Uranus orbiter and probe

The Uranus orbiter and probe, also known as Uranus Pathfinder by the European Space Agency, is a concept study by NASA and ESA on a mission to the planet Uranus. The mission would be a follow-up to Voyager 2's flyby in 1986. Two possibilities for transfer to Uranus have been considered: one, using an Atlas V 551 to launch the spacecraft into a trajectory that will make use of multiple gravity assists from Earth, Venus, and Jupiter, and the other using the Space Launch System to launch the spacecraft directly towards Uranus.

History
The Uranus orbiter and probe was evaluated in 2010 by the Applied Physics Laboratory, recommended to NASA in 2011 by its Planetary Science Decadal Survey 2013–2022, as well as evaluated in 2011 and proposed in 2015 to the ESA as the ODINUS mission, which includes an identical twin spacecraft to orbit Neptune. A mission study was conducted which also considered a Neptune orbiter, however, for feasibility reasons Neptune was dropped in favor of Uranus. Two white papers on Uranus exploration were also submitted to the Decadal Survey. The survey listed the Uranus orbiter and probe as the third priority for a Flagship mission class after the MAX-C rover and the Jupiter Europa Orbiter. Both of these missions have since been transformed into other, similar missions, once again leaving the Uranus orbiter as the third priority after the Mars 2020 rover and Europa Multiple-Flyby Mission.

Launch vehicles


The launch vehicles considered for the probe have changed over the years, with the Atlas V 521, Ariane 5, and Soyuz-2 rockets all being considered. Currently, the plan is for the Uranus orbiter to be launched on either the Atlas V 551 or Space Launch System Block IB.

Objectives
In the baseline concept, the Uranus orbiter could be an ESA-NASA bilateral mission and launching on an Atlas V 551 on a Venus-Earth-Earth-Jupiter gravity-assisted interplanetary transfer to Uranus with a cruise phase lasting 12.8 years and arrival in 2037. The Atlas V-launched version would also have a three-NEXT solar electric propulsion tug that is detached after 2 years of the cruise to Uranus. It could also be launched on a Space Launch System Block IB on a direct interplanetary transfer to Uranus. If selected and launched, it would become the first spacecraft to enter into orbit around Uranus.

Power
The Uranus orbiter was planned to be powered by Advanced Stirling radioisotope generators, but has since switched to being powered by conventional Multi-Mission Radioisotope Thermoelectric Generators upon the ASRG's cancellation. The MMRTGs expected to be used on the Uranus orbiter will each produce about 110 watts of power at the start of the mission.

Scientific payload
The scientific payload includes a narrow angle camera, visible/near-IR imaging spectrometer, thermal IR bolometer, radio science, magnetometer, radio and plasma wave detector, and a plasma detector. It may also use leftover hardware from previous NASA and ESA interplanetary probe missions, namely New Horizons's body and a Multi-Mission Radioisotope Thermoelectric Generator similar to Curiosity and the Mars 2020 rover's.

The following six instruments are considered essential to the mission: The following two additional instruments are strongly desired by the mission proposers:
 * Camera (Wide and Narrow Angle) - Designed to image the planet at the same level of detail as missions to the two gas giants have provided
 * VIS-NIR Image Spectrometer
 * Magnetometer - To study the magnetic field of Uranus
 * Mass Spectrometer (Ions and Neutrals, INMS)
 * Doppler Spectro-Imager - To take seismic measurements
 * Microwave Radiometer
 * Energetic Neutral Atoms Detector - To complement the measurements of the INMS
 * High-sensitivity Accelerometer - To be used in the atmospheric descent phase of the probe