China's nuclear mission to Neptune-Rahab

In addition to its intriguing internal structure (and strange phenomena like diamond rain!), scientists believe that Neptune played an important role in the formation of the solar system and that its composition includes large amounts of gas that was part of the prestellar nebula from which the solar system formed

Several bold and advanced space missions are proposed for the decade ahead, as is clear from the Planetary Decade Survey for 2023-32, among them a nuclear-powered Chinese mission to Neptune to explore the giant ice planet, its largest moon (Triton), and other satellites and rings.

In fact, this mission was the subject of research conducted by researchers from the China National Space Agency, the Chinese Academy of Sciences, the China Atomic Energy Authority, the China Academy of Space Technology, and many universities and institutes. The lead author of the paper describing their findings is Guobin Yu.

Ice giants like Neptune are a potential treasure trove of scientific discoveries, as the authors describe in the paper. In addition to its intriguing internal structure (and strange phenomena like diamond rain!), scientists believe that Neptune played an important role in the formation of the solar system. In one sentence, its composition includes large amounts of gas that was part of the prestellar nebula from which the solar system formed. At the same time, Neptune's position indicates the region where the planets formed before moving into their current orbits.

There are also mysteries surrounding Neptune's largest moon, Triton, which astronomers think is a planetoid ejected from the solar system and captured by Neptune's gravity. It is also thought that the arrival of this planetoid caused an upheaval in Neptune's natural satellites, causing them to break up and merge to form new moons. It is also assumed that Triton will eventually break up and form a halo around Neptune or collide with it. The study of Neptune, its satellites and the dynamics of the orbits could provide answers to how the solar system was formed and developed, with implications regarding the beginning of life.

Unfortunately, due to the difficulties of sending missions into deep space (which include launch windows, a power source and communications), only one mission has visited Neptune so far. It was the Voyager 2 probe, which passed by the system in 1989 and obtained most of what we know about this ice giant and its system. In addition, the nature of Voyager 2's science instruments imposed certain limitations on the amount of data it could obtain. In recent years, NASA has proposed sending a mission to explore Neptune and Triton (the Trident spacecraft).

However, this mission was not prioritized in the Planetary Science and Astrobiology Decadal Survey 2023-2032 and instead it was decided to launch the Uranus Orbiter (UOP) spacecraft to Uranus-Uron. But given the potential and the vast improvements made to the spacecraft's instruments since Neptune's last visit, Yu and his colleagues recommend that the time has come for another mission to Neptune.

When examining the problem of the spacecraft's power source, Yu and his colleagues needed a source that could safely and reliably provide electricity for at least 15 years. They determined that a thermoelectric radioisotope generator with an energy capacity of 10 kilowatts would be sufficient. This nuclear battery, which is similar to what is used by the Coriosote rover and the Perspirance vehicle on Mars, converts heat energy from the decay of radioactive material into electricity.

They also recommend that the power source system be based on a scheme of using one heat pipe, one set of thermoelectric conversion units and one set of heat collectors as one power source unit. It is then possible to simultaneously connect multiple power source units, where the heat energy is converted to electrical energy, to supply power to the spacecraft.

This system, they write, will be able to provide the mission with "eight years of operation at full power of 10 kilowatts and another seven years of operation at low power of 2 kilowatts, and this will effectively ensure the reliability and safety of the system for the duration of the mission."

More of the topic in Hayadan:

• New Moon to Neptune-Rhab
• Neptune "kidnapped" Triton from another planet