We know that Venus, our closest planetary neighbour, has a volcanic terrain and a hellish atmosphere with extreme temperatures. But we don’t know much about seismic activity on the planet, which in turn could give us more clues about its internal composition.
Now, NASA has a rather exciting proposal to try and answer those questions: a bunch of hot air balloons.
Recent tests carried out in the Nevada desert show that helium-filled balloons – either tethered or free-flying – can indeed be used to measure vibrations and quakes happening far below, and if the technology can be transferred to the second planet from the Sun it could give us unprecedented insight into its make-up and history.
The heat and pressure on the surface of Venus mean that any lander probe that tries to monitor Venusquakes would quickly get crushed and melted out of existence. However, the conditions in the upper atmosphere are much more clement.
“We’ve never made a direct seismic measurement on Venus,” Siddharth Krishnamoorthy, from NASA’s Jet Propulsion Laboratory (JPL) in California, told Adam Mann at Science Magazine. “There is a lot balloons can offer in terms of unlocking some major questions about the planet.”
For the Nevada desert test carried out on the 19th of December, a team from the US Department of Energy created a magnitude 3-4 tremor with the help of a 50-ton chemical explosion that happened around 300 metres (984 feet) underground.
Up in the sky above, two helium-filled balloons were carrying instruments to detect changes in atmospheric pressure and low-frequency infrasound waves beyond our hearing – both tell-tale signs of earthquake activity. One balloon was tethered to the ground, while the other was left to float freely.
Add the new experiments to previous tests carried out last year, and it seems this sort of approach might work on Venus. A pair of Russian balloons were used to explore the Venusian atmosphere back in the 1980s, though they only lasted for a couple of days and weren’t designed to measure seismic activity.
Getting this tech working on Venus won’t be easy though, even with that precedent. While the atmosphere on Venus is thicker – and therefore easier to measure infrasound waves through – it’s also home to supersonic winds that could quickly confuse the balloon’s finely tuned instruments.
Nevertheless, the scientists think balloons could measure quakes as slight as magnitude 2, and help confirm a long-running hypothesis that heat is still trying to escape the core of the planet Venus – a process that would trigger surface tremors.
While Venus shares a lot of similarities with Earth (including its mass and proximity to the Sun), there are also plenty of questions about why it ended up evolving so differently, with no magnetic field and no water. A fleet of hot air balloons dispatched to measure Venusquakes could help us find some answers to those questions.
Future experiments are planned in Oklahoma as the NASA team works to get the technology more accurate and operating over longer distances. After that, it might be time to start prepping a mission to Venus.
Meanwhile, NASA is also working on a plan to develop drones capable of operating in the Venusian atmosphere – which at 96 percent carbon dioxide is rather toxic, though pressures and temperatures away from the planet’s surface are similar to those on Earth. These remote workers could teach us more about Venus even from a long way up.
“We know, with a degree of certainty, that Venus has no global plate tectonics like on Earth,” Krishnamoorthy told Seeker last year. “Below the surface, there is seismic activity of a different nature, but we don’t know exactly what.”