It’s official—NASA is being sent to orbit the seventh planet Uranus and land on Saturn’s moon Enceladus.
It should arrive at these two distant targets in 2045 and 2050, respectively.
The National Academy of Sciences today finally published its Decadal Survey for Planetary Science and Astrobiology. It’s regarded as both a “wish list” for planetary scientists and a “to do” list for NASA.
It also includes the expected instruction to NASA to go get the samples of Martian rock currently being collected by the Perseverance rover, but this Mars Sample Return mission must not be allowed to “undermine the the long-term programmatic balance of the planetary portfolio.”
In other words, NASA is going to send a fully-equipped orbiter—with an atmospheric probe to dive beneath its clouds—to Uranus. The report says it should be NASA’s highest priority large mission for the next decade. That would put its cost in the region of $2 billion or more.
However, time is tight. The position of Jupiter means it would need to launch in 2032 to arrive at Uranus in 2045. The cloudy planet has not been visited since Voyager 2 made a brief flyby in 1986.
“Today we’re one step closer to seeing that ambitious orbital mission to an “ice giant” system that we’ve been working towards for so long,” said Professor Leigh Fletcher of the School of Physics and Astronomy at the University of Leicester, and a member of the Giant Planets panel for this survey.
Fletcher added that he felt “elation, relief, pride in the team that made this happen, and a little trepidation about the road ahead.”
It’s the second Decadal Survey in a row that a mission to the “ice giant” has been recommended. However, last time it Uranus was the third priority after the Perseverance rover already on Mars and Europa, which is on the cusp of launch. Now Uranus is top priority.
The report also says that the Enceladus Orbilander should be NASA’s second-highest priority large mission. This mission to orbit and land on Saturn’s tiny active moon—which has a an ocean underneath an icy crust—will investigate the plumes spilling into space from cracks in its icy surface. It could launch in 2038 and arrive in 2050.
The missions complement each other because scientists will be able to compare the moons of Uranus—some of them thought to be ocean worlds—with Enceladus.
Since the Mars Sample Return mission to go collect the Perseverance rover’s rock samples is already being planned by NASA it was thought that Uranus would likely miss out on a full flagship mission, instead being commuted to a cheaper flyby mission.
“This larger mission can deliver an atmospheric probe, as well as get into orbit at Uranus,” said Amy Simon, senior scientist for Planetary Atmospheres Research in the Solar System Exploration Division at the NASA Goddard Space Flight Center, and a member of the committee that prepared the report. “This allows for detailed study of the atmosphere, the gravity field and the magnetic field, as well as a several year tour of the moons.”
Planetary scientists that specialize in Uranus and the outer solar system are excited.
“It’s the culmination of 15 years of research, white papers, mission proposals, and international meetings,” said Fletcher. “The science case has only improved with time, particularly as Ice-Giant-sized worlds (or slightly smaller) appear commonplace in the pantheon of exoplanets … this decadal survey prioritisation is a wonderful leap forward for the outer solar system community.”
“This is excellent news—the Uranian system is fascinating and still poorly understood,” said Dr. Richard Cartwright, a planetary scientist and astronomer at NASA Ames Research Center and lead author of a white paper proposing a Uranus Orbiter. “Uranus’ moons are candidate ocean worlds that may have harbored life in the past.”
He says that a close-up exploration of Uranus’ five large moons—Miranda, Ariel, Umbriel, Titania and Oberon—with a full suite of scientific instruments on a flagship orbiter would help scientists determine whether they are like the the ancient ocean world of Ceres or the active ocean world Enceladus.
“A flagship mission to the Uranian system will provide an incredible opportunity to explore how ice giant systems, which are common in the galaxy, formed and evolved,” said Dr. Chloe Beddingfield, a planetary scientist and astronomer at NASA Ames Research Center, leading expert on Uranian moon geology and lead author of a white paper on the exploration of “ice giants” considered by the report. “This opportunity will allow us to address fundamental questions including how Uranus migrated through the solar system and whether the large moons are ocean worlds that may harbor life.”
Whether the report’s recommendations come to fruition depend largely on NASA’s budget—and that could spell trouble for the Enceladus Orbilander. Though it’s now ranked as NASA’s second-highest priority large mission costing around $2 billion, the report also says that if the budget doesn’t permit than NASA should instead consider an Enceladus Multiple Flyby mission, a pared-down, more affordable fly-by concept costing under $900 million.
“When we generate a Decadal Survey, we do not know what the budget will be over that ten years, and there are many pulls on the funding,” said Simon. “While we’d like two new Flagships to be started in the decade, that may or may not be affordable, so allowing Enceladus to remain in New Frontiers allows extra flexibility.”
Compiled by scientists at the cutting edge of their fields and specifically designed to be fair and honest, the Decadal Survey will set out the priorities for NASA for the next 10 years. Congress usually follows its recommendations.
Wishing you clear skies and wide eyes.