Astronomy:Uranus Orbiter and Probe

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Short description: Proposed NASA space mission to Uranus
Uranus Orbiter and Probe
Uranus Montage.jpg
Mosaic of images of Uranus and its 5 major moons from Voyager 2
Mission typeUranus orbiter
Mission durationCruise: 13.4 years
Science phase: 4.5 years[1]
Spacecraft properties
Launch mass7,235 kg (15,950 lb)[1]
Dry mass2,756 kg (6,076 lb)[1]
Payload mass60.5 kg (133 lb) plus 19.7 kg (43 lb) atmospheric probe[1]
DimensionsHeight: 7.1 m (23 ft)
Diameter: less than 5 m (16 ft)[1]
Power735 W (0.986 hp) from 3 Mod1 Next-Generation Radioisotope thermoelectric generators[1]
Start of mission
Launch datenot earlier than 2031[1][2]
RocketFalcon Heavy Expendable (proposed)[1]
Launch siteCape Canaveral AFS
Flyby of Earth (gravity assist)
Closest approachnot earlier than 2033
Distance450 km (280 mi)
Flyby of Jupiter (gravity assist)
Closest approachnot earlier than 2035
Distance370,000 km (230,000 mi)
Uranus orbiter
Orbital insertionnot earlier than 2044
Uranus atmospheric probe
Atmospheric entrynot earlier than 2045

The Uranus Orbiter and Probe is an orbiter mission concept to study Uranus and its moons.[1] The orbiter would also deploy an atmospheric probe to characterize Uranus's atmosphere. The concept is being developed as a potential large strategic science mission for NASA. The science phase would last 4.5 years and include multiple flybys of each of the major moons.

The mission concept was selected as the highest priority Flagship-class mission by the 2023–2032 Planetary Science Decadal Survey, ahead of the Enceladus Orbilander.[3][4] A Neptune orbiter mission concept, Neptune Odyssey, that would address many of the same scientific goals regarding ice giants was also considered, but for logistical and cost reasons a mission to Uranus was favored.

The original proposal targeted a launch in 2031 using a Falcon Heavy expendable launch vehicle with a gravity assist at Jupiter, allowing arrival at Uranus in 2044. In 2023, however, NASA announced that due to a shortfall in plutonium production a mid to late 2030s launch would be more likely.[2]


Voyager 2 is the only space probe to have visited the Uranus system, completing a flyby on January 24, 1986. The 2011-2022 Planetary Science Decadal Survey recommended a Flagship-class orbiter mission to an ice giant with priority behind what would become the Mars 2020 rover and the Europa Clipper.[5][6][7] Ice giants are now appreciated as a common type of exoplanet, precipitating the need for further study of ice giants in the Solar System.[8] The ice giants Uranus and Neptune were seen as unique yet equally compelling scientific targets, but a Uranus orbiter and atmospheric probe was given preference for logistical and cost reasons.[5][7] A Uranus orbiter would logically follow Flagship-class orbiter missions undertaken at Jupiter and Saturn (Galileo and Cassini, respectively).

In 2017, prior to the 2023–2032 survey, a committee narrowed twenty mission concepts to three scenarios for Uranus and a fourth for Neptune.[8][9][10][11] A mission to Neptune is viewed by some to be of greater scientific merit[12] because Triton, likely a captured Kuiper belt object and ocean world, is a more compelling astrobiology target than the moons of Uranus (though Ariel and Miranda in particular are possible ocean worlds).[13] There was also a study that considered a New Frontiers-level Uranus orbiter mission concept if a Flagship-class mission to Neptune were favored.[14] Nevertheless, again due to cost and logistical considerations including launch vehicle availability and available launch windows, the 2023–2032 Planetary Science Decadal Survey recommended the Uranus Orbiter and Probe instead of an analogous proposal for Neptune, Neptune Odyssey.[3][4]

Key science questions

The orbiter paired with an atmospheric probe will address a variety of scientific questions across all aspects of the Uranus system:[3]

Origin, interior, and atmosphere


Satellites and rings

  • What are the internal structures and rock-to-ice ratios of the large Uranian moons and which moons possess substantial internal heat sources or possible oceans?
  • How do the compositions and properties of the Uranian moons constrain their formation and evolution?
  • What geological history and processes do the surfaces record and how can they inform outer solar system impactor populations? What evidence of exogenic interactions do the surfaces display?
  • What are the compositions, origins and history of the Uranian rings and inner small moons, and what processes sculpted them into their current configuration?

Mission details

The atmospheric probe element of this mission would study the vertical distribution of cloud-forming molecules, thermal stratification, and wind speed as a function of depth. The 2010 mission design envisioned a probe of 127 kg (280 lb), less than half that of the Galileo atmospheric probe.[7] A later design study suggested results could be significantly enhanced by adding a second probe which could be as small as 30 kg (66 lb) in mass and about 0.5 m (20 in) in diameter.[15]

Orbiter instruments

The orbiter is proposed to carry the following instruments in the baseline concept, with additional instruments possible should they prove to be within mass, power, and cost limitations:[1]

Instrument Heritage Instrument Heritage Mission
Magnetometer MESSENGER Magnetometer MESSENGER
Narrow-Angle Camera Long Range Reconnaissance Imager (LORRI) New Horizons
Thermal Infrared Camera Diviner Lunar Reconnaissance Orbiter
Langmuir Probe and Waves MAVEN Langmuir Probe and Waves (LPW) MAVEN
Search coil magnetometer TRACERS search coil magnetometer (MSC) TRACERS
Fast imaging plasma spectrometer MESSENGER energetic particle and plasma spectrometer (EPPS) MESSENGER
Electrostatic analyzers Solar Wind Electrons Alphas and Protons (SWEAP) Parker Solar Probe
Energetic Charged Particle Detector EPI-Lo Parker Solar Probe
Visible-Near Infrared Imaging Spectrometer & Wide-angle camera L'Ralph Lucy
Radio Science Experiment UltraStable Oscillator none (part of spacecraft communications system)

Atmospheric probe instruments

The atmospheric probe is proposed to carry 4 scientific instruments as part of the baseline concept.[1]

Instrument Heritage Instrument Heritage Mission
Double focus mass spectrometer Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) Rosetta
Atmospheric Structure Instrument Huygens Atmospheric Structure Instrument (HASI) Huygens
Ortho-Para H2 Detector (in development)[8] none
Radio Science Experiment UltraStable Oscillator none (part of probe communications system)

See also

Uranus mission proposals


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Simon, Amy; Nimmo, Francis; Anderson, Richard C. (7 June 2021). "Journey to an Ice Giant System: Uranus Orbiter and Probe". Planetary Mission Concept for the 2023–2032 Planetary Science Decadal Survey (NASA). Retrieved 1 May 2022. 
  2. 2.0 2.1 Foust, Jeff (2023-05-03). "Plutonium availability constrains plans for future planetary missions" (in en-US). 
  3. 3.0 3.1 3.2 Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032 (Prepublication ed.). National Academies Press. 2022. pp. 800. doi:10.17226/26522. ISBN 978-0-309-47578-5. Retrieved 30 April 2022. 
  4. 4.0 4.1 Foust, Jeff (19 April 2022). "Planetary science decadal endorses Mars sample return, outer planets missions". SpaceNews. 
  5. 5.0 5.1 "Visions and Voyages for Planetary Science in the Decade 2013–2022". 
  6. Chris Gebhardt (20 November 2013). "New SLS mission options explored via new Large Upper Stage". NASASpaceFlight. 
  7. 7.0 7.1 7.2 Hubbard, William B. (3 June 2010). "SDO-12345: Ice Giants Decadal Study". National Academy of Sciences. 
  8. 8.0 8.1 8.2 "Ice Giants Pre-Decadal Survey Mission Report". 
  9. It’s time to explore Uranus and Neptune again — and here's how NASA could do it. Loren Grush, The Verge. 16 June 2017.
  10. Revisiting the ice giants: NASA study considers Uranus and Neptune missions. Jason Davis. The Planetary Society. 21 June 2017.
  11. NASA Completes Study of Future ‘Ice Giant’ Mission Concepts. NASA TV. 20 June 2017.
  12. Moore, Jeff; Spilker, Linda; Bowman, Jeff; Cable, Morgan; Edgington, Scott; Hendrix, Amanda; Hofstadter, Mark; Hurford, Terry et al. (2021). "Exploration Strategy for the Outer Planets 2023–2032: Goals and Priorities". Bulletin of the AAS 53 (4). doi:10.3847/25c2cfeb.1f297498. Bibcode2021BAAS...53d.371M. Retrieved 20 April 2021. 
  13. Hendrix, Amanda R.; Hurford, Terry A.; Barge, Laura M.; Bland, Michael T.; Bowman, Jeff S.; Brinckerhoff, William; Buratti, Bonnie J.; Cable, Morgan L. et al. (2019). "NASA Roadmap to Ocean Worlds". Astrobiology 19 (1): 1–27. doi:10.1089/ast.2018.1955. PMID 30346215. Bibcode2019AsBio..19....1H. 
  14. THE CASE FOR A URANUS ORBITER, Mark Hofstadter et al.
  15. K. M. Sayanagi, R. A. Dillman, A. A. Simon, et al. " Small Next-generation Atmospheric Probe (SNAP) Concept", LPI 2083 (2018): 2262. Long version of paper: Space Sci Rev, 216, 72 (June 10, 2020) Small Next-Generation Atmospheric Probe (SNAP) Concept to Enable Future Multi-Probe Missions: A Case Study for Uranus. Retrieved June 22, 2020.