Unique alignment creates tight window to study Uranus like never before

Artist concept of Uranus with 3 of its moons Oberon, Titania, and Umbriel (forplayday/iStock)

Dan Broadbent

Researchers discovered a unique planetary alignment that creates an opportunity to study Neptune and Uranus in depth.

The ice giants Neptune and Uranus have only been explored by a probe a single time. Voyager 2 whizzed by Uranus in 1986, and flew by Neptune in 1989.

Even with gravity assists from other planets, it still took Voyager 2 about 9 years to reach Uranus and about 12 years to fly by Neptune. Much like New Horizons, which launched in 2006 and flew by Pluto in 2015, the probes had a very small window to gather data about these distant worlds. Obviously, having a probe in orbit around these planets would give researchers much more insight into them.

Now, according to a paper published in Nature earlier this week, scientists may have a rather rare opportunity to get deeper insight into Uranus. (And yeah, Neptune too, I guess.)

Interest in the ice giants has grown exponentially, says Amy Simon, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who co-organized a meeting at the Royal Society in London in January, dedicated to exploring such a mission. NASA’s Voyager 2 is the only spacecraft to have visited Uranus and Neptune, in brief fly-bys in the 1980s. The ice giants therefore represent fresh territory for a wide range of researchers — for the study of planetary rings, atmospheres, moons and oceans, says Simon.

(Credit: Nature)

(I'm glad they explained it's not to scale, since the spacecraft would be about 1/3 the size of the sun.)

The window is “the right time to launch”, Mark Hofstadter, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, California, said at the London meeting. “We don’t want to miss this one.” But the timing is tight. NASA is the most likely space agency to lead the kind of multibillion-dollar ‘flagship’ mission that scientists want. These typically take 7–10 years to prepare, and any green light from NASA would depend on the mission being prioritized in the agency’s Planetary Science Decadal Survey, which reports in 2022. A mission to Neptune or Uranus would also face competition from proposals to return a sample from Mars or explore Venus.

The problem in the past has not necessarily been getting to the planets, it's the "slowing down" part. In order to go fast enough to reach the planets in a reasonable timeframe, they use gravity assists from other planets to, basically, slingshot them. A gravity assist is when a spacecraft flies near another body and basically "steals" a bit of the gravity from that planet or moon to propel itself faster. The spacecraft tugs on the planet/moon as the planet/moon tugs on the spacecraft, speeding up the craft.

This also saves fuel. Because, of course, in order for the craft to have fuel in space, that fuel needs to be launched into space. And since fuel has mass, it takes more fuel to launch that fuel.

(Is this meme format still viable? Do people even know who Xzibit even is anymore?)

However, as they pointed out in the paper, 2030 isn't exactly as far away as it might seem.

But some are concerned by the timescale. It is “the day after tomorrow” in space terms, Fabio Favata, head of strategy, planning and community coordination at ESA, told the meeting. The agency is already working on two major missions for the early 2030s, he said, so even if its forthcoming prioritization exercise, called Voyage 2050, recommends a visit to the ice giants, the agency could not make the launch window.

But not all hope is lost.

Alternatively, ESA could contribute to a NASA-led mission, but that would require a US decision, he added. Either agency could also send lighter, cheaper missions, for example to fly by one of the ice giants. These would produce valuable science, but not provide the comprehensive study that scientists hope for, said Hofstadter.

But another issue is that any mission to Uranus would become the butt of many jokes, as one scientist pointed out in the paper. Not that I've ever done anything like that before.

Heidi Hammel, a planetary astronomer and executive vice-president of the Association of Universities for Research in Astronomy in Washington DC, flagged another issue scientists might face with a mission to Uranus: jokes about the planet’s name. “I’m sorry I’m saying this. But I really do think that’s a legitimate problem we would face,” she said.


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