کاوشگر نقشهبردار فروسرخ میدان وسیع یا (دبلیوآیاسای WISE) یک تلسکوپ فضاییفروسرخاخترشناسیناسا است. که در دسامبر ۲۰۰۹ به فضا فرستاده شد. از آنجایی که تابش فروسرخ از تمامی اجسام منتشر میشود، تلسکوپهای فروسرخ را به کمک دستگاههای سردکننده در دمای بسیار پایین و نزدیک به صفر مطق نگهداری میکنند.
کاوشگر مساحی میدان دید باز وایز، در فوریه ۲۰۱۱ پس از خاموش شدن فرستنده هاش، به خواب زمستانی فرورفت و بار دیگر در سال ۲۰۱۳ فعال شد.
WISE تمام آسمان را در طول ۱۰ ماه با ۴ فیلتر ۳٫۴، ۴٫۶، ۱۲ و ۲۲ میکرومتر مساحی کرد. پس از اینکه مخزنهای سیستم سردکننده تلسکوپ به اتمام رسید، به مدت ۴ ماه، مأموریت به NEOWISE تغییر نام داد و به جستجوی اجرام نزدیک زمین مثل دنباله دارها، و سیارکها پرداخت. دادههای این مساحی شامل، تصاویر پردازش شده، کاتالوگ اجرام، و دادههای خام در ۱۴ مارس ۲۰۱۲ به صورت رایگان در آرشیو علوم فروسرخ قابل دریافت شد.
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 ten-month mission, during which it has taken 1.5 million images, one every 11 seconds. 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-arcsecondresolution. 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. 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, 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. Infrared measurements from the WISE astronomical survey have been particularly effective at unveiling previously undiscovered star clusters. Examples of such embedded star clusters are Camargo 18, Camargo 440, Majaess 101, and Majaess 116. In addition, 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 proto-planetary discs. WISE satellite was expected to find at least 1,000 of those proto-planetary discs.
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.
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 micrometers (aka microns). WISE achieved at least 68, 98, 860, and 5400 µJy 5-sigma sensitivity at 3.4, 4.6, 12, and 22 micrometers for the WISE All-Sky data release. 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 micrometers (micron) 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 micrometers. On the other hand, IRAS could also observe 60 and 100 micron wavelengths.
Band 1 – 3.4 micrometers (microns) – broad-band sensitivity to stars and galaxies
Band 2 – 4.6 micrometers – detect thermal radiation from the internal heat sources of sub-stellar objects like brown dwarfs
Band 3 – 12 micrometers – detect thermal radiation from asteroids
The primary mission lasted ten months: one month for checkout, six months for a full-sky survey, then an additional three months of survey until 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.
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.
By October 2010, over 33,500 new asteroids and comets were discovered, and nearly 154,000 Solar System objects were observed by WISE.
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:
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.
January 14, 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.
January 25, 2010 — WISE detects a never-before-seen near Earth asteroid, designated 2010 AB78.
February 25, 2010 — WISE website reports it has surveyed over a quarter of the sky to a depth of 7 overlapping image frames.
April 10, 2010 — WISE website reports it has surveyed over half of the sky to a depth of 7 overlapping image frames.
May 26, 2010 — WISE website reports it has surveyed over three-quarters of the sky to a depth of 7 overlapping image frames.
July 16, 2010 — Press release announces that total sky coverage will be completed on July 17, 2010. 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.
January 2011 — Entire sky surveyed to an image density of at least 16+ frames (i.e. second scan of sky completed).
February 17, 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.
August 23, 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.
March 14, 2012 — Release of the WISE All-Sky data to the scientific community.
August 29, 2012 — WISE reveals millions of black-holes.
September 20, 2012 — WISE was successfully contacted to check its status.
August 21, 2013 — NASA announced it would recommission WISE with a new mission to search for asteroids.
December 19, 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.
March 7, 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.
April 26, 2014 — The Penn State Center for Exoplanets and Habitable Worlds reports that WISE has found the coldest known brown dwarf, between -48 and -13 degrees Celsius, 7.2 light years away from the Sun.
This first light image is a false color infrared image of the sky in the direction of the Carina constellation.
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. 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.
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 December 29, 2009. A first light image was released on January 6, 2010: an eight-second exposure in the Carinaconstellation 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 micrometers, respectively. On January 14, 2010, the WISE mission started its official sky survey.
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 micrometers 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.
By October 2010, over 33,500 new asteroids and comets were discovered, and over 154,000 Solar System objects were observed by WISE. While active it found dozens of previously unknown asteroids every day. In total, it captured more than 2.7 million images during its primary mission.
Some of the comets discovered during the pre-hibernation NEOWISE
In October 2010, NASA extended the mission by one month with a program called Near-Earth Object WISE (NEOWISE). Due to its success, the program was extended a further three months. 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 cryogen). In February 2011, NASA announced that NEOWISE had discovered many new objects in the Solar System, including twenty comets. During its primary and extended missions, the spacecraft delivered characterizations of 158,000 minor planets, including more than 35,000 newly discovered objects.
Hibernation and recommissioning
After completing a full scan of the asteroid belt for the NEOWISE mission, the spacecraft was put into hibernation on February 1, 2011. The spacecraft was briefly contacted to check its status on September 20, 2012.
On August 21, 2013, NASA announced it would recommission WISE to continue its search for near-Earth objects 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 $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.
WISE was successfully taken out of hibernation in September 2013. 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. Its instruments were then re-calibrated, and the first post-hibernation photograph was taken on December 19, 2013.
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. 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. The average albedo of asteroids larger than 100 meters discovered by NEOWISE is 0.14.
First four years of NEOWISE data starting in December 2013
On April 14, 2011, a preliminary release of WISE data was made public, covering 57 percent of the sky observed by the spacecraft. On March 14, 2012, a new atlas and catalog of the entire infrared sky as imaged by WISE was released to the astronomic community. On July 31, 2012, NEOWISE Post-Cryo Preliminary Data was released. A release called AllWISE, combining all data, was released on November 13, 2013. NEOWISE data is released annually.
In 2018, the reliability of the data was challenged in a paper by Nathan Myhrvold, who stated that the NEOWISE data suffers from systemic errors due to the spacecraft being designed to observe very distant objects rather than asteroids in the Solar System.
The nearest brown dwarfs discovered by WISE within 20 light-years include:
^ abcMainzer, 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)"(PDF). Proceedings of the SPIE – UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts II. 5899: 262–273. Retrieved March 5, 2010.