(486958) 2014 MU69

(486958) 2014 MU69

New Horizons target, 2014 MU69 (green circles), as it travels across a dense field of stars and noise in the background. Images taken at 10-minute intervals by WFC3 in 2014.
Discovery [1][2]
Discovered by Hubble Space Telescope
Discovery site Earth's orbit
Discovery date 26 June 2014
Designations
MPC designation (486958) 2014 MU69
2014 MU69 · PT1 [3]
1110113Y [4] · 11 [5]
cubewano [4] · TNO [1]
distant [2]
Orbital characteristics [1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 5[1] · 2[2]
Observation arc 118 days[1] · 851 days[2]
Aphelion 46.434 AU
Perihelion 42.341 AU
44.387 AU
Eccentricity 0.0461[1] · 0.036[6]
295.73 yr
(108,015 days)
4.47 km/s
304.15°
0° 0m 11.88s / day
Inclination 2.4521°[1] · 1.9° [6]
158.98°
185.14°
Physical characteristics
Dimensions

Primary: 20 km (12 mi), Secondary: 18 km (11 mi)[7]

30–45 km (19–28 mi)[4]
25–45 km (16–28 mi)[5]
18–41 km (11–25 mi)
30 km (19 mi)[8]
0.04–0.10 (assumed)[4]
0.04–0.15 (assumed)[5]
26.8[9]
10.9[1]

    (486958) 2014 MU69 (initially called "PT1" and "1110113Y" by the New Horizons and Hubble teams, respectively) is a classical Kuiper belt object.[10] It is the target for the New Horizons probe for a flyby on 1 January 2019, after its Pluto flyby.[3] It was selected as New Horizons' target in August 2015.[11] After four course changes in October and November 2015, New Horizons is on course toward 2014 MU69.[12][13]

    History

    Discovery

    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 with an apparent magnitude of nearly 27 it 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.[9][14][15]

    Designation

    When 2014 MU69 was first observed, it was labelled 1110113Y,[16] and nicknamed "11", for short.[5][3] Its existence as a potential target of the New Horizons probe was announced by NASA in October 2014[17][18] and it was unofficially designated PT1 ("Potential Target 1"). Its official designation, 2014 MU69, was assigned by the Minor Planet Center (MPC) in March 2015 after sufficient orbital information was gathered.[3] After further observations pinning down its orbit, it was officially given the permanent minor planet number 486958 in MPC 103886 on 12 March 2017.[19]

    The name 2014 MU69 is a provisional designation and indicates that it was the 1745th object (("U" = 20) + ("69" × 25)) discovered between 16 and 30 June 2014 ("2014", "M").

    Characteristics

    Based on its brightness and distance, 2014 MU69 was first estimated to have a diameter of 18–41 km (10–30 mi).[4] Observations in 2017 concluded that the object is no more than 30 km (20 mi) long and very elongated. 2014 MU69 may actually be a close or contact binary.[8] In an occultation on July 17, 2017, a two-lobed shape was revealed, with diameters of 20 and 18 km (12 and 11 miles), respectively.[7] This means that 2014 MU69 is likely a primordial binary in the Kuiper Belt.[20]

    Its orbital period 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.[4] Observations in May and July 2015 as well as in July and October 2016 greatly reduced the uncertainties in the orbit.[9][2] The updated orbit parameters are available in the MPC database.

    2014 MU69 has a red spectrum, making it the smallest Kuiper belt object to have its color measured.[22]

    Between 25 June and 4 July 2017, the Hubble Space Telescope spent 24 orbits observing 2014 MU69, in an effort to determine its rotation period and further reduce the orbit uncertainty.[23] First results show that the brightness of 2014 MU69 varies by less than 20 percent as it rotates.[7] This places significant constraints on the axis ratio of 2014 MU69 to <1.14 assuming an equatorial view. Together with the fact that its shape has been shown to be very irregular[8], the small amplitude indicates that its pole is pointed towards Earth. This means that the timing of the New Horizons fly-by does not need to be adjusted to look at the "larger" axis of the object, simplifying the engineering of the fly-by significantly. The small amplitude makes it difficult to uniquely identify the rotation period at this time. Distant satellites of 2014 MU69 have been excluded to a depth of >29th magnitude.[24]

    Stellar occultations

    In June and July 2017, 2014 MU69 occulted three background stars.[25] The team behind New Horizons has formed a specialised "KBO Chasers" team to observe these stellar occultations from South America, Africa and the Pacific Ocean.[26][27][28]

    Predicted ground tracks of the stellar occultations for 2014 MU69

    On 3 June 2017, two teams of NASA scientists tried to detect the shadow of 2014 MU69 from Argentina and South Africa.[29] 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 or as dark as previously expected, and that it might be highly reflective or even a swarm.[30][31]. 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.[32][33]

    2014 MU69's shadow traces its most likely binary shape, as seen in the stellar occultation that occurred over Argentina on 17 July 2017. The best-fit red circles reveal MU69's possible doubled-lobed – or binary – nature.

    On 10 July 2017, the NASA Stratospheric Observatory for Infrared Astronomy (SOFIA) airborne telescope 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 has successfully been collected, but again the central shadow was missed.[10] The data collected by SOFIA will still be valuable to put constraints on dust near 2014 MU69.[34][35] Detailed results of the search for hazardous material will be presented on the 49th Meeting of the AAS Division for Planetary Sciences, on 20 October 2017.[36]

    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.[37] For the third and final occultation, team members set up another groundbased "fence line" of 24 small, mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina (Chubut and Santa Cruz Provinces) to try to better constrain, or even determine, the size of 2014 MU69.[27][38] The average spacing between these telescopes was as small as 4.5 km (2.8 mi).[39] 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.[38] Combined with the SOFIA observations, this will put good constraints on possible debris near 2014 MU69.[35][33]

    First 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.[8][40] According to the number and duration of the observed chords, 2014 MU69 has two "lobes", with diameters of 20 km and 18 km, respectively.[7]

    There are currently two potentially useful 2014 MU69 occultations predicted for 2018, but neither is as good as the three 2017 events.[25]

    Exploration

    Having completed its flyby of Pluto, the New Horizons spacecraft has been maneuvered for a flyby of 2014 MU69, which will occur on 31 December 2018 or 1 January 2019, at which point it will be 43.4 AU from the Sun in the constellation Sagittarius.[41][42][43][44] 2014 MU69 is the first object to be targeted for a flyby that was discovered after the spacecraft was launched.[9]

    See also

    References

    1. 1 2 3 4 5 6 7 8 "JPL Small-Body Database Browser: 486958 (2014 MU69)" (2014-10-22 last obs.). Jet Propulsion Laboratory. Retrieved 15 March 2017.
    2. 1 2 3 4 5 "486958 (2014 MU69)". Minor Planet Center. Retrieved 15 March 2017.
    3. 1 2 3 4 Talbert, Tricia (28 August 2015). "NASA's New Horizons Team Selects Potential Kuiper Belt Flyby Target". NASA. Retrieved 4 September 2015.
    4. 1 2 3 4 5 6 Lakdawalla, Emily (15 October 2014). "Finally! New Horizons has a second target". Planetary Society blog. Planetary Society. Archived from the original on 15 October 2014.
    5. 1 2 3 4 Buie, Marc (15 October 2014). "New Horizons HST KBO Search Results: Status Report" (PDF). Space Telescope Science Institute. p. 23.
    6. 1 2 Stern, Alan (August 2015). "OPAG: We Did It!" (PDF). Presentation to the Outer Planets Assessment Group (OPAG) of the Lunar and Planetary Institute. Universities Space Research Association. p. 33.
    7. 1 2 3 4 "The PI's Perspective: The Heroes of the DSN and the 'Summer of MU69'". Retrieved 8 August 2017.
    8. 1 2 3 4 "New Horizons' Next Target Just Got a Lot More Interesting". NASA. 3 August 2017.
    9. 1 2 3 4 Lakdawalla, Emily (1 September 2015). "New Horizons extended mission target selected". Planetary Society blog. Planetary Society.
    10. 1 2 3 4 Chang, Kenneth (8 August 2017). "Chasing Shadows for a Glimpse of a Tiny World Beyond Pluto". The New York Times. Retrieved 9 August 2017.
    11. ↑ Barnett, Amanda (28 August 2015). "Pluto probe gets new assignment". CNN. Retrieved 7 October 2015.
    12. ↑ Dunn, Marcia (22 October 2015). "NASA's New Horizons on new post-Pluto mission". AP News. Retrieved 25 October 2015.
    13. ↑ "NASA's New Horizons Completes Record-Setting Kuiper Belt Targeting Maneuvers". New Horizons Team. 5 November 2015. Retrieved 6 November 2015.
    14. ↑ J. R. Spencer; M. W. Buie; et al. (2015). "The Successful Search for a Post-Pluto KBO Flyby Target for New Horizons Using the Hubble Space Telescope" (PDF). European Planetary Science Congress (EPSC) Abstract. Copernicus Office.
    15. ↑ S. B. Porter; et al. (2017). Ultra-High Resolution Orbit Determination of (486958) 2014 MU69: Predicting an Occultation with 1% of an Orbit. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.02. Retrieved 9 August 2017.
    16. ↑ "Hubble Survey Finds Two Kuiper Belt Objects to Support New Horizons Mission". HubbleSite news release. Space Telescope Science Institute. 1 July 2014.
    17. ↑ "NASA's Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission". HubbleSite. 15 October 2014.
    18. ↑ Wall, Mike (15 October 2014). "Hubble Telescope Spots Post-Pluto Targets for New Horizons Probe". Space.com. Archived from the original on 15 October 2014.
    19. ↑ "The Minor Planet Circulars, M.P.C. 103886" (PDF). Minor Planet Center. 12 March 2017. Retrieved 9 August 2017.
    20. ↑ A. H. Parker; et al. (2017). Multiplicity of the New Horizons Extended Mission Target (486958) 2014 MU69. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.04.
    21. ↑ Porter, S. B.; Parker, A. H.; et al. (eds.). Orbits and Accessibility of Potential New Horizons KBO Encounter Targets (PDF). 46th Lunar and Planetary Science Conference (2015).
    22. ↑ "Scientists Determine Color of Kuiper Belt Objects JR1 and MU69 | Planetary Science, Space Exploration". Sci-News.com. Retrieved 2 November 2016.
    23. ↑ "The Lightcurve of New Horizons Encounter TNO 2014 MU69". Retrieved 27 July 2017.
    24. ↑ S. D. Benecchi; et al. (2017). The HST Lightcurve of (486958) 2014MU69. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.07.
    25. 1 2 "Mission Support of the New Horizons 2014 MU69 Encounter via Stellar Occultations". Retrieved 27 July 2017.
    26. ↑ "2014MU69 occultation campaign". Retrieved 27 July 2017.
    27. 1 2 "KBO Chasers". NASA. Retrieved 27 July 2017.
    28. ↑ M. W. Buie; et al. (2017). Overview of the strategies and results of the 2017 occultation campaigns involving (486958) 2014 MU69. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.01.
    29. ↑ A. J. Verbiscer; et al. (2017). Portable Telescopic Observations of the 3 June 2017 Stellar Occultation by New Horizons Kuiper Extended Mission Target (486958) 2014 MU69. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.05.
    30. ↑ "New Mysteries Surround New Horizons’ Next Flyby Target: NASA’s New Horizons spacecraft doesn’t zoom past its next science target until New Year’s Day 2019, but the Kuiper Belt object, known as 2014 MU69, is already revealing surprises.". NASA. 5 July 2017.
    31. ↑ "The Case of the Dog that Didn’t Bark in the Night". 7 July 2017.
    32. ↑ "June 3rd got the hazard search we wanted done but didn't put telescopes in the right place because back then we didn't have the MU69 orbit prediction well enough in hand. Subsequent HST June-July data helped with that.". 20 July 2017.
    33. 1 2 "The #mu69occ campaign: Occam's razor wins again...". 21 July 2017.
    34. ↑ "SOFIA to Make Advance Observations of Next New Horizons Flyby Object". NASA. 10 July 2017.
    35. 1 2 "SOFIA in Right Place at Right Time to Study Next New Horizons Flyby Object". NASA. 11 July 2017.
    36. ↑ E. F. Young; et al. (2017). Debris search around (486958) 2014 MU69: Results from SOFIA and ground-based occultation campaigns. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.06.
    37. ↑ J. Kammer; et al. (2017). Probing the Hill Sphere of 2014 MU69 with HST FGS. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 216.04.
    38. 1 2 "NASA's New Horizons Team Strikes Gold in Argentina". NASA. 19 July 2017.
    39. ↑ "2014 MU69 presentation". Retrieved 27 July 2017.
    40. ↑ A. M. Zangari; et al. (2017). A stellar occultation by (486958) 2014 MU69: results from the 2017 July 17 portable telescope campaign. 49th Meeting of the AAS Division for Planetary Sciences Abstract. 504.03.
    41. ↑ "Maneuver Moves New Horizons Spacecraft toward Next Potential Target". 23 October 2015. Retrieved 5 November 2015.
    42. ↑ "New Horizons Continues Toward Potential Kuiper Belt Target". 26 October 2015. Retrieved 5 November 2015.
    43. ↑ "On Track: New Horizons Carries Out Third KBO Targeting Maneuver". 29 October 2015. Retrieved 5 November 2015.
    44. ↑ "Asteroid 2014 MU69". The Sky Live. Retrieved 11 November 2015.
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