(486958) 2014 MU69

From Infogalactic: the planetary knowledge core
(Redirected from Arrokoth)
Jump to: navigation, search

Lua error in package.lua at line 80: module 'strict' not found.

(486958) 2014 MU69
2014MU69 MVIC crop2.jpg
2014 MU69 in grayscale[lower-alpha 1]
Discovery [2][3]
Discovered by Hubble Space Telescope
Discovery site Earth's orbit
Discovery date 26 June 2014
Designations
  • Ultima Thule (unofficial)[4]
  • PT1[5]
  • 1110113Y[6]
  • Object 11[7]
Orbital characteristics[3]
Epoch 2019 April 27 (JD 2458600.5)
Uncertainty parameter 2
Observation arc 851 days
Aphelion 46.442 AU
Perihelion 42.7212447±0.0014309 AU
44.5813998 AU
Eccentricity 0.0417249±0.0000346
298 yr
316.55086°
Inclination 2.45116°±0.000012°
158.99773°±0.00045°
174.418°±0.037°
Physical characteristics
Dimensions ≈ 35 km  by ≈ 15 km[9]
≈ 10–20 hours
0.04–0.10 (assumed)[6]
0.04–0.15 (assumed)[7]
26.8[10]
11.1[3]

(486958) 2014 MU69, nicknamed Ultima Thule, is a trans-Neptunian object located in the Kuiper belt. It is a contact binary with an estimated diameter of 30 km (20 mi). With an orbital period of 300 years and a low inclination and eccentricity, it is classified as a classical Kuiper belt object and suspected to have not undergone significant perturbations and to be only moderately cratered. It seems to have a binary-like shape as seen during a stellar occultation, yet has a very flat light curve more consistent with a spherical body. 2014 MU69 was discovered on 26 June 2014 by astronomers using the Hubble Space Telescope as part of a search for a Kuiper belt object for the New Horizons mission to target in its first extended mission; it was chosen over two other candidates to become the primary target of the mission. Its nickname, a Latin metaphor for a place located beyond the borders of the known world, was chosen as part of a public competition in 2018. The New Horizons team plans to submit a proper name to the International Astronomical Union after the spacecraft's flyby on 1 January 2019, when the nature of the object is better known. 2014 MU69 is the farthest object in the Solar System visited by a spacecraft.

Nomenclature

When 2014 MU69 was first observed, it was labelled 1110113Y,[11] nicknamed "11", for short.[7][5] Its existence as a potential target of the New Horizons probe was announced by NASA in October 2014[12][13] and it was unofficially designated as "Potential Target 1", or PT1.[5] Its official designation, 2014 MU69 (a provisional designation indicating that it was the 1745th object discovered during the second half of June 2014), was assigned by the Minor Planet Center (MPC) in March 2015 after sufficient orbital information was gathered.[5] After further observations pinning down its orbit, it was given the permanent minor planet number 486958 on 12 March 2017 (as announced in M.P.C. 103886).[14]

An official name for the object, consistent with the naming guidelines of the International Astronomical Union, will be selected by the New Horizons team after the spacecraft's flyby in January 2019, when the properties of (486958) 2014 MU69 are known well enough to choose a suitable name.[15][16] In the interim, NASA invited suggestions from the public on a nickname to be used.[16] The campaign involved 115,000 participants from around the world, who suggested some 34,000 names. Of those, 37 reached the ballot for voting and were evaluated for popularity–this included eight names suggested by the New Horizons team and 29 suggested by the public. "Ultima Thule"[17] which was selected on 13 March 2018,[4] was nominated by about 40 members of the public and was one of the highest vote-getters among the nominees.[4]:{{{3}}} It is named after the Latin phrase ultima Thule (literally farthermost Thule), an expression referencing the most distant place beyond the borders of the known world.[4]

Characteristics

The orbits of New Horizons potential targets 1-3. 2014 MU69 (PT1) is in blue. 2014 OS393 (PT2) is in red. 2014 PN70 is in green.

In 2014, 2014 MU69 was estimated to have a diameter of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). based on its brightness and distance.[6] Observations in 2017 concluded that 2014 MU69 is no more than 30 km (20 mi) long and very elongated, possibly a close or contact binary.[18] Based on models from the New Horizons Pluto flyby, it has been predicted that 2014 MU69 is only moderately cratered, with no more than 25 to 50 craters larger than the effective resolution limit of 200 metres (660 ft). Unlike in the inner Solar System, where collisions typically occur at velocities above 10 km per second, it is expected that most craters on 2014 MU69 were formed at much lower speeds. Their morphology may differ from that seen on previously visited asteroids. If the cratering rate is low then most of the surface is expected to be pristine, possibly showing signs of the original accretion, 4.6 billion years ago.[19] 2014 MU69 has a red spectrum, and is the smallest Kuiper belt object to have its colors measured.[20]

Polar view of 2014 MU69's rotation over two and a half hours.[1]

2014 MU69's orbital period around the Sun is slightly more than 295 years and it has a low inclination and low eccentricity compared to other objects in the Kuiper belt.[21] These orbital properties mean that it is a cold classical Kuiper belt object which is unlikely to have undergone significant perturbations.[6] Observations in May and July 2015 as well as in July and October 2016 greatly reduced the uncertainties in the orbit.[10][3] Results from Hubble Space Telescope observations[22] show that the brightness of 2014 MU69 varies by less than 20 percent as it rotates.[23] This placed significant constraints on the axis ratio of 2014 MU69 to <1.14, having assumed an equatorial view. Despite 2014 MU69's irregular shape, there is no detectable light curve amplitude, as its axis is oriented on its side, pointing towards the Sun.[1][24] Distant satellites of 2014 MU69 have been excluded to a depth of >29th magnitude.[25]

Observation

Discovery

Discovery images of 2014 MU69, cropped from five Wide Field Camera 3 images taken on 26 June 2014.

On 26 June 2014, 2014 MU69 was discovered using the Hubble Space Telescope during a preliminary survey to find a suitable Kuiper belt object for the New Horizons probe to fly by. The discovery required the use of the Hubble Space Telescope, because ground-based observations had not found a Kuiper belt object in the zone of space that can be accessed by New Horizons. With an apparent magnitude of nearly 27, 2014 MU69 is too faint for all but the most powerful telescopes. The Hubble Space Telescope is also capable of very precise astrometry and hence a reliable orbit determination.[10][26][27]

2017 occultations

In June and July 2017, 2014 MU69 occulted three background stars.[28] The team behind New Horizons formed a specialised "KBO Chasers" team to observe these stellar occultations from South America, Africa, and the Pacific Ocean.[29][30][31] On 3 June 2017, two teams of NASA scientists tried to detect the shadow of 2014 MU69 from Argentina and South Africa.[32] When they found that none of their telescopes had observed the object's shadow, it was initially speculated that 2014 MU69 might be neither as large nor as dark as previously expected, and that it might be highly reflective or even a swarm.[33][34] Additional data taken with the Hubble Space Telescope in June and July 2017 revealed that the telescopes had been placed in the wrong location, and that these speculations were wrong.[35][36]

2014 MU69 briefly blocked the light from an unnamed star in Sagittarius during an occultation on 17 July 2017. Data from five telescopes that captured this event revealed 2014 MU69's possible doubled-lobed or binary shape.

On 10 July 2017, the airborne telescope SOFIA was successfully placed close to the predicted centerline for the second occultation while flying over the Pacific Ocean from Christchurch, New Zealand. The main purpose of those observations was the search for hazardous material like rings or dust near 2014 MU69 that could threaten the New Horizons spacecraft during its flyby in 2019. Data collection was successful. A preliminary analysis suggested that the central shadow was missed;[37] only in January 2018 was it realized that SOFIA had indeed observed a very brief dip from the central shadow.[38] The data collected by SOFIA will also be valuable to put constraints on dust near 2014 MU69.[39][40] Detailed results of the search for hazardous material were presented on the 49th Meeting of the AAS Division for Planetary Sciences, on 20 October 2017.[41]

On 17 July 2017, the Hubble Space Telescope was used to check for debris around 2014 MU69, setting constraints on rings and debris within the Hill sphere of 2014 MU69 at distances of up to 75,000 km from the main body.[42] For the third and final occultation, team members set up another ground-based "fence line" of 24 mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina (Chubut and Santa Cruz Provinces) to better constrain the size of 2014 MU69.[30][43] The average spacing between these telescopes was as small as 4.5 km (2.8 mi).[44] Using the latest observations from Hubble, the position of 2014 MU69 was known with much better precision than for the June 3 occultation, and this time the shadow of 2014 MU69 was successfully observed by at least five of the mobile telescopes.[43] Combined with the SOFIA observations, this will put good constraints on possible debris near 2014 MU69.[40][36]

Results from the occultation on 17 July show that 2014 MU69 has a very irregular shape (an "extreme prolate spheroid"), or may even be a close or contact binary.[18][45] According to the number and duration of the observed chords, 2014 MU69 has two "lobes", with diameters of 20 km and 18 km, respectively.[23] A preliminary analysis of all collected data did suggest that 2014 MU69 may be accompanied by an orbiting moonlet about 200-300 km away.[46][47] However, it was later realized that a problem with the data processing software was responsible for a shift in the apparent location of the target. After accounting for the software bug, the short dip observed on 10 July is now considered to be a detection of the primary body.[38]

2018 occultations

Path of 2014 MU69's shadow on Earth during its 4 August 2018 occultation of an unnamed star in Sagittarius. This event was successfully observed from locations in Senegal and Colombia.

There have been two potentially useful 2014 MU69 occultations predicted for 2018: One on 16 July, one on 4 August. Neither of these was as good as the three 2017 events.[28] No attempts were made to observe the 16 July 2018 occultation, which took place over the South Atlantic and Indian Ocean. For the 4 August 2018 event, two teams, consisting of about 50 researchers in total, went to locations in Senegal and Colombia.[48] The event gathered media attention in Senegal, where it was used as an opportunity for science outreach.[49] Despite some stations being affected by bad weather, the event was successfully observed, as reported by the New Horizons team.[50] Initially, it was unclear whether a chord on the target had been recorded. On 6 September 2018, NASA confirmed that the star has indeed been seen to dip by at least one observer, providing important information about the size and shape of 2014 MU69.[51]

Hubble observations were carried out on 4 August 2018, to support the occultation campaign.[52][48] Hubble could not be placed in the narrow path of the occultation, but due to the favourable location of Hubble at the time of the event, the space telescope was able to probe the region down to 1,600 kilometres (990 mi) from 2014 MU69. This is much closer than the 20,000 kilometres (12,000 mi) region that could be observed during the 17 July 2017 occultation. No brightness changes of the target star have been seen by Hubble, ruling out any optically thick rings or debris down to 1,600 kilometres (990 mi) from Ultima Thule.[51] Results of the 2017 and 2018 occultation campaigns were presented at the 50th meeting of the AAS Division for Planetary Sciences, on 26 October 2018.[53]

Exploration

<templatestyles src="Module:Hatnote/styles.css"></templatestyles>

See also: New Horizons § Encounter with (486958) 2014 MU69
2014 MU69 among the stars of Sagittarius, imaged by New Horizons in late 2018. Its apparent magnitude from the spacecraft decreased from 20 to 15.[54]

Having completed its flyby of Pluto in July 2015, the New Horizons spacecraft made four course changes in October and November 2015 to place itself on a trajectory towards 2014 MU69.[55][56] It is the first object to be targeted for a flyby that was discovered after the visiting spacecraft was launched,[10] and is the farthest object in the Solar System ever to be visited by a spacecraft.[5][57][58] New Horizons came within 3,500 km (2,200 mi) of 2014 MU69, three times closer than the spacecraft's earlier encounter with Pluto. Closest approach occured at 12:33 a.m., January 1, 2019 (EST),[47] at which point it was 43.4 AU from the Sun in the direction of the constellation Sagittarius.[59][60][61][62] At this distance, the one-way transit time for radio signals between Earth and New Horizons was 6 hours.[47] The science objectives of the flyby include characterizing the geology and morphology of 2014 MU69, mapping the surface composition (searching for ammonia, carbon monoxide, methane, and water ice). Surveys of the surrounding environment to detect possible orbiting moonlets, a coma, or rings, were conducted.[47] Images with a resolution as fine as 30 m (98 ft) to 70 m (230 ft) are expected.[47][63]

New Horizons made its first detection of 2014 MU69 on 16 August 2018, from a distance of Lua error in Module:Convert at line 272: attempt to index local 'cat' (a nil value)..[64] At that time, 2014 MU69 was visible at magnitude 20, in the direction of the constellation Sagittarius.[65] 2014 MU69 was expected to be magnitude 18 by mid-November, and magnitude 15 by mid-December. It reached naked eye brightness (magnitude 6) from the spacecraft's point of view just 3-4 hours before closest approach.[54] If obstacles were detected, the spacecraft had the option of diverting to a more distant rendezvous, though no moons, rings or other hazards were seen.[47][66] First high-resolution images are expected on January 1 and January 2.[67] The downlink of data collected from the flyby is expected to last 20 months, through to September 2020.[67]

See also

References

Notelist

  1. ↑ Photograph taken by the Long Range Reconnaissance Imager aboard New Horizons on 31 December 2018, displaying 2014 MU69's "bowling pin" shape.[1]

Citations

  1. ↑ 1.0 1.1 1.2 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Ultima Thule Looks Like a Bowling Pin in Space in New Horizons Flyby Photo. Mike Wall. Space.com 1 January 2019.
  10. ↑ 10.0 10.1 10.2 10.3 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ 16.0 16.1 Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Normally pronounced /ˈθjuːliː/ THEW-lee [US THOO-lee],Lua error in package.lua at line 80: module 'strict' not found.
    though a NASA press kit suggests the pseudo-Latin pronunciation /ˈtuːliː/ TOO-lee
    Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ 18.0 18.1 Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  23. ↑ 23.0 23.1 Lua error in package.lua at line 80: module 'strict' not found.
  24. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  25. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  26. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  27. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  28. ↑ 28.0 28.1 Lua error in package.lua at line 80: module 'strict' not found.
  29. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  30. ↑ 30.0 30.1 Lua error in package.lua at line 80: module 'strict' not found.
  31. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  32. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  33. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  34. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  35. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  36. ↑ 36.0 36.1 Lua error in package.lua at line 80: module 'strict' not found.
  37. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  38. ↑ 38.0 38.1 Lua error in package.lua at line 80: module 'strict' not found.
  39. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  40. ↑ 40.0 40.1 Lua error in package.lua at line 80: module 'strict' not found.
  41. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  42. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  43. ↑ 43.0 43.1 Lua error in package.lua at line 80: module 'strict' not found.
  44. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  45. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  46. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  47. ↑ 47.0 47.1 47.2 47.3 47.4 47.5 Lua error in package.lua at line 80: module 'strict' not found.
  48. ↑ 48.0 48.1 Lua error in package.lua at line 80: module 'strict' not found.
  49. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  50. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  51. ↑ 51.0 51.1 Lua error in package.lua at line 80: module 'strict' not found.
  52. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  53. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  54. ↑ 54.0 54.1 Lua error in package.lua at line 80: module 'strict' not found.
  55. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  56. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  57. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  58. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  59. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  60. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  61. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  62. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  63. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  64. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  65. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  66. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  67. ↑ 67.0 67.1 Lua error in package.lua at line 80: module 'strict' not found.

External links

Template:2018 in space Template:NH1

Retrieved from "https://infogalactic.com/w/index.php?title=(486958)_2014_MU69&oldid=725826780"