The best way to learn about Venus might be with a fleet of balloons

Interest in Venus exploration has soared recently, especially after a controversial recent discovery of phosphine, a potential biosignature, in the planet’s atmosphere. Many missions to Venus have been proposed, and NASA and ESA have recently funded several. However, these are mostly orbiters, trying to look inside the planet from above. But they face a challenge because they have to see through tens of kilometers of an atmosphere made up of sulfuric acid.

The same atmosphere is challenging for ground missions. While some of the newly funded missions include a ground component, they miss an opportunity not afforded to many other planets in the solar system—driving through the atmosphere. Technologists have proposed everything from simple balloons to entire floating cities—we’ve even heard of a plan to encase the entire Venus in a shell and live on the surface of that shell.

But for now, balloons seem to be a clearer answer. That’s the mission method proposed by a team of researchers at NASA’s Jet Propulsion Laboratory to find out more about something that was confirmed to exist on Venus just last week – volcanism.

Scientists have long believed that there are active volcanoes on Venus. Some earlier probes collected data that hinted at this, but it wasn’t until a recent study that analyzed data from Magellan that we knew the volcanoes on Venus were still active. At this point, it’s anyone’s guess what this means for the study of the planet’s seismology, evolution, and even geophysiology. But the proposed JPL balloon mission would help shed some light on it.

Their mission design, detailed in a paper freely released on one of the author’s personal websites, involves using a grid network of balloons and an orbiting satellite to detect and travel to active volcanic events and collect as much as much data as possible from them. This may sound difficult, especially without people “in the loop” and controlling where the balloons go, but it’s definitely better than letting the wind take them.

It’s much better — 63% better at making close-up observations of active or recently active volcanoes, according to the team’s simulations. But how they arrived at that number could use some further explanation. First, how can you tell when a volcano is erupting on a planet that is completely obscured from outside view?

They proposed using a technology called ultrasonic microbarometers—basically, these tiny instruments detect pressure differences in the atmosphere caused by volcanic eruptions. If you’re looking for a volcanic eruption, analyzing data from one of these instruments can at least point you in the direction of the pressure wave they’re creating. Even if you’re pointing in the right direction, how can a balloon without its own active propulsion system get close enough to start collecting data?

According to the paper, they can simply ride the winds. The atmosphere of Venus is complex and different layers can have different wind directions and different speeds. A balloon could rise or fall in the right wind current and drive it in the direction of the explosion. That sounds pretty cool, but a balloon alone wouldn’t necessarily be able to detect wind currents outside of its immediate area, making it difficult, if not impossible, to plot a route to the volcano. That’s where the mesh comes in.

Orbiting above the planet and looking down through the atmosphere has an advantage – it allows the orbiter to see different wind currents that could be used to steer the balloons in the right direction. Even better, if a balloon detects an interesting pressure change but can’t find a way out of the local wind situation, the orbiter could relay that information directly to one of the other balloons in the group, which might have a better chance to get there because of its own local winds.

So, in addition to acting as a navigator for a single balloon, it can also act as a relay and coordinator for a whole fleet of them.

People can still be useful, increasing the time near potential points of interest if they participated in the course of the balloon system. But people also have to eat, sleep, and do things besides monitor distant robotic probes, so their response times can sometimes result in a lag that would make them unable to take advantage of current wind conditions. Therefore, a planet-wide automated system could serve as the best and fastest way to find the sensor’s way to these spectacular events.

Once a balloon reaches one, they could even drop a payload directly into the volcano’s caldera, gathering invaluable information, however short-lived the mission. Get enough odds on that, and the discovery of finding a single volcano on Venus will go down in scientific history as we begin to understand what did and did make our twin planet hit.