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Wide-field Infrared Survey Explorer
WISE spacecraft
NamesExplorer 92
SMEX-6
NEOWISE
Near-Earth Object WISE
Mission typeInfrared telescope
OperatorNASA / JPL
COSPAR ID2009-071A Edit this at Wikidata
SATCAT no.36119
Websitewww.nasa.gov/wise
Mission duration10 months (planned)
14 years, 10 months and 19 days (achieved)
Spacecraft properties
SpacecraftExplorer XCII
Spacecraft typeWide-field Infrared Survey Explorer
BusRS-300
ManufacturerBall Aerospace & Technologies
Launch mass661 kg (1,457 lb) [1]
Payload mass347 kg (765 lb)
Dimensions2.85 × 2 × 1.73 m (9 ft 4 in × 6 ft 7 in × 5 ft 8 in)
Power551 watts
Start of mission
Launch date14 December 2009,
14:09:33 UTC
RocketDelta II 7320-10C (Delta 347)
Launch siteVandenberg, SLC-2W
ContractorUnited Launch Alliance
Entered service2010
End of mission
Deactivated8 August 2024
Last contact31 July 2024
Decay date2 November 2024,
00:49 UTC
Orbital parameters
Reference systemGeocentric orbit
RegimeSun-synchronous orbit
Perigee altitude488.3 km (303.4 mi)
Apogee altitude494.8 km (307.5 mi)
Inclination97.50°
Period94.45 minutes
Main telescope
Diameter40 cm (16 in) [1]
Wavelengths3.4, 4.6, 12 and 22 μm
Instruments
Four infrared detectors
Explorer Program
← IBEX (Explorer 91)
NuSTAR (Explorer 93) →

Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.[2][3][4] WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid.[5][6][7][8][9][10] WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a 40 cm (16 in) diameter infrared telescope in Earth orbit.[11]

After its solid hydrogen coolant depleted, it was placed in hibernation mode in February 2011.[5] In 2013, NASA reactivated the WISE telescope to search for near-Earth objects (NEO), such as comets and asteroids, that could collide with Earth.[12][13]

The reactivation mission was called Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE).[13] As of August 2023, NEOWISE was 40% through the 20th coverage of the full sky.[citation needed]

Science operations and data processing for WISE and NEOWISE take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, California. The WISE All-Sky (WISEA) data, including processed images, source catalogs and raw data, was released to the public on 14 March 2012, and is available at the Infrared Science Archive.[14][15][16]

The NEOWISE mission was originally expected to end in early 2025 with the satellite reentering the atmosphere some time after.[17] However, the NEOWISE mission concluded its science survey on 31 July 2024 with the satellite expected to reenter Earth's atmosphere later the same year (2 November 2024). This decision was made due to increased solar activity hastening the decay of its orbit and the lack of an onboard propulsion system for orbital maintenance. The onboard transmitter was turned off on 8 August, marking the formal decommissioning of the spacecraft.[18]

Mission goals

[edit]

The mission was planned to create infrared images of 99% of the sky, with at least eight images made of each position on the sky in order to increase accuracy. The spacecraft was placed in a 525 km (326 mi), circular, polar, Sun-synchronous orbit for its ten-month mission, during which it has taken 1.5 million images, one every 11 seconds.[19] The satellite orbited above the terminator, its telescope pointing always to the opposite direction to the Earth, except for pointing towards the Moon, which was avoided, and its solar cells towards the Sun. Each image covers a 47 arcminute field of view (FoV), which means a 6 arcsecond resolution. Each area of the sky was scanned at least 10 times at the equator; the poles were scanned at theoretically every revolution due to the overlapping of the images.[20][21] The produced image library contains data on the local Solar System, the Milky Way, and the more distant Universe. Among the objects WISE studied are asteroids, cool and dim stars such as brown dwarfs, and the most luminous infrared galaxies.

Targets within the Solar System

[edit]

WISE was not able to detect Kuiper belt objects, because their temperatures are too low.[22] Pluto is the only Kuiper belt object that was detected.[23] It was able to detect any objects warmer than 70–100 K. A Neptune-sized object would be detectable out to 700 Astronomical unit (AU), a Jupiter mass object out to 1 light year (63,000 AU), where it would still be within the Sun's zone of gravitational control. A larger object of 2–3 Jupiter masses would be visible at a distance of up to 7–10 light years.[22]

At the time of planning, it was estimated that WISE would detect about 300,000 main-belt asteroids, of which approximately 100,000 will be new, and some 700 Near-Earth objects (NEO) including about 300 undiscovered. That translates to about 1000 new main-belt asteroids per day, and 1–3 NEOs per day. The peak of magnitude distribution for NEOs will be about 21–22 V. WISE would detect each typical Solar System object 10–12 times over about 36 hours in intervals of 3 hours.[20][21][needs update]

Targets outside the Solar System

[edit]

Star formation, a process where visible light is normally obscured by interstellar dust, is detectable in infrared, since at this wavelength electromagnetic radiation can penetrate the dust. Infrared measurements from the WISE astronomical survey have been particularly effective at unveiling previously undiscovered star clusters.[10] Examples of such embedded star clusters are Camargo 18, Camargo 440, Majaess 101, and Majaess 116.[24][25] In addition, galaxies of the young Universe and interacting galaxies, where star formation is intensive, are bright in infrared. At infrared wavelengths, interstellar gas clouds are also detectable, as well as proto-planetary discs. The WISE satellite was expected to find at least 1,000 proto-planetary discs.

Spacecraft

[edit]

The WISE satellite bus was built by Ball Aerospace & Technologies in Boulder, Colorado. The spacecraft was derived from the Ball Aerospace & Technologies RS-300 spacecraft architecture, particularly the NEXTSat spacecraft built for the successful Orbital Express mission launched on 9 March 2007. The flight system had an estimated mass of 560 kg (1,230 lb). The spacecraft was three-axis stabilized, with body-fixed solar arrays. It used a high-gain antenna in the Ku-band to transmit to the ground through the Tracking and Data Relay Satellite System (TDRSS) geostationary system. Ball also performed the testing and flight system integration.[26]

  • WISE spacecraft
    WISE spacecraft
  • Scheme of the spacecraft
    Scheme of the spacecraft
  • Scheme of the telescope
    Scheme of the telescope
  • Scheme of the instruments
    Scheme of the instruments

Telescope

[edit]
WISE prior to its mission into orbit

Construction of the WISE telescope was divided between Ball Aerospace & Technologies (spacecraft, operations support), SSG Precision Optronics, Inc. (telescope, optics, scan mirror), DRS Technologies and Rockwell International (focal planes), Lockheed Martin (cryostat, cooling for the telescope), and Space Dynamics Laboratory (instruments, electronics, and testing). The program was managed through the Jet Propulsion Laboratory.[12]

The WISE instrument was built by the Space Dynamics Laboratory in Logan, Utah.

Mission

[edit]
Comet C/2007 Q3 (Siding Spring) in infrared by WISE
A scaffolding structure built around WISE allows engineers access while its hydrogen coolant is being frozen.

WISE surveyed the sky in four wavelengths of the infrared band, at a very high sensitivity. Its design specified as goals that the full sky atlas of stacked images it produced have 5-sigma sensitivity limits of 120, 160, 650, and 2600 microjanskies (μJy) at 3.3, 4.7, 12, and 23 μm (aka microns).[27] WISE achieved at least 68, 98, 860, and 5400 μJy; 5 sigma sensitivity at 3.4, 4.6, 12, and 22 μm for the WISE All-Sky data release.[28] This is a factor of 1,000 times better sensitivity than the survey completed in 1983 by the IRAS satellite in the 12 and 23 μm bands, and a factor of 500,000 times better than the 1990s survey by the Cosmic Background Explorer (COBE) satellite at 3.3 and 4.7 μm.[27] On the other hand, IRAS could also observe 60 and 100 μm wavelengths.[29]

  • Band 1 – 3.4 μm (micrometre) – broad-band sensitivity to stars and galaxies
  • Band 2 – 4.6 μm – detect thermal radiation from the internal heat sources of sub-stellar objects like brown dwarfs
  • Band 3 – 12 μm – detect thermal radiation from asteroids
  • Band 4 – 22 μm – sensitivity to dust in star-forming regions (material with temperatures of 70–100 kelvins)

The primary mission lasted 10 months: one month for checkout, six months for a full-sky survey, then an additional three months of survey until the cryogenic coolant (which kept the instruments at 17 K) ran out. The partial second survey pass facilitated the study of changes (e.g. orbital movement) in observed objects.[30]

Congressional hearing - November 2007

[edit]

On 8 November 2007, the House Committee on Science and Technology's Subcommittee on Space and Aeronautics held a hearing to examine the status of NASA's Near-Earth Object (NEO) survey program. The prospect of using WISE was proposed by NASA officials.[31]

NASA officials told Committee staff that NASA planned to use WISE to detect near-Earth objects in addition to performing its science goals. It was projected that WISE could detect 400 NEOs (or roughly 2% of the estimated NEO population of interest) within its one-year mission.

Results

[edit]

By October 2010, over 33,500 new asteroids and comets were discovered, and nearly 154,000 Solar System objects had been observed by WISE.[32]

Discovery of an ultra-cool brown dwarf, WISEPC J045853.90+643451.9, about 10~30 light years away from Earth, was announced in late 2010 based on early data.[33] In July 2011, it was announced that WISE had discovered the first Earth trojan asteroid, 2010 TK7.[34] Also, the third-closest star system, Luhman 16.

As of May 2018, WISE / NEOWISE had also discovered 290 near-Earth objects and comets (see section below).[35]

Project milestones

[edit]

The WISE mission is led by Edward L. Wright of the University of California, Los Angeles. The mission has a long history under Wright's efforts and was first funded by NASA in 1999 as a candidate for a NASA Medium-class Explorer (MIDEX) mission under the name Next Generation Sky Survey (NGSS). The history of the program from 1999 to date is briefly summarized as follows:[citation needed]

  • January 1999 — NGSS is one of five missions selected for a Phase A study, with an expected selection in late 1999 of two of these five missions for construction and launch, one in 2003 and another in 2004. Mission cost is estimated at US$139 million at this time.
  • March 1999 — WIRE infrared telescope spacecraft fails within hours of reaching orbit.
  • October 1999 — Winners of MIDEX study are awarded, and NGSS is not selected.
  • October 2001 — NGSS proposal is re-submitted to NASA as a MIDEX mission.
  • April 2002 — NGSS proposal is accepted by the NASA Explorer office to proceed as one of four MIDEX programs for a Pre-Phase A study.
  • December 2002 — NGSS changes its name to Wide-field Infrared Survey Explorer (WISE).
  • March 2003 — NASA releases a press release announcing WISE has been selected for an Extended Phase-A study, leading to a decision in 2004 on whether to proceed with the development of the mission.
  • April 2003 — Ball Aerospace & Technologies is selected as the spacecraft provider for the WISE mission.
  • April 2004 — WISE is selected as NASA's next MIDEX mission. WISE's cost is estimated at US$208 million at this time.
  • November 2004 — NASA selects the Space Dynamics Laboratory at Utah State University to build the telescope for WISE.
  • October 2006 — WISE is confirmed for development by NASA and authorized to proceed with development. Mission cost at this time is estimated to be US$300 million.
  • WISE being connected to its adapter for launch
    WISE being connected to its adapter for launch
  • WISE during the payload fairing installation
    WISE during the payload fairing installation
  • Delta II launch vehicle with WISE aboard
    Delta II launch vehicle with WISE aboard
  • Infrared image of WISE's launch from Vandenberg AFB
    Infrared image of WISE's launch from Vandenberg AFB
  • 14 December 2009 — WISE successfully launched from Vandenberg Air Force Base, California.
  • 29 December 2009 — WISE successfully jettisoned instrument cover.
  • 6 January 2010 — WISE first light image released.
  • 14 January 2010 — WISE begins its regular four wavelength survey scheduled for nine months duration. It is expected to cover 99% of the sky with overlapping images in the first 6 months and continuing with a second pass until the hydrogen coolant is exhausted about three months later.
  • 25 January 2010 — WISE detects a never-before-seen near Earth asteroid, designated 2010 AB78.[36]
  • 11 February 2010 — WISE detects a previously unknown comet, designated P/2010 B2 (WISE).[37]
  • 25 February 2010 — WISE website reports it has surveyed over 25% of the sky to a depth of 7 overlapping image frames.
  • 10 April 2010 — WISE website reports it has surveyed over 50% of the sky to a depth of 7 overlapping image frames.
  • 26 May 2010 — WISE website reports it has surveyed over 75% of the sky to a depth of 7 overlapping image frames.
  • 16 July 2010 — Press release announces that 100% sky coverage will be completed on 17 July 2010.[38] About half of the sky will be mapped again before the instrument's block of solid hydrogen coolant sublimes and is exhausted.
  • October 2010 — WISE hydrogen coolant runs out. Start of NASA Planetary Division funded NEOWISE mission.[12]
  • January 2011 — Entire sky surveyed to an image density of at least 16+ frames (i.e. second scan of sky completed).

Hibernation

  • 17 February 2011 — WISE Spacecraft transmitter turned off at 20:00 UTC by principal investigator Ned Wright. The spacecraft will remain in hibernation without ground contacts awaiting possible future use.[39]
Comet C/2013 A1 Siding Spring multiple exposure – four separate images superimposed against the same background stars (NEOWISE; 28 July 2014). (The four reddish smudges, center; the blue/white ovals top left are galaxies.)
  • 14 April 2011 — Preliminary release of data covering 57% of the sky as seen by WISE.[40]
  • 27 July 2011 — First Earth trojan asteroid discovered from WISE data.[6][7]
  • 23 August 2011 — WISE confirms the existence of a new class of brown dwarf, the Y dwarf. Some of these stars appear to have temperatures less than 300 K, close to room temperature at about 25 °C. Y dwarfs show ammonia absorption, in addition to methane and water absorption bands displayed by T dwarfs.[8][9]
  • 14 March 2012 — Release of the WISE All-Sky data to the scientific community.[41]
  • 29 August 2012 — WISE reveals millions of black-holes.[42]
  • 20 September 2012 — WISE was successfully contacted to check its status.[5]
  • 21 August 2013 — NASA announced it would recommission WISE with a new mission to search for asteroids.[13]

Reactivation

  • 19 December 2013 — NASA releases a new image taken by the reactivated WISE telescope, following an extended cooling down phase. The revived NeoWise mission is underway and collecting data.
  • 7 March 2014 — NASA reports that WISE, after an exhaustive survey, has not been able to uncover any evidence of "planet X", a hypothesized planet within the Solar System.[43]
  • 26 April 2014 — The Penn State Center for Exoplanets and Habitable Worlds reports that WISE has found the coldest known brown dwarf, between −48 °C and −13 °C, 7.2 light years away from the Sun.[44]
  • 21 May 2015 — NASA reports the discovery of WISE J224607.57-052635.0, the most luminous known galaxy in the Universe.[45][46]

History

[edit]
Animation of WISE's orbit around Earth. Earth is not shown.
This first light image is a false color infrared image of the sky in the direction of the Carina constellation.

Launch

[edit]

The launch of the Delta II launch vehicle carrying the WISE spacecraft was originally scheduled for 11 December 2009. This attempt was scrubbed to correct a problem with a booster rocket steering engine. The launch was then rescheduled for 14 December 2009.[47] The second attempt launched on time at 14:09:33 UTC from Vandenberg Air Force Base in California. The launch vehicle successfully placed the WISE spacecraft into the planned polar orbit at an altitude of 525 km (326 mi) above the Earth.[4]

WISE avoided the problem that affected Wide Field Infrared Explorer (WIRE), which failed within hours of reaching orbit in March 1999.[48] In addition, WISE was 1,000 times more sensitive than prior surveys such as IRAS, AKARI, and COBE's DIRBE.[27]

"Cold" mission

[edit]

A month-long checkout after launch found all spacecraft systems functioning normally and both the low- and high-rate data links to the operations center working properly. The instrument cover was successfully jettisoned on 29 December 2009.[49] A first light image was released on 6 January 2010: an eight-second exposure in the Carina constellation showing infrared light in false color from three of WISE's four wavelength bands: Blue, green and red corresponding to 3.4, 4.6, and 12 μm, respectively.[50] On 14 January 2010, the WISE mission started its official sky survey.[51]

The WISE group's bid for continued funding for an extended "warm mission" scored low by a NASA review board, in part because of a lack of outside groups publishing on WISE data. Such a mission would have allowed use of the 3.4 and 4.6 μm detectors after the last of cryo-coolant had been exhausted, with the goal of completing a second sky survey to detect additional objects and obtain parallax data on putative brown dwarf stars. NASA extended the mission in October 2010 to search for near-Earth objects (NEO).[12]

By October 2010, over 33,500 new asteroids and comets were discovered, and over 154,000 Solar System objects were observed by WISE.[32] While active it found dozens of previously unknown asteroids every day.[52] In total, it captured more than 2.7 million images during its primary mission.[53]

NEOWISE (pre-hibernation)

[edit]
"NEOWISE" redirects here. For the comet, see Comet NEOWISE.
Some of the comets discovered during the pre-hibernation NEOWISE.
Number of near-Earth objects detected by various projects:
  LINEAR
  NEAT
  Spacewatch
  LONEOS 		  CSS
  Pan-STARRS
  NEOWISE
  others

In October 2010, NASA extended the mission by one month with a program called Near-Earth Object WISE (NEOWISE).[12] Due to its success, the program was extended a further three months.[5] The focus was to look for asteroids and comets close to Earth orbit, using the remaining post-cryogenic detection capability (two of four detectors on WISE work without cryogenic).[12] In February 2011, NASA announced that NEOWISE had discovered many new objects in the Solar System, including twenty comets.[54] During its primary and extended missions, the spacecraft delivered characterizations of 158,000 minor planets, including more than 35,000 newly discovered objects.[55][56]

Hibernation and recommissioning

[edit]

After completing a full scan of the asteroid belt for the NEOWISE mission, the spacecraft was put into hibernation on 1 February 2011.[57] The spacecraft was briefly contacted to check its status on 20 September 2012.[5]

On 21 August 2013, NASA announced it would recommission NEOWISE to continue its search for near-Earth objects (NEO) and potentially dangerous asteroids. It would additionally search for asteroids that a robotic spacecraft could intercept and redirect to orbit the Moon. The extended mission would be for three years at a cost of US$5 million per year, and was brought about in part due to calls for NASA to step up asteroid detection after the Chelyabinsk meteor exploded over Russia in February 2013.[13]

NEOWISE was successfully taken out of hibernation in September 2013.[58] With its coolant depleted, the spacecraft's temperature was reduced from 200 K (−73 °C; −100 °F) — a relatively high temperature resulting from its hibernation — to an operating temperature of 75 K (−198.2 °C; −324.7 °F) by having the telescope stare into deep space.[5][53] Its instruments were then re-calibrated,[53] and the first post-hibernation photograph was taken on 19 December 2013.[58]

NEOWISE (post-hibernation)

[edit]
Concept art for 2016 WF9, discovered by WISE under the NEOWISE mission.
First four years of NEOWISE data starting in December 2013 to December 2017. Green dots represent near-Earth objects. Gray dots represent all other asteroids which are mainly in the main asteroid belt between Mars and Jupiter. Yellow squares represent comets. White dots are asteroids in view of NEOWISE.

The post-hibernation NEOWISE mission was anticipated to discover 150 previously unknown near-Earth objects and to learn more about the characteristics of 2,000 known asteroids.[53][59] Few objects smaller than 100 m (330 ft) in diameter were detected by NEOWISE's automated detection software, known as the WISE Moving Object Processing Software (WMOPS), because it requires five or more detections to be reported.[60] The average albedo of asteroids larger than 100 m (330 ft) discovered by NEOWISE is 0.14.[60]

The telescope was turned on again in 2013, and by December 2013 the telescope had cooled down sufficiently to be able to resume observations.[61] Between then and May 2017, the telescope made almost 640,000 detections of over 26,000 previously known objects including asteroids and comets.[61] In addition, it discovered 416 new objects and about a quarter of those were near-Earth objects classification.[61]

As of July 2024, WISE / NEOWISE statistics lists a total of 399 near-Earth objects (NEOs), including 2016 WF9 and C/2016 U1, discovered by the spacecraft:[35]

  • 365 NEAs (subset of NEOs)
  • 66 PHAs (subset of NEAs)
  • 34 comets

Of the 365 near-Earth asteroids (NEAs), 66 of them are considered potentially hazardous asteroids (PHAs), a subset of the much larger family of NEOs, but particularly more likely to hit Earth and cause significant destruction.[35] NEOs can be divided into NECs (comets only) and NEAs (asteroids only), and further into subcategories such as Atira asteroids, Aten asteroids, Apollo asteroids, Amor asteroids and the potentially hazardous asteroids (PHAs).[62]

NEOWISE has provided an estimate of the size of over 1,850 near-Earth objects. NEOWISE mission was extended for two more years (1 July 2021 – 30 June 2023).[63]

As of June 2021 NEOWISE's replacement, the next-generation NEO Surveyor, is scheduled to launch in 2028, and will greatly expand on what humans have learned, and continue to learn, from NEOWISE.[63]

"As of August 2023 NEOWISE is 40% through the 20th coverage of the full sky since the start of the Reactivation mission."[64]

End of mission

[edit]

On 13 December 2023, the Jet Propulsion Laboratory (JPL), announced that the satellite would enter a low orbit causing it to be unusable by early 2025. Increased solar activity as the sun approaches solar maximum during Solar cycle 25 was expected to increase atmospheric drag causing orbital decay. The satellite was expected to subsequently reenter the earth's atmosphere.[17] On 8 August 2024, the Jet Propulsion Laboratory updated its estimate of orbital decay to sometime in late 2024 and announced that NEOWISE's science survey had ended on 31 July.[18] NEOWISE entered and burnt up in the Earth's atmosphere at 8:49 p.m. EDT on 1 November 2024.[65]

Data releases

[edit]

On 14 April 2011, a preliminary release of WISE data was made public, covering 57% of the sky observed by the spacecraft.[66] On 14 March 2012, a new atlas and catalog of the entire infrared sky as imaged by WISE was released to the astronomic community.[41] On 31 July 2012, NEOWISE Post-Cryo Preliminary Data was released.[5] A release called AllWISE, combining all data, was released on 13 November 2013.[67] NEOWISE data is released annually.[67]

The WISE data include diameter estimates of intermediate precision, better than from an assumed albedo but not nearly as precise as good direct measurements, can be obtained from the combination of reflected light and thermal infrared emission, using a thermal model of the asteroid to estimate both its diameter and its albedo. In May 2016, technologist Nathan Myhrvold questioned the precision of the diameters and claimed systemic errors arising from the spacecraft's design.[68][69][70] The original version of his criticism itself faced criticism for its methodology[71] and did not pass peer review,[69][72] but a revised version was subsequently published.[73][74] The same year, an analysis of 100 asteroids by an independent group of astronomers gave results consistent with the original WISE analysis.[74]

unWISE and CatWISE

[edit]
Comparison between the Atlas images of Allwise (left) and the coadds of unWISE (right), using IC 1590 as an example.

The Allwise co-added images were intentionally blurred, which is optimal for detecting isolated point sources. This has the disadvantage that many sources are not detected in crowded regions. The unofficial, unblurred coadds of the WISE imaging (unWISE) creates sharp images and masks defects and transients.[75] unWISE coadded images can be searched by coordinates on the unWISE website.[76] unWISE images are used for the citizen science projects Disk Detective and Backyard Worlds.[77]

In 2019, a preliminary catalog was released. The catalog is called CatWISE. This catalog combines the WISE and NEOWISE data and provides photometry at 3.4 and 4.6 μm. It uses the unWISE images and the Allwise pipeline to detect sources. CatWISE includes fainter sources and far more accurate measurement of the motion of objects. The catalog is used to extend the number of discovered brown dwarfs, especially the cold and faint Y dwarfs. CatWISE is led by Jet Propulsion Laboratory (JPL), California Institute of Technology, with funding from NASA's Astrophysics Data Analysis Program.[78][79] The CatWISE preliminary catalog can be accessed through Infrared Science Archive (IRSA).[80]

Discovered objects

[edit]
WISE discovered the first Y dwarf (artist concept).

In addition to numerous comets and minor planets, WISE and NEOWISE discovered many brown dwarfs, some just a few light years from the solar system; the first Earth trojan; and the most luminous galaxies in the universe.

Nearby stars

[edit]

Nearby stars discovered using WISE within 30 light years:

Object ly Spectral type Constellation Right ascension Declination
WISEA J1540–5101 17.4 M7 Norma 15h 40m 43.537s −51° 01′ 35.968″
WISE J0720−0846 22.2 M9.5+T5.5 Monoceros 07h 20m 03.254s −08° 46′ 49.90″

Brown dwarfs

[edit]

The nearest brown dwarfs discovered by WISE within 20 light-years include:

Object ly Spectral
type		 Constellation Right
ascension		 Declination
Luhman 16 6.5 L8 + T1 Vela 10h 49m 15.57s −53° 19′ 06″
WISE 0855−0714 7.3 Y Hydra 8h 55m 10.83s −7° 14′ 22.5″
WISE 1639-6847 15.5 Y0pec Triangulum Australe 16h 39m 40.83s −68° 47′ 38.6″
WISE J0521+1025 16 T7.5 Orion 05h 21m 26.349s 10° 25′ 27.41″
WISE 1506+7027 16.9 T6 Ursa Minor 15h 06m 49.89s 70° 27′ 36.23″
WISE 0350−5658 18 Y1 Reticulum 03h 50m 00.32s −56° 58′ 30.2″
WISE 1741+2553 18 T9 Hercules 17h 41m 24.22s 25° 53′ 18.96″
WISE 1541−2250 19 [81] Y0.5 Libra 15h 41m 51.57s −22° 50′ 25.03″

Before the discovery of Luhman 16 in 2013, WISE 1506+7027 at a distance of 11.1+2.3
−1.3 light-years was suspected to be closest brown dwarf on the list of nearest stars (also see § Map with nearby WISE stars).[82]

Directly-imaged exoplanets

[edit]

Directly imaged exoplanets first detected with WISE. See Definition of exoplanets: IAU working definition as of 2018 requires Mplanet ≤ 13 MJ and Mplanet/Mcentral < 0.04006. Mmin and Mmax are the lower and upper mass limit of the planet in Jupiter masses.

Host name Planet name distance to earth (ly) V-mag host star (mag) projected separation (AU) Mass planet (Mjup) Discovery year Note and reference Planet according to IAU working definition
L 34-26 WISEPA J075108.79-763449.6 (COCONUTS-2b) 36 11.3 6471 4.4-7.8 2011/2021 first discovered with WISE in 2011, but planet status was established in 2021 by taking the listed proper motion of the planet and matching it with the Gaia proper motion of the star[83] Mmin=4.4<13

Mmax=7.8<13 Mmax/Mcentral=0.02<0.04

BD+60 1417 CWISER J124332.12+600126.2 (BD+60 1417 b) 144 9.4 1662 10-20 2021 Only the minimum mass is within the IAU working definition[84] Mmin=10<13

Mmax=20>13 Mmax/Mcentral=0.019<0.04

GJ 900 CW2335+0142 68 9.5 12000 10.5 2024 [85] Mplanet=10.5<13

Mplanet/Mcentral=0.009<0.04

2MASS J05581644–4501559 CWISE J055816.67-450233.4

(0558 B)

88 14.9 1043 6-12 2024 [86] Mmax=12<13

Mmax/Mcentral=?

Disks and young stars

[edit]

The sensitivity of WISE in the infrared enabled the discovery of disk around young stars and old white dwarf systems. These discoveries usually require a combination of optical, near infrared and WISE or Spitzer mid-infrared observations. Examples are the red dwarf WISE J080822.18-644357.3, the brown dwarf WISEA J120037.79-784508.3 and the white dwarf LSPM J0207+3331. The NASA citizen science project Disk Detective is using WISE data. Additionally researchers used NEOWISE to discover erupting young stellar objects.[87]

Nebulae

[edit]

Researchers discovered a few nebulae using WISE. Such as the type Iax remnant Pa 30. Nebulae around the massive B-type stars BD+60° 2668 and ALS 19653,[88] an obscured shell around the Wolf-Rayet star WR 35[89] and a halo around the Helix Nebula, a planetary nebula[90] were also discovered with WISE.

Extragalactic discoveries

[edit]

Active galactic nuclei (AGN) can be identified from their mid-infrared color. One work used for example a combination of Gaia and unWISE data to identify AGNs.[91] Luminous infrared galaxies can be detected in the infrared. One study used SDSS and WISE to identify such galaxies.[92] NEOWISE observed the entire sky for more than 10 years and can be used to find transient events. Some of these discovered transients are Tidal Disruption Events (TDE) in galaxies[93] and infrared detection of supernovae similar to SN 2010jl.

Minor planets

[edit]
Discovery image of comet C/2020 F3 (NEOWISE)
For a more comprehensive list, see List of minor planets discovered using the WISE spacecraft.

WISE is credited with discovering 3,088 numbered minor planets.[94] Examples of the mission's numbered minor planet discoveries include:

Comet C/2020 F3 (NEOWISE)

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On 27 March 2020, the comet C/2020 F3 (NEOWISE) was discovered by the WISE spacecraft. It eventually became a naked-eye comet and was widely photographed by professional and amateur astronomers. It was the brightest comet visible in the northern hemisphere since comet Hale-Bopp in 1997.

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Full sky views by WISE

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Selected images by WISE

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Map with nearby WISE stars

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Nearby stars with WISE discoveries WISE 0855−0714 and Luhman 16 (WISE 1049−5319)

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Wide-field Infrared Survey Explorer

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The Wide-field Infrared Survey Explorer (WISE) was a space telescope mission launched on December 14, 2009, from Vandenberg Air Force Base in California aboard a Delta II , designed to conduct an all-sky survey in wavelengths to detect and catalog cool, faint objects invisible to visible-light telescopes, such as , asteroids, and ultra-luminous galaxies. The spacecraft, weighing 661 kg and equipped with a 40-cm cryogenic telescope and four infrared detectors operating at wavelengths of 3.4, 4.6, 12, and 22 micrometers, completed its primary survey phase from December 2009 to February 2011, mapping the entire sky 1.5 times during the full cryogenic operation and additional coverage in shorter wavelengths after the solid hydrogen coolant depleted in September 2010. WISE's primary science goals included discovering the coldest brown dwarfs nearest to the Solar System, identifying the most luminous galaxies in the universe, and characterizing the infrared properties of asteroids and other Solar System objects, ultimately producing the AllWISE catalog containing over 747 million infrared sources detected across the sky. In late 2013, the mission was reactivated without cryogen as NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer), focusing on the detection and characterization of near-Earth objects (NEOs) and other Solar System bodies using the remaining 3.4 and 4.6 micrometer bands, which enabled repeated sky scans—over 21 full-sky equivalents by 2024—to track potentially hazardous asteroids and comets. Key discoveries from NEOWISE include the identification of over 3,000 NEOs and over 290 comets, as well as the spectacular Comet C/2020 F3 (NEOWISE), visible to the naked eye in July 2020, alongside millions of active galactic nuclei. The mission concluded operations on July 31, 2024, with decommissioning on August 8, 2024, followed by atmospheric reentry on November 1, 2024, leaving a legacy of publicly available data through NASA's that continues to support in and planetary defense.

Mission Objectives

Solar System Targets

The Wide-field Survey Explorer (WISE) was designed to detect and characterize a wide array of Solar System objects, with a primary emphasis on minor bodies such as near-Earth objects (NEOs), main-belt asteroids, and Trojans. These observations leveraged WISE's sensitivity to emission from thermally heated surfaces, enabling the identification of objects that are faint or invisible in optical wavelengths due to low albedos. The mission aimed to catalog hundreds of NEOs, including asteroids and comets on Earth-crossing orbits, while surveying hundreds of thousands of main-belt asteroids larger than 3 km in diameter and probing Trojans to refine population models. Thermal modeling formed a cornerstone of WISE's Solar System investigations, using multi-band photometry at wavelengths of 3.4, 4.6, 12, and 22 μm to derive physical properties. By measuring thermal emission fluxes, the mission facilitated estimates of sizes and through standard radiometric techniques, achieving diameter accuracies of about 10% when combined with optical data. For instance, could be determined from the ratio of to optical fluxes, revealing compositional insights such as primitive, low- carbonaceous materials versus higher- S-types. flux measurements enable estimation of diameters largely independent of by modeling thermal emission from the 's surface, often combined with optical H to derive via the ratio of to optical fluxes. Additionally, observations of asymmetries between an 's morning and afternoon sides enabled studies of orbital perturbations via the Yarkovsky effect, improving long-term orbit predictions. The survey extended to outer Solar System populations, targeting objects (KBOs) and comets to detect signatures of dust, ice, and volatile ices in the . WISE's all-sky coverage, with multiple scans per position, was expected to reveal faint thermal emissions from these distant, cold bodies, contributing to understanding their size distributions and surface properties. observations proved particularly advantageous for such low-albedo objects, where thermal reradiation dominates over reflected sunlight. A key goal was the identification of potentially hazardous asteroids (PHAs) among the NEO population, using infrared flux measurements to estimate diameters independent of albedo assumptions. This approach addressed limitations of optical surveys by providing direct size constraints for impact risk assessment. Overall, WISE anticipated coverage of over 150,000 minor planets, yielding statistical insights into size distributions, albedo trends, and population demographics across the and beyond.

Extrasolar Targets

The conducted an all-sky survey in four mid-infrared bands centered at 3.4 μm (W1), 4.6 μm (W2), 12 μm (W3), and 22 μm (W4) to detect and characterize extrasolar objects invisible or faint at optical wavelengths. This survey targeted cool stars, , and ultracool objects down to spectral types T and Y, leveraging the sensitivity of the W2 band to temperatures below 750 for identifying the nearest and coldest such objects within the solar neighborhood. Expected outcomes included the discovery of around 1,000 new within 25 light-years, potentially revealing the closest star system to the Sun. The mission's design enabled the cataloging of hundreds of thousands of these low-mass stellar and substellar objects, providing a comprehensive to study the low end of the and Galactic kinematics. Within the , WISE mapped interstellar dust distributions, star-forming regions, and protoplanetary disks through their thermal mid-infrared emission. The W3 and W4 bands were particularly effective for tracing (PAH) features and warm dust continuum, revealing the structure of molecular clouds and embedded young stellar objects out to distances of several kiloparsecs. Additionally, the survey identified infrared excesses around main-sequence stars indicative of debris disks, offering insights into the architecture and evolution of circumstellar material analogous to our . On extragalactic scales, WISE detected active galactic nuclei (AGN), starburst galaxies, and large-scale cosmic structures by their luminosity, penetrating dust-obscured regions where optical surveys fall short. The instrument's 5σ sensitivity limits of 0.08 mJy (W1), 0.11 mJy (W2), 1 mJy (W3), and 6 mJy (W4) in unconfused regions allowed detection of luminous galaxies (LIRGs) with luminosities exceeding 1011L⊙10^{11} L_\odot out to redshifts z≈1z \approx 1, as well as tracing galaxy clusters and the stellar mass density across the local up to z≈0.5z \approx 0.5. This capability supported studies of galaxy evolution, accretion, and the cosmic background, with goals including the identification of millions of ultraluminous galaxies from when the was about 3 billion years old.

Spacecraft and Instrumentation

Spacecraft Design

The Wide-field Infrared Survey Explorer (WISE) spacecraft was designed as a three-axis stabilized platform, built by Corporation, with the science instrument integrated by the Space Dynamics Laboratory. It was launched aboard a Delta II 7320 vehicle from Vandenberg Air Force Base, achieving insertion into a Sun-synchronous at an altitude of 525 km with a 97.5° inclination. This orbit enabled continuous scanning while maintaining stable thermal conditions for observations. The cryogenic subsystem centered on a solid hydrogen-filled , containing 15.7 kg of cryogen, which passively cooled the to below 12 K and the silicon arsenide (Si:As) detectors to approximately 7.8 K. Thermal management incorporated on the outer surfaces and vapor-cooled shields to reject parasitic heat from the bus, ensuring a mission lifetime of about 10 months before cryogen depletion. The overall structure was an eight-sided aluminum bus housing the instrument, with the forming the core enclosure. Attitude determination and control relied on two star trackers for coarse pointing, a fiber-optic for rate sensing, and four reaction wheels for fine adjustments, augmented by magnetic torquer rods for momentum dumping; this system delivered an absolute pointing accuracy of 6 arcseconds (3-sigma) and stability better than 0.3 arcseconds rms. Power generation came from body-fixed solar arrays spanning 2 m by 1.6 m, producing over 500 W orbit average, supplemented by a 20 amp-hour for eclipse periods, with total spacecraft power consumption averaging 301 W. The telescope was mounted within the atop the bus, oriented for viewing during scans. The complete flight system measured 2.85 m in height, 2 m in width, and 1.73 m in depth, resembling a large cylindrical canister, with a total launch of 661 kg including the cryogen. and command communications used S-band omni-directional antennas at rates of 2–16 kbps, while science data downlinks reached 100 Mbps via a fixed Ku-band high-gain antenna through 's System; onboard storage buffered up to 96 GB of compressed images between contacts.

Telescope and Detectors

The Wide-field Infrared Survey Explorer (WISE) features a cryogenically cooled 40 cm diameter infrared telescope designed for all-sky surveying in four mid- bands. The optical system employs an afocal off-axis with a primary mirror, tertiary mirror, and reimaging , achieving an effective focal ratio of f/3.375 and a square of 47.1 arcminutes to enable wide-area imaging with a plate scale of 2.75 arcseconds per in the shorter wavelength bands. This configuration provides diffraction-limited performance, with resolutions of approximately 6 arcseconds in the 3.4 μm and 4.6 μm bands, degrading to 12 arcseconds at 22 μm. The is housed within a that maintains the below 12 K to minimize thermal emission and during observations. The focal plane assembly consists of four 1024 × 1024 detector arrays, each tailored to one of the survey bands centered at 3.4 μm (W1), 4.6 μm (W2), 12 μm (W3), and 22 μm (W4). The W1 and W2 bands use (HgCdTe) arrays cooled to approximately 32 K via a secondary cryogen tank, optimizing sensitivity for near- to mid-infrared detection while balancing power and lifetime constraints. In contrast, the W3 and W4 bands employ silicon arsenide (Si:As) blocked impurity band detectors cooled to 7.8 ± 0.5 K by the primary cryogen tank, essential for suppressing thermal noise in the longer wavelengths where blackbody emission from the instrument itself is significant. The W4 array is binned 2×2 to a 5.5 arcsecond per scale, enhancing signal-to-noise for fainter sources. These detectors achieve 5σ sensitivities of 0.08 mJy (W1), 0.11 mJy (W2), 1 mJy (W3), and 6 mJy (W4), with saturation limits for bright s at roughly 0.3 Jy (W1), 0.5 Jy (W2), 5 Jy (W3), and 10 Jy (W4). A two-position scan mirror enables efficient sky coverage by freezing the line of sight on the focal plane for 8.8 seconds per frame, followed by a 1.1-second flyback, resulting in an effective scanning rate of about 3.8 arcminutes per second synchronized with the spacecraft's orbit. This mechanism, combined with the orbit's stability, supports overlapping exposures (typically 8–12 per position) for robust photometry and . Operating in the allows WISE to pierce interstellar dust extinction, which absorbs and scatters visible , revealing obscured objects such as star-forming regions, active galactic nuclei, and ultraluminous infrared galaxies hidden from optical telescopes. In the Rayleigh-Jeans tail of the blackbody relevant to these wavelengths, the flux density approximates Fν∝ν2TF_\nu \propto \nu^2 T, where TT is , providing a linear measure of dust and enabling temperature mapping of cool sources. Instrument calibration relies on observations of standard stars like to establish absolute flux scales, with relative responses derived from the spectral response function S=∫R(λ)Fλ dλS = \int R(\lambda) F_\lambda \, d\lambda, where SS is the measured signal, R(λ)R(\lambda) the detector response, and FλF_\lambda the source flux. from interplanetary dust, the dominant foreground in surveys, is subtracted using models fitted to the data, ensuring accurate photometry for extragalactic and Galactic sources. These techniques maintain photometric accuracy to within 2–5% across the sky.

Mission Timeline

Development and Launch

The Wide-field Infrared Survey Explorer (WISE) was proposed in 2001 and selected in June 2002 as NASA's sixth Medium-class Explorer (MIDEX) mission following a competitive process within the Explorer program. The project, with an initial cost estimate of $208 million covering development, launch, and operations, was managed by the (JPL) and led by Edward L. Wright from the (UCLA). Development faced funding challenges, including significant budget reductions of approximately 50% in 2005 and nearly 60% in 2006, which delayed the launch from mid-2008 to late 2009 and increased overall costs to about $320 million. These cuts stemmed from broader constraints in NASA's Science Mission Directorate, prompting a "stop-and-go" funding approach that heightened risks of cancellation. The spacecraft was assembled and tested by Ball Aerospace & Technologies Corporation, with the science instrument—comprising a 40 cm and focal plane arrays—developed by the Space Dynamics Laboratory and delivered for integration in May 2009. Environmental testing, including vibration and thermal vacuum simulations, was completed that year to verify performance under space conditions. WISE launched successfully on December 14, 2009, at 9:09 a.m. PST from Space Launch Complex 2 at Vandenberg Air Force Base, , aboard a Delta II 7320-10C rocket provided by . The spacecraft achieved a sun-synchronous at 525 km altitude with a 97-degree inclination, enabling consistent lighting conditions for observations. During the subsequent in-orbit checkout phase, lasting about one month, mission operators confirmed the functionality of key systems, including the hydrogen-filled maintaining detector temperatures below 18 K and the mechanical for the shorter-wavelength bands.

Primary "Cold" Mission

The primary "cold" mission of the Wide-field Infrared Survey Explorer (WISE) commenced on January 14, 2010, following a one-month checkout period after launch, and lasted until September 29, 2010, spanning approximately seven months. During this phase, the spacecraft's cryogenically cooled detectors operated in all four bands (W1 at 3.4 μm, W2 at 4.6 μm, W3 at 12 μm, and W4 at 22 μm), enabling a full-sky survey that completed 1.5 passes over the entire . This effort produced a comprehensive capturing emissions from a wide array of astronomical sources, including stars, galaxies, and solar system objects, with sensitivities reaching 5σ limits of approximately 0.08, 0.11, 1, and 6 mJy for the respective bands. WISE achieved its survey through a at an altitude of about 525 km, providing 360° of coverage per day while steering to avoid the Sun-avoidance zone extending 47.5° ahead and 93° behind the spacecraft-Sun line. The scanning strategy employed a cryogenic scan mirror to freeze the field of view for 9.9-second exposures, resulting in overlapping frames that yielded 95% coverage of the in the W3 and W4 bands, with deeper sensitivities in regions of multiple passes. This approach ensured uniform all-sky mapping, prioritizing completeness over depth in the longer-wavelength bands limited by the finite cryogen supply. On September 29, 2010, the solid hydrogen cryogen was fully depleted, terminating operations in the W3 and W4 bands due to insufficient cooling for those detectors, while the shorter-wavelength W1 and W2 bands remained functional at slightly elevated temperatures. Early data validation during the mission confirmed the instrument's performance by detecting known infrared sources from prior surveys, such as objects in the Infrared Astronomical Satellite (IRAS) catalog, achieving positional accuracies better than 1 arcsecond and photometric consistency with expectations. Initial discoveries of near-Earth objects (NEOs) also validated the survey's capability to identify moving sources, with preliminary processing pipelines enabling rapid alerts to ground-based observers. Operationally, the maintained three-axis stabilization using four reaction wheels to store , with excess buildup dumped periodically—every few days—via onboard magnetic torquer rods interacting with , ensuring attitude control below 1.3 arcseconds. This non-propulsive method minimized disturbances to the sensitive observations, though it required precise modeling of geomagnetic variations for optimal performance.

Initial NEOWISE Phase

Following the depletion of its cryogen in September 2010, the Wide-field Infrared Survey Explorer transitioned to the Initial NEOWISE Phase in October 2010, focusing on (NEO) detection using only the two shortest-wavelength bands, W1 (3.4 μm) and W2 (4.6 μm), which were still operational for detecting emission from asteroids and comets. This phase, funded by NASA's NEO Observations Program within the Planetary Science Division, extended what was initially proposed as a brief post-cryogenic survey before , allowing continued operations until February 2011 to prioritize Solar System science over the broader astrophysical goals of the primary mission. The loss of the longer-wavelength W3 and W4 bands limited sensitivity to colder objects but enabled efficient NEO hunting in the remaining regime. During this four-month period, NEOWISE surveyed the entire sky once in the W1 and W2 bands, achieving comprehensive coverage while operating in a mode similar to the primary mission but with adjustments to enhance NEO detection efficiency. The detected over 157,000 asteroids, including more than 500 NEOs (with 135 previously unknown) and approximately 120 comets (including 20 new discoveries), providing uniform photometry that helped characterize sizes, albedos, and properties less biased by visible-light surveys. To support moving object detection, the NEOWISE enhancement to the WISE incorporated the Wide-field Moving Object Processing System (WMOPS), which identified transient sources in single-exposure images and generated tracklets reported to the within days for follow-up; these data integrated with databases like JPL's Small-Body Database and the NEODyS system for orbital refinement and hazard assessment. Operational scanning was biased to avoid the crowded , reducing stellar confusion and prioritizing regions where NEOs are more likely to appear. The key output of this phase was the NEOWISE Post-Cryo Preliminary Data Release on July 31, 2012, which included single-exposure images and source extractions from the W1 and W2 observations, enabling detailed characterization of hundreds of NEOs through modeling and contributing foundational to planetary defense efforts. This release, archived at the Science Archive, supported analyses that refined NEO population estimates and highlighted the mission's role in unbiased surveys of potentially hazardous objects.

Hibernation and Reactivation

Following the exhaustion of its coolant in September 2010, the Wide-field Infrared Survey Explorer entered mode on February 17, 2011, to conserve battery power and extend the spacecraft's potential lifespan. Placed in a safe-hold configuration, the telescope was oriented away from the Sun, with ground controllers at NASA's remotely monitoring and managing its orbit to counteract gradual decay from residual atmospheric drag in low-Earth orbit. This dormant phase lasted over two and a half years, during which no science observations were conducted, but the spacecraft's core systems remained viable for potential future use. In 2013, selected the Wide-field Infrared Survey Explorer for reactivation under the Near-Earth Object Observations Program, prioritizing its infrared capabilities for surveying asteroids and comets that could pose risks to , in alignment with planetary defense objectives. The decision leveraged the spacecraft's proven sensitivity to thermal emissions from dark, low-albedo objects, complementing visible-light surveys. Funded through NASA's Planetary Science Division and the , the recovery effort enabled a three-year extension focused on NEO characterization. The mission was redesignated NEOWISE to reflect its new emphasis. Reactivation commenced in September 2013, with S-band communications re-established on after powering up the and allowing the to passively cool to approximately 73 K using its radiators. Functionality of the two shorter-wavelength detectors (W1 at 3.4 μm and W2 at 4.6 μm) was successfully verified, as these bands do not require cryogen, while the longer-wavelength arrays remained inoperable. Scanning resumed on December 23, 2013, supported by updated flight software optimized for efficient NEO detection, including improved moving object identification algorithms. Within six days, NEOWISE identified its first post-reactivation target, the potentially hazardous near-Earth 2013 YP139, demonstrating the mission's immediate operational readiness. The initial post-reactivation survey achieved one full-sky coverage by mid-2014, enabling the detection of thousands of solar system objects. In its first year alone, NEOWISE characterized nearly 8,000 asteroids, including 201 near-Earth objects, providing diameters and albedos that refined population models for potentially hazardous bodies. However, the mission encountered operational challenges from heightened atmospheric drag due to solar activity, resulting in an orbit decay of about 20 km over the early years; this necessitated frequent attitude control maneuvers to preserve the and minimize stray light interference during observations.

Extended NEOWISE Operations

Following its reactivation in , the NEOWISE mission entered an extended phase of operations focused on conducting repeated surveys of the sky to detect and characterize near-Earth objects (NEOs). This period, spanning from to July 2024, involved annual passes covering the entire sky, enabling multiple observations of the same regions to track moving solar system targets. Over these 10.6 years, NEOWISE completed more than 20 full-sky surveys, totaling 21.3 complete sky mappings. To enhance detection capabilities, mission teams developed improved pipelines optimized for identifying faint moving objects in the bands at 3.4 and 4.6 micrometers. These upgrades, implemented progressively during the extended operations, allowed for better sensitivity to low-albedo NEOs that are challenging for ground-based optical telescopes to observe. Additionally, integration with initiatives, such as the Active Asteroids project, enabled volunteers to flag potential anomalies like cometary activity in NEOWISE images, supplementing automated detections and improving the identification of transient phenomena. Operationally, the spacecraft's low-Earth orbit experienced gradual decay due to atmospheric drag, with the altitude lowering from around 500 km at reactivation to approximately 360 km by mid-2024. By 2020, efforts increasingly emphasized the reprocessing and reactivation of archived data from earlier surveys to refine NEO characterizations, maximizing the utility of the full dataset amid the orbital constraints. As of February 2024, these operations had yielded over 1.5 million measurements of 43,926 solar system objects, including 1,571 NEOs for which size and estimates were derived using thermal modeling. The extended NEOWISE phase provided critical groundwork for planetary defense, amassing a comprehensive infrared census of NEOs that informed trajectory predictions and physical property assessments. This legacy directly supported the transition to NASA's mission, launched in 2027 as a dedicated successor, by validating infrared survey techniques and highlighting gaps in dark or faint that future observatories aim to address.

Mission End

The NEOWISE mission completed its survey operations on July 31, 2024, after nearly 15 years of observations since its launch as WISE in December 2009, with the final scans focusing on regions of interest for detection to maximize its planetary defense contributions in the mission's closing phase. On , 2024, survey activities were formally halted due to the spacecraft's declining altitude, and the mission team initiated the decommissioning sequence. Engineers at NASA's sent the final commands on August 8, 2024, shutting off the transmitter and placing the into a hibernation mode to conclude active operations safely. The spacecraft's orbit continued to decay naturally, leading to its uncontrolled re-entry into Earth's atmosphere on , 2024 UTC, where it burned up harmlessly from its orbit, which had decayed to approximately 400 km by the end of operations in July 2024. Following the end of flight operations, ground-based data processing persisted at the Infrared Processing and Analysis Center, culminating in the Final Data Release on November 14, 2024, which incorporated the mission's last year of observations. This release supports continued scientific analysis, with NEOWISE's legacy paving the way for NASA's mission, slated for launch no earlier than 2027 to enhance surveying. Over its lifetime, NEOWISE generated data from more than 26 million images, yielding nearly 200 billion detections that cataloged millions of unique astronomical sources across the sky and provided over 1.6 million measurements of nearly 44,600 solar system objects, facilitating ongoing research in and planetary defense.

Data Releases and Products

Early and All-WISE Releases

The WISE Preliminary Data Release, made public on April 14, 2011, provided initial access to data collected during the first 105 days of the cryogenic survey phase, from January 14 to April 29, 2010. This release covered approximately 57% of the sky, spanning about 23,600 square degrees in the ecliptic longitude ranges 27.8° < λ < 133.4° and 201.9° < λ < 309.6°. The Source Catalog included photometry in all four WISE bands (W1 at 3.4 μm, W2 at 4.6 μm, W3 at 12 μm, and W4 at 22 μm) for 257,310,278 sources, enabling early scientific analyses of infrared objects across diverse astronomical populations. Building on the primary mission data, the NEOWISE Preliminary Release was issued on March 14, 2012, incorporating detections of moving objects identified during the survey. This release added infrared measurements for over 157,000 asteroids, including more than 500 near-Earth objects and approximately 120 comets, by processing single-exposure frames to track solar system bodies. These data complemented the static source catalog from the WISE Preliminary Release, focusing on transient detections to support studies of asteroid albedos, diameters, and thermal properties. The All-WISE Data Release, publicly available starting November 13, 2013, represented the culmination of processing for the full cryogenic mission dataset, combining W1 and W2 observations from all survey phases with W3 and W4 data from the 4-band cryogenic phase. It delivered a full-sky Source Catalog containing positions, apparent motions, and profile-fit photometry for 747,634,026 sources, achieving 5σ point-source sensitivities of 0.054 mJy in W1, 0.071 mJy in W2, 0.73 mJy in W3, and 5.0 mJy in W4 in low-coverage regions away from the Galactic plane. Among these, millions of sources had reliable detections in the longer-wavelength W3 and W4 bands, limited by the mission's cryogenic lifetime. Source extraction in these releases relied on profile-fit photometry, which modeled source fluxes using point-spread functions fitted simultaneously across bands and exposures to account for spatial variations and source blending. Artifact rejection algorithms removed spurious detections from zodiacal foreground emission, latent images (lattice patterns), and other instrumental effects, ensuring high reliability through quality flags and multi-frame consistency checks. All data products, including catalogs, atlas images, and reject tables, are accessible through the NASA/IPAC Infrared Science Archive (IRSA) at IPAC.

NEOWISE Annual Releases

The NEOWISE annual releases commenced with the first data release on March 26, 2015, encompassing single-exposure images and extracted source detections from the spacecraft's initial scans spanning December 13, 2013, to December 13, 2014. This release covered nearly two full sky surveys, yielding approximately 137,000 confirmed detections of around 10,200 small Solar System bodies, including near-Earth objects (NEOs), based on linkages with Minor Planet Center tracklets. These data enabled initial characterizations of NEO thermal emissions and orbits, supporting planetary defense efforts by providing infrared observations of known and newly detected objects during the early reactivation phase. Subsequent annual releases from 2016 through 2023 incrementally expanded the dataset, with each iteration incorporating new observations from the ongoing survey and adding roughly 200,000 fresh detections of Solar System objects. By the 2023 release, the cumulative archive included over 1.4 million infrared measurements of asteroids and other bodies, facilitating time-domain analyses across multiple epochs. These releases emphasized NEO and Solar System targets, delivering enhanced coverage with up to 18 full-sky scans by that point, and supported the detection of variability in object populations through repeated observations. A key feature of the annual releases is the provision of multiepoch lightcurves, which capture brightness variations due to rotation, shape, and surface properties, alongside data for thermal modeling to infer physical characteristics. Diameters DD of asteroids are estimated via near-Earth asteroid thermal models (NEATM), following the relation D∝1/p×FD \propto 1 / \sqrt{p \times F}
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