KECK INSTITUTE FOR SPACE STUDIES

       



NASA Balloon Detects California Earthquake – Next Stop, Venus?

Jennifer Jackson is the William E. Leonhard Professor of Mineral Physics in the Seismological Laboratory at Caltech. Her research focuses on developing experimental methods to better understand planetary interiors. By combining a suite of spectroscopic methods, primarily at advanced radiation sources, Jennifer's group measures the elastic, vibrational, and chemical properties of candidate planetary materials under extreme conditions of pressure and temperature. Through collaborations with colleagues, Jennifer and her group integrate the most recent mineral physics results with seismic observations, geodynamic modeling, and inferences from geochemistry to gain a multi-dimensional understanding of the deepest parts of Earth's interior. "While this is possible on Earth, there are significant challenges to such an approach on other planets - in particular, seismic observations."

The first detection of an earthquake by a balloon has now been demonstrated by scientists at JPL/Caltech/Sandia National Laboratory, paving the way for future balloon-based missions to Venus. Why balloons? Harsh surface conditions on Venus do not favor long-lived deployments of ground-based seismometers, thus demanding innovative approaches to measure seismicity.

Under the auspices of KISS, a multidisciplinary study team was formed to explore the feasibility of investigating the interior of the planet with seismological techniques. Most of the team’s work was conducted in a five-day workshop held at the KISS facility at the California Institute of Technology (Caltech) campus from June 2–6, 2014. This report contains the key findings of that workshop and recommendations for future work.

“The nature of my research involves understanding the composition and physical state of Earth’s interior, through experiments conducted under extreme high-pressure-temperature conditions and interpreted using seismic observations. There are still many unanswered questions about Earth’s interior and its connection to the surface, in particular its evolution through geologic time. The more we learn about other terrestrial planets in our solar system, the more we understand Earth.

To this end, I participated in the 2014 multidisciplinary KISS study and was a co-Lead on the technical follow-on study, Probing the Interior Structure of Venus, which identified aerial-platform infrasound as a promising, albeit unconventional, method to detect seismicity on Venus. Detecting and locating seismic events on Venus would enable us to understand why Venus, although similar to Earth in size and density, lacks an internally-generated magnetic field, has a dense CO2-rich atmosphere, and currently lacks evidence of Earth-like plate tectonics. ”


KISS understands the long lead time necessary for space research and is willing to take on riskier projects in order to demonstrate feasibility.

"The first detection of an earthquake from a balloon is the culmination of a 7 year effort that involved Caltech, JPL, Sandia National Laboratory, and UCLA. The effort also benefited from collaborations with ISAE-SUPAERO, the University of Paris (IPGP) and CNRS-LMD in France. KISS understands the long lead time necessary for space research and is willing to take on riskier projects in order to demonstrate feasibility. After validation, NASA is more willing to fund the next steps. This is indeed what is happening with a grant awarded to JPL-Caltech through NASA’s PSTAR program to detect seismicity in an active region of Oklahoma."

The technique is being developed to detect venusquakes. A new study details how, in 2019, it made the first balloon-borne detection of a quake much closer to home. JPL and Caltech have been developing this balloon-based seismology technique since 2016. Because seismic waves produce sound waves, information is translated from the subsurface and into the atmosphere. Valuable science can then be gathered by studying sound waves from the air.


Detecting and locating seismic events on Venus would enable us to understand why Venus, although similar to Earth in size and density, lacks an internally-generated magnetic field, has a dense CO2-rich atmosphere, and currently lacks evidence of Earth-like plate tectonics.

Jennifer Jackson

Extreme temperature and pressure conditions on the surface of Venus present formidable technological challenges against performing ground-based seismology. Efficient coupling between the Venusian atmosphere and the solid planet theoretically allows the study of seismically generated acoustic waves using balloons in the upper atmosphere, where conditions are far more clement.


The JPL and Caltech researchers will continue flying the balloons over seismically active regions to better understand the infrasound that earthquakes generate on Earth so the technique might one day be applied during a mission to Venus. Credit: NASA/JPL-Caltech