Scientists Identify Tight Window to Visit Uranus

The approach of a rare cosmic alignment could cut down travel time to Uranus and Neptune. Will scientists be able to meet the deadline?
March 5, 2020, 1:00pm
​Concept art of Uranus from its moon Ariel. Image: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images
Concept art of Uranus from its moon Ariel. Image: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images

Uranus is a fascinating planet that has been lamentably underrated as a target for exploration, partly because its name is the butt of many jokes. Neptune may have lucked out in the name game, but its enormous distance from Earth also makes it an inconvenient destination for space probes.

As a result, Uranus and Neptune are the least explored planets in the solar system, having only ever been visited briefly by NASA’s Voyager 2 flyby in the 1980s. But that may change due to the approach of a rare cosmic alignment that is encouraging scientists to send probes back to these lonely gas giants in the outer solar system.

The Sun’s light takes about eight minutes to reach Earth, but it takes around 2.7 hours to reach Uranus and 4.2 hours to reach Neptune, which shows how drastically distant they are from the inner solar system. In order to limit the travel time to these worlds, scientists need to use the gravitational pull of other planets to slingshot probes into higher speeds.

Voyager 2 was accelerated by flybys with Jupiter and Saturn, which enabled it to reach both Uranus and Neptune within 12 years of its launch. In the 2030s, Jupiter will once again be in the right position to give a speed burst to probes on their way out to Uranus and Neptune. A probe launched during this window could reach either one of the gas giants in about 12 to 13 years, arriving in the 2040s, according to Nature

Of course, that may still seem like an awfully long trek, but it’s important that these hypothetical probes don’t travel so fast that they become unable to brake and insert themselves into orbit around Uranus or Neptune. Voyager 2 was able to save time because it simply zoomed past the planets on its way out of the solar system, but scientists aren’t likely to return to the outer gas giants without the aim of spending at least a few years studying them.

To that point, Uranus and Neptune are intriguing destinations for orbiters because we know very little about them. Both have unique characteristics—for instance, the fastest winds in the solar system are on Neptune, and Uranus appears to have been knocked onto its side at some point, making it the only planet with such an odd axial tilt. They also both have tantalizing moon and ring systems filled with prime landing sites for a surface probe.

But if the space community wants to finally return to these distant planets, it will need to greenlight, design, build, and launch the probes within a decade, which is a tight deadline for deep space exploration. Some scientists have already started advocating for these missions, including anticipating the “legitimate problem” posed by the distracting nature of Uranus’ name.

In other words, it looks like it’s time to embrace the ill-named planet for what it is because letting any innuendo prevent us from seeing Uranus up close would be a bum deal.