Uranus is a lonely world. Nearly 40 years ago, the ice giant received his one fleeting visitor when the Voyager 2 spacecraft flew within 81,800 kilometers of her from its cloud tops. After taking thousands of pictures of the planet, revealing a mysterious world and asking more questions than answers, the spacecraft sped off toward the outer solar system. No rover has set foot there since. “The Uranus system is his one of the big blank spots left on our map,” says Francis Nimmo, a planetary scientist at the University of California, Santa Cruz. But that may be about to change.
Last year, the National Academy of Sciences, Engineering and Medicine released a decade-long study calling on NASA to send the next big “flagship” mission to the ice giant. Specifically, the study recommends her $4.2 billion mission, which includes a rover that will place spacecraft in Uranus’ orbit for years and plunge into the planet’s atmosphere. This will also ultimately help scientists better understand the origin and evolution of our own solar system. The most common type of planet in the galaxy. But the largest splash may be lurking deep within Uranus’ largest moon, which, like many other ice bodies in the outer Solar System, may host subterranean oceans of liquid water. I have.
With NASA’s sights set on Uranus, planetary scientists around the world have had heated debates over the past year, discussing mission critical science and key questions that need answers in advance. . They are hopeful but realistic. Congress has yet to allocate funds and the clock is ticking. To reach the ice giant during the equinox when the sun fully illuminates the planet, its rings and the moon, the mission needs to begin within ten years. Planning and executing a mission of this magnitude, especially when space agencies are overwhelmed by astronomically large to-do lists.
If the mission arrives too late, the planet and part of the moon will return to darkness. So is our answer.
Intriguing Tip
When Voyager 2 passed Uranus, it revealed an upside-down milky blue marble unlike any other planet in our solar system. The planet’s upper atmosphere is cold, very cold, and models cannot explain why distant Neptune is actually warmer than Uranus. It is surrounded by a dozen mystical rings and holds at least 27 moons. Some of them are stitched together from hodgepodges of material like the moon version of Frankenstein’s monster. But perhaps most bizarre is the fact that at some point in its history, the ice giant was defeated and left spinning sideways. “It must have been a very spectacular event, like the impact of moon formation on Earth, but it required steroids,” says Nemo.
To better understand the impact, scientists want to peer beneath the planet’s cloud tops. This event likely destroyed Uranus’ interior, so an orbiter capable of detecting fluctuations in the planet’s gravitational field could map the internal anomalies created by the giant smashup. In addition, scientists hope to better understand how ancient collisions continued to dominate planetary atmospheres. The sun burns it, and the other pole freezes in the dark. Because Uranus orbits the Sun every 84 years of her life, its seasons last for decades and affect the atmosphere in ways scientists cannot yet imagine, affecting chemistry, clouds and circulation patterns. In this way, the orbiter will make global observations, while the probe will plunge into the atmosphere itself and make measurements at greater depths.
Such detailed observations of the planets help scientists understand not only the origin and history of Uranus and its icy companion Neptune, but also the evolution of our solar system and the cosmic context. Both worlds may have migrated early in their lives, shifting positions around the Sun and sending barrages of water-rich comets toward Earth and other inner planets. Broadly speaking, both Uranus and Neptune may represent a class of planets that exist throughout the galaxy. About 50% of the known exoplanets are ice giant-sized.
The orbiter will also peer outward to image the planet’s faint rings. This appears to defy the laws of physics by some estimates. Like Saturn’s rings, Uranus’ bracelets are made up of millions of ice particles and are shaped by gravitational interactions between the planet and its moons. But Uranus’ rings are much narrower than scientists usually think. Think of them as rings with a radius of 50,000 km and rims only 10 km wide. “That shouldn’t happen,” says Matthew Hedman, a planetary scientist at the University of Idaho. “Particles should hit each other and spread out. Something is storing material in a particular place.” It could be a small moon in a ring. It could be the gravitational asymmetry inside Uranus. Or maybe the rings aren’t as wide as we think they are. “There may be something fundamentally missing,” Hedman says.
Credit: NASA/JPL/USGS
Some scientists use orbiters to search for the tiny shepherd’s moon, while others probe the planet’s larger moons. “Voyager provided images of the moon’s surface that were very different from what we had expected,” said Kathleen Mant, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory. Consider Miranda, a moon with pockmarked plains, intersecting ridges. It’s warm enough that you don’t have to dig deep to reach ambient temperatures above. To test the orbiter’s magnetic field, the orbiter will monitor the lunar magnetic field to see if it changes as a result of internal sloshing of liquid water, as well as the ongoing geological field where Voyager 2 failed. Image the entire lunar surface to search for activity.
When the historic spacecraft passed the ice giant in 1986, only half of each moon was visible. At that time, the planet and its many moons were on their southern summer solstice, with the South Pole in full light and the North Pole in darkness. “There are regions on Uranus’ moons that neither the human eye nor the robot eye could see before,” says Lee Fletcher, a planetary scientist at the University of Leicester in England. Naturally, scientists hope the next Uranus mission will reach the system during the vernal equinox, when the sun’s light bathes the entire planet and its moons from north pole to south pole. It’s 2050. That may sound far in the future, but to traverse the vast distances to Uranus, the mission would have to start relatively soon. In fact, his 10-year study recommended launching missions by 2032. This is the timeline that will allow the spacecraft to take advantage of Jupiter’s enormous gravity to gain speed and reach Uranus, arriving well before the vernal equinox, thus preserving this epoch-making seasonal transition. can fully comprehend.
racing the sun
It will take a tremendous effort to meet the 2032 launch deadline. And whether the scientific community will be ready within his decade is an open question. Otherwise, scientists risk missing out on seeing this system in all its splendor. This is especially concerning as the next opportunity won’t occur until his 2091.
“A Uranus Orbiter sitting on a Walmart shelf can be purchased and assembled with a swipe of a credit card,” said Casey Dreyer, Space Policy Director for the Planetary Society. A spacecraft similar to NASA’s highly successful Cassini mission, which explored the Saturn system from 2017 to 2017, was recommended, but the ice giant is a different beast. But before we can scientifically design parachutes and heat shields that slow down to maximum penetration velocities, we need better telescopic data on the planet’s upper atmosphere, as well as scouting for dangerous debris between the upper atmosphere and the rings. This region is the one that missions must traverse to successfully enter orbit around the ice giant, so many observatories, including the James Webb Space Telescope, are planning to visit Uranus in the next few years. will turn their gaze.
“Uranus is much more difficult to study from our terrestrial perspective, so before the huge, expensive, once-in-a-lifetime spacecraft are actually acquired, we have all of the arsenals in our arsenal to characterize the environment. You have to throw stuff in there,” says Fletcher.
Ultimately, however, NASA’s Uranus mission will be determined not by telescope observations or rocket technology, but rather by money. In NASA’s presidential budget request released earlier last month, NASA said he wouldn’t even ask for funding for the mission until 2025, after which the amount of funding requested would increase modestly. “Then he won’t be ready for the 2032 launch,” he says.
Nonetheless, the planetary science community believes that the space agency will eventually launch this mission purely because the U.S. federal government traditionally dedicates 10-year research recommendations. A survey recommended that the community prioritize two flagships. One to retrieve samples from Mars and another to explore Jupiter’s icy moon Europa. Both of these priorities show up in real missions. But even such an inviolable, decade-long “to do” list has its problems. NASA’s Planetary Science Division is working under huge budget stress as her two flagships are already at work and waiting ahead of the Uranus mission. “This is an extraordinary commitment,” he says Dreier. Plans for a Mars sample return are particularly worrisome because of its complex mission’s multiple phases (and multi-billion dollar budget) involving international partners operating on relatively time-sensitive deadlines. For such a mission, some degree of overruns and delays seems inevitable, and could have devastating effects on an all-too-thin planetary science portfolio. , it will be difficult, if not impossible,” he says.
Additionally, Mars and Jupiter aren’t the only ones in the planetary lineup. NASA will soon begin missions to Venus, Saturn’s moon Titan, and even distant asteroids, pushing the workforce to its limits.Psyche For example, a mission scheduled to rendezvous with an asteroid has been postponed to June 2022. The spacecraft was ready for launch, the rocket was available, and the weather was great. However, there were not enough workers to fully test the spacecraft’s software in time. “It’s excess wealth,” says William McKinnon, a planetary scientist at Washington University in St. Louis. “We’re mission-approved, talented, and have great goals. But just trying to do it all at once proved difficult.”
Still, McKinnon and his associates hope that once the mission to Europa begins, a wedge of both labor and budget will open to focus on Uranus. “Just because you’re a little grumpy right now doesn’t mean you’ll never change,” says Dreier. He refers to NASA’s Europa mission (now Europa Clipper). For much of the 2010s, space agency budgets were shrinking. Visiting Europa risked breaking the bank and was widely seen as an almost impossible dream. At least until the mission’s many scientific advocates found an unlikely political advocate in the form of then-Texas representative John Culberson. Allocated hundreds of millions of dollars to the effort. Now the Europa Clipper is ready and waiting for the launch next October.
Only time will tell if the ice giants will find a champion. “It’s an uphill battle, but we’ve done it before,” he says Dreier. “Don’t assume we’ll be in the graveyard by the time we get data back from the Uranus mission.”
