View source for Wilkinson Microwave Anisotropy Probe

{{Short description|NASA satellite of the Explorer program}}
{{Use American English|date=December 2021}}
{{Use dmy dates|date=December 2021}}
{{Infobox spaceflight
| name              = Wilkinson Microwave Anisotropy Probe
| names_list        = Explorer 80<br>MAP<br>Microwave Anisotropy Probe<br>MIDEX-2<br>WMAP
| image             = WMAP spacecraft.jpg
| image_caption     = Wilkinson Microwave Anisotropy Probe (WMAP) satellite
| image_size        = 300px

| mission_type      = [[Cosmic microwave background]] [[Astronomy]]
| operator          = [[NASA]]
| COSPAR_ID         = 2001-027A
| SATCAT            = 26859
| website           = http://map.gsfc.nasa.gov/
| mission_duration  = 27 months (planned)<br>9 years (achieved)<ref>{{cite web |url=https://map.gsfc.nasa.gov/news/events.html|title=WMAP News: Events Timeline}}</ref>

| spacecraft        = Explorer LXXX
| spacecraft_type   = Wilkinson Microwave Anisotropy Probe
| spacecraft_bus    = WMAP
| manufacturer      = [[National Radio Astronomy Observatory|NRAO]]
| launch_mass       = {{cvt|840|kg}}<ref name=WMAP>{{cite book |url=https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf |title=Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016|last1=Siddiqi|first1=Asif|publisher=NASA History Program Office|edition=second|year=2018}}</ref>
| dry_mass          = {{cvt|763|kg}}
| dimensions        = {{cvt|3.6|xx|5.1|m}}
| power             = 419 [[watt]]s

| launch_date       = 30 June 2001, 19:46:46 [[Coordinated Universal Time|UTC]]<ref name="nasaEvents">{{cite web|date=December 27, 2010|title=WMAP News: Events Timeline |url=http://map.gsfc.nasa.gov/news/events.html|publisher=NASA|access-date=July 8, 2015}}</ref>
| launch_rocket     = [[Delta II|Delta II 7425-10]] (Delta 246)
| launch_site       = [[Cape Canaveral Space Force Station|Cape Canaveral]], [[Cape Canaveral Space Launch Complex 17|SLC-17B]]
| launch_contractor = [[Boeing Defense, Space & Security|Boeing Launch Services]]

| entered_service   = 1 October 2001
| disposal_type     = [[Graveyard orbit]]
| deactivated       = 20 October 2010<ref>[https://map.gsfc.nasa.gov/news/events.html NASA.gov] {{PD-notice}}</ref>
| last_contact      = 19 August 2010

| orbit_reference   = [[Lagrange point#L2 | Sun-Earth L<sub>2</sub> orbit]]
| orbit_regime      = [[Lissajous orbit]]

| telescope_type       = [[Gregorian telescope|Gregorian]]
| telescope_diameter   = {{cvt|1.4|xx|1.6|m}}
| telescope_wavelength = 23 GHz to 94 GHz

| instruments       = Pseudo-Correlation Radiometer

| insignia          = WMAP collage.jpg
| insignia_caption  = Wilkinson Microwave Anisotropy Probe mission patch
| insignia_size     = 250px

| programme         = '''Explorer program'''
| previous_mission  = [[HETE-2]] (Explorer 79)
| next_mission      = [[Ramaty High Energy Solar Spectroscopic Imager|RHESSI]] (Explorer 81)
}}

The '''Wilkinson Microwave Anisotropy Probe''' ('''WMAP'''), originally known as the '''Microwave Anisotropy Probe''' ('''MAP''' and '''Explorer 80'''), was a [[NASA]] spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the [[cosmic microwave background]] (CMB) – the radiant heat remaining from the [[Big Bang]].<ref>{{cite web |date=August 4, 2009|title=Wilkinson Microwave Anisotropy Probe: Overview|url=http://lambda.gsfc.nasa.gov/product/map/current/|publisher=Goddard Space Flight Center|quote=The WMAP (Wilkinson Microwave Anisotropy Probe) mission is designed to determine the geometry, content, and evolution of the universe via a 13 [[Minute and second of arc|arcminutes]] [[Full width at half maximum|FWHM]] resolution full sky map of the temperature anisotropy of the cosmic microwave background radiation.|access-date=September 24, 2009}} {{PD-notice}}</ref><ref>{{cite web|date=July 2009|title=Tests of Big Bang: The CMB|url=http://map.gsfc.nasa.gov/universe/bb_tests_cmb.html |publisher=Goddard Space Flight Center|quote=Only with very sensitive instruments, such as COBE and WMAP, can cosmologists detect fluctuations in the cosmic microwave background temperature. By studying these fluctuations, cosmologists can learn about the origin of galaxies and large-scale structures of galaxies, and they can measure the basic parameters of the Big Bang theory.|access-date=September 24, 2009}} {{PD-notice}}</ref> Headed by Professor [[Charles L. Bennett]] of [[Johns Hopkins University]], the mission was developed in a joint partnership between the NASA [[Goddard Space Flight Center]] and [[Princeton University]].<ref name="2003PressRelease"/> The WMAP spacecraft was launched on 30 June 2001 from [[Florida]]. The WMAP mission succeeded the [[Cosmic Background Explorer|COBE]] space mission and was the second medium-class (MIDEX) spacecraft in the NASA [[Explorer program]]. In 2003, MAP was renamed WMAP in honor of cosmologist [[David Todd Wilkinson]] (1935–2002),<ref name="2003PressRelease"/> who had been a member of the mission's science team. After nine years of operations, WMAP was switched off in 2010, following the launch of the more advanced [[Planck (spacecraft)|Planck spacecraft]] by [[European Space Agency]] (ESA) in 2009.

WMAP's measurements played a key role in establishing the current Standard Model of Cosmology: the [[Lambda-CDM model]]. The WMAP data are very well fit by a universe that is dominated by [[dark energy]] in the form of a [[cosmological constant]]. Other cosmological data are also consistent, and together tightly constrain the Model.  In the Lambda-CDM model of the universe, the [[age of the universe]] is {{val|13.772|0.059}} billion years. The WMAP mission's determination of the age of the universe is to better than 1% precision.<ref>{{cite book|editor-last=Glenday|editor-first=C.|year=2010|title=Guinness World Records 2010: Thousands of new records in The Book of the Decade!|page=7|publisher=Bantam Books|isbn=978-0553593372|url-access=registration|url=https://archive.org/details/guinnessworldrec00vari/page/7}}</ref> The current expansion rate of the universe is (see [[Hubble's law|Hubble constant]]) {{val|69.32|0.80|u=km·s<sup>−1</sup>·Mpc<sup>−1</sup>}}. The content of the universe currently consists of {{val|4.628|0.093|u=%}} ordinary [[Baryonic#Baryonic matter|baryonic matter]]; {{val|24.02|+0.88|-0.87|u=%}} [[cold dark matter]] (CDM) that neither emits nor absorbs light; and {{val|71.35|+0.95|-0.96|u=%}} of [[dark energy]] in the form of a cosmological constant that [[Accelerating expansion of the universe|accelerates]] the [[expansion of the universe]].<ref>{{cite web|last=Beringer|first=J. |collaboration=Particle Data Group|year=2013|title=Astrophysics and Cosmology|publisher=Review of Particle Physics|url=http://pdg.lbl.gov/2013/astrophysics-cosmology/astro-cosmo.html}} {{PD-notice}}</ref> Less than 1% of the current content of the universe is in neutrinos, but WMAP's measurements have found, for the first time in 2008, that the data prefer the existence of a [[cosmic neutrino background]]<ref name="2009Hinshaw">Hinshaw et al. (2009)</ref> with an effective number of neutrino species of {{val|3.26|0.35}}. The contents point to a Euclidean [[Shape of the universe|flat geometry]], with curvature (<math>\Omega_{k}</math>) of {{val|-0.0027|+0.0039|-0.0038}}. The WMAP measurements also support the [[Inflation (cosmology)|cosmic inflation]] paradigm in several ways, including the flatness measurement.

The mission has won various awards: according to ''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|date=October 2005|title="Super Hot" Papers in Science|url=http://www.unafold.org/in-cites.html |publisher=unafold|access-date=December 2, 2022}}</ref> Of the all-time most referenced papers in physics and astronomy in the [[INSPIRE-HEP]] database, only three have been published since 2000, and all three are WMAP publications. Bennett, [[Lyman Page|Lyman A. Page Jr.]], and David N. Spergel, the latter both of Princeton University, shared the 2010 [[Shaw Prize]] in astronomy for their work on WMAP.<ref>{{cite web|title=Announcement of the Shaw Laureates 2010|url=http://www.shawprize.org/en/shawprize2010/announcement/announcement.html|url-status=dead|archive-url=https://web.archive.org/web/20100604044215/http://www.shawprize.org/en/shawprize2010/announcement/announcement.html|archive-date=June 4, 2010}}</ref> Bennett and the WMAP science team were awarded the 2012 [[Gruber Prize]] in cosmology. The 2018 [[Breakthrough Prize in Fundamental Physics]] was awarded to Bennett, Gary Hinshaw, Norman Jarosik, Page, Spergel, and the WMAP science team.

In October 2010, the WMAP spacecraft was [[:Category:Derelict satellites in heliocentric orbit|derelict]] in a [[Heliocentric orbit|heliocentric]] [[graveyard orbit]] after completing nine years of operations.<ref name=dn20101007>{{cite news|date=October 7, 2010|title=Mission Complete! WMAP Fires Its Thrusters For The Last Time|url=https://www.seeker.com/mission-complete-wmap-fires-its-thrusters-for-the-last-time-1765122826.html|publisher=Discovery News|access-date=2021-09-03}}</ref> All WMAP data are released to the public and have been subject to careful scrutiny. The final official data release was the [[Wilkinson Microwave Anisotropy Probe#Nine-year data release|nine-year release]] in 2012.<ref name="Space-20121221">{{cite web|last=Gannon|first=M.|date=December 21, 2012|title=New 'Baby Picture' of Universe Unveiled  |url=http://www.space.com/19027-universe-baby-picture-wmap.html|publisher=Space.com|access-date=December 21, 2012}}</ref><ref name="arXiv-20121220">{{cite journal |last=Bennett |first=C. L. |display-authors=et al. |date=2013 |title=Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results |journal=Astrophysical Journal Supplement |volume=208 |issue=2 |page=20 |arxiv=1212.5225 |bibcode=2013ApJS..208...20B |doi=10.1088/0067-0049/208/2/20 |s2cid=119271232 }}</ref>

Some aspects of the data are statistically unusual for the Standard Model of Cosmology. For example, the largest angular-scale measurement, the [[quadrupole moment]], is somewhat smaller than the Model would predict, but this discrepancy is not highly significant.<ref>{{cite journal|last1=O'Dwyer|first1=I. J.|display-authors=et al.|year=2004|title=Bayesian Power Spectrum Analysis of the First-Year Wilkinson Microwave Anisotropy Probe Data|journal=Astrophysical Journal Letters|volume=617|issue=2|pages=L99–L102|bibcode=2004ApJ...617L..99O|doi=10.1086/427386|arxiv=astro-ph/0407027|s2cid=118150531 }}</ref> A large [[WMAP cold spot|cold spot]] and other features of the data are more statistically significant, and research continues into these.

== Objectives ==
[[File:CMB Timeline75.jpg|thumb|left|The universe's timeline, from the [[Big Bang]] to the WMAP]]
[[File:BigBangNoise.jpg|thumb|right|A comparison of the sensitivity of WMAP with COBE and Penzias and Wilson's [[Holmdel Horn Antenna|telescope]] (simulated data)]]

The WMAP objective was to measure the temperature differences in the [[Cosmic microwave background radiation|Cosmic Microwave Background (CMB) radiation]]. The anisotropies then were used to measure the universe's geometry, content, and [[Evolution of the universe|evolution]]; and to test the [[Big Bang]] model, and the [[cosmic inflation]] theory.<ref name="2003Bennett"/> For that, the mission created a full-sky map of the CMB, with a 13 [[Minute and second of arc|arcminutes]] resolution via multi-frequency observation. The map required 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">Bennett et al. (2003b)</ref> The telescope also measured the CMB's E-mode polarization,<ref name="2003Bennett" /> and foreground polarization.<ref name="2009Hinshaw" /> Its service life was 27 months; 3 to reach the {{L2}} position, and 2 years of observation.<ref name="2003Bennett" />

== Development ==
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=April 22, 2008|access-date=April 27, 2008}} {{PD-notice}}</ref><ref name="news_events">{{cite web|url=http://map.gsfc.nasa.gov/news/events.html|title=WMAP News: Events|publisher=NASA|date=April 17, 2008|access-date=April 27, 2008}} {{PD-notice}}</ref>

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. [[Cosmic Background Explorer|COBE]] satellite that first reported large-scale CMB fluctuations. The WMAP was 45 times more sensitive, with 33 times the angular resolution of its COBE satellite predecessor.<ref name="2008Limon">Limon et al. (2008)</ref> The successor European Planck mission (operational 2009–2013) had a higher resolution and higher sensitivity than WMAP and observed in 9 frequency bands rather than WMAP's 5, allowing improved astrophysical foreground models.

== Spacecraft ==
[[File:WMAP spacecraft diagram.jpg|thumb|left|WMAP spacecraft diagram]]
[[File:WMAP receivers.png|thumb|right|Illustration of WMAP's receivers]]

The telescope's primary reflecting mirrors are a pair of [[Gregorian telescope|Gregorian]] {{cvt|1.4|xx|1.6|m}} dishes (facing opposite directions), that focus the signal onto a pair of {{cvt|0.9|xx|1.0|m}} 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 [[Cardinal point (optics)|focal plane]] array box beneath the primary reflectors.<ref name="2003Bennett" />

The receivers are [[Polarization (waves)|polarization]]-sensitive differential [[radiometer]]s measuring the difference between two telescope beams. The signal is amplified with [[High-electron-mobility transistor]] (HEMT) [[low-noise amplifier]]s, built by the [[National Radio Astronomy Observatory]] (NRAO). 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°; the total angle is 141°. To improve subtraction of foreground signals from our [[Milky Way]] galaxy, the WMAP used five discrete radio frequency bands, from 23&nbsp;GHz to 94&nbsp;GHz.<ref name="2003Bennett" />

{| class="wikitable" style="margin:1em auto;"
|+ Properties of WMAP at different frequencies<ref name="2003Bennett" />
|- style="background:#b0c4de; text-align:center;"
! 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 radiometers || 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 {{cvt|5.0|m}}-diameter [[solar panel]] array that keeps the instruments in shadow during CMB observations, (by keeping the craft constantly angled at 22°, 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, {{cvt|33|cm}}-long thermal isolation shell atop the deck.<ref name="2003Bennett" />

Passive thermal radiators cool the WMAP to approximately {{cvt|90|K}}; they are connected to the [[low-noise amplifier]]s. The telescope consumes 419 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 2-GHz [[Transponder (satellite communications)|transponder]] providing a 667 [[kbit/s]] downlink to a {{cvt|70|m}} [[NASA Deep Space Network|Deep Space Network]] station. The spacecraft has two transponders, one a redundant backup; they are minimally active – about 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 sensor]]s, and is steered with eight [[hydrazine]] thrusters.<ref name="2003Bennett" />

== Launch, trajectory, and orbit ==
{{multiple image | align =right| direction = vertical| width = 
| header   = Animation of WMAP's trajectory 
| image1   = Animation of Wilkinson Microwave Anisotropy Probe trajectory.gif
| caption1 = Oblique view
| image2   = Animation of Wilkinson Microwave Anisotropy Probe trajectory - Viewd from Earth.gif 
| caption2 = Viewed from Earth
| footer   = {{legend2| RoyalBlue| Earth}}{{·}}{{legend2|Magenta|WMAP}}
}}

The WMAP spacecraft arrived at the [[Kennedy Space Center]] on 20 April 2001. After being tested for two months, it was launched via [[Delta II]] 7425 launch vehicle on 30 June 2001.<ref name="news_facts" /><ref name="2008Limon" /> It began operating on its internal power five minutes before its launching, and continued so operating until the solar panel array deployed. The WMAP was activated and monitored while it cooled. On 2 July 2001, it began working, first with in-flight testing (from launching until 17 August 2001), 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 2001, en route to the Sun-Earth {{L2}} [[Lagrange point]], arriving there on 1 October 2001, becoming the first CMB observation mission posted there.<ref name="news_facts" />

Locating the spacecraft at [[Lagrange point|Lagrange 2]], ({{cvt|1500000|km}} from Earth) thermally stabilizes it and minimizes the contaminating solar, terrestrial, and lunar emissions registered. To view the entire sky, without looking to the Sun, the WMAP traces a path around {{L2}} in a [[Lissajous orbit]] ca. 1.0° to 10°,<ref name="2003Bennett" /> with a 6-month period.<ref name="news_facts" /> The telescope rotates once every 2 minutes 9 seconds (0.464 [[Revolutions per minute|rpm]]) and [[Precession|precesses]] at the rate of 1 revolution per hour.<ref name="2003Bennett" /> WMAP measured the entire sky every six months, and completed its first, full-sky observation in April 2002.<ref name="news_events" />

<gallery mode="packed" heights="180">
File:WMAP launch.jpg|WMAP launches from [[Kennedy Space Center]], 30 June 2001
File:WMAP trajectory and orbit.jpg|The WMAP's trajectory and orbit
File:WMAP orbit.jpg|WMAP's orbit and sky scan strategy
</gallery>

== Experiment ==
=== Pseudo-Correlation Radiometer ===
The WMAP instrument consists of pseudo-correlation differential radiometers fed by two back-to-back {{cvt|1.5|m}} primary Gregorian reflectors. This instrument uses five frequency bands from 22&nbsp;GHz to 90&nbsp;GHz to facilitate rejection of foreground signals from our own Galaxy. The WMAP instrument has a 3.5° x 3.5° [[field of view]] (FoV).<ref name="Experiment1">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=2001-027A-01|title=Experiment: Pseudo-Correlation Radiometer|publisher=NASA|date= 28 October 2021|access-date=3 December 2021}} {{PD-notice}}</ref>

== Foreground radiation subtraction ==
The WMAP observed 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 [[Bremsstrahlung|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 was reduced by using only the full-sky map portions with the least foreground contamination, while masking the remaining map portions.<ref name="2003Bennett"/>

{| class="wikitable"
|+ The five-year models of foreground emission, at different frequencies. Red = Synchrotron; Green = free-free; Blue = thermal dust.
|-
| [[File:WMAP 2008 23GHz foregrounds.png|150px|23-GHz]] || [[File:WMAP 2008 33GHz foregrounds.png|150px|33-GHz]] || [[File:WMAP 2008 41GHz foregrounds.png|150px|41-GHz]] || [[File:WMAP 2008 61GHz foregrounds.png|150px|61-GHz]] || [[File: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 ===
[[File:Baby Universe.jpg|thumb|right|One-year WMAP image of background cosmic radiation (2003)]]

On 11 February 2003, NASA published the first-year's worth of WMAP data. The latest calculated age and composition of the early universe were presented. In addition, an image of the early universe, that "contains such stunning detail, that it may be one of the most important scientific results of recent years" was presented. The newly released 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=February 11, 2003|access-date=April 27, 2008 |archive-url=https://web.archive.org/web/20080227175308/http://www.gsfc.nasa.gov/topstory/2003/0206mapresults.html <!-- Bot retrieved archive --> |archive-date=February 27, 2008}}</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 [[Cosmic Background Imager|CBI]]), and constraints from the [[2dF Galaxy Redshift Survey]] and [[Lyman alpha forest]] measurements. 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" />

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ Best-fit cosmological parameters from WMAP one-year results<ref name="2003spergel">Spergel et al. (2003)</ref>
|- style="background:#b0c4de; text-align:center;"
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP, extra parameter) !! Best fit (all data)
|-
| [[Age of the universe]] ([[Annum|Ga]]) || <math>t_0</math> || {{val|13.4|0.3}} || – ||{{val|13.7|0.2}}
|-
| [[Hubble's constant]] ( {{frac|km|[[parsec|Mpc]]·s}} ) || <math>H_0</math> || {{val|72|5}} || {{val|70|5}} || {{val|71|+4|-3}}
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || {{val|0.024|0.001}} || {{val|0.023|0.002}} || {{val|0.0224|0.0009}}
|-
| Matter content || <math>\Omega_m h^2</math> || {{val|0.14|0.02}} || {{val|0.14|0.02}} || {{val|0.135|+0.008|-0.009}}
|-
| [[Optical depth]] to [[reionization]] || <math>\tau</math> || {{val|0.166|+0.076|-0.071}} || {{val|0.20|0.07}} || {{val|0.17|0.06}}
|-
| Amplitude || ''A'' || {{val|0.9|0.1}} || {{val|0.92|0.12}} || {{val|0.83|+0.09|-0.08}}
|-
| Scalar spectral index || <math>n_s</math> || {{val|0.99|0.04}} || {{val|0.93|0.07}} || {{val|0.93|0.03}}
|-
| Running of spectral index || <math>dn_s / dk</math> ||—|| {{val|-0.047|0.04}} || {{val|-0.031|+0.016|-0.017}}
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc|| <math>\sigma_8</math> || {{val|0.9|0.1}} ||—|| {{val|0.84|0.04}}
|-
| Total [[density of the universe]] ||<math>\Omega_{tot}</math> || – || – || {{val|1.02|0.02}}
|}

Using the best-fit data and theoretical models, the WMAP team determined the times of important universal events, including the redshift of [[reionization]], {{val|17|4}}; the redshift of [[Decoupling (cosmology)|decoupling]], {{val|1089|1}} (and the universe's age at decoupling, {{val|379|+8|-7|u=kyr}}); and the redshift of matter/radiation equality, {{val|3233|+194|-210}}. They determined the thickness of the [[surface of last scattering]] to be {{val|195|2}} in redshift, or {{val|118|+3|-2|u=kyr}}. They determined the current density of [[baryon]]s, {{val|2.5|0.1|e=-7|u=cm<sup>−1</sup>}}, and the ratio of baryons to photons, {{val|6.1|+0.3|-0.2|e=-10}}. 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. <!-- Sentence doesn't make sense:
Also, they observed the [[Sunyaev–Zeldovich effect]] at 2.5-[[standard deviation|σ]] the strongest source is the [[Coma cluster]].<ref name="2003Bennettb"/> -->

=== Three-year data release ===
[[File:Microwave Sky polarization.png|thumb|right|Three-year WMAP image of background cosmic radiation (2006)]]

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 (cosmology)|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 ([[Arcminute Cosmology Bolometer Array Receiver]] (ACBAR), [[Cosmic Background Imager]] (CBI) and [[BOOMERanG experiment|BOOMERANG]]), [[Sloan Digital Sky Survey]] (SDSS), the [[2dF Galaxy Redshift Survey]], the [[Supernova Legacy Survey]] and constraints on the [[Hubble's law|Hubble constant]] from the [[Hubble Space Telescope]].<ref name="2007Spergel" />

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ Best-fit cosmological parameters from WMAP three-year results<ref name="2007Spergel">Spergel et al. (2007)</ref>
|- style="background:#b0c4de; text-align:center;"
! Parameter !! Symbol !! Best fit (WMAP only)
|-
| [[Age of the universe]] ([[Annum|Ga]]) || <math>t_0</math> || {{val|13.73|+0.16|-0.15}}
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || {{val|73.2|+3.1|-3.2}}
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || {{val|0.0229|0.00073}}
|-
| Matter content || <math>\Omega_m h^2</math> || {{val|0.1277|+0.0080|-0.0079}}
|-
| [[Optical depth]] to [[reionization]] <sup>{{ref|a|[a]}}</sup> || <math>\tau</math> || {{val|0.089|0.030}}
|-
| Scalar spectral index ||<math>n_s</math> || {{val|0.958|0.016}}
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc ||<math>\sigma_8</math> || {{val|0.761|+0.049|-0.048}}
|-
| Tensor-to-scalar ratio <sup>{{ref|b|[b]}}</sup> || ''r'' || <0.65
|}

[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 [[Sloan Digital Sky Survey|SDSS]] data. No indication of non-gaussianity.<ref name="2007Spergel" />

=== Five-year data release ===
[[File:WMAP 2008.png|thumb|right|Five-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 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 reveals neutrinos, end of dark ages, first second of universe
|publisher=NASA / WMAP team|date=March 7, 2008|access-date=April 27, 2008}} {{PD-notice}}</ref>

{{Multiple image|direction=horizontal|align=left|width=150|image1=WMAP 2008 TT and TE spectra.png|image2=WMAP 2008 universe content.png|caption1=The five-year total-intensity and polarization spectra from WMAP |caption2=Matter/energy content in the current universe (top) and at the time of photon decoupling in the [[Recombination (cosmology)|recombination]] [[Epoch (astronomy)|epoch]] 380,000 years after the Big Bang (bottom)|footer=|header=}}

The improvement in the results came from both having an extra two 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 33-GHz observations for estimating cosmological parameters; previously only the 41-GHz and 61-GHz channels had been used.

Improved masks were used to remove foregrounds.<ref name="2009Hinshaw" /> Improvements to the spectra were in the 3rd acoustic peak, and the polarization spectra.<ref name="2009Hinshaw" />

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" /> It also constrained the content of the present-day universe; 4.6% atoms, 23% dark matter and 72% dark energy.<ref name="2009Hinshaw"/>

The WMAP five-year data was combined with measurements from [[Type Ia supernova]] (SNe) and [[Baryon acoustic oscillations]] (BAO).<ref name="2009Hinshaw" />

The elliptical shape of the WMAP skymap is the result of a [[Mollweide projection]].<ref>[http://lambda.gsfc.nasa.gov/product/map/pub_papers/firstyear/basic/wmap_cb1_images.cfm WMAP 1-year Paper Figures], Bennett, et al. {{PD-notice}}</ref>

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP five-year results<ref name="2009Hinshaw" />
|- style="background:#b0c4de; text-align:center;"
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP + SNe + BAO)
|-
| [[Age of the universe]] (Ga) || <math>t_0</math> || {{val|13.69|0.13}} || {{val|13.72|0.12}}
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || {{val|71.9|+2.6|-2.7}} || {{val|70.5|1.3}}
|-
| [[Baryon]]ic content || <math>\Omega_b h^2</math> || {{val|0.02273|0.00062}} || {{val|0.02267|+0.00058|-0.00059}}
|-
| Cold dark matter content || <math>\Omega_c h^2</math> || {{val|0.1099|0.0062}} || {{val|0.1131|0.0034}}
|-
| [[Dark energy]] content || <math>\Omega_\Lambda</math> || {{val|0.742|0.030}} || {{val|0.726|0.015}}
|-
| [[Optical depth]] to [[reionization]] || <math>\tau</math> || {{val|0.087|0.017}} || {{val|0.084|0.016}}
|-
| Scalar spectral index || <math>n_s</math> || {{val|0.963|+0.014|-0.015}}|| {{val|0.960|0.013}}
|-
| Running of spectral index || <math>dn_s / dlnk</math> || {{val|-0.037|0.028}} || {{val|-0.028|0.020}}
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc || <math>\sigma_8</math> || {{val|0.796|0.036}} || {{val|0.812|0.026}}
|-
| Total density of the universe || <math>\Omega_{tot}</math> || {{val|1.099|+0.100|-0.085}} || {{val|1.0050|+0.0060|-0.0061}}
|-
| Tensor-to-scalar ratio || ''r'' || <0.43 || <0.22
|}

The data puts limits on the value of the tensor-to-scalar ratio, r <0.22 (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 {{val|10.9|1.4}}, the redshift of [[Decoupling (cosmology)|decoupling]], {{val|1090.88|0.72}} (as well as age of universe at decoupling, {{val|376.971|+3.162|-3.167|u=kyr}}) and the redshift of matter/radiation equality, {{val|3253|+89|-87}}.<ref name="2009Hinshaw"/>

The [[extragalactic]] source catalogue was expanded to include 390 sources, and variability was detected in the emission from [[Mars]] and [[Saturn]].<ref name="2009Hinshaw"/>

{| class="wikitable"
|+ The five-year maps at different frequencies from WMAP with foregrounds (the red band)
|-
| [[File:WMAP 2008 23GHz.png|150px|23-GHz]] || [[File:WMAP 2008 33GHz.png|150px|33-GHz]] || [[File:WMAP 2008 41GHz.png|150px|41-GHz]] ||[[File:WMAP 2008 61GHz.png|150px|61-GHz]] || [[File:WMAP 2008 94GHz.png|150px|94-GHz]]
|-
| 23 GHz || 33 GHz || 41 GHz || 61 GHz || 94 GHz
|}

=== Seven-year data release ===
[[File:WMAP 2010.png|thumb|right|7-year WMAP image of background cosmic radiation (2010)]]

The seven-year WMAP data were released on 26 January 2010. As part of this release, claims for inconsistencies with the standard model were investigated.<ref name="WMAP CMB">{{cite journal|last1=Bennett |first1=C. L.|display-authors=et al.|year=2011|title=Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Are There Cosmic Microwave Background Anomalies?|journal=Astrophysical Journal Supplement Series|volume=192|issue=2|page=17|arxiv=1001.4758|bibcode=2011ApJS..192...17B|doi=10.1088/0067-0049/192/2/17|s2cid=53521938}}</ref> Most were shown not to be statistically significant, and likely due to ''a posteriori'' selection (where one sees a weird deviation, but fails to consider properly how hard one has been looking; a deviation with 1:1000 likelihood will typically be found if one tries one thousand times). For the deviations that do remain, there are no alternative cosmological ideas (for instance, there seem to be correlations with the ecliptic pole). It seems most likely these are due to other effects, with the report mentioning uncertainties in the precise beam shape and other possible small remaining instrumental and analysis issues.

The other confirmation of major significance is of the total amount of matter/energy in the universe in the form of dark energy – 72.8% (within 1.6%) as non 'particle' background, and dark matter – 22.7% (within 1.4%) of non baryonic (sub-atomic) 'particle' energy.  This leaves matter, or [[baryonic particles]] (atoms) at only 4.56% (within 0.16%).

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP seven-year results<ref name="Jarosik2010">Table 8 on p. 39 of {{cite web|author=Jarosik, N.|display-authors=et al.|others=WMAP Collaboration
|title=Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Sky Maps, Systematic Errors, and Basic Results |url=http://lambda.gsfc.nasa.gov/product/map/dr4/pub_papers/sevenyear/basic_results/wmap_7yr_basic_results.pdf|publisher=NASA|access-date=December 4, 2010}}  (from NASA's [http://lambda.gsfc.nasa.gov/product/map/dr4/map_bibliography.cfm WMAP Documents] page) {{PD-notice}}</ref>
|- style="background:#b0c4de; text-align:center;"
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP + [[Baryon Acoustic Oscillations|BAO]]<ref name="Percival2010">{{cite journal|author=Percival, Will J.|display-authors=et al.|title=Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Data Release 7 Galaxy Sample|journal=Monthly Notices of the Royal Astronomical Society|volume=401|issue=4|pages=2148–2168|date=February 2010 |doi=10.1111/j.1365-2966.2009.15812.x|doi-access=free |bibcode=2010MNRAS.401.2148P|arxiv=0907.1660|s2cid=9350615}}</ref> + H<sub>0</sub><ref name="Riess2009">{{cite web|author=Riess, Adam G.|display-authors=et al.|title=A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder|url=http://hubblesite.org/pubinfo/pdf/2009/08/pdf.pdf|publisher=hubblesite.org|access-date=December 4, 2010}}</ref>)
|-
| [[Age of the universe]] (Ga) || <math>t_0</math> || {{val|13.75|0.13}} || {{val|13.75|0.11}}
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || {{val|71.0|2.5}} || {{val|70.4|+1.3|-1.4}}
|-
| [[Baryon]] density || <math>\Omega_b</math> || {{val|0.0449|0.0028}} || {{val|0.0456|0.0016}}
|-
| Physical [[baryon]] density || <math>\Omega_b h^2</math> || {{val|0.02258|+0.00057|-0.00056}} || {{val|0.02260|0.00053}}
|-
| [[Dark matter]] density || <math>\Omega_c</math> || {{val|0.222|0.026}} || {{val|0.227|0.014}}
|-
| Physical [[dark matter]] density || <math>\Omega_c h^2</math> || {{val|0.1109|0.0056}} || {{val|0.1123|0.0035}}
|-
| [[Dark energy]] density || <math>\Omega_\Lambda</math> || {{val|0.734|0.029}} || {{val|0.728|+0.015|-0.016}}
|-
| Fluctuation amplitude at 8h<sup>−1</sup> Mpc || <math>\sigma_8</math> || {{val|0.801|0.030}} || {{val|0.809|0.024}}
|-
| Scalar spectral index || <math>n_s</math> || {{val|0.963|0.014}}|| {{val|0.963|0.012}}
|-
| [[Reionization]] [[optical depth]] || <math>\tau</math> || {{val|0.088|0.015}} || {{val|0.087|0.014}}
|-
| *Total density of the universe || <math>\Omega_{tot}</math> || {{val|1.080|+0.093|-0.071}} ||{{val|1.0023|+0.0056|-0.0054}}
|-
| *Tensor-to-scalar ratio, k<sub>0</sub> = 0.002 Mpc<sup>−1</sup> || ''r'' || <&nbsp;0.36 (95% CL) || <&nbsp;0.24 (95% CL)
|-
| *Running of spectral index, k<sub>0</sub> = 0.002 Mpc<sup>−1</sup> || <math>dn_s / d\ln k</math>|| {{val|-0.034|0.026}} || {{val|-0.022|0.020}}
|-
| Note: * = Parameters for extended models<br />(parameters place limits on deviations<br />from the [[Lambda-CDM model]])<ref name="Jarosik2010" />
|}

{| class="wikitable"
|+ The Seven-year maps at different frequencies from WMAP with foregrounds (the red band)
|-
| [[File:WMAP 2010 23GHz.png|150px|23-GHz]] || [[File:WMAP 2010 33GHz.png|150px|33-GHz]] || [[File:WMAP 2010 41GHz.png|150px|41-GHz]] || [[File:WMAP 2010 61GHz.png|150px|61-GHz]] || [[File:WMAP 2010 94GHz.png|150px|94-GHz]]
|-
| 23-GHz || 33-GHz || 41-GHz || 61-GHz || 94-GHz
|}

=== Nine-year data release ===
[[File:WMAP 2012.png|thumb|9-year WMAP image of background cosmic radiation (2012)]]

On 29 December 2012, the nine-year WMAP data and related images were released. {{val|13.772|0.059}} billion-year-old temperature fluctuations and a temperature range of ± 200 micro[[kelvin]]s are shown in the image. In addition, the study found that 95% of the early universe is composed of [[dark matter]] and [[dark energy]], the curvature of space is less than 0.4% of "flat" and the universe emerged from the [[Chronology of the universe#Dark Ages|cosmic Dark Ages]] "about 400 million years" after the [[Big Bang]].<ref name="Space-20121221" /><ref name="arXiv-20121220" /><ref name="arXiv-1212.5226">[http://adsabs.harvard.edu/abs/2012arXiv1212.5226H Hinshaw, et al., 2013]</ref>

<!---please check table data values & related (22/12/2012, [[User:Drbogdan|Drbogdan]])--->
{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ Best-fit [[Lambda-CDM model|cosmological parameters]] from WMAP nine-year results<ref name="arXiv-20121220" />
|- style="background:#b0c4de; text-align:center;"
! Parameter !! Symbol !! Best fit (WMAP only) !! Best fit (WMAP + eCMB + [[Baryon acoustic oscillations|BAO]] + H<sub>0</sub>)
|-
| [[Age of the universe]] (Ga) || <math>t_0</math> || {{val|13.74|0.11}} || {{val|13.772|0.059}}
|-
| [[Hubble's constant]] ( {{frac|km|Mpc·s}} ) || <math>H_0</math> || {{val|70.0|2.2}} ||  {{val|69.32|0.80}}
|-
| [[Baryon]] density || <math>\Omega_b</math> || {{val|0.0463|0.0024}} || {{val|0.04628|0.00093}}
|-
| Physical [[baryon]] density || <math>\Omega_b h^2</math> || {{val|0.02264|0.00050}} ||  {{val|0.02223|0.00033}}
|-
| [[Cold dark matter]] density || <math>\Omega_c</math> || {{val|0.233|0.023}} || {{val|0.2402|+0.0088|-0.0087}}
|-
| Physical [[cold dark matter]] density || <math>\Omega_c h^2</math> || {{val|0.1138|0.0045}} || {{val|0.1153|0.0019}}
|-
| [[Dark energy]] density || <math>\Omega_\Lambda</math> || {{val|0.721|0.025}} ||  {{val|0.7135|+0.0095|-0.0096}}
|-
| Density fluctuations at 8h<sup>−1</sup> Mpc || <math>\sigma_8</math> || {{val|0.821|0.023}} ||{{val|0.820|+0.013|-0.014}}
|-
| Scalar spectral index || <math>n_s</math> || {{val|0.972|0.013}}||  {{val|0.9608|0.0080}}
|-
| [[Reionization]] [[optical depth]] || <math>\tau</math> || {{val|0.089|0.014}} ||  {{val|0.081|0.012}}
|-
| Curvature || 1 <math>-</math> <math>\Omega_{\rm tot}</math> || {{val|-0.037|+0.044|-0.042}} || {{val|-0.0027|+0.0039|-0.0038}}
|-
| Tensor-to-scalar ratio (k<sub>0</sub> = 0.002 Mpc<sup>−1</sup>) || ''r'' || <&nbsp;0.38 (95% CL)|| <&nbsp;0.13 (95% CL)
|-
| Running scalar spectral index || <math>dn_s / d\ln k</math>|| {{val|-0.019|0.025}} || {{val|-0.023|0.011}}
|}

== Main result ==
[[File:WMAP.ogv|thumb|right|Interviews with Charles Bennett and Lyman Page about WMAP]]

The main result of the mission is contained in the various oval maps of the CMB temperature differences. These oval images present the temperature distribution derived by the WMAP team from the observations by the telescope during the mission. Measured is the temperature obtained from a [[Planck's law]] interpretation of the microwave background. The oval map covers the whole sky. The results are a snapshot of the universe around 375,000 years after the [[Big Bang]], which happened about 13.8 billion years ago. The microwave background is very homogeneous in temperature (the relative variations from the mean, which presently is still 2.7 kelvins, are only of the order of {{val|5|e=-5}}). The temperature variations corresponding to the local directions are presented through different colors (the "red" directions are hotter, the "blue" directions cooler than the average).{{Citation needed|date=January 2022}}

== Follow-on missions and future measurements ==
[[File:PIA16874-CobeWmapPlanckComparison-20130321.jpg|thumb|right|Comparison of [[CMB]] results from [[Cosmic Background Explorer|COBE]], [[WMAP]] and [[Planck (spacecraft)|Planck]] – 21 March 2013]]

The original timeline for WMAP gave it two years of observations; these were completed by September 2003. Mission extensions were granted in 2002, 2004, 2006, and 2008 giving the spacecraft a total of 9 observing years, which ended August 2010<ref name="news_facts" /> and in October 2010 the spacecraft was moved to a [[Heliocentric orbit|heliocentric "graveyard" orbit]].<ref name=dn20101007 />

The [[Planck (spacecraft)|Planck]] spacecraft also measured the CMB from 2009 to 2013 and aims to refine the measurements made by WMAP, both in total intensity and polarization. Various ground- and balloon-based instruments have also made CMB contributions, and others are being constructed to do so. Many are aimed at searching for the B-mode polarization expected from the simplest models of inflation, including [[The E and B Experiment]] (EBEX), [[Spider (polarimeter)|Spider]], [[BICEP and Keck Array]] (BICEP2), [[Keck Array|Keck]], [[QUIET]], [[Cosmology Large Angular Scale Surveyor]] (CLASS), [[South Pole Telescope]] (SPTpol) and others.

On 21 March 2013, the European-led research team behind the Planck spacecraft released the mission's all-sky map of the cosmic microwave background.<ref name="NASA-20130321">{{cite web|last1=Clavin|first1=Whitney|last2=Harrington|first2=J. D.|title=Planck Mission Brings Universe Into Sharp Focus|url=http://www.jpl.nasa.gov/news/news.php?release=2013-109&rn=news.xml&rst=3739|date=March 21, 2013|publisher=NASA|access-date=March 21, 2013}} {{PD-notice}}</ref><ref name="NYT-20130321g">{{cite news|title=Mapping the Early Universe|url=https://www.nytimes.com/interactive/2013/03/21/science/space/0321-universe.html|date=March 21, 2013|newspaper=The New York Times|access-date=March 23, 2013}}</ref> The map suggests the [[universe]] is slightly older than previously thought. According to the map, subtle fluctuations in temperature were imprinted on the deep sky when the cosmos was about 370,000 years old. The imprint reflects ripples that arose as early, in the existence of the universe, as the first nonillionth (10<sup>−30</sup>) of a second. Apparently, these ripples gave rise to the present vast [[Cosmic Web#Large-scale structure|cosmic web]] of [[galaxy cluster]]s and [[dark matter]]. Based on the 2013 data, the universe contains 4.9% [[matter|ordinary matter]], 26.8% [[dark matter]] and 68.3% [[dark energy]]. On 5 February 2015, new data was released by the Planck mission, according to which the age of the universe is [[Planck (spacecraft)#2015 data release|13.799 ± 0.021]] [[1,000,000,000 (number)|billion]] years and the Hubble constant is [[Planck (spacecraft)#2015 data release|67.74 ± 0.46 (km/s)/Mpc]].<ref name="Planck 2015">{{cite journal|last1=Ade|first1=P. A.|year=2016|display-authors=et al.|title=Planck 2015 results. XIII. Cosmological parameters|journal=Astronomy & Astrophysics|volume=594 |page=A13|arxiv=1502.01589|bibcode=2016A&A...594A..13P|doi=10.1051/0004-6361/201525830|s2cid=119262962}}</ref>

== See also ==
{{Portal|Spaceflight}}
* [[Explorers Program]]
* [[Illustris project]]
* [[List of cosmic microwave background experiments]]
* [[List of cosmological computation software]]
* [[S150 Galactic X-Ray Mapping]]

== References ==
{{Reflist}}

=== Primary sources ===
{{Refbegin}}
* {{cite journal|title=The Microwave Anisotropy Probe (MAP) Mission|first=C.|last=Bennett|display-authors=et al.|journal=Astrophysical Journal|volume=583|issue=1|pages=1–23|date=2003
|bibcode=2003ApJ...583....1B|doi=10.1086/345346|arxiv=astro-ph/0301158|s2cid=8530058}}
* {{cite journal|title=First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission|last=Bennett|first=C.|display-authors=et al.|journal=Astrophysical Journal Supplement|volume=148
|issue=1|pages=97–117|date=2003|doi=10.1086/377252|bibcode=2003ApJS..148...97B|arxiv=astro-ph/0302208|s2cid=10612050}}
* {{cite journal|doi=10.1086/513698|title=Three-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Temperature Analysis|first=G.|last=Hinshaw|display-authors=et al.|journal=Astrophysical Journal Supplement|volume=170|issue=2|pages=288–334|date=2007|bibcode=2007ApJS..170..288H|arxiv=astro-ph/0603451|s2cid=15554608}}
* {{cite journal|author=Hinshaw, G.|display-authors=et al.|others=WMAP Collaboration|title=Five-Year Wilkinson Microwave Anisotropy Probe Observations: Data Processing, Sky Maps, and Basic Results|journal=The Astrophysical Journal Supplement|date=February 2009|volume=180|issue=2|pages=225–245|doi=10.1088/0067-0049/180/2/225|bibcode=2009ApJS..180..225H|arxiv=0803.0732|s2cid=3629998}}
* {{cite web|title=Wilkinson Microwave Anisotropy Probe (WMAP): Five–Year Explanatory Supplement|author-link=Michele Limon|display-authors=et al.|date=March 20, 2008
|url=http://lambda.gsfc.nasa.gov/product/map/dr3/pub_papers/fiveyear/supplement/WMAP_supplement.pdf}}
* {{cite journal|author-link=Charles Seife|last=Seife|first=Charles|title=Breakthrough of the Year: Illuminating the Dark Universe|journal=Science|date=2003|volume=302|pages=2038–2039
|doi=10.1126/science.302.5653.2038|pmid=14684787|issue=5653|s2cid=120116611|url=https://semanticscholar.org/paper/1ef56d5f1ec6207095ff89520f76d45adeb1bef6|doi-access=free}}
* {{cite journal|title=First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters|last=Spergel|first=D. N.|display-authors=et al.|journal=Astrophysical Journal Supplement|volume=148|issue=1|pages=175–194|date=2003|doi=10.1086/377226|bibcode=2003ApJS..148..175S|arxiv=astro-ph/0302209|s2cid=10794058}}
* {{cite journal|title=Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for Cosmology|last=Sergel|first=D. N.|display-authors=et al.|journal=Astrophysical Journal Supplement
|volume=170|issue=2|pages=377–408|date=2007|doi=10.1086/513700|bibcode=2007ApJS..170..377S|arxiv=astro-ph/0603449|s2cid=1386346}}
* {{cite journal|author1=Komatsu|author2=Dunkley|author3=Nolta|author4=Bennett|author5=Gold|author6=Hinshaw|author7=Jarosik|author8=Larson|author9=Limon|title=Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation|doi=10.1088/0067-0049/180/2/330|date=2009|journal=The Astrophysical Journal Supplement Series|volume=180|issue=2|pages=330–376|arxiv=0803.0547 |bibcode=2009ApJS..180..330K|display-authors=8|last10=Page|first10=L.|last11=Spergel|first11=D. N.|last12=Halpern|first12=M.|last13=Hill|first13=R. S.|last14=Kogut|first14=A.|last15=Meyer|first15=S. S. |last16=Tucker|first16=G. S.|last17=Weiland|first17=J. L.|last18=Wollack|first18=E.|last19=Wright|first19=E. L.|s2cid=119290314}}
{{Refend}}

== Further reading ==
* {{cite journal |last1=Bennett |first1=Charles |author-link=Charles L. Bennett |year=2007 |title=Wilkinson microwave anisotropy probe |journal=Scholarpedia |volume=2 |issue=10 |page=4731 |doi=10.4249/scholarpedia.4731 |bibcode=2007SchpJ...2.4731B |doi-access=free }}

== External links ==
{{Commons category}}
* [http://www.bioedonline.org/news/news.cfm?art=977 Sizing up the universe]
* [https://www.newscientist.com/article.ns?id=dn4879 Big Bang glow hints at funnel-shaped Universe], [[New Scientist]], 15 April 2004
* [http://www.nasa.gov/home/hqnews/2006/mar/HQ_06097_first_trillionth_WMAP.html NASA 16 March 2006 WMAP inflation related press release] {{Webarchive|url=https://web.archive.org/web/20131122192419/http://www.nasa.gov/home/hqnews/2006/mar/HQ_06097_first_trillionth_WMAP.html |date=22 November 2013 }}
* {{cite journal |last=Seife |first=Charles |title=With Its Ingredients MAPped, Universe's Recipe Beckons |journal=Science |date=2003 |volume=300 |issue=5620 |pages=730–731 |doi=10.1126/science.300.5620.730 |pmid=12730575 |s2cid=585072 }}

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