Scientists reveal the best opportunities for finding life on other planets

We should go and look for alien life on Uranus and Enceladus, scientists have urged.

Nasa should prioritise missions to the distant planet and moon of Saturn, say researchers in a new planetary science and astrobiology decadal survey published by the US National Academies of Sciences, Engineering, and Medicine.

The survey report recommends priorities for the research community over the next 10 years, including the best opportunities in the search for alien life. It draws on input from scientists through panels, papers, speakers and more.

The report titled “Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032,” argues Nasa’s highest priority flagship class planetary science mission over the next decade should be the Uranus Orbiter and Probe. The robotic mission would flyby the Uranus system and deliver a probe into the ringed gas giant’s atmosphere, the second mission ever to visit the world and the first since Voyager 2 flew by Uranus in 1986.

A mission of second-highest priority should head to the Saturn system to search for signs of alien life, according to the recommendations in the report. The Enceladus Orbilander would orbit Saturn’s Moon Enceladus and later land on its icy surface to spend two years studying material believed to have erupted from a liquid ocean beneath the moon’s icy crust.

The decadal is published every 10 years after a study by a panel of planetary scientists and astrobiologists looking at outstanding questions, resources, and strategic goals for the next 10 years. A similar decadal survey conducted by astronomers and published in November made recommendations about space and ground telescope research and development priorities over the next decade.

“This recommended portfolio of missions, high-priority research activities, and technology development will produce transformative advances in human knowledge and understanding about the origin and evolution of the solar system, and of life and the habitability of other bodies beyond Earth,” Robin Canup, the co-chair of the National Academies’ steering committee for the survey, said in a statement.

The previous planetary science decadal survey looking from 2013 forward through 2022 also recommended a mission to Uranus, but placed the mission at slightly lower priority than missions to Mars to collect and return soil samples to Earth, and a mission to visit Jupiter’s icy moon Europa. Both of the latter missions have become reality, with Nasa’s Perseverance rover drilling and storing samples on the Red Planet for the past year and the space agency’s Europa Clipper mission expected to launch in the fall of 2024.

The survey report published Tuesday does not ignore missions already launched, and notes that the Mars sample return mission should be of the highest scientific priority for Nasa, but with previously recommended missions already underway, returned to Uranus as a key objective for the next decade.

“Uranus is one of the most intriguing bodies in the solar system,” the survey reads. Its low internal energy but active atmosphere, along with a complex magnetic field, present major puzzles, per the report, while Uranus’s five major moons are potential ocean worlds much like Enceladus.

A Uranus Orbiter and Probe could launch using existing rocket technology as early as 2031, according to the survey report.

If Uranus’s moons are partly of interest because of their similarity to Saturn’s moon Enceladus, Enceladus is also a priority due to its similarities to Jupiter’s moon Europa. Both the Jovian and Saturnian moons are believed to harbor global liquid water oceans beneath their icy shells, and where liquid water may come into contact with rocky materials — and sources of geothermic heart from the moons’ cores — there could be the possibility of life.

Enceladus is particularly tantalizing to planetary scientists and astrobiologists because of plumes of water and/or gas and other materials seen spewing out into space from the moon’s interior during Nasa’s Cassini mission to the Saturn system. Such plumes could allow an orbilander mission to sample with the interior waters of Enceladus without having to drill though many kilometers of ice.

“Study of the plume material allows direct study of the ocean’s habitability, addressing a fundamental question,” the survey report reads, “is there life beyond Earth and if not, why not?”

The decadal survey addressing many more aspects of planetary science than just flagship missions, and also makes recommendations for smaller missions and research and development and infrastructure priorities over the next decade. Smaller missions recommended include an orbiter for Saturn’s moon Titan, a mission to Venus, and a sample return mission to the large asteroid Ceres in the main asteroid belt, for example.

The report also recommends Nasa invest more in planetary defense and develop and launch the Near Earth Object Surveyor mission, a space-based near-infrared observatory designed to detect potentially hazardous space rocks. Nasa has already completed a survey of more than 90% of potentially hazardous asteroids one kilometer ore more in diameter, and the space agency is currently working on cataloging potentially hazardous asteroids 140-meters in diameter or greater.

After launching a Near Earth Object Surveyor and completing its ongoing Double Asteroid Redirection Test (DART), the report recommends Nasa launch a rapid mission to newly discovered near Earth asteroid of 50 to 100 meters in diameter, “which is representative of the population of objects posing the highest probability of a destructive Earth impact,” according to a National Academies’ media statement about the decadal survey. Such a mission should assess the capabilities and limitations of flyby characterization methods to better prepare for a short-warning time [near Earth object) threat.”