A key committee of scientists has recommended that a flagship mission to Uranus be NASA’s highest-priority planetary science mission for the next decade.
Uranus it is a largely uncharted world; NASA’s only visit to the seventh planet was traveler 2Brief flyby on January 24, 1986, during which scientists discovered the planet’s rings and some additional moons.
The new recommendation comes from a process called the decadal survey, which is led by the National Academy of Sciences and offers NASA guidance for prioritizing science goals. that committee new report, published Tuesday (April 19), highlighted a mission concept called the Uranus Orbiter and Probe (UOP) for a multi-year orbital tour during which it should jettison an atmospheric probe. The committee called Uranus “one of the most intriguing bodies in the solar system” and pointed to launch opportunities in the early 2030s for a 12- to 13-year cruise to begin observations.
“When I first read that recommendation, I was afraid I might be dreaming!” Leigh Fletcher, a planetary scientist at the University of Leicester in the UK who was involved in the decadal survey process, told Space.com. “This decadal survey prioritization is a wonderful step forward for the outer solar system community.”
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A new flagship mission
For now, the Uranus Orbiter and Probe is not a specific mission, but a concept. The previous decennial survey, released in 2011, listed the idea as the third priority for a flagship mission, following ideas that matured into the perseverance vehicle now at work on Mars and the Clippers Europe The mission will launch in 2024.
Other reports have also emphasized the need for a fully equipped Uranus orbiter, complete with atmospheric probe to dive below the planet’s clouds. The pre-Decadal Survey Ice Giants study report included a variety of options for the Uranus and Neptune spacecraft, while a white paper called Exploration of the Giant Ice Systems also presented to the decennial study committee discusses the need for an orbiter/probe combination in a flagship-class mission.
So perhaps it’s no surprise that Uranus is now at the top of the agenda.
The lead author of the latest report on ice giants is Chloe Beddingfield, a planetary scientist and astronomer at NASA Ames Research Center in California, who believes extensive planetary and even exoplanet science should be done on Uranus. “A flagship mission to the Uranus system will provide an incredible opportunity to explore how ice giant systems, which are common in the galaxy, formed and evolved,” she told Space.com. That crossover with exoplanet science may have helped the Uranus cause.
The Uranus Orbiter and Probe mission will cost about $4.2 billion, according to initial estimates. Some scientists thought that a more affordable concept costing less than $900 million would be the only way to get a Uranus mission off the ground. (NASA calls the missions in this budget “New Frontiers” missions; examples include the June mission to Jupiter and the OSIRIS-REx mission to search for an asteroid sample.)
“A New-Frontiers-level mission could only scratch the surface, unable to explore the entire ice giant system in all its rich diversity,” Fletcher said.
“To fully explore Uranus we need to be in orbit, exploring the interior, atmosphere and magnetosphere, and scouring the myriad of moons and icy rings,” he added. “If it’s worth doing, then it’s worth doing right!”
arrive on time
How long it will take to reach Uranus depends on when a spacecraft is launched. A gravity assist of Jupiter it is required for a larger spacecraft to avoid an unduly long journey. The giant planet’s position means that a Uranus mission would preferably launch in 2031 or 2032 to reach Uranus in 2044 or 2045. It could depart land until 2038, but that would mean a 15-year journey.
However, there is a good scientific reason to arrive at Uranus in 2045. A year on Uranus lasts 84 Earth years and Voyager 2 flew by during the southern hemisphere summer, so if scientists want the greatest contrast with views from that mission, then the new spacecraft must arrive before the austral spring begins in 2049.
That timing would also give the probe entirely new views of the southern hemispheres of Uranus’ moons, intriguing worlds in their own right.
Uranus has 27 moons, but scientists believe that its five largest moons – Miranda, Ariel, Umbriel, Titania and Oberon – may be ocean worlds that could possibly support life. “Investigation of these moons would improve our understanding of where potentially habitable bodies exist in our solar system,” Beddingfield said. These moons are not covered in craters, suggesting that they may be geologically active with shifting surfaces, possibly due to ice volcanoes.
“Uranus’ large moons are really strange,” said Richard Cartwright, a planetary scientist and astronomer at NASA Ames Research Center and lead author of a paper proposing a Uranus Orbiter, he told Space.com. He noted that Voyager 2’s brief flyby captured snapshots of the moons’ surfaces that show evidence of geological activity on Miranda and Ariel in particular.
“However, the northern hemispheres of Uranus’ moons were shrouded in winter darkness at the time of the flyby and were largely unimaged, leaving many unanswered questions about the origin and evolution of these icy bodies,” he said. For now, Cartwright has arranged to use the recently released James Webb Space Telescope to search for chemicals that may have leaked from the internal oceans on these worlds, but that doesn’t compare to visiting up close.
searching for a name
The committee recommended that work on an actual mission design should start in 2024, budgets permitting, but any Uranus mission will need an iconic name.
“A good possible name for the orbiter is ‘Caelus,’ which is the Roman counterpart of the Greek god Uranus,” Beddingfield offered. “This would be appropriate because Uranus is the only planet in our solar system named after a character from Greek mythology rather than Roman.”
But there are likely to be two pieces of hardware: an orbiting satellite and an atmospheric probe. For comparison, NASA named its casini orbiter, which studied Saturn from 1997 to 2017, after the discovery of Saturn’s moons. The mission’s European-made probe, which descended to the surface of the strange moon Titan, was named huygens after the astronomer who confirmed Saturn has rings.
Another option could be “Shakespeare” for the Uranus orbiter and “Papa” for the atmospheric probe. After all, the moons of Uranus are named after characters from the works of William Shakespeare and the British poet Alexander Pope. For example, Ariel and Miranda appear in Shakespeare’s “The Tempest”, while Titania and Oberon appear in “A Midsummer Night’s Dream”.
“I think Shakespeare is a great choice for the name of the mission,” said Cartwright. “An inspiring and well-known name!”
But while Uranus scientists are celebrating the new recommendation, a Uranus mission is not yet a reality. “There are a lot of hurdles to come, political, financial, technical, so we’re under no illusions,” Fletcher said. “We have about a decade to go from a mission on paper to a hardware in a launch fairing. There is no time to waste.”
Jamie Carter is the author of “A stargazing program for beginners(Springer, 2015) and edit WhenIsTheNextEclipse.com. Follow him on Twitter @jamieacarter. Follow us on twitter @Spacepointcom or in Facebook.