User:Makyen/sandbox/cite highlight/test01
From Wikipedia, the free encyclopedia
Kepler is a space observatory launched by NASA to discover Earth-like planets orbiting other stars.[5] The spacecraft, named after the Renaissance astronomer Johannes Kepler,[6] was launched on March 7, 2009.[7]
Mission type | Space Telescope |
---|---|
Operator | LASP NASA |
COSPAR ID | 2009-011A |
SATCAT no. | 34380 |
Website | kepler |
Mission duration | planned: 3.5 years elapsed: 15 years, 2 months and 5 days |
Spacecraft properties | |
Manufacturer | Ball Aerospace & Technologies Corp. |
Launch mass | 1,052.4 kg (2,320 lb)[1] |
Dry mass | 1,040.7 kg (2,294 lb) |
Payload mass | 478 kg (1,054 lb) |
Dimensions | 4.7 m × 2.7 m (15.4 ft × 8.9 ft) |
Power | 1100 watts |
Start of mission | |
Launch date | March 7, 2009, 03:49:57 (2009-03-07UTC03:49:57Z) UTC[2] |
Rocket | Delta II (7925-10L) |
Launch site | Space Launch Complex 17-B Cape Canaveral Air Force Station |
Contractor | United Launch Alliance |
Entered service | May 12, 2009, 09:01 (2009-05-12UTC09:01Z) UTC |
Orbital parameters | |
Reference system | Heliocentric |
Regime | Earth-trailing |
Period | 372.5 days |
Main Telescope | |
Type | Schmidt camera |
Diameter | 0.95 m (3.1 ft) |
Collecting area | 0.708 m2[upper-alpha 1] |
Wavelengths | 400–865 nm[4] |
Transponders | |
Band | X band (TT&C) Ka band (data acquisition) |
Bandwidth | few kbit/s (X Band) ~4.3 Mbit/s (Ka band) |
Designed to survey a portion of our region of the Milky Way to discover dozens of Earth-size extrasolar planets in or near the habitable zone and estimate how many of the billions of stars in our galaxy have such planets,[8][9] Kepler's sole instrument is a photometer that continually monitors the brightness of over 145,000 main sequence stars in a fixed field of view.[10] This data is transmitted to Earth, then analyzed to detect periodic dimming caused by extrasolar planets that cross in front of their host star.
Kepler is part of NASA's Discovery Program of relatively low-cost, focused primary science missions. The telescope's construction and initial operation were managed by NASA's Jet Propulsion Laboratory, with Ball Aerospace responsible for developing the Kepler flight system. The Ames Research Center is responsible for the ground system development, mission operations since December 2009, and science data analysis. The initial planned lifetime was 3.5 years,[11] but greater-than-expected noise in the data, from both the stars and the spacecraft, meant additional time was needed to fulfill all mission goals. Initially, in 2012, the mission was expected to last until 2016,[12] but this would only have been possible if all remaining reaction wheels used for pointing the spacecraft remained reliable.[13] On May 11, 2013, a second of four reaction wheels failed, disabling the collection of science data[14] and threatening the continuation of the mission.[15]
As of June 2014[update], Kepler and its follow-up observations had found 977 confirmed exoplanets in more than 400 stellar systems, along with a further 3,277 unconfirmed planet candidates.[upper-alpha 2][16][17] In November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of sun-like stars and red dwarf stars within the Milky Way Galaxy.[18][19][20] 11 billion of these estimated planets may be orbiting sun-like stars.[21] The nearest such planet may be 12 light-years away, according to the scientists.[18][19]
On August 15, 2013, NASA announced that they had given up trying to fix the two failed reaction wheels. This meant the current mission needed to be modified, but it did not necessarily mean the end of planet-hunting. NASA had asked the space science community to propose alternative mission plans "potentially including an exoplanet search, using the remaining two good reaction wheels and thrusters".[22][23][24][25] On November 18, 2013, the K2 (also named "Second Light") plan proposal, which would include utilizing the disabled Kepler in a way that could detect habitable planets around smaller, dimmer red dwarf stars, was reported.[26][27][28][29] On May 16, 2014, NASA announced the approval of extending the Kepler mission to the K2 mission.[30]