Seismology has been ubiquitous on Earth for decades, and missions like InSight have recently provided similar data for the interior of Mars. Understanding the inner workings of the planet is key to understanding its geology and climate. However, the inner workings of Venus, perhaps our closest sister planet, remain a mystery. The sulfuric acid cloud and the scorching surface temperatures probably aren’t helping. But Siddharth Krishnamurthy of NASA’s Jet Propulsion Laboratory and Daniel Bowman of Sandia National Laboratory think they have found a way out using seismometers suspended from balloons.

This idea has been around for a while. However, this may seem counterintuitive – wouldn’t seismometers normally sit on the ground to detect anything? Conventional seismometers, yes. However, another type of seismometer is only now becoming more acceptable. An infrasonic seismometer monitors infrasonic pressure waves generated by seismic activity transmitted from a medium other than the ground, such as the atmosphere.

Venus has a lot of atmosphere, so it seems like an ideal place to use this technology. Even better, the upper reaches of the cloud layer are one of the places in the solar system that most closely resemble the environment on Earth, so there are many ideas for creating “cloud cities” on Venus.

There’s no need to build an entire city to house the sensors that collect infrasound data, so the high-altitude balloon serves the purpose perfectly. This solves one of the most difficult problems of Venus exploration: the development of materials that can survive on its surface. NASA has spent millions of dollars developing radiation-shielded sensors that can withstand extreme pressures and temperatures at the surface. But even these are relatively simple, so a sensor airborne at a reasonable temperature and pressure would not require any extra effort for this particular use case.

In this regard, an obvious question arises – how will the signal reach the sensors floating in the atmosphere from the ground? Earthquakes (or Venus earthquakes as in this case) cause deafening sounds that are then transmitted through the atmosphere at low frequencies. Sensitive microphones, such as those in a balloon, can read these signals.

One such experiment was recently performed on Earth, where an infrasound microphone could pick up signals from two earthquakes of magnitude 7.3 and 7.5, despite being 3,000 km away from the epicenter of earthquakes in the stratosphere. Using this experiment as a template, researchers can develop a similar system for use on Venus, with the appropriate modifications necessary for that planet’s environment. Additionally, it was much farther away than previous experiments with ultrasonic seismometers, and much closer to the actual distance such a sensor would be from the epicenter of an earthquake on Venus.

However, there are still many problems. First, let alone a mission with sensitive seismometers, we failed to successfully launch a balloon at Venus. Second, we got the “ground truth” in the Earth experiment, meaning that researchers knew an earthquake had occurred when they received the signal from other sources. Since there are no other sensors on Venus that can provide such control, researchers will likely have to speculate as to what caused the particular pattern in the data – there may have been an earthquake on Venus, or perhaps the balloon was shaken in some way. .

Also, earthquakes above magnitude seven are considered large here on Earth, and it’s unclear whether seismometers can pick up even smaller earthquakes on our home planet. Venus may have the same range of seismic activity or be even more active, but with lower intensity, making detecting smaller earthquakes a priority. The JPL team recorded a 4.2 magnitude jolt, but the balloon was much closer than a few thousand kilometers.

It’s always a good idea to use technology developed on Earth to explore space, and this seems like a new way to use these seismometers in a new way. However, despite about a dozen missions planned to Venus in the near future, there are currently no mission plans using these features. For now, we will have to wait to understand the inner workings of our nearest sister planet. Source