Can we detect volcanic eruptions and venusquakes from a balloon floating high above Venus?
Siddharth Krishnamoorthy – siddharth.krishnamoorthy@jpl.nasa.gov
NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, United States
Daniel C. Bowman2, Emalee Hough3, Zach Yap3, John D. Wilding4, Jamey Jacob3, Brian Elbing3, Léo Martire1, Attila Komjathy1, Michael T. Pauken1, James A. Cutts1, Jennifer M. Jackson4, Raphaël F. Garcia5, and David Mimoun5
1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
2. Sandia National Laboratories, Albuquerque, New Mexico, USA
3. Oklahoma State University, Stillwater, OK, USA
4. Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA
5. Institut Supérieur de l’Aéronautique et de l’Espace (ISAE-SUPAERO), Toulouse, France
Popular version of 4aPAa1 – Development of Balloon-Based Seismology for Venus through Earth-Analog Experiments and Simulations
Presented at the 184 ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0018837
Venus has often been described as a “hellscape” and deservedly so – the surface of Venus simultaneously scorches and crushes spacecraft that land on it with temperatures exceeding 460 degrees Celsius (~850 F) and atmospheric pressure exceeding 90 atmospheres. While the conditions on the surface of Venus are extreme, the temperature and pressure drop dramatically with altitude. At about 50-60 km above the surface, temperature (-10-70 C) and pressure (~0.2-1 atmosphere) resemble that on Earth. At this altitude, the challenge of surviving clouds of sulfuric acid is more manageable than that of surviving the simultaneous squeeze and scorch at the surface. This is evidenced by the fact that the two VeGa balloons floated in the atmosphere of Venus by the Soviet Union in 1985 transmitted data for approximately 48 hours (and presumably survived for much longer) compared to 2 hours and 7 minutes, which is the longest any spacecraft landed on the surface has survived. A new generation of Venus balloons is now being designed that can last over 100 days and can change their altitude to navigate different layers of Venus’ atmosphere. Our research focuses on developing technology to detect signatures of volcanic eruptions and “venusquakes” from balloons in the Venus clouds. Doing so allows us to quantify the level of ongoing activity on Venus, and associate this activity with maps of the surface, which in turn allows us to study the planet’s interior from high above the surface. Conducting this experiment from a balloon floating at an altitude of 50-60 km above the surface of Venus provides a significantly extended observation period, surpassing the lifespan of any spacecraft landed on the surface with current technology.
We propose to utilize low-frequency sound waves known as infrasound to detect and characterize Venus quakes and volcanic activity. These waves are generated due to coupling between the ground and the atmosphere of the planet – when the ground moves, it acts like a drum that produces weak infrasound waves in the atmosphere, which can then be detected by pressure sensors deployed from balloons as shown in figure 1. On Venus, the process of conversion from ground motion to infrasound is up to 60 times more efficient than Earth.
Figure 1: Infrasound is generated when the atmosphere reverberates in response to the motion of the ground and can be detected on balloons. Infrasound can travel directly from the site of the event to the balloon (epicentral) or be generated by seismic waves as they pass underneath the balloon and travel vertically upward (surface wave infrasound).
We are developing this technique by first demonstrating that earthquakes and volcanic eruptions on Earth can be detected by instruments suspended from balloons. These data also allow us to validate our simulation tools and generate estimates for what such signals may look like on Venus. In flight experiments over the last few years, not just several earthquakes of varying magnitudes and volcanic eruptions, but also other Venus-relevant phenomena such as lightning and mountain waves have been detected from balloons as shown in figure 2.
Figure 2: Venus-relevant events on Earth detected on high-altitude balloons using infrasound. Pressure waves from the originating event travel to the balloon and are recorded by barometers suspended from the balloon.
In the next phase of the project, we will generate a catalog of analogous signals on Venus and develop signal identification tools that can autonomously identify signals of interest on a Venus flight.
Copyright 2023, all rights reserved. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).
Figure 1. a) A satellite image of Sakurajima Volcano, adapted from Kim and Lees (2014). Five stand-alone infrasound sensors were deployed around Showa Crater in July 2013, indicated by inverted triangles. b) An image of a typical explosive eruption observed during the field campaign.
Figure 2. a) Sound pressure level in dB relative to the peak pressure at the source position. b) Variation of infrasound waveforms across the network caused by propagation path effects.
Figure 3. Volume flux history inferred from infrasound data. In Case 1, the Green’s function is computed by 3-D numerical modeling considering volcanic topography. In Case 2, the analytic solution of the wave equation in a half-space is used, neglecting the topography.