Friday, 22 February 2013

What Shall we take to Jupiter? [Updated!]

[Note that this post is now out of date, and full information on the payload for the JUICE mission can be obtained here:]

Yesterday the European Space Agency held a crucial decision meeting for the Jupiter Icy Moons Explorer (JUICE, to be launched to Jupiter in 2022), as part of the 140th meeting of the Science Program Committee (SPC) on February 21-22 2013.  Having spent most of 2012 preparing, writing and submitting a vast range of instrument proposals for JUICE, the Outer Planets community held its breath for the outcome.  Details remain rather hazy, and the decision-making process may never be entirely clear, involving so many national funding agencies vying to get as much as possible for their investments.  The proposals were reviewed by a Payload Review Committee (PRC), an Instrument Review Panel (IRP), and recommendations were sent by the Solar System and Exploration Working Group (SSEWG) and Space Science Advisory Committee (SSAC).   Now that the list has been published, the teams are probably being consolidated and potential new collaborations are being organised - they're almost always multi-national, so agreements have to be forged to ensure that the finance is in guaranteed so that development can get off to a racing start.  The same is true here in the UK, and things are likely to move rather quickly in the next few weeks.
Artists impression of JUICE,

Here's a collection of the details we know so far from the ESA and NASA press releases (I'll update these as I learn more):

JANUS: Jovis, Amorum ac Natorum Undique Scrutator, a camera system that certainly wins the prize for the most imaginative acronym.  The instrument, to be built by a consortium  (the principal investigator is P. Palumbo of Naples, Italy, along with R. Jaumann from DLR), is described in a DLR press release here. This camera is destined to map the clouds of Jupiter and the icy surfaces of the satellites in unprecedented detail.

MAJIS: Moons and Jupiter Imaging Spectrometer (led by Y. Langevin of Orsay, France, along with G. Piccioni of INAF, Italy) is a near-infrared imaging spectrometer to be built by an Italian-French consortium, with heritage from Cassini/VIMS, Venus Express/VIRTIS and Juno/JIRAM, among others.  This instrument will provide image cubes of a variety of jovian targets from the visible spectrum to the 5-µm region, and will feature a passive cooler.

UVS: UV Imaging Spectrograph (Randy Gladstone et al.) to be built by the Southwest Research Institute in San Antonio, Texas, and the only US-led instrument on the payload.  This spectrograph will target the surfaces and tenuous atmospheres of the Galilean satellites plus the upper atmosphere and aurorae of the giant planet.  The team is building on their UVS instrument currently on its way to Jupiter aboard the Juno mission.

SWI: Sub-millimetre Wave Instrument (P. Hartogh et al.) is a high-resolution heterodyne spectrometer operating at sub-mm wavelengths to sound fine emission lines from the jovian middle atmosphere and the tenuous sputtered atmospheres of the satellites.  Particularly exciting for Jupiter science, as this will directly measure wind speeds in the stratosphere for the first time, something that's never been done before.  To be built by a consortium based at the Max Planck Institute for Solar System Research (Germany).

GALA: Ganymede Laser Altimeter to map the surface topology of the Galilean satellites, particularly the prime target of the mission (Ganymede).  It will be built by a DLR-led consortium (H. Hussman, Germany) with Japanese collaborators.  GALA is described in a German press release, here, and will use laser pulses reflected from the surfaces to determine the precise heights of features on the moons.

RIME: Radar for Icy Moons Exploration (L. Bruzzone et al., Italy) is a radar sounder to penetrate the icy crusts of the Galilean satellites (to around 5-miles depth, depending on the precise structural composition), to be built by a consortium led by the Universita degli Studi di Trento in Italy.

J-MAG: Magnetometer for JUICE (M. Dougherty et al.) will be a British-built magnetometer led by the team at Imperial College, London and building on extensive heritage from the Cassini magnetometer.  A press release from Imperial describes some of the benefits to this UK institution of being selected to build hardware for JUICE, a prize that many of us had hoped for!  This version does not feature the scalar magnetometer originally proposed.

PEP: Particle Environment Package (S. Barabash et al., Sweden) will study the complex magnetic and charged-particle environment of the jovian system in situ, led by the Swedish Institute of Space Physics and the Swedish National Space Board, with contributions from the John Hopkins Applied Physics Laboratory (including JENI, the Jovian Energetic Neutrals and Ions instrument; and JoEE, an energetic electrons instrument).

RPWI: Radio & Plasma Wave Investigation, led by J.E. Wahlund of Sweden.  This is a reduced package consisting of Langmuir proves (two booms instead of four), a radio wave instrument and a medium frequency radio and density observer.

3GM: Radio science experiment, investigating the gravity & geophysics of Jupiter and Galilean Moons (led by L. Iess of Italy & Stevenson, via @jeanlucmargot).  Features a K-band antenna and ultra-stable oscillator.

PRIDE: Planetary Radio Interferometer & Doppler Experiment (note this does not include spacecraft hardware but will exploit VLBI – Very Large Base Interferometry – to conduct radio science).  This will be led by L. Gurvits of the Netherlands.

From my perspective as a Jupiter atmospheric specialist I'm particularly excited by UVS, MAJIS and SWI, but the most disappointing omission from this list is anything in the thermal infrared, leaving a gaping hole in the spectral coverage beyond 5 µm.  The thermal infrared is crucial if we want to map jovian meteorology (temperature, humidity, composition, clouds and winds), and identify sources of emission and activity on the Galilean satellites.  Its absence comes as a great disappointment for a large number in our community (particularly the 3-4 teams, including Oxford, that spent so much effort on designing such instruments!), but I'm sure we're not alone.  Its absence from the JUICE model payload (which evolved from the Jupiter Ganymede Orbiter) was the primary issue, despite thermal capabilities being a strong element of the original EJSM mission (NASA's Jupiter Europa Orbiter would have carried the thermal-IR mapper).   ESA still has a great mission here, even if it doesn't satisfy everyone, and there always has to be winners and losers in this sort of competition.  It'll be fascinating to watch as the spacecraft develops in the coming months and years.

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