MUSE (spacecraft)


MUSE 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 on the Uranus Science Orbit 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 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, the orbiter would not be able to use solar panels, requiring instead four Advanced Stirling Radioisotope Generators to be developed by ESA. The propulsion system for the Earth-Uranus transfer would be chemical: Monomethylhydrazine and Mixed Oxides of Nitrogen 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. 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.
InstrumentDescriptionDimension, range, resolutionHeritage
VINIRSVisible and Near Infrared SpectrometerElectromagnetic radiation:
λ: 0.25–5 μm
96 bands 		Dawn
IRSThermal Infrared SpectrometerElectromagnetic radiation:
λ: 7.16–16.67 μm
1×10 array of 0.273 mrad squares		Cassini
UVISUltraviolet Imaging SpectrographElectromagnetic radiation:
λ: 55.8–190 nm		Cassini
RPWRadio and Plasma Wave InstrumentElectromagnetic radiation and plasma waves:
1 Hz–16 MHz 		Cassini
MAGFluxgate MagnetometerMagnetic fields:
0–20000 nT
Dual 3-axis
<1 nT accuracy		Juno MAG
Swarm
TELFA and ELF AntennaElectromagnetic radiation:
Schumann resonances		C/NOFS antennas
ICIIon Composition InstrumentPositive ions:
25 eV–40 keV 		Rosetta ICA
EISElectron and Ion SensorElectrons and ions:
1 eV/e–22 keV/e 		Rosetta IES
EPDEnergetic Particle DetectorParticles :
Protons: 15 keV–3 MeV
Alphas: 25 keV–3 MeV
CNO: 60 keV–30 MeV
Electrons: 15 keV–1 MeV		New Horizons PEPSSI
NACNarrow Angle CameraElectromagnetic radiation:
350–1050 nm
6 μrad/pixel		Cassini
WACWide Angle CameraElectromagnetic radiation:
350–1050 nm
60 μrad/pixel		Cassini ISS
RSERadio Science ExperimentAllan variance of radio oscillators:
T = 100 s of 1×10−13
Transponders operating at S, X and Ka band		Cassini
MWRMicrowave RadiometerElectromagnetic radiation:
0.6–22 GHz
Gain up to 80 dB
Determines temperature profile down to 200 bar atmospheric pressure		Juno MWR
DCDust AnalyzerInterplanetary dust particles:
10−15–10−9 kg
1–10 μm 		Cassini
New Horizons SDC
DWEDoppler Wind ExperimentVelocity of wind:
Resolution of 1 m/s
Determines wind profile down to 20 bar atmospheric pressure		Huygens
AP3Atmospheric Physical Properties PackageTemperature, pressure and density profiles:
Depth: 0–20 bar		Huygens
GCMSGas Chromatograph and Mass SpectrometerAtoms and compounds:
Heavy elements, noble gases, key isotopic ratios and disequilibrium species		Huygens
AS & NEPAerosol Sampling System and NephelometerAtmospheric particle size:
0.2–20 μm
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.