NASA Balloon Detects California Earthquake – Next Stop, Venus?|Make a Planetary Exploration Balloon

The technique is being developed to detect venusquakes. A new study details how, in 2019, it made the primary balloon-borne detection of a quake much closer to home.


Between july 4 and July 6, 2019, a sequence of powerful earthquakes rumbled near Ridgecrest, California, triggering quite 10,000 aftershocks over a six-week period. Seeing an opportunity, researchers from NASA’s Jet Propulsion Laboratory and Caltech flew instruments attached to high-altitude balloons over the region in hopes of making the first balloon-borne detection of a naturally occurring earthquake.

When heated by the Sun, these balloons rise into the atmosphere; at dusk they descend. The low-frequency acoustic waves generated by an aftershock were recorded by one of the balloons as it ascended during one flight on July 22, 2019.
When heated by the Sun, these balloons rise into the atmosphere; at dusk they descend. The low-frequency acoustic waves generated by an aftershock were recorded by one of the balloons as it ascended during one flight on July 22, 2019.
Credits: NASA/JPL-Caltech

Their goal: to check the technology for future applications at Venus, where balloons equipped with science instruments could float above the planet’s exceedingly inhospitable surface.


And they succeeded. On July 22, sensitive barometers (instruments that measure changes in air pressure) on one among the balloons detected the low-frequency sound waves caused by an aftershock on the ground.

In their new study, published on June 20 in Geophysical Research Letters, the team behind the balloons describes how an identical technique could help reveal the innermost mysteries of Venus, where surface temperatures are hot enough to melt lead and atmospheric pressures are high enough to crush a submarine.

Planetary Rumbles 


Approximately the dimensions of Earth, Venus is assumed to possess once been more hospitable before evolving into an area that’s remarkably different from our habitable world. Scientists aren’t sure why that happened.


One key thanks to understand how a rocky planet evolved is to study what’s inside, and one among the simplest ways to try to to that’s to measure the seismic waves that bounce around below its surface. On Earth, different materials and structures refract these subsurface waves in several ways.

By studying the strength and speed of waves produced by an earthquake or explosion, seismologists can determine the character of rocky layers beneath the surface and even pinpoint reservoirs of liquid, such as oil or water. These measurements also can be wont to detect volcanic and tectonic activity.

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.
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.
Credits: NASA/JPL-Caltech


“Much of our understanding about Earth’s interior – how it cools and its relationship to the surface, where life resides – comes from the analysis of seismic waves that traverse regions as deep as Earth’s inner core,” said Jennifer M. Jackson, the William E. Leonhard Professor of Mineral Physics at Caltech’s Seismological Laboratory and a study co-author.

“Tens of thousands of ground-based seismometers populate spatially-dense or permanent networks, enabling this possibility on Earth. We don’t have this luxury on other planetary bodies, particularly on Venus. Observations of seismic activity there would strengthen our understanding of rocky planets, but Venus’ extreme environment requires us to research novel detection techniques.”


JPL and Caltech are 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 during a similar way that seismologists would study seismic waves from the ground.


If this might be achieved at Venus, scientists will have found how to review the planet’s enigmatic interior without having to land any hardware on its extreme surface.

The Ridgecrest Quakes


During the aftershocks following the 2019 Ridgecrest earthquake sequence, JPL’s Attila Komjathy and his colleagues led the campaign by releasing two “heliotrope” balloons. Based on a design developed by study co-author Daniel Bowman of Sandia National Laboratories in Albuquerque, New Mexico , the balloons rise to altitudes of about 11 to fifteen miles (18 to 24 kilometers) when heated by the Sun and return to the ground at dusk.

As the balloons drifted, barometers they carried measured changes in atmospheric pressure over the region while the faint acoustic vibrations of the aftershocks traveled through the air.

One of the “heliotrope” balloons is being prepared for flight soon after the 2019 Ridgecrest earthquake sequence. The balloons were launched from California’s Mojave Desert and allowed to drift over the region.
One of the “heliotrope” balloons is being prepared for flight soon after the 2019 Ridgecrest earthquake sequence. The balloons were launched from California’s Mojave Desert and allowed to drift over the region.
Credits: NASA/JPL-Caltech


“Trying to detect present earthquakes from balloons may be a challenge, and once you first check out the info , you’ll feel disappointed, as most low-magnitude quakes don’t produce strong sound waves in the atmosphere,” said Quentin Brissaud, a seismologist at Caltech’s Seismological Laboratory and the Norwegian Seismic Array (NORSAR) in Oslo, Norway. “All sorts of environmental noise is detected; even the balloons themselves generate noise.”


During previous tests, the researchers detected the acoustic signals from seismic waves generated by a seismic hammer (a heavy mass that’s dropped to the ground), also as explosives detonated on the ground below tethered balloons. But could the researchers do an equivalent with free-floating balloons above a natural earthquake? The main challenge among others: There was no guarantee an earthquake would even happen while the balloons were aloft.


On July 22, that they had a lucky break: Ground-based seismometers registered a magnitude 4.2 aftershock nearly 50 miles (80 kilometers) away. About 32 seconds later, one balloon detected a low-frequency acoustic vibration – a type of sound wave below the threshold of human hearing called infrasound – wash over it as it was ascending to an altitude of nearly 3 miles (4.8 kilometers). Through analysis and comparisons with computer models and simulations, the researchers confirmed that they had, for the first time, detected a naturally occurring earthquake from a balloon-borne instrument.


“Because there’s such a dense network of seismometer ground stations in Southern California, we were ready to get the ‘ground truth’ on timing of the quake and its location,” said Brissaud, the study’s lead author. “The wave we detected was strongly correlated with nearby ground stations, and in comparison to modeled data, that convinced us – we had heard an earthquake.”


The researchers will continue flying the balloons over seismically active regions to become more conversant in the infrasound signatures related to these events. By adding several barometers to an equivalent balloon and flying multiple balloons directly , they hope to pinpoint where a quake occurs without having confirmation from ground stations.

From California to Venus

Sending balloons to Venus has already been proven feasible. The two Vega mission balloons deployed there in 1985 by a Soviet-led cooperative transmitted data for over 46 hours. Neither carried instruments to detect seismic activity. Now this study demonstrates that the technique for detecting infrasound at Venus may be possible also . In fact, because Venus’ atmosphere is far denser than Earth’s, sound waves travel much more efficiently.


“The acoustic coupling of quakes into the atmosphere is calculated to be 60 times stronger on Venus than on Earth, meaning it should be easier to detect venusquakes from the cool layers of Venus’ atmosphere between 50 to 60 kilometers [about 31 to 37 miles] in altitude,” said JPL technologist Siddharth Krishnamoorthy, principal investigator of the analysis effort. “We should be ready to detect venusquakes, volcanic processes, and outgassing events while characterizing the amount of activity.”


What interests Krishnamoorthy the foremost about flying balloons on Venus is that scientists could use them to drift over regions that appear as if they ought to be seismically active supported satellite observations and determine whether or not they really are. “If we drift over a hotspot, or what seems like a volcano from orbit, the balloon would be ready to listen for acoustic clues to figure out if it’s indeed acting sort of a terrestrial volcano,” said Krishnamoorthy, who was also technical lead for the Ridgecrest balloon campaign. “In this manner , balloons could provide the bottom truth for satellite measurements.”


While the Venus balloon team continues to explore those possibilities, colleagues at NASA are going to be moving ahead with two missions the agency recently selected to travel to Venus between 2028 and 2030: VERITAS will study the planet’s surface and interior, and DAVINCI+ will study its atmosphere. ESA (European Space Agency) has also announced its own mission to Venus, EnVision. These missions will offer new clues on why the once-Earth-like planet became so inhospitable.

You might already know that NASA uses spacecraft and satellites to explore space, but did you know we also use balloons? In this project, you’ll find out how NASA uses balloons to explore Earth and space and then take on a challenge to design your own balloon explorer inspired by what you’ve learned!

Make a Planetary Exploration Balloon

You might already know that NASA uses spacecraft and satellites to explore space, but did you know we also use balloons? In this project, you’ll find out how NASA uses balloons to explore Earth and space and then take on a challenge to design your own balloon explorer inspired by what you’ve learned!

Make a Planetary Exploration Balloon

Materials

  • 2-3 latex balloons filled with helium (Mylar balloons are not recommended)
  • Paper or plastic cup, or another small container
  • String or ribbon (approximately 36 inches, or 1 meter)
  • Tape
  • Ruler or measuring tape
  • Stopwatch, smartphone timer, or online timer
  • Small objects such as plastic beads, metal washers, or other items to serve as ballast (material that will help keep your design stable)
  • (Optional) scale for measuring mass (kitchen scale with ounces or grams)
  • (Optional) hanging scale for measuring the upward force of the balloon
Make a Planetary Exploration Balloon

1. Learn about scientific balloons

When people think of NASA, they don’t usually think of balloons. But NASA has been using balloons to explore Earth and space since 1983! NASA launches 10-15 balloons a year from locations around the world for technology development, scientific research, and education purposes.

Balloon missions are cheaper than space missions and they also take less time to plan and develop than a spacecraft. Because of this, NASA can test out new technologies on balloon missions before sending the technology all the way to space.

NASA uses balloons in many different ways. In 2014, they used a balloon to test technology for landing on Mars.

In 2019, the first detection of an earthquake from a balloon was made using sensors floating about 16,000 feet (4.8 kilometers) high. In the future, NASA hopes to use balloons floating in Venus’ atmosphere to detect quakes – something that can’t be done on Venus’ incredibly hot, high-pressure surface.

In 2023, NASA plans to launch a telescope aboard a balloon as part of the ASTHROS mission – short for Astrophysics Stratospheric Telescope for High Spectral Resolution Observations at Submillimeter-wavelengths. The ASTHROS balloon will spend three to four weeks floating about 130,000 feet (40,000 meters) above Antarctica observing star-forming regions of space as well as planets forming around newborn stars.

NASA is also studying the use of balloons to explore places like Mars, Venus, and Saturn’s moon Titan. Balloon missions to these places could allow for measurements at different altitudes that other types of spacecraft can’t reach.


About the image: This illustration shows a balloon ascending into Earth’s upper atmosphere while carrying a small scientific device. Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab/Michael Lentz | 

Make a Planetary Exploration Balloon

2. Think about forces

Now, it’s your turn to design your own balloon explorer. But before you begin, consider this: When a balloon floats, rises or falls, different forces act on the balloon. Think about how a force like gravity will pull on a balloon, and how a force like lift will push on a balloon. Then, draw a balloon and add arrows representing gravity and lift. Draw the arrows so that they point in the direction that each force acts on the balloon.

Make a Planetary Exploration Balloon

3. Brainstorm and sketch your design

Think of ways you can combine the materials you have (balloon, cup, string or ribbon, and tape) to make a gondola that will hang from your balloon. Note: Your gondola will need to stay attached to the balloon and hold the items you place inside of it in Step 6.

Sketch your design, but be ready to make changes as you build and test.

Make a Planetary Exploration Balloon

4. Choose your mission

Decide which of the following three mission challenges you want to complete.

  • Maintain altitude: Find the right amount of objects to place in the gondola that will cause the balloon to float and maintain a steady altitude, or height above the surface, of approximately 36 inches (1 meter) for 30 seconds.
  • Controlled ascent: Find the right amount of objects to place in the cup that will cause the balloon to slowly rise at a rate between 10 and 20 inches per second (0.25 to 0.5 meters per second).
  • Controlled descent: Find the right amount of objects to place in the cup that will cause the balloon to fall at a slow rate between 10 and 20 inches per second (0.25 to 0.5 meters per second).

Predict how many objects you will need to successfully complete your challenge. You can attempt other challenges after completing one and compare your results.

Make a Planetary Exploration Balloon

5. Build your balloon and gondola system

Build your balloon and gondola system according to your design. Note: So your balloon doesn’t pop or float away and contribute to land and air pollution, remember to build and fly your balloon indoors.

While you build, place several objects such as beads, metal washers or coins in the gondola as it hangs from the balloon to make sure the items stay inside. (These items will act as ballast–material that stabilizes balloon flight and controls the rate of rise and fall.) If you need to, adjust your design so it can better support ballast placed in the gondola. Remember, you may need to use more than one balloon to support the weight of your gondola as well as the objects placed inside of it.

Make a Planetary Exploration Balloon

6. Complete the challenge

With your balloon and gondola system built, add the number of objects you predicted to the gondola and observe how your design performs. You may need to add or remove objects from the gondola, depending on what you notice about how it performs.

You can measure the performance of your design to see if you met the goals of the challenge using one of these methods:

  • Tape a meter stick against a wall, or tape height markings on the wall that you can use to measure the height of your balloon during your test flights.
  • Use a stopwatch to measure the time it takes your balloon to rise or fall and calculate the rate (inches / seconds).
  • Use the camera on a mobile device to record your balloon’s rise or fall and calculate the rate using the time count of your video.
Make a Planetary Exploration Balloon

7. Analyze your results

How close was your prediction to the number of items you actually needed?

If you have a scale, remove the balloons from the gondola system. Weigh the gondola with the objects inside. When measuring the weight of your gondola, be sure to include any ribbon or tape that you used.

Make a Planetary Exploration Balloon

Think about your balloon flight and think back to the forces you drew in Step 2. Can you improve your balloon’s flight? Try one of the following ideas for your next flight!

  • Speed up your balloon: Increase the speed at which your balloon moved up or down while maintaining a controlled float.
  • Slow down your balloon: Decrease the speed at which your balloon moved up or down while maintaining a controlled float.
  • Choose one of the other challenges in Step 4 and use what you learned from your first flight to better predict how much ballast you’ll need to add.