The case for Uranus: Outlining the next decade of discovery

By Brendan Byrne

Published April 26, 2022 at 8:39 AM EDT

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This is a composite image of Uranus by Voyager 2 and two different observations made by Hubble — one for the ring and one for the aurorae. PhotoL ESA/Hubble & NASA/L. Lammy — Ever since Voyager 2 beamed home spectacular images of the planets in the 1980s, planet-lovers have been hooked on extra-terrestrial aurorae. Aurorae are caused by streams of charged particles like electrons, that come from various origins such as solar winds, the planetary ionosphere, and moon volcanism. They become caught in powerful magnetic fields and are channelled into the upper atmosphere, where their interactions with gas particles, such as oxygen or nitrogen, set off spectacular bursts of light. The alien aurorae on Jupiter and Saturn are well-studied, but not much is known about the aurorae of the giant ice planet Uranus. In 2011, the NASA/ESA Hubble Space Telescope became the first Earth-based telescope to snap an image of the aurorae on Uranus. In 2012 and 2014 astronomers took a second look at the aurorae using the ultraviolet capabilities of the Space Telescope Imaging Spectrograph (STIS) installed on Hubble. They tracked the interplanetary shocks caused by two powerful bursts of solar wind travelling from the Sun to Uranus, then used Hubble to capture their effect on Uranus’ aurorae — and found themselves observing the most intense aurorae ever seen on the planet. By watching the aurorae over time, they collected the first direct evidence that these powerful shimmering regions rotate with the planet. They also re-discovered Uranus’ long-lost magnetic poles, which were lost shortly after their discovery by Voyager 2 in 1986 due to uncertainties in measurements and the featureless planet surface. This is a composite image of Uranus by Voyager 2 and two different observations made by Hubble — one for the ring and one for the aurorae.

Every 10 years, the National Academies submits a report, outlining what it thinks NASA should focus on when it comes to planetary science efforts. Uranus came out the big winner.

In its decadal survey, scientists recommend NASA send a mission to the ice giant on the outskirts of our solar system. It would be the first mission to the planet since Voyager 2 zoomed by the planet back in 1986.

So why Uranus? We’ll speak with Paul Byrne, a planetary scientist at Washington University in St. Louis about the selection and what scientists hope to learn about a flagship mission to this mysterious planet.

Then, the decadal also made recommendations for other planetary missions, including the continued exploration of the red planet. We’ll speak with University of Florida astrobiologist Amy Williams about the decadal’s recommendations for Mars explorers and how the group also took a look at diversity, equity, inclusion and accessibility in the field of planetary sciences.

The next 10 years of exploration! That’s ahead on Are We There Yet, here on WMFE -- America’s Space Station.