| OCEANUS (Origins and Composition of the Exoplanet Analog Uranus System) | |||||||
| Mission Type: | Reconnaissance | ||||||
| Operator: | NASA/JPL | ||||||
| Mission Duration: | ≥1.5 years | ||||||
| Launch Mass: | ≈3,939 kg | ||||||
| Bol Mass: | ≈2,000 kg | ||||||
| Dry Mass: | ≈1,110 kg | ||||||
| Power: | 290 W | ||||||
| Launch Date: | 2030 (suggested) | ||||||
| Launch Rocket: | Atlas V 511 or SLS | ||||||
| Interplanetary: |
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OCEANUS (Origins and Composition of the Exoplanet Analog Uranus System) is a mission concept conceived in 2016 and presented in 2017 as a potential future contestant as a New Frontiers program mission to the planet Uranus.[1] [2] The concept was developed by the Astronautical engineering students of Purdue University during the 2017 NASA/JPL Planetary Science Summer School. OCEANUS is an orbiter, which would enable a detailed study of the structure of the planet's magnetosphere and interior structure that would not be possible with a flyby mission.[1]
Because of the required technology development and planetary orbital dynamics, the concept suggests a launch in August 2030 on an Atlas V 511 rocket and entering Uranus' orbit in 2041.[2]
Ice giant sized planets are the most common type of planet according to Kepler data. The little data available on Uranus, an ice giant planet, come from ground-based observations and the single flyby of the Voyager 2 spacecraft, so its exact composition and structure are essentially unknown, as are its internal heat flux, and the causes of its unique magnetic fields and extreme axial tilt or obliquity,[2] making it a compelling target for exploration according to the Planetary Science Decadal Survey.[1] [3] The primary science objectives of OCEANUS are to study Uranus' interior structure, magnetosphere, and the Uranian atmosphere.[2]
The required mission budget is estimated at $1.2 billion.[2] The mission concept has not been formally proposed to NASA's New Frontiers program for assessment and funding. The mission is named after Oceanus, the Greek god of the ocean; he was son of the Greek god Uranus.[4]
Since Uranus is extremely distant from the Sun (20 AU), and relying in solar power is not possible past Jupiter, the orbiter is proposed to be powered by three multi-mission radioisotope thermoelectric generators (MMRTG),[1] [2] a type of radioisotope thermoelectric generator. There is enough plutonium available to NASA to fuel only three more MMRTG like the one used by the Curiosity rover.[5] [6] One is already committed to the Mars 2020 rover.[5] The other two have not been assigned to any specific mission or program, [6] and could be available by late 2021.[5] A second possible option for powering the spacecraft other than a plutonium powered RTG would be a small nuclear reactor powered by uranium, such as the Kilopower system in development as of 2019.
The trajectory to Uranus would require a Jupiter gravity assist, but such alignments are calculated to be rare in the 2020s and 2030s, so the launch windows will be scant and narrow.[1] To overcome this problem two Venus gravity assists (in November 2032 and August 2034) and one Earth gravity assist (October 2034) are planned along with the use of solar-electric propulsion within 1.5 AU.[2] The science phase would take place from a highly elliptical orbit and perform a minimum of 14 orbits.[2] If launching in 2030, reaching Uranus would occur 11 years later, in 2041,[2] and it would use two bipropellant engines for orbital insertion.[2]
Alternatively, the SLS rocket could be used for a shorter cruise time,[7] but it would result in a faster approach velocity, making orbit insertion more challenging, especially since the density of Uranus' atmosphere is unknown to plan for safe aerobraking.[6]
The 12.5 kg scientific payload would include instruments for a detailed study of the magnetic fields and to determine Uranus' global gravity field: [1] [2]