Why should the European Space Agency join the U.S. mission to Uranus? We found the answer to this question.

Without international partnership, NASA's innovative mission may not have time to prepare for the optimal launch period.

This week, astronauts and planetary scientists meet at the Goddard Space Flight Center in Greenbelt, Maryland, to discuss NASA's new flagship mission - the Uranus orbiter and probe. This project is still under development. It involves sending a spacecraft to the orbit of Uranus and landing the probe in the atmosphere of the planet. The spaceship, which can be built and launched within a decade, will explore the nature of Uranus, including its unusual slope and magnetic field. It will also look for signs of hidden oceans and other potentially habitable environments on the planet's satellites.

Such a mission would be innovative - the first to enter the orbit of the ice giant planet. The ice giants Uranus and Neptune, which are believed to consist mainly of ice or perhaps consist of stones, have a more exotic chemical composition than Jupiter and Saturn, which, being "gas giants", consist mainly of hydrogen and helium1,2. Ice giants are also the most common type of exoplanet in the Milky Way. Given the characteristics that lie between the characteristics of gas giants, the Earth and other planets of the terrestrial group, it is extremely important to know how such systems were formed and developed.

That's why the orbiter and probe of Uranus received priority status in the Ten-Year Review of Planetary Science and Astrobiology of the United States 2022. And NASA intends to lead him. At the Goddard seminar, scientists will determine the scale of the mission and consider its design, technology and cost.

The mission has been discussed for some time, and it will be interesting to see how it will begin to take shape. But to make sure that it is successful and happens as quickly as possible and at minimal cost, we would like other people to participate in its development. As a first step, we call on the European Space Agency (ESA) to join the project, for example, by building an input probe - an opportunity that was provided for in the ten-year report and evaluated by ESA, but has not yet been agreed.

The window for such an agreement closes quickly. There is a great scientific benefit from reaching Uranus around 2050, when its position in orbit will mean that sunlight will fully illuminate all parts of the rotating planet and its rotating satellites. Given the typical 10-year development time of the flagship mission combined with the long flight time to Uranus (12-15 years, depending on the launch date and vehicle), this will require the start of work on the orbiter and the Uranus probe in the next few years.

NASA said it hoped to start funding the mission in 2026 or 2027. On the contrary, the current ESA budget program does not include any significant contribution to NASA's flagship mission in the coming years. This is a disturbing and, in our opinion, short-sighted position with long-term consequences. That's why.