NASA eyes Neptune and Uranus for missions in the 2030s

Written by John Wenz

NASA is planning to visit Uranus (left) or Neptune.

Uranus and Neptune have never got much attention from us – we’ve only passed each once and never hung around. But that could change. A NASA group has now outlined possible missions to make it to one of these outer worlds to gather data on their composition. This should teach us about them and similar planets in other solar systems.

“The preferred mission is an orbiter with an atmospheric probe to either Uranus or Neptune – this provides the highest science value, and allows in-depth study of all aspects of either planet’s system: rings, satellites, atmosphere, magnetosphere,” says Amy Simon, co-chair of the Ice Giants Pre-Decadal Study group.

There are four proposed missions – three orbiters and a fly-by of Uranus, which would include a narrow-angle camera to draw out details, especially of the ice giant’s moons. It would also drop an atmospheric probe to take a dive into Uranus’s atmosphere to measure the levels of gas and heavy elements there.

The three must-haves for each orbiter mission are a narrow-angle camera, a Doppler imager, and a magnetometer, while an orbiter containing 15 instruments would add plasma detectors, infrared and UV imaging, dust detection, and microwave radar capability.

The orbiter could be either a Neptune mission with an atmospheric probe, a Uranus probe of the same design, or a craft sent to a Uranus that ditches the atmospheric probe for the suite of 15 instruments.

Heavy weather

The two biggest science priorities are determining the composition of the icy giant the probe visits, and determining its internal structure and the abundance of heavy elements.

Other goals include studying energy fields, weather and climate; in-depth studies of the moons; and finding out more about the composition and formation of the ring systems that orbit Neptune and Uranus like the rings of Saturn. A Neptune mission would also focus on its largest moon Triton, a likely captured Kuiper belt object with geysers and a tenuous atmosphere.

“Compared to Neptune, Uranus has a larger satellite system that likely formed in a disk around the planet (like the Jupiter and Saturn satellite systems) which is helpful for comparative planetary science, and I am excited to better understand the diversity of these small worlds,” says Jonathan Fortney at the University of California, Santa Cruz. He prefers the idea of a Uranus mission.

So why visit these ice giants at all? Of the exoplanets we’ve discovered to date, the Neptune-sized ones are the most plentiful. Simon says understanding how Uranus and Neptune formed could show how ice giants differ from gas giants, and why the former are more abundant.

“This might have implications for how you form a planet of that mass in exoplanet systems, for example,” she says.

Read more at New Scientist

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