Uranus should be a top target for NASA and SpaceX missions. Here's why

It's time.
Brad Bergan
An illustration of Uranus (left), and a Falcon Heavy test launch (right).1, 2

In April, a team of planetary scientists spread across the U.S. authored a report as part of the Planetary Science Decadal Survey, placing scientific pressure on NASA to build and loft a probe capable of exploring the planet Uranus. If it goes forward, a launch between 2023 and 2032 "is viable on currently available launch vehicles" — which means we don't even need to innovate new technology to make it happen.

The proposed mission — dubbed the Uranus Orbiter and Probe (UOP) — might even drop a probe into the atmosphere of the ice giant, revealing more than we've ever known about a gas giant we know very little about.

But with NASA's Artemis crawling toward viable moon programs with SpaceX and other private partners, compounded by other crewed missions to the International Space Station and additional rovers like Perseverance on Mars, it might seem to some like Uranus just isn't the priority.

Here's why the ice giant should be one of them.

SpaceX's Falcon Heavy could be the only way to Uranus

A mission to Uranus seems like a long shot (and it is), but NASA wouldn't even need to develop or adapt its nascent SLS launch system for the extended journey. In an April report from Teslarati, it's suggested that SpaceX's Falcon Heavy rocket could make the journey.

This is significant because the United Launch Alliance's (ULA's) Vulcan Centaur rocket hasn't made its first lift-off, and Blue Origin's suite of rockets has yet to ascend beyond Earth orbit. Even an already greenlit project to Jupiter's moon, called the Europa Clipper, will require substantial upgrades to be made to NASA's SLS.

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In other words, while current technology could make the trip to Uranus, the only functional launch system in the United States capable of making the journey is Elon Musk's Falcon Heavy. And if it does, we could solve several mysteries about Uranus, which we know very little about.

So far, scientists are fairly confident that its composition includes mostly hydrogen, ices, helium, and rock. If we learn what the inside of Uranus looks like with exacting precision, we may also glean new insights about how our solar system formed — and by extrapolation — about how solar systems capable of supporting intelligent life might form elsewhere in the universe.

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A diagram comparing three layers of aerosols in the atmospheres of Neptune and Uranus (the height scale represents 10 bar of pressure). Source: International Gemini Observatory/NOIRLab/NSF/AURA, J. da Silva/NASA /JPL-Caltech /B. Jónsson

Comparing multiple wavelengths of Neptune and Uranus

"Our understanding of the interior structure of the interior structure of the planet is so poor that we really have very little idea what the ratio of those three things are to each other," said UC Santa Cruz Professor Jonathan Fortney, who wrote a study about the feasibility of exploring Neptune and Uranus, in a report from The Verge.

However, it's not the case that we know nothing about Uranus. A recent study in the Journal of Geophysical Research: Planets suggests that the concentrated haze on both ice giants is actually thicker on Uranus, causing it to "whiten" more than Neptune. If neither planet had this haze, then both ice giants would appear with the same melancholy blue.

This discovery came from a model theorized by a global team to explain aerosol layers in the atmospheres of Uranus and Neptune. Unlike previous studies of the two planets, which looked at specific wavelengths of light, the new model examined several layers of their atmospheres. This is significant because it enabled scientists to see how observations of either planet matched and differed from one another across a wide spectrum of wavelengths.

Uranus could hold the secret to life-friendly solar systems

Crucially, the novel model also posits haze particles at far deeper layers than scientists initially thought — where previously only clouds of methane and hydrogen sulfide ices were presumed to be present. "This is the first model to simultaneously fit observations of reflected sunlight from ultraviolet to near-infrared wavelengths," said Professor Patrick Irwin, of Oxford University, who led the recent study, in a press release.

"It's also the first to explain the difference in visible color between Uranus and Neptune," added Irwin. This model even lends data to support theories on why the dark spots sometimes seen on Neptune seem to happen more often than they do on Uranus. According to the research, a darkening of the particles in the deep abyssal layers of the new model would yield dark spots resembling what we see from Earth orbit.

If we want to confirm the cause of these dark spots and gain a more complete picture of how habitable solar systems form, we need to explore all of the gas giants. Since the Voyager 2 spacecraft flew by Uranus and Neptune in 1986 and 1989, respectively, we've only returned to Jupiter and Saturn's planetary systems. We even have more missions to set to explore both gas giants' moons. Since Neptune and Uranus are similar (as ice giants), and Uranus is far closer — the only thing stopping us from the next step in planetary science is the decision to commit, and send a probe.

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