Wide-field Infrared Survey Explorer

Wide-field Infrared Survey Explorer (WISE)

WISE prior to its mission into orbit
General information
NSSDC ID	2009-071A
Organization	NASA/JPL
Major contractors	Ball Aerospace Lockheed Martin Space Dynamics Laboratory SSG Precision Optronics, Inc.
Launch date	2009-12-14 14:09:33 UTC
Launched from	Space Launch Complex 2W Vandenberg Air Force Base Lompoc, California
Launch vehicle	Delta II 7320-10
Mass	750 kg (1,650 lb)
Type of orbit	Sun-synchronous polar Inclination: 97.5°
Orbit height	525 km (326 mi)
Orbit period	95 minutes, 15 times per day
Location	Low Earth Orbit
Wavelength	3.4, 4.6, 12, 22 μm bands
Diameter	0.4 m
Website	wise.ssl.berkeley.edu

Wide-field Infrared Survey Explorer (WISE) is a NASA infrared-wavelength astronomical space telescope launched on December 14, 2009,^[1][2][3] and decommissioned/hibernated on February 17, 2011 when its transmitter was turned off.^[4] The US$320 million mission launched an Earth-orbiting satellite with a 40 cm (16 in) diameter infrared telescope, which performed an all-sky astronomical survey with images in 3, 5, 12 and 22 μm wavelength range bands, over 10 months.^[5] The initial mission length was limited by its hydrogen coolant, but a secondary post-crygenic mission continued for four more months.^[4][6]

By October 2010, WISE hydrogen coolant and original NASA funding ran out, and the proposed WISE warm mission, using remaining functionality, was not approved by NASA.^[6] Rather than abandon the spacecraft, the NASA Planetary division stepped in with funding for a shorter fourth month mission extension called NEOWISE, to search for small solar system bodies close to Earth's orbit.^[6]

WISE served as a replacement for the Wide Field Infrared Explorer (WIRE), which failed within hours of reaching orbit in March 1999.^[7] In certain measurements, WISE is over 1,000 times more sensitive than prior infrared space surveys such as IRAS, AKARI, and COBE's DIRBE.^[8]

During its active mission it found dozens of previously unknown asteroids every day.^[9] Over 33,500 new asteroids and comets were discovered, and over 154,000 solar system objects were observed by WISE by October 2010.^[10]

Results of the full survey are scheduled to be released by March 2012.^[11]

The first Earth Trojan asteroid was discovered using WISE data, announced on July 27, 2011.^[12][13]

A new type of star called Y dwarfs are discovered with WISE, announced August 23, 2011.^[14][15]

Planned goals

Artist's concept of the Wide-field Infrared Survey Explorer

The mission was planned to create infrared images of 99 percent 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 10 month mission, during which it has taken 1.5 million images, one every 11 seconds.^[16] 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, 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.^[17] The produced image library contains data on the local Solar System, the Milky Way Galaxy, and the more distant universe. Among the objects WISE studied are asteroids, cool, dim stars such as brown dwarfs, and the most luminous infrared galaxies.

Targets outside the Solar system

Stellar nurseries, which are covered by interstellar dust, are detectable in infrared, since at this wavelength electromagnetic radiation can penetrate the dust. Thus galaxies of the young Universe and interacting galaxies, where star formation is intensive, are bright in infrared. On this wavelength the interstellar gas clouds are also detectable, as well as protoplanetary discs, out of them it was expected to discover some thousand.

Targets within the Solar system

WISE was not able to detect Kuiper belt objects, as their temperature is too low.^[18] It was able to detect any objects warmer than 70-100 Kelvins. A Neptune-sized object would be detectable out to 700 AU, a Jupiter-mass object out to one 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 seven to ten light years.^[18]

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 including about 300 undiscovered. That translates to ~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 with the interval of 3 hours.^[17]

Construction of the WISE telescope was divided between Ball Aerospace & Technologies (spacecraft, operations support), SSG Precision Optronics, Inc. (telescope, optics, scan mirror), DRS and Rockwell (focal planes), Lockheed Martin (cryostat, cooling for the telescope), and Space Dynamics Laboratory (instruments, electronics, and testing). The program is managed through the Jet Propulsion Laboratory.^[6]

Spacecraft

The WISE spacecraft was built by Ball Aerospace and Technologies Corp. in Boulder, Colorado. The spacecraft is derived from the Ball Aerospace RS-300 spacecraft architecture, particularly the NEXTSat spacecraft built for the successful Orbital Express mission launched on March 9, 2007. The flight system has an estimated mass of 560 kg (1,200 lb). The spacecraft is three-axis stabilized, with body-fixed solar arrays. It uses a high-gain antenna in the K_u band to transmit to the ground through the TDRSS geostationary system. Ball also performed the testing and flight system integration.

Mission

WISE surveyed the sky in four wavelengths of the infrared band, at a very high sensitivity. Its detector arrays have 5-sigma sensitivity limits of 120, 160, 650, and 2600 microjanskies (µJy) at 3.3, 4.7, 12, and 23 micrometres (aka microns).^[8] 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 micrometres 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 micrometres.^[8] On the other hand, IRAS could also observe 60 and 100 micron wavelengths, which WISE does not.^[19]

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

A scaffolding structure built around WISE allowed engineers to freeze its hydrogen coolant

The primary mission lasts ten months: one month for checkout, six months for a full-sky survey, then an additional three months of survey until cryogenic coolant runs out. The partial second survey pass will facilitate the study of changes (e.g. orbital movement) in observed objects.^[20]

Congressional hearing

On November 8, 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.^[21]

NASA officials told Committee staff that NASA plans 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 percent of the estimated NEO population of interest) within its one-year mission.

Results

By May 27, 2010, WISE discovered 12,141 previously unknown asteroids, of which 64 were considered near-Earth, and 11 new comets.^[22] This grew to 113 near-Earth asteroids and 16 comets by August 26, 2010.^[23] Two unambiguous brown dwarfs have been detected, although their distances are unknown, as well as some brown dwarf candidates.^[24]

By October 2010, over 33,500 new asteroids and comets were discovered, and nearly 154,000 solar system objects were observed by WISE.^[10] Out of this total on that date, 136 new NEA, PHA, & Comets were discovered.^[25] Out of these, 19 were new potentially hazardous asteroids, celestial objects both more likely to hit Earth and cause significant destruction (not to be confused with the more common but less dangerous Near Earth object (NEO)).^[25] As of Oct 2010, there are 1,151 PHA are known, including those found by WISE.^[26]

Discovery of an ultra-cool brown dwarf, WISEPC J045853.90+643451.9, about 10 to 30 light years away from Earth, was announced in late 2010 based on early data.^[27] In July of 2011 it was announced that WISE had discovered the first Earth trojan asteroid, 2010 TK7.^[28]

Project milestones

Delta II launch rocket of WISE

An infrared image of the launch of WISE on December 14, 2009, from Vandenberg Air Force Base on its Delta 2 rocket.

The WISE Mission is led by Dr. 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:

• 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 $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 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 $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 $300 million.
• 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.^[29]
• 11 February 2010  — WISE detects a previously unknown comet, designated P/2010 B2 (WISE).^[30]
• 25 February 2010  — WISE website reports it has surveyed over a quarter of the sky to a depth of 7 overlapping image frames.
• 10 April 2010  — WISE website reports it has surveyed over half of the sky to a depth of 7 overlapping image frames.
• 26 May 2010  — WISE website reports it has surveyed over three-quarters of the sky to a depth of 7 overlapping image frames.
• 16 July 2010  — Press release announces that total sky coverage will be completed on 17 July 2010.^[31] 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.^[6]
• January 2011  — Entire sky surveyed to an image density of at least 16+ frames (ie. second scan of sky completed).
• 17 February 2011  — WISE Spacecraft transmitter turned off at 12:00 noon PST by Principal Investigator Ned Wright. The Spacecraft will remain in hibernation without ground contacts awaiting possible future use.^[32]
• 14 April 2011  — Preliminary release of data covering 57 percent of the sky as seen by WISE.^[33]
• 27 July 2011  — First Earth Trojan asteroid discovered from WISE data.^[34][35]
• 23 Aug 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 25C. Y dwarfs show ammonia absorption, in addition to methane and water absorption bands displayed by T dwarfs.^[14][15]

Status

Circled in green in the bottom right is 2010 TK7, the first known Earth trojan and discovered from data collected during the extended "warm" mission^[4]

The launch of the Delta II rocket carrying the WISE spacecraft was originally scheduled for December 11, 2009. This attempt was scrubbed to correct a problem with a booster rocket steering engine. The launch was then rescheduled for December 14, 2009.^[36] The second attempt launched on time at 14:09:33 UTC (06:09 local PST) from Vandenberg Air Force Base in California. The rocket successfully placed the WISE spacecraft into the planned polar orbit at an altitude of 326 miles (525 km) above the Earth.^[3]

The WISE spacecraft underwent a month long checkout after launch, which 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 December 29, 2009.^[37] The first light image from WISE was released on January 6, 2010. It was an eight-second exposure taken in the direction of 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 micrometres, respectively.^[38] On January 14, 2010, the WISE mission started its official sky survey.^[39] 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 micrometres 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. Rather than see the 320 million dollar spacecraft abandoned, the NASA Planetary Division stepped in as an alternate source of funding in October 2010.^[6]

NEOWISE

In October 2010, the NASA Planetary Division saved the spacecraft from termination with a 400 000 US$ one month program extension called "Near-Earth Object WISE" (NEOWISE).^[6] If the one month post-cryogenic mission proved a success, it would be extended for an additional three months- it was, and the mission continued.^[4] The focus of the extended mission 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 cryogen.^[6] In February 2011, NASA announced that NEOWISE had discovered many new objects in the Solar System, including 20 comets.^[40] The spacecraft was put into hibernation on February 1, 2011.^[4]

Preliminary data release

On April 14, 2011, a preliminary release of WISE data was made public, covering 57 percent of the sky observed by the spacecraft.^[41]

Gallery

• 

  This first light image is a false color infrared image of the sky in the direction of the Carina constellation.

• 

  This sharp, wide-field view features infrared light from the spiral Andromeda Galaxy (M31).

• 

  Andromeda Galaxy seen by the longest-wavelength infrared detectors with 12-micrometres light color coded orange, and 22-micrometres light, red.

• 

  WISE's last snapshot of the sky.

• 

  20 comets discovered by the NEOWISE portion of the WISE mission.

See also

• Tyche (hypothetical planet)
• Nemesis (hypothetical star)

References

1. ^ Ray, Justin (2008-12-14). "Mission Status Center: Delta/WISE". Spaceflight Now. http://www.spaceflightnow.com/delta/d347/status.html. Retrieved 2009-12-26. 
2. ^ Rebecca Whatmore; Brian Dunbar (14 December 2009). "WISE". NASA. http://www.nasa.gov/mission_pages/WISE/main/index.html. Retrieved 2009-12-26. 
3. ^ ^{a b} Clavin, Whitney (14 December 2009). "NASA's WISE Eye on the Universe Begins All-Sky Survey Mission". NASA Jet Propulsion Laboratory. http://www.nasa.gov/mission_pages/WISE/news/wise20091214.html. Retrieved 2009-12-26. 
4. ^ ^{a b c d e} Wide-field Infrared Survey Explorer
5. ^ Wide-field Infrared Survey Explorer (WISE)
6. ^ ^{a b c d e f g h} Debra Werner (5 October 2010). "Last-minute Reprieve Extends WISE Mission". Space News. http://www.spacenews.com/civil/101005-last-minute-reprieve.html. Retrieved 29 October 2010. 
7. ^ William Graham (2009-12-14). "ULA Delta II Successfully Launches with WISE". NASASpaceFlight.com. http://www.nasaspaceflight.com/2009/12/live-ula-delta-ii-launch-with-wise/. Retrieved 2009-12-26. 
8. ^ ^{a b c} Mainzer, Amanda K.; Eisenhardt, Peter; Wright, Edward L.; Liu, Feng-Chuan; Irace, William; Heinrichsen, Ingolf; Cutri, Roc; Duval, Valerie (August 10, 2005). MacEwen, Howard A.. ed. Preliminary design of the Wide-field Infrared Survey Explorer (WISE). Proceedings of the SPIE - UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts II. vol.5899. pp. 262–273. http://wise.ssl.berkeley.edu/documents/WISESPIE_SanDiego05.pdf. Retrieved 2010-03-05. 
9. ^ "An Avalanche of Dark Asteroids". NASA SMD. 2010-03-26. http://science.nasa.gov/headlines/y2010/26mar_darkasteroids.htm?list994055. 
10. ^ ^{a b} Lisa Grossman (October 5, 2010). "Top 10 Deep-Space Photos From Infrared Telescope’s Final Days". Wired Science. http://www.wired.com/wiredscience/2010/10/wise-gallery/?pid=319. Retrieved 29 October 2010. 
11. ^ Clavin, Whitney (July 18, 2011). "Can WISE Find the Hypothetical 'Tyche'?". NASA.gov. http://www.nasa.gov/mission_pages/WISE/news/wise20110218.html. Retrieved July 19, 2011. 
12. ^ JPL - NASA's WISE Finds Earth's First Trojan Asteroid (July 27, 2011)
13. ^ Berkley - NASA's WISE Finds Earth's First Trojan Asteroid (July 27, 2011)
14. ^ ^{a b} WISE Public Web Site - UCLA
15. ^ ^{a b} Morse, Jon. "Discovered: Stars as Cool as the Human Body". http://science.nasa.gov/science-news/science-at-nasa/2011/23aug_coldeststars/. Retrieved 24 August 2011. 
16. ^ Griggs, Brandon (14 December 2009). "NASA launches infrared telescope to scan entire sky". CNN (Turner Broadcasting). http://www.cnn.com/2009/TECH/space/12/14/wise.spacecraft.launch/index.html. Retrieved 2009-12-26. 
17. ^ ^{a b} Posting on Minor Planet Mailing List by Amy Mainzer, principal investigator (WISE NEO Section)
18. ^ ^{a b} Lakdawalla, Emily (27 August 2009). "The Planetary Society Blog: "WISE Guys"". The Planetary Society. http://www.planetary.org/blog/article/00002070/. Retrieved 2009-12-26. 
19. ^ Schmadel, Lutz D. (2003). Dictionary of minor planet names. Berlin; New York: Springer. p. 315. ISBN 9783540299257. http://books.google.com/?id=KWrB1jPCa8AC&pg=PA315&dq=3728+IRAS#v=onepage&q=3728%20IRAS&f=false. Retrieved 23 November 2010. 
20. ^ Rebecca Whatmore (10 December 2009). "NASA's Wide-field Infrared Survey Explorer". NASA Jet Propulsion Laboratory. http://www.jpl.nasa.gov/wise/overview.cfm. Retrieved 2009-12-26. 
21. ^ United States House Committee on Science and Technology (7 November 2007). "Hearing Charter: Near-Earth Objects: Status of the Survey Program and Review of NASA's 2007 Report to Congress". SpaceRef Canada. http://www.spaceref.ca/news/viewsr.html?pid=25960. Retrieved 2009-12-25. 
22. ^ "MPC/MPO/MPS Archive". IAU Minor Planet Center. 5 June 2010. http://www.minorplanetcenter.org/iau/ECS/MPCArchive/MPCArchive_TBL.html. Retrieved 27 August 2010. 
23. ^ Alan Chamberlin (26 August 2010). "WISE NEA/Comet Discovery Statistics". NASA. http://neo.jpl.nasa.gov/stats/wise/. Retrieved 27 August 2010. 
24. ^ John Matson (May 27, 2010). "WISE satellite already spots two brown dwarfs". Scientific American. http://www.scientificamerican.com/blog/post.cfm?id=wise-satellite-already-spots-two-br-2010-05-27. Retrieved 27 August 2010. 
25. ^ ^{a b} NASA JPL: WISE NEA/Comet Discovery Statistics (accessed October 15, 2010)
26. ^ "Potentially Hazard Asteroids". http://neo.jpl.nasa.gov/neo/pha.html. Retrieved April 4, 2010. 
27. ^ Nicole Gugliucci (Thursday Novemver 18, 2010). "Infrared Telescopes Find Ultra-Cool Brown Dwarf". Discovery News. http://news.discovery.com/space/infrared-telescopes-find-ultra-cool-brown-dwarf.html. Retrieved 10 November 2010. 
28. ^ http://www.space.com/12443-earth-asteroid-companion-discovered-2010-tk7.html
29. ^ Michael Cooney (26 January 2010). "NASA space telescope spots asteroid". Techworld. http://news.techworld.com/sme/3211166/nasa-space-telescope-spots-asteroid/. Retrieved 10-02-21. 
30. ^ "WISE Spies a Comet with its Powerful Infrared Eye". NASA. http://www.nasa.gov/mission_pages/WISE/news/wise20100211.html. Retrieved 10-02-11. 
31. ^ NASA's WISE Mission to Complete Extensive Sky Survey
32. ^ "WISE - News & Events: The WISE Spacecraft transmitter was turned off for the final time". 2011-02-17. http://wise.ssl.berkeley.edu/news.html. Retrieved 2011-02-19. 
33. ^ "Mapping the Infrared Universe: Part 1". 2011-04-14. http://wise.ssl.berkeley.edu/gallery_allsky.html. Retrieved 2011-07-06. 
34. ^ JPL - NASA's WISE Finds Earth's First Trojan Asteroid (July 27, 2011)
35. ^ Berkley - NASA's WISE Finds Earth's First Trojan Asteroid (July 27, 2011)
36. ^ Whitney Clavin (December 10, 2009). "Mission News: WISE Launch Rescheduled for December 14". NASA. http://www.nasa.gov/mission_pages/WISE/news/wise20091210b.html. Retrieved 2009-12-23. 
37. ^ Whitney Clavin (29 December 2009). "NASA's WISE Space Telescope Jettisons Its Cover". NASA. http://www.jpl.nasa.gov/news/news.cfm?release=2009-206&cid=release_2009-206&msource=2009206&tr=y&auid=5763743. Retrieved 2009-12-29. 
38. ^ "WISE 'First-Light' Image". NASA. 6 January 2010. http://www.nasa.gov/mission_pages/WISE/multimedia/wise20100106.html. Retrieved 2010-01-06. 
39. ^ "WISE - News & Events". NASA. 11 February 2010. http://wise.ssl.berkeley.edu/news.html. Retrieved 2010-02-21. 
40. ^ "NASA's NEOWISE Completes Scan for Asteroids and Comets". 1 February 2011. http://www.nasa.gov/mission_pages/WISE/news/wise20110201.html. Retrieved 3 February 2011. 
41. ^ "WISE Delivers Millions of Galaxies, Stars, Asteroids". 2011-04-14. http://www.jpl.nasa.gov/news/news.cfm?release=2011-117. Retrieved 2011-07-06. 

External links

• WISE mission website at UCLA
• WISE mission website at Berkeley
  • WISE mission multimedia gallery
  • WISE mission Fact Sheet
  • WISE mission Press Kit
• WISE mission Profile by NASA's Solar System Exploration