MUSE (spacecraft)

MUSE (Mission to Uranus for Science and Exploration[3]) is a European proposal for a dedicated mission to the planet Uranus to study its atmosphere, interior, moons, rings, and magnetosphere.[2][4] It is proposed to be launched with an Ariane 6 in 2026, travel for 16.5 years to reach Uranus in 2044, and would operate until 2050.[4]

Mission to Uranus for Science and Exploration (MUSE)
Mission typeReconnaissance, atmospheric probe
OperatorEuropean Space Agency[1]
Spacecraft properties
SpacecraftMUSE
Launch mass4,219 kg (9,301 lb)[2]
Dry mass2,073 kg (4,570 lb)
Payload massOrbiter: 252 kg (556 lb)
Probe: 150 kg (330 lb)[3]
Dimensionscylindrical bus 3 m × 1.6 m[3]
Power436 W
Li-ion batteries: 3,376 Wh
Generator: four ASRGs
Start of mission
Launch dateSeptember 2026 (proposed)
November 2029 (if delayed)
RocketAriane 6 (proposed)
Uranus orbiter
Orbital insertion2044 (proposed)
2049 (if delayed)
Orbits36
Uranus atmospheric probe
Spacecraft componentEntry probe
Atmospheric entry2044 (proposed)
 

The European Space Operations Centre would monitor and control the mission, as well as generate and provide the raw data sets. In 2012, the cost was estimated at €1.8 billion.[2] The mission addresses the themes of the ESA Cosmic Vision 2015-2025.[2] This was designed as an L-Class flagship level mission; however, it is constrained by the need for RTGs.[5] MUSE was also analyzed in the US as an Enhanced New Frontiers class mission in 2014.[3]

Orbiter
Uranus and its six largest moons compared at their proper relative sizes and relative positions. From left to right: Puck, Miranda, Ariel, Umbriel, Titania, and Oberon

The orbiter science phase would consist on the Uranus Science Orbit (USO) phase of approximately 2 years in a highly elliptic polar orbit to provide best gravimetry data, during which 36 Uranus orbits are performed.[4]

Subsequently, the orbiter will continue to the Moon Tour (MT) phase, which would last three years. During this phase, the periapsis would be raised, facilitating nine flybys of each of Uranus' five major moons: Miranda, Ariel, Umbriel, Titania, and Oberon.[2][4]

Because of the long distance from the Sun (20 AU on average), the orbiter would not be able to use solar panels, requiring instead four Advanced Stirling Radioisotope Generators (ASRGs) to be developed by ESA.[2][4] The propulsion system for the Earth-Uranus transfer would be chemical: Monomethylhydrazine and Mixed Oxides of Nitrogen (MMH/MON) propellant combination is used.[4]

Atmospheric probe
See also: Atmosphere of Uranus

Understanding why Uranus emits such a small amount of heat can only be done in the context of thermodynamic modeling of the atmosphere (density, pressure, and temperature). Therefore, the atmosphere needs to be characterized from both a composition and a thermodynamic point of view.[2] The chemical information to retrieve is the elemental concentrations, especially of disequilibrium species, isotopic ratios and noble gases, in combination with information regarding the distribution of aerosol particles with depth.

Twenty days before entry, the atmospheric probe would separate from the spacecraft and enter the outer atmosphere of Uranus at an altitude of 700 km at 21.8 km/s. It would descend by free fall and perform atmospheric measurements for about 90 minutes down to a maximum of 100 bars (1,500 psi) pressure.[2][4]

Proposed instruments

The total mass budget for scientific instruments is 150 kg (330 lb); if all of proposed instruments are selected, they would sum a total payload mass of 108.4 kg (239 lb). In the table below, a green background denotes instruments to go on the entry probe; the rest are for the orbiter.[4]

Instrument Description Dimension, range, resolution Heritage
VINIRS Visible and Near Infrared Spectrometer Electromagnetic radiation:
λ: 0.25–5 μm
96 bands (1.8 nm per band)		 Dawn VIR
IRS Thermal Infrared Spectrometer Electromagnetic radiation:
λ: 7.16–16.67 μm
1×10 array of 0.273 mrad squares		 Cassini CIRS
UVIS Ultraviolet Imaging Spectrograph Electromagnetic radiation:
λ: 55.8–190 nm		 Cassini UVIS
RPW Radio and Plasma Wave Instrument Electromagnetic radiation and plasma waves:
1 Hz–16 MHz (various channels)		 Cassini RPWS
MAG Fluxgate Magnetometer Magnetic fields:
0–20000 nT
Dual 3-axis
<1 nT accuracy		 Juno MAG
Swarm VFM
TELFA TLF and ELF Antenna Electromagnetic radiation:
Schumann resonances		 C/NOFS VEFI antennas
ICI Ion Composition Instrument Positive ions:
25 eV–40 keV (dE/E = 0.07)		 Rosetta ICA
EIS Electron and Ion Sensor Electrons and ions:
1 eV/e–22 keV/e (dE/E = 0.04)		 Rosetta IES
EPD Energetic Particle Detector Particles (free solar wind and those contained in Van Allen radiation belts):
Protons: 15 keV–3 MeV
Alphas: 25 keV–3 MeV
CNO: 60 keV–30 MeV
Electrons: 15 keV–1 MeV		 New Horizons PEPSSI
NAC Narrow Angle Camera Electromagnetic radiation:
350–1050 nm
6 μrad/pixel		 Cassini ISS
WAC Wide Angle Camera Electromagnetic radiation:
350–1050 nm
60 μrad/pixel		 Cassini ISS
RSE Radio Science Experiment Allan variance of radio oscillators:
T = 100 s of 1×10−13
Transponders operating at S, X and Ka band		 Cassini RSS
MWR Microwave Radiometer Electromagnetic radiation:
0.6–22 GHz
Gain up to 80 dB
Determines temperature profile down to 200 bar atmospheric pressure		 Juno MWR
DC Dust Analyzer Interplanetary dust particles:
10−15–10−9 kg
1–10 μm (radius)		 Cassini CDA
New Horizons SDC
DWE Doppler Wind Experiment Velocity of wind:
Resolution of 1 m/s
Determines wind profile down to 20 bar atmospheric pressure		 Huygens DWE
AP3 Atmospheric Physical Properties Package Temperature, pressure and density profiles:
Depth: 0–20 bar		 Huygens HASI
GCMS Gas Chromatograph and Mass Spectrometer Atoms and compounds:
Heavy elements, noble gases, key isotopic ratios (H2/He, D/H, PH3, CO) and disequilibrium species		 Huygens GCMS
AS & NEP Aerosol Sampling System and Nephelometer Atmospheric particle size:
0.2–20 μm (radius)
Works at concentrations up to 1 cm³		 Huygens ACP
Galileo GPNE

MUSE as new New Frontiers mission

In 2014 a paper was released considering MUSE under the constraints of an enhanced New Frontiers mission. This included a cost cap of US$1.5 billion, and one of the big differences was the use of an Atlas V 551 rocket.[3]

See also
Uranus mission proposals

References
  1. Kane, Van (25 September 2013). "Europe Will Select Its Next Major Science Mission in November". The Planetary Society. Retrieved 2016-03-31.
  2. Costa, M.; Bocanegra, T.; Bracken, C.; et al. (June 2012). Mission to the Uranus System: MUSE. Unveiling the evolution and formation of icy giants (PDF). 2012 Post Alpbach Summer School. Madrid, Spain.
  3. Saikia, S. J.; Daubar, I. J.; et al. (2014). Na new frontiers mission concept for the exploration of Uranus (PDF). 45th Lunar and Planetary Science Conference.
  4. Bocanegra-Bahamón, Tatiana (2015). "MUSE Mission to the Uranian System: Unveiling the evolution and formation of ice giants" (PDF). Advances in Space Research. 55 (9): 2190–2216. Bibcode:2015AdSpR..55.2190B. doi:10.1016/j.asr.2015.01.037.
  5. Bocanegra-Bahamón, Tatiana; Bracken, Colm; Costa Sitjà, Marc; Dirkx, Dominic; Gerth, Ingo; Konstantinidis, Kostas; Labrianidis, Christos; Laneuville, Matthieu; Luntzer, Armin (2015-05-01). "MUSE - Mission to the Uranian system: Unveiling the evolution and formation of ice giants". Advances in Space Research. 55 (9): 2190–2216. Bibcode:2015AdSpR..55.2190B. doi:10.1016/j.asr.2015.01.037. ISSN 0273-1177.
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