Sand dunes that form on our ocean floors could help us understand the landscape of Venus.

Our near-neighbour Venus may be roughly the same size as Earth, but its conditions are very different. Beneath its thick atmosphere, the surface is much hotter and at a higher pressure than that of our planet. As a result, we have struggled to understand Venus’s landscape and how it forms.

In the 1990s, the Magellan spacecraft’s synthetic aperture radar revealed the presence of sand dune-like structures in a couple of locations. This, combined with evidence of fine-grained material on the surface from Venus lander missions in the 1970s, promised to open a window into the geological processes that occur on Venus.

However, because sand dunes on Earth form under much lower atmospheric pressures, it is difficult to use them to understand what is happening on Venus.

Closer match

Now, astronomer at New Mexico State University and his team think they have a solution. They point out that dunes can also form on the floor of Earth’s oceans. These underwater dunes may offer a closer match for dunes that form in environments with thick atmospheres, such as on Venus.

His team’s study, based on a review of existing literature, suggests there are indeed similarities between the dunes of Venus and those that form underwater on Earth. For instance, some studies of astronomical data suggest the dunes on Venus are about 40 to 80 metres tall, whereas similar wind-blown, or aeolian, dunes on Earth typically grow to a height of 200 metres or more. Underwater, where particles move differently, dunes tend to be much smaller and more like those on Venus.

This indicates that studies into the movement of particles through water on Earth could help understand the way particles are carried on the Venusian winds. Neakrase and his colleagues note, for instance, that particles blown by Earth’s winds typically ping other particles into the air as they bounce along the ground. Particles carried through water travel more slowly and don’t usually trigger the launch of other particles when they land – the researchers think particles carried on the Venusian wind may behave in this way too.

Water and wind

“There are many similarities between what has been studied in marine settings on Earth and the possibility for bed forms on Venus specifically, but also maybe [Saturn’s moon] Titan,” says Neakrase.

“The results of this paper have already started to have the desired effect of bringing the marine and the planetary aeolian communities together to talk about the research and how it applies to thicker atmosphere bodies in the solar system,” he says.

“The overall approach is a really interesting one in studying other planets,” says at the University of Minnesota.

“One of the striking things about looking at these aeolian worlds is that they have landscapes that look very familiar to what we see on Earth,” he says. Studies of Earth’s underwater systems could help make most sense of those similarities.

at NASA’s Jet Propulsion Laboratory in California is also impressed. He says researchers in the US and Europe are working on mission concepts to Venus that could provide higher resolution images of the planet’s surface. “The smaller dunes on Venus will be better resolved and we will need a framework to understand them,” he says.

Read more: NASA eyes Neptune and Uranus for missions in the 2030s

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