29. December 2018

NASA’s New Hori­zons space­craft on tar­get to reach Ul­ti­ma Thule

New Horizons’ close flyby of Ultima Thule
New Hori­zons’ close fly­by of Ul­ti­ma Thule on 1 Jan­uary 2019
Image 1/5, Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Steve Gribben

New Horizons’ close flyby of Ultima Thule on 1 January 2019

In 61 years of space ex­plo­ration, no space­craft has ex­am­ined an ob­ject fur­ther away from the Earth and Sun at close quar­ters: on 1 Jan­uary 2019, NASA’s New Hori­zons space­craft will fly past the ap­prox­i­mate­ly 30-kilo­me­tre trans-Nep­tu­ni­an ob­ject, 2014 MU69, which is 6.5 bil­lion kilo­me­tres from the Sun. The body has been giv­en the pro­vi­sion­al name Ul­ti­ma Thule by the project sci­en­tists. Ul­ti­ma Thule is an ob­ject in the Kuiper-Edge­worth belt. New Hori­zons – in front of the Sun (up­per right cor­ner) in this artist’s im­pres­sion – will pass Ul­ti­ma Thule at a dis­tance of just 3500 kilo­me­tres. It takes a sig­nal from New Hori­zons over six hours to reach Earth (one way).
Graphic: The route from New Horizons to Ultima Thule
The route from New Hori­zons to Ul­ti­ma Thule
Image 2/5, Credit: NASA/APL.

The route from New Horizons to Ultima Thule

New Hori­zons is a space probe from NASA's New Fron­tiers pro­gramme. The main goal is the in­ves­ti­ga­tion of the dwarf plan­et Plu­to up close. Launched on 19 Jan­uary 2006, it reached its des­ti­na­tion on 14 Ju­ly 2015. The im­ages from the Plu­to-Charon sys­tem tak­en from a dis­tance of 12,500 kilo­me­tres were a sen­sa­tion. Since the New Hori­zons space­craft is not an or­biter, af­ter the en­counter with Plu­to-Charon there was an op­por­tu­ni­ty to tar­get an­oth­er tar­get in the Kuiper Belt. The Kuiper Belt is a re­gion that ex­tends be­yond Nep­tune's or­bit to 18 bil­lion kilo­me­tres from the Sun. Here, there are thou­sands of 'Kuiper-Belt Ob­jects' (KBOs) at ex­treme­ly low tem­per­a­tures, from prim­i­tive bod­ies on­ly a few kilo­me­tres in size to the di­men­sions of dwarf plan­ets. And it is there that New Hori­zons is vis­it­ing 2014MU69, which is cur­rent­ly known as 'Ul­ti­ma Thule'.
The idea of Ultima Thule being two bodies
The idea of Ul­ti­ma Thule be­ing two bod­ies
Image 3/5, Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker

The idea of Ultima Thule being two bodies

The ex­act shape of Ul­ti­ma Thule, which NASA’s New Hori­zons space­craft will fly past on 1 Jan­uary at a dis­tance of 3500 kilo­me­tres, is not yet known. Based on light curve anal­y­sis dur­ing a stel­lar oc­cul­ta­tion in Ju­ly 2017, sci­en­tists as­sume that Ul­ti­ma Thule ex­tends for 30 kilo­me­tres, has an ir­reg­u­lar shape and pre­sum­ably con­sists of two bod­ies. It could there­fore be a so-called con­tact bi­na­ry with pos­si­bly on­ly ex­treme­ly loose co­he­sion – sim­i­lar to the comet, 67P/Churyu­mov-Gerasi­menko.
Artist’s impression of Ultima Thule as a single body
Ul­ti­ma Thule as a sin­gle body
Image 4/5, Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker

Ultima Thule as a single body

Artist’s im­pres­sion of the trans-Nep­tu­ni­an ob­ject (486958) 2014 MU69, or Ul­ti­ma Thule, as a 30-kilo­me­tre co­her­ent body. Based on the light curves ob­tained from ground-based tele­scopes and the SOFIA air­borne ob­ser­va­to­ry, it is not en­tire­ly clear whether the tar­get ob­ject of NASA’s New Hori­zons space­craft for 1 Jan­uary 2019 has one or pos­si­bly two bod­ies, which are ei­ther to­tal­ly sep­a­rate or weak­ly joined.
Composition of New Horizons spacecraft
New Hori­zons
Image 5/5, Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

New Horizons

NASA's New Hori­zons space­craft is 0.7 me­tres tall, 2.1 me­tres long, 2.7 me­tres at its widest and weighs 478 kilo­grams. With an ini­tial speed of 16 kilo­me­tres per sec­ond, it was the fastest space­craft to leave Earth. The sci­ence pay­load has a mass of 31 kilo­grams that con­sume 30 watts. There are sev­en ex­per­i­ments: Al­ice: Ul­tra­vi­o­let imag­ing spec­trom­e­ter; anal­y­ses com­po­si­tion and struc­ture of Plu­to's at­mo­sphere and looks for at­mo­spheres around Charon and Kuiper Belt Ob­jects; LOR­RI Long Range Re­con­nais­sance Im­ager (20.8 cm Tele­scop­ic cam­era; ob­tains en­counter da­ta at long dis­tances); PEPSSI - Plu­to En­er­get­ic Par­ti­cle Spec­trom­e­ter Sci­ence In­ves­ti­ga­tion (En­er­get­ic par­ti­cle spec­trom­e­ter; in­ves­ti­gats the im­me­di­ate en­vi­ron­ment of the body); Ralph - Vis­i­ble and in­frared im­ager/spec­trom­e­ter (pro­vides colour, com­po­si­tion and ther­mal maps); REX - Ra­dio Sci­ence EX­per­i­ment (Mea­sures at­mo­spher­ic com­po­si­tion and tem­per­a­ture; pas­sive ra­diome­ter); SDC - Stu­dent Dust Counter (mea­sures the space dust); SWAP - So­lar Wind Around Plu­to (Mea­sures in­ter­ac­tion so­lar wind and mag­net­ic field).
  • On 1 January 2019, NASA’s New Horizons spacecraft will encounter the Kuiper Belt object nicknamed Ultima Thule.
  • The appearance and composition of this object are as yet unknown.
  • On board the spacecraft is the REX radio experiment funded by the DLR Space Administration.
  • Focus: exploration, space travel, planetary research

A very special encounter is set to take place in the Kuiper Belt, six and a half billion kilometres from Earth, right at the beginning of the New Year. NASA’s New Horizons spacecraft will visit object 2014 MU69, better known as Ultima Thule. At 06:33 CET, New Horizons will fly past Ultima Thule and use its measuring equipment to examine the object from a distance of just 3500 kilometres. New Horizons was launched to space approximately 13 years ago to investigate the dwarf planet Pluto. This is the first close-up exploration of a body beyond Pluto.

During the relatively brief Ultima Thule flyby phase, at a speed of 14 kilometres per second, seven scientific experiments will record images, spectra and physical measurement values. On board the spacecraft are two plasma instruments (PEPSSI and SWAP), one dust detector (Venetia), a radio experiment (REX) and three optical devices: the UV spectrometer Alice and the LORRI and Ralph high-resolution camera systems. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) Space Administration has supported Martin Pätzold’s participation in the REX experiment with funds provided by the German Federal Ministry for Economic Affairs and Energy (Bundesministerium für Wirtschaft und Energie; BMWi). REX will use radio waves to determine the thermal radiation and mass of Ultima Thule. It is the only instrument on board New Horizons that involves a contribution by German planetary researchers. During the flyby, Pätzold, Deputy Director of the Rhenish Institute for Environmental Research at the University of Cologne (EURAD), together with Michael Bird will perform two measuring procedures. REX will determine the surface temperature, mass and density of Ultima Thule. These values will provide an indication of the object’s internal composition and how it formed over four and a half billion years ago at the edge of the solar nebula.

First impression of the unknown object

In the run-up to the forthcoming rendezvous, planetary researchers managed to gain a ‘glimpse’ of Ultima Thule. In mid-August 2018, the Long Range Reconnaissance Imager (LORRI) spotted the relatively small object from a distance of 172 million kilometres as a tiny pinprick of light surrounded by a multitude of background stars. Although no surface structures were discernible from this distance, the position confirmed that New Horizons was on the right course to pass Ultima Thule as predicted on the morning of 1 January 2019 – a premiere for all solar system researchers. By the end of New Year Day, when the first images arrive, scientists are likely to know whether it is a round or oblong object, whether there are one or more objects, and what the surface is like. Researchers assume that Ultima Thule will be between 20 and 30 kilometres in size.

Ultima Thule – mystery at the edge of the Solar System

Ultima Thule was discovered on 26 June 2014 with the Hubble Space Telescope during a search for possible objects in the Kuiper Belt that appeared to be potential targets for NASA’s New Horizons spacecraft during the period following its flyby of the dwarf planet Pluto and its moon Charon. Ultima Thule orbits the Sun at distances of between 6.4 and almost seven billion kilometres.

The new object was initially labelled 1110113Y. In May 2015, when its orbit was determined with sufficient accuracy, it was given the official designation 2014 MU69. In March 2018, the New Horizons team selected the nickname, Ultima Thule, from the suggestions submitted. According to Celtic-German legend Ultima Thule represents a fictional, far-flung place in the far north, beyond the mythical island of Thule at the end of the world – a symbolic name for the exploration of the unknown. Ultima Thule will only be given its definitive name after the coming flyby, once it is clear what the object actually looks like.

In 2017 and 2018, the observations of stellar occultation by Ultima Thule indicated that the object may consist of two bodies orbiting each other. The DLR- and NASA- operated SOFIA airborne observatory played a decisive role in these observations. The upcoming observations will therefore be extremely exciting and enlightening for the planetary researchers.

The Kuiper Belt

The Kuiper Belt, sometimes also referred to as the Kuiper-Edgeworth Belt, is the cosmic home of Ultima Thule. It is a donut-shaped region of icy, sometimes extremely primitive, bodies ranging from a few kilometres to several thousand kilometres in diameter, such as the dwarf planets Pluto, Eris, Makemake and Haumea. The Kuiper Belt is immediately adjacent to Neptune and probably extends to a distance of 18 billion kilometres from the Sun. It is also the source of most short-period comets. Together, all the objects in the Kuiper Belt have only a fraction of the Earth’s mass.

  • Ultima Thule in numbers
    Discovery26 June 2014
    BDesignation(486958) 2014 MU69, Ultima Thule; 110113Y
    Minor planet number486958
    Orbital parameters:
    Aphelion distance6983 million kilometres
    Perihelion distance6355 million kilometres
    Semi-major axis6667 million kilometres
    Orbital inclination2.45 degrees
    Orbital eccentricity0.036
    Orbital period297 years
    Physical data
    Mean diameter25 kilometres (min.) - 45 kilometres (max.)
    Apparent magnitude26.8 mag
    Absolute magnitude11.1 mag
  • The New Horizons spacecraft
    New Horizons was launched from Cape Canaveral (Florida) on 19 January 2006 with the aim of flying to the dwarf planet Pluto and continuing through the Kuiper Belt. On 28 February 2007, this almost 500-kilogram spacecraft was boosted to its final cruising speed during a close-up flyby of the giant planet Jupiter. It then travelled away from the Sun at 83,600 kilometres per hour, flying past Pluto and Charon on 14 July 2015 at a speed of 50,400 kilometres per hour. The images revealed the entirely unexpected, astonishing surface structures of the dwarf planet Pluto and its moon Charon. Its forthcoming flyby of 2014 MU69 is also expected to deliver surprising results.
  • Andreas Schütz
    DLR Spokesper­son, Head of Me­dia Re­la­tions
    Ger­man Aerospace Cen­ter (DLR)
    Me­dia Re­la­tions
    Telephone: +49 2203 601-2474
    Fax: +49 2203 601-3249
    Linder Höhe
    51147 Cologne
  • Manfred Gaida
    Ger­man Aerospace Cen­ter (DLR)
    Space Ad­min­is­tra­tion
    Space Sci­ence
    Telephone: +49 228 447-417
    Fax: +49 228 447-745
    Königswinterer Straße 522-524
    53227 Bonn
  • Ulrich Köhler
    Pub­lic re­la­tions co­or­di­na­tor
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Telephone: +49 30 67055-215
    Fax: +49 30 67055-402
    Rutherfordstraße 2
    12489 Berlin
  • Martin Pätzold
    Rhen­ish In­sti­tute for En­vi­ron­men­tal Re­search at the Uni­ver­si­ty of Cologne (EU­RAD)
    Plan­e­tary Sci­ence
    Telephone: +49 170 2947-318


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