMAP orbit.jpg|thumb|WMAP's orbit and sky scan strategy]]
The satellite's orbit at Lagrange 2, (1.5 million kilometers from Earth) minimizes the amount of contaminating solar, terrestrial, and lunar emissions registered, and to thermally stabilize it. To view the entire sky, without looking to the sun, the WMAP orbits around L2 in a [[Lissajous orbit]] ca. 1.0 degree to 10 degrees,<ref name="2003Bennett" /> with a 6-month period.<ref name="news_facts" /> The telescope rotates once every 2 minutes, 9 seconds" (0.464 rpm) and processes at the rate of 1 revolution per hour.<ref name="2003Bennett" /> WMAP measures the entire sky every six months, and completed its first, full-sky observation in April 2002.<ref name="news_events" />
== Foreground radiation subtraction ==
The WMAP observes in five frequencies, permitting the measurement and subtraction of foreground contamination (from the Milky Way and extra-galactic sources) of the CMB. The main emission mechanisms are [[synchrotron radiation]] and [[free-free emission]] (dominating the lower frequencies), and [[astrophysical dust]] emissions (dominating the higher frequencies). The spectral properties of these emissions contribute different amounts to the five frequencies, thus permitting their identification and subtraction.<ref name="2003Bennett" />
Foreground contamination is removed in several ways. First, subtract extant emission maps from the WMAP's measurements; second, use the components' known, spectral values to identify them; third, simultaneously fit the position and spectra data of the foreground emission, using extra data sets. Foreground contamination also is reduced by using only the the full-sky map portions with the least foreground contamination, whilst masking the remaining map portions.<ref name="2003Bennett" />
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; font-size: 90%;"
|+ The five-year models of foreground emission, at different frequencies. Red = Synchrotron; Green = free-free; Blue = thermal dust.
|-
| [[Image:WMAP 2008 23GHz foregrounds.png|150px|23 GHz]] || [[Image:WMAP 2008 33GHz foregrounds.png|150px|33 GHz]] || [[Image:WMAP 2008 41GHz foregrounds.png|150px|41 GHz]] || [[Image:WMAP 2008 61GHz foregrounds.png|150px|61 GHz]] || [[Image:WMAP 2008 94GHz foregrounds.png|150px|94 GHz]]
|-
| 23 GHz || 33 GHz || 41 GHz || 61 GHz || 94 GHz
|}
== Measurements and discoveries ==
=== One-year data release ===
[[Image:Baby Universe.jpg|thumb|The first-year map of the CMB.]]
On 11 February 2003, based upon one year's worth of WMAP data, NASA published the latest calculated age, composition, and image of the universe to date, that "contains such stunning detail, that it may be one of the most important scientific results of recent years"; the data surpass previous CMB measurements.<ref name="2003PressRelease">{{cite web | url=http://www.gsfc.nasa.gov/topstory/2003/0206mapresults.html | title=New image of infant universe reveals era of first stars, age of cosmos, and more | publisher=NASA / WMAP team | date=[[11 February]] [[2003]] | accessdate=2008-04-27}}</ref>
Based upon the [[Lambda-CDM model]], the WMAP team produced cosmological parameters from the WMAP's first-year results. Three sets are given below; the first and second sets are WMAP data; the difference is the addition of spectral indices, predictions of some inflationary models. The third data set combines the WMAP constraints with those from other CMB experiments ([[ACBAR]] and [[CBI]]), and constraints from the [[2dF Galaxy Redshift Survey]] and [[Lyman alpha forest]] measurements. Note that there are degenerations among the parameters, the most significant is between <math>n_s</math> and <math>\tau</math>; the errors given are at 68% confidence.<ref name="2003spergel" />
<center>
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; text-align:center;"
|- bgcolor="#B0C4DE" align="center"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP one-year results<ref name="2003spergel">Spergel et al. (2003)</ref>
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP, extra parameter) !! Best fit (all data)
|-
| [[Hubble's constant]] ( {{frac|km|[[parsec|Mpc]]·s}} ) || <math>H_0</math> || 0.72 ± 0.05 || 0.70 ± 0.05 || <math>0.71^{+0.04}_{-0.03}</math>
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || 0.024 ± 0.001 || 0.023 ± 0.002 || 0.0224 ± 0.0009
|-
| Matter content || <math>\Omega_m h^2</math> || 0.14 ± 0.02 || 0.14 ± 0.02 || <math>0.135^{+0.008}_{-0.009}</math>
|-
| [[Optical depth]] to [[reionization]] || <math>\tau</math> || <math>0.166^{+0.076}_{-0.071}</math> || 0.20 ± 0.07 || 0.17 ± 0.06
|-
| Amplitude || <math>A</math> || 0.9 ± 0.1 || 0.92 ± 0.12 || <math>0.83^{+0.09}_{-0.08}</math>
|-
| Scalar spectral index || <math>n_s</math> || 0.99 ± 0.04 || <math>0.93^{+0.07}_{-0.07}</math> || 0.93 ± 0.03
|-
| Running of spectral index || <math>dn_s / dk</math> ||—||-0.047 ± 0.04 || <math>-0.031^{+0.016}_{-0.017}</math>
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc|| <math>\sigma_8</math> || 0.9 ± 0.1 ||—|| 0.84 ± 0.04
|-
| [[Age of the universe]] ([[Annum|Ga]]) || <math>t_0</math> || 13.4 ± 0.3|| — || 13.7 ± 0.2
|-
| Total density of the universe || <math>\Omega_{tot}</math> || — || — || 1.02 ± 0.02
|}
</center>
Using the best-fit data and theoretical models, the WMAP team determined the times of important universal events, including the redshift of [[reionization]], 17 ± 4; the redshift of [[decoupling]], 1089 ± 1 (and the universe's age at decoupling, <math>379^{+8}_{-7}</math> kyr); and the redshift of matter/radiation equality, <math>3233^{+194}_{-210}</math>. They determined the thickness of the [[surface of last scattering]] to be 195 ± 2 in redshift, or <math>118^{+3}_{-2}</math> kyr. They determined the current density of baryons, <math>(2.5 \pm 0.1) \times 10^{-7} cm^{-1}</math>, and the ratio of baryons to photons, <math>(6.1^{+0.3}_{-0.2}) \times 10^{-10}</math>. The WMAP's detection of an early reionization excluded [[warm dark matter]].<ref name="2003spergel" />
The team also examined Milky Way emissions at the WMAP frequencies, producing a 208-[[point source]] catalogue. Also, they observed the [[Sunyaev-Zel'dovich effect]] at <math>2.5 \sigma</math> the strongest source is the [[Coma cluster]].<ref name="2003Bennettb">Bennett et al. (2003b)</ref>
=== Three-year data release ===
[[Image:Microwave Sky polarization.png|thumb|A map of the polarization from the 3rd year results]]
The three-year WMAP data were released on 17 March 2006. The data included temperature and [[polarization]] measurements of the CMB, which provided further confirmation of the standard flat [[Lambda-CDM model]] and new evidence in support of inflation.
The 3-year WMAP data alone shows that the universe must have dark matter. Results were computed both only using WMAP data, and also with a mix of parameter constraints from other instruments, including other CMB experiments ([[ACBAR]], [[CBI]] and [[BOOMERANG]]), [[SDSS]], the [[2dF Galaxy Redshift Survey]], the [[Supernova Legacy Survey]] and constraints on the Hubble constant from the [[Hubble Space Telescope]].<ref name="2007Spergel" />
<center>
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; text-align:center;"
|- bgcolor="#B0C4DE" align="center"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP three-year results<ref name="2007Spergel">Spergel et al. (2007)</ref>
! Parameter !! Symbol !! Best fit (WMAP only)
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || <math>0.732^{+0.031}_{-0.032}</math>
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || 0.0229 ± 0.00073
|-
| Matter content || <math>\Omega_m h^2</math> || <math>0.1277^{+0.0080}_{-0.0079}</math>
|-
| [[Optical depth]] to [[reionization]] <sup>{{ref|a|[a]}}</sup> || <math>\tau</math> || 0.089 ± 0.030
|-
| Scalar spectral index ||<math>n_s</math> || 0.958 ± 0.016
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc ||<math>\sigma_8</math> || <math>0.761^{+0.049}_{-0.048}</math>
|-
| [[Age of the universe]] ([[Annum|Ga]]) || <math>t_0</math> || <math>13.73^{+0.16}_{-0.15}</math>
|-
| Tensor-to-scalar ratio <sup>{{ref|b|[b]}}</sup> || <math>r</math> || <0.65
|}
</center>
[a] {{note|a}} Optical depth to reionization improved due to polarization measurements.<ref name="2007Hinshaw">Hinshaw et al. (2007)</ref><br>
[b] {{note|b}} < 0.30 when combined with [[SDSS]] data. No indication of non-gaussianity.<ref name="2007Spergel" />
=== Five-year data release ===
[[Image:WMAP 2008.png|thumb|5 year WMAP image of background cosmic radiation (2008)]]
The five-year WMAP data were released on 28 February 2008. The data included new evidence for the [[cosmic neutrino background]], evidence that it took over half a billion years for the first stars to reionize the universe, and new constraints on [[cosmic inflation]].<ref name="2008PressRelease">{{cite web | url=http://map.gsfc.nasa.gov/news/ | title=WMAP Press Release — WMAP reveals neutrinos, end of dark ages, first second of universe | publisher=NASA / WMAP team | date=[[7 March]] [[2008]] | accessdate=2008-04-27}}</ref>
The improvement in the results came from both having an extra 2 years of measurements (the data set runs between midnight on 10 August 2001 to midnight of 9 August 2006), as well as using improved data processing techniques and a better characterization of the instrument, most notably of the beam shapes. They also make use of the 33GHz observations for estimating cosmological parameters; previously only the 41 and 61GHz channels had been used. Finally, improved masks were used to remove foregrounds.<ref name="2008Hinshaw" />
[[Image:WMAP 2008 TT and TE spectra.png|thumb|The five-year total-intensity and polarization spectra from WMAP]]
Improvements to the spectra were in the 3rd acoustic peak, and the polarization spectra.<ref name="2008Hinshaw" />
The measurements put constraints on the content of the universe at the time that the CMB was emitted; at the time 10% of the universe was made up of neutrinos, 12% of atoms, 15% of photons and 63% dark matter. The contribution of dark energy at the time was negligible.<ref name="2008PressRelease" />
The WMAP five-year data was combined with measurements from [[Type Ia supernova]] (SNe) and [[Baryon acoustic oscillations]] (BAO).<ref name="2008Hinshaw" />
[[Image:WMAP 2008 universe content.png|thumb|Matter content in the current universe]]
<center>
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; font-size: 90%;"
|- bgcolor="#B0C4DE" align="center"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP five-year results<ref name="2008Hinshaw" />
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP + SNe + BAO)
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || <math>0.719^{+0.026}_{-0.027}</math> || 0.701 ± 0.013
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || 0.02273 ± 0.00062 || 0.02265 ± 0.00059
|-
| Cold dark matter content || <math>\Omega_c h^2</math> || 0.1099 ± 0.0062 || 0.1143 ± 0.0034
|-
| [[Dark energy]] content || <math>\Omega_\Lambda</math> || 0.742 ± 0.030 || 0.721 ± 0.015
|-
| [[Optical depth]] to [[reionization]] || <math>\tau</math> || 0.087 ± 0.017 || 0.084 ± 0.016
|-
| Scalar spectral index || <math>n_s</math> || <math>0.963^{+0.014}_{-0.015}</math>|| <math>0.960^{+0.014}_{-0.013}</math>
|-
| Running of spectral index || <math>dn_s / dk</math> || −0.037 ± 0.028 || <math>-0.032^{+0.021}_{-0.020}</math>
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc || <math>\sigma_8</math> || 0.796 ± 0.036 || 0.817 ± 0.026
|-
| [[Age of the universe]] (Ga) || <math>t_0</math> || 13.69 ± 0.13 || 13.73 ± 0.12
|-
| Total density of the universe || <math>\Omega_{tot}</math> || <math>1.099^{+0.100}_{-0.085}</math> || 1.0052 ± 0.0064
|-
| Tensor-to-scalar ration || <math>r</math> || <0.20 || —
|}
</center>
The data puts a limits on the value of the tensor-to-scalar ratio, r < 0.20 (95% certainty), which determines the level at which gravitational waves affect the polarization of the CMB, and also puts limits on the amount of primordial [[non-gaussianity]]. Improved constraints were put on the redshift of reionization, which is 10.8 ± 1.4, the redshift of [[decoupling]], <math>1091.00^{+0.72}_{-0.73}</math> (as well as age of universe at decoupling, <math>375,938^{+3148}_{-3115}</math> years) and the redshift of matter/radiation equality, <math>3280^{+88}_{-89}</math>.<ref name="2008Hinshaw" />
The [[extragalactic]] source catalogue was expanded to include 390 sources, and variability was detected in the emission from [[Mars]] and [[Saturn]].<ref name="2008Hinshaw" />
{| border="2" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 0; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse; font-size: 90%;"
|- bgcolor="#B0C4DE" align="center"
|+ The five-year maps at different frequencies from WMAP with foregrounds (the red band)
|-
| [[Image:WMAP 2008 23GHz.png|150px|23 GHz]] || [[Image:WMAP 2008 33GHz.png|150px|33 GHz]] || [[Image:WMAP 2008 41GHz.png|150px|41 GHz]] || [[Image:WMAP 2008 61GHz.png|150px|61 GHz]] || [[Image:WMAP 2008 94GHz.png|150px|94 GHz]]
|-
| 23 GHz || 33 GHz || 41 GHz || 61 GHz || 94 GHz
|}
== Future measurements ==
[[Image:Planck satellite.jpg|thumb|upright|Artist's impression of the [[Planck satellite]]]]
The original timeline for WMAP gave it two years of observations; these were completed by September 2003. Mission extensions were granted in both 2002 and 2004, giving the spacecraft a total of 8 observing years (the originally proposed duration), which end in September 2009.<ref name="news_facts" />
WMAP's results will be built upon by several other instruments that are currently under construction. These will either be focusing on higher sensitivity total intensity measurements or measuring the polarization more accurately in the search of [[B-mode polarization]] indicative of primordial [[gravitational wave]]s.
The next space-based instrument will be the [[Planck satellite]], which is currently being built and will launch in early 2009. This instrument aims to measure the CMB more accurately than WMAP at all angular scales, both in total intensity and polarization. Various ground- and balloon-based instruments are being constructed to look for B-mode polarization, including [[Clover (telescope)|Clover]] and [[The E and B Experiment|EBEX]].
== References ==
{{Reflist|2}}
=== Technical pages ===
{{refbegin}}
* {{cite journal | title=The Microwave Anisotropy Probe (MAP) Mission | first=C. | last=Bennett | coauthors=et al. | journal=[[Astrophysical Journal]] | volume=583 | pages=1–23 | year=2003a | url=http://adsabs.harvard.edu/abs/2003ApJ...583....1B | doi=10.1086/345346}}
* {{cite journal | title=First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission | last=Bennett | first=C. | coauthors=et al. | journal=Astrophysical Journal Supplement | volume=148 | pages=97–117 | year=2003b | doi=10.1086/377252}}
* {{cite journal | doi= 10.1086/513698 | title=Three-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Temperature Analysis | first=G. | last=Hinshaw | coauthors=et al. | journal=Astrophysical Journal Supplement | volume=170 | pages=288–334 | year=2007}}
* {{cite journal | title=Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results | first=G. | last=Hinshaw | coauthors=et al. | journal=[[Astrophysical Journal]] Supplement (submitted) | year=2008 | url=http://lambda.gsfc.nasa.gov/product/map/dr3/pub_papers/fiveyear/basic_results/wmap5basic.pdf |format=PDF| id={{arxiv|0803.0732}}}}
* {{cite web | title=Wilkinson Microwave Anisotropy Probe (WMAP): Five–Year Explanatory Supplement |
first=M. | last=Limon | coauthors=et al. | date=[[20 March]] [[2008]] | url=http://lambda.gsfc.nasa.gov/product/map/dr3/pub_papers/fiveyear/supplement/WMAP_supplement.pdf | format=[[PDF]]}}
* {{cite journal | authorlink=Charles Seife | last=Seife | first= Charles | title=Breakthrough of the Year: Illuminating the Dark Universe | url=http://www.sciencemag.org/cgi/content/full/302/5653/2038 | journal=Science | year=2003 | volume=302 | pages=2038–2039 | doi=10.1126/science.302.5653.2038 | pmid=14684787}}
* {{cite journal | title=First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters | last=Spergel | first=D. N. | coauthors=et al. | journal=Astrophysical Journal Supplement | volume=148 | pages=175–194 | year=2003 | url=http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:astro-ph/0302209 | doi=10.1086/377226}}
* {{cite journal | title=Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for Cosmology | last=Sergel | first=D. N. | coauthors=et al. | journal=Astrophysical Journal Supplement | volume=170 | pages=377–408 | year=2007 | url=http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:astro-ph/0603449 | doi=10.1086/513700}}
* [http://arxiv.org/abs/0803.0547v2 E. Komatsu ''et al.'': ''WMAP Cosmological Interpretation'' 2008]
{{refend}}
== External links ==
{{commonscat|WMAP}}
* [http://www.bioedonline.org/news/news.cfm?art=977 Sizing up the universe]
* [http://www.space.com/scienceastronomy/map_mission_basics_030211.html About WMAP and the Cosmic Microwave Background] - Article at Space.com
* [http://www.newscientist.com/article.ns?id=dn4879 Big Bang glow hints at funnel-shaped Universe], [[NewScientist]], [[2004-04-15]]
* [http://www.nasa.gov/home/hqnews/2006/mar/HQ_06097_first_trillionth_WMAP.html NASA [[March 16]], [[2006]] WMAP inflation related press release]
* {{cite journal | last = Seife | first = Charles |authorlink=Charles Seife | title=With Its Ingredients MAPped, Universe's Recipe Beckons | journal=Science | year=2003 | volume=300 | issue=5620 |
pages=730–731 | url=http://adsabs.harvard.edu/abs/1998RPPh...61...77K | doi=10.1126/science.300.5620.730 | pmid=12730575 }}
{{CMB_experiments}}
{{Explorer program}}
{{Space telescopes}}
[[Category:Cosmic Microwave Background Experiments]]
[[Category:NASA probes]]
[[Category:Space telescopes]]
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[[Category:Explorer program]]
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