MUSE (Mission to Uranus for Science and Exploration) is a European proposal for a dedicated mission to the planet Uranus to study its atmosphere, interior, moons, rings, and magnetosphere. 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.

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. The mission addresses the themes of the ESA Cosmic Vision 2015–2025. This was designed as an L-Class flagship level mission; however, it is constrained by the need for RTGs. MUSE was also analyzed in the US as an Enhanced New Frontiers class mission in 2014.

Orbiter

The orbiter science phase would consist of 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.

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.

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. The propulsion system for the Earth-Uranus transfer would be chemical: Monomethylhydrazine and Mixed Oxides of Nitrogen (MMH/MON) propellant combination is used.

Atmospheric probe

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. 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 pressure.

Proposed instruments The total mass budget for scientific instruments is ; if all of proposed instruments are selected, they would sum a total payload mass of . In the table below, a green background denotes instruments to go on the entry probe; the rest are for the orbiter. Instrument Description Dimension, range, resolution Heritage VINIRSVisible and Near Infrared SpectrometerElectromagnetic radiation:λ: 0.25–5 μm96 bands (1.8 nm per band) Dawn IRSThermal Infrared Spectrometer Electromagnetic radiation:λ: 7.16–16.67 μm1×10 array of 0.273 mrad squares Cassini UVIS Ultraviolet Imaging Spectrograph Electromagnetic radiation:λ: 55.8–190 nm Cassini RPW Radio and Plasma Wave Instrument Electromagnetic radiation and plasma waves:1 Hz–16 MHz (various channels) Cassini MAGFluxgate Magnetometer Magnetic fields:0–20000 nTDual 3-axis<1 nT accuracy Juno MAGSwarm TELFA and ELF Antenna Electromagnetic radiation:Schumann resonances C/NOFS antennas ICI Ion Composition Instrument Positive ions:25 eV–40 keV (dE/E = 0.07) Rosetta ICA IES Ion and Electron SensorElectrons and ions:1 eV/e–22 keV/e (dE/E = 0.04) Rosetta IES EPD Energetic Particle DetectorParticles (free solar wind and those contained in Van Allen radiation belts):Protons: 15 keV–3 MeVAlphas: 25 keV–3 MeVCNO: 60 keV–30 MeVElectrons: 15 keV–1 MeV New Horizons PEPSSI NAC Narrow Angle Camera Electromagnetic radiation:350–1050 nm6 μrad/pixel Cassini WAC Wide Angle Camera Electromagnetic radiation:350–1050 nm60 μrad/pixel Cassini ISS RSE Radio Science ExperimentAllan variance of radio oscillators:T = 100 s of 1×10−13Transponders operating at S, X and Ka band Cassini MWRMicrowave Radiometer Electromagnetic radiation:0.6–22 GHz Gain up to 80 dBDetermines temperature profile down to 200 bar atmospheric pressure Juno MWR DC Dust AnalyzerInterplanetary dust particles:10−15–10−9 kg1–10 μm (radius) Cassini New Horizons SDC DWE Doppler Wind ExperimentVelocity of wind:Resolution of 1 m/sDetermines wind profile down to 20 bar atmospheric pressure Huygens AP3 Atmospheric Physical Properties Package Temperature, pressure and density profiles:Depth: 0–20 bar Huygens GCMSGas Chromatograph and Mass SpectrometerAtoms and compounds:Heavy elements, noble gases, key isotopic ratios (H2/He, D/H, PH3, CO) and disequilibrium species Huygens AS & NEP Aerosol Sampling System and Nephelometer Atmospheric particle size:0.2–20 μm (radius)Works at concentrations up to 1 cm³ Huygens 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.

See also Atmosphere of Uranus Exploration of Uranus Moons of Uranus Uranus mission proposals ODINUS NASA Uranus orbiter and probe Oceanus Uranus Pathfinder

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