NASA is going to Uranus! This week the National Academy of Sciences finally published its Decadal Survey for Planetary Science and Astrobiology—widely regarded as a “to do” list for NASA—and star of the show was the recommendation for a mission to the seventh planet.
It’s going to be an incredible occasion, but prepare yourself for a very long wait.
Here are seven things you didn’t know about the plans for a Uranus Orbiter and Probe to finally unveil the mysterious seventh planet:
1. SpaceX will probably launch it
The Decadal Survey recommends the Uranus Orbiter and Probe be developed from 2024 for a launch in 2031 or 2032 on a commercial heavy lift rocket—very likely the SpaceX Falcon Heavy.
That would take advantage of a gravity-assist from Jupiter, which would mean it would arrive at Uranus in 2044 or 2045. Just 22 years from now!
2. Mars means NASA may not reach Uranus until 2053
If development stalls or if budgets struggle to support both it and the Mars Sample Return mission simultaneously then the Decadal Survey says that the Uranus Orbiter and Probe can go as late as 2038. It’s actually already first on the list of things to delay.
In that case there would be no Jupiter to help out, which would mean, ironically, a bigger rocket and a slower 15-year direct journey (arriving in 2053!). The report doesn't mention this, but it would then likely need to be launched on a super-heavy lift rocket such as NASA’s Space Launch System or SpaceX’s Starship ... both of which are still in development.
“As with all missions, cost overruns and surprises can pose a risk,” said “ice giants” expert 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. “Outer planet exploration touches on key scientific questions about the origins of worlds and the nature of our Solar System, so I would hope that this complements the ongoing exploration of Mars.”
3. It’s a full flagship like Cassini, not a flyby
Although the same Uranus Orbiter and Probe was the third-highest priority of the survey a decade ago—and simply ignored by a cash-poor NASA—the recommendation of a $4.2 billion flagship mission is significantly more than many proposers of missions to Uranus had hoped for. In fact, most of the proposals considered by the committees had been for more affordable New Frontiers flyby missions costing no more than $900 million.
“A New-Frontiers level flyby mission would not have been compelling,” said Fletcher. “To fully explore this representative of a whole class of worlds—Ice-Giant-sized planets—we need to be in orbit, exploring the interior, atmosphere and magnetosphere, and touring the myriad icy moons and rings—and that deserves a flagship.”
4. It’s actually more about exoplanets than Uranus
The reason why “ice giant” planets have moved up the agenda is because most of the 5,000+ exoplanets found by astronomers in other star systems are about the same size of Uranus and Neptune. Since we’ve not fully explored either of the “ice giant” planets in our own star system, scientists have no baseline to make comparisons.
“I started thinking about Ice Giant exploration in 2008, ahead of the last decadal survey that ranked Uranus as a third priority after Mars and Europa,” said Fletcher. “The science case has only improved with time, particularly as Ice-Giant-sized worlds (or just smaller) appear commonplace in the pantheon of exoplanets.”
Besides, the main reason NASA is being sent to Uranus is because Neptune is trickier.
5. Uranus beat Neptune because of a celestial fluke
The selection of Uranus means a planned mission to Neptune—the “other” ice giant—misses out. “Both Uranus and Neptune are scientifically compelling, but Uranus ranked higher because it is technologically achievable right now,” 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. “Neptune is much farther away, making it difficult to reach; we don’t currently have the right combination of launch vehicle, trajectory, and propulsion to confidently launch a large Flagship mission there just yet.”
The main reason for that lack of confidence is trajectory. A gravity-assist is required from Jupiter to get to the ice giants in a semi-reasonable time-frame—and Jupiter is going to be badly placed for a slingshot to Neptune after 2030. That’s too soon—and a mission to Neptune would cost at least another $300 million.
6. It will inspire the next generation of scientists
This is a mission for the future. Arriving in the mid-2040s and likely to still be going by the early 2060s, most of the scientists who have been pushing a mission to an “ice giant” won’t be around.
“Planetary exploration takes patience, but – like Cassini – all good things come to those who wait, and the Ice Giants truly are the last major class of Solar System planet to have an orbital explorer,” said Fletcher, who thinks that thousands of future scientists out there today will get to make their own discoveries in the Uranian System. “Cassini shaped planetary science and outer-planet discoveries for a generation and an Ice Giant flagship will do the same,” he said.
7. Images of its ‘ocean moons’ will inspire the world
The outer solar system is definitely hard to reach, but when NASA finally gets there ... wow! For starters, no space agency has been there since a brief flyby in 1986 by Voyager 2. “We expect that a mission to Uranus will be transformative and very exciting and as with Saturn and Jupiter we’ll almost certainly make amazing discoveries we can’t even imagine right now,” said Simon. “Uranus also has moons that are candidate ocean worlds, as well as rings, and a complicated magnetic field, and I think the public will be engaged by our views of these exotic worlds!”
Wishing you clear skies and wide eyes.
