A mission to Uranus and Neptune could act as massive gravitational-wave detector

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space. He contributed this article to Space.com’s Expert Voices: Opinions and Insights.

What if one mission could study the gravitational waves triggered by some of the most violent events in the universe — on the way to observing the least-known planets of our solar system?

Planetary scientists are desperate for a new probes to Uranus and Neptune, since these ice giant worlds haven’t been visited since the Voyager mission flybys of the late 1980s. And while such a spacecraft would unearth a treasure trove of information about these solar system siblings, it could also peer much deeper into the universe, scientists say in a new analysis: By carefully monitoring variations in the radio signals from one or more such spacecraft, astronomers could potentially see the ripples in gravity caused by some of the most violent events in the universe.

Related: Voyager at 40: 40 Photos from NASA’s epic ‘grand tour’ mission

Ice, ice baby

Poor Uranus and Neptune. The only close-up images we have of those outer worlds come to us from the Voyager 2 spacecraft, which swung by those planets on its “Grand Tour” in the late 1980s. Since then, we’ve sent probes to Mercury, missions to Jupiter and Saturn (including landing on the latter’s moon Titan), collected samples of asteroids and comets, and launched rover after rover to Mars.

But not Uranus or Neptune. Those worlds, now known as “ice giants” because water and ammonia ices dominate their composition, sit lonely in the outer fringes of our celestial neighborhood. There are no other worlds in the solar system quite like them, and an entire generation of planetary scientists have been able to study them  with