Where will the next stop of the balloon used by NASA to detect the California earthquake? -It may be Venus
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Their goal is to test this technology for future applications on Venus. On Venus, balloons equipped with scientific instruments can float on the extremely uninhabitable surface of the planet. on.
They succeeded in the end. On July 22, 2019 local time, a high-sensitivity barometer (an instrument that measures changes in air pressure) on one of the balloons detected low-frequency sound waves caused by aftershocks on the ground.
The team behind the balloon in June 2021 In an article published in “Geophysical Research Letters” on the 20th, they described a similar technique that helped reveal the deepest secrets of Venus. It is reported that there, the surface temperature is high enough to melt lead, and the atmospheric pressure is high enough to squash a submarine.
Venus is about the same size as the Earth, and it is believed that Venus was once more habitable before it evolved into a place completely different from our habitable world. Scientists are not sure why this happened.
A key way to understand how a rocky planet evolves is to study its interior, and one of the best ways is to measure the seismic waves that bounce off its surface. On Earth, different materials and structures refract these underground waves in different ways. By studying the strength and velocity of waves produced by earthquakes or explosions, seismologists can determine the characteristics of the rock formations below the surface and even pinpoint reservoirs of liquids such as oil or water. These measurements can also be used to detect volcanic and tectonic activity.
“We know a lot about the inside of the earth- -How it cools, its relationship to the earth’s surface, and the place where life lives-all come from the analysis of seismic waves that pass through areas as deep as the core of the earth,” Jennifer M., co-author of the research paper. Jackson pointed out, “Tens of thousands of ground geophones are distributed in a dense or permanent network of space, making this possibility on Earth possible. On other planets, we don’t have this kind of enjoyment, especially on Venus. On. Observation of seismic activity there will strengthen our understanding of rocky planets, but the extreme environment of Venus requires us to study new detection technologies.”
Since 2016, JPL and California Institute of Technology have been This balloon-based seismology technology is being developed. Because seismic waves produce sound waves, information can be translated from underground to the atmosphere. Then, just as seismologists study seismic waves from the ground, valuable scientific data can be collected by studying sound waves from the air.
If this can be achieved on Venus, then scientists will be able to find a way to study the mysterious interior of the planet without having to land any hardware on its extreme surface.
In the aftershocks following the 2019 Ridgecrest earthquake sequence, Attila Komjathy of JPL and his colleagues released two heliotrope balloons and led the event. Based on a design developed by Daniel Bowman, a research co-author at Sandia National Laboratory in Albuquerque, New Mexico, these balloons rise to an altitude of about 11 to 15 miles after being heated by the sun before returning to the ground at dusk. When the balloons floated, the barometers they carried measured changes in the air pressure over the area, and the weak sound vibrations produced by aftershocks propagated in the air.
Quentin Brissaud, a seismologist at the Seismic Laboratory of the California Institute of Technology and the Norwegian Seismic Array (NORSAR), said: “Trying to detect naturally occurring earthquakes with balloons is a challenge. When you see the data for the first time, You will be disappointed at the time, because most low-level earthquakes do not produce strong sound waves in the atmosphere. Various environmental noises are detected; even the balloon itself produces noise.”
In previous tests, the researchers detected a seismic hammer (heavy object falling on the ground) The resulting acoustic signals of seismic waves and explosives detonated on the ground under the tethered balloon. But can researchers use free-floating balloons to do the same thing on natural earthquakes? The main challenge is that there is no guarantee that an earthquake will occur when the balloon is lifted off.
On July 22, they had a lucky breakthrough: the ground seismograph recorded a 4.2 magnitude aftershock nearly 50 miles (80 kilometers) away. About 32 seconds later, when a balloon rose to an altitude of nearly 3 miles (4.8 kilometers), it detected low-frequency acoustic vibrations–a sound wave below the threshold of human hearing, called infrasound–passing the balloon. Through analysis and comparison with computer models and simulations, the researchers confirmed that for the first time they detected a naturally occurring earthquake through the balloon-carried instrument.
“Because Southern California has such a dense network of seismograph ground stations, we can get the’ground truth’ about the time and location of the earthquake,” said Brisaud, the lead author of the research paper, “We detected The seismic waves are closely related to nearby ground stations. Compared with the model data, this convinced us that we heard the earthquake.”
Researchers will continue to fly balloons over seismically active areas to become more familiar Infrasound signals associated with these events. By adding several barometers to the same balloon and releasing multiple balloons at the same time, they hope to determine the location of the earthquake without confirmation from the ground station.
The launch of balloons to Venus has proven to be feasible. In 1985, a cooperative organization led by the former Soviet Union deployed two mission balloons there for more than 46 hours of data transmission. However, neither of the balloons carried equipment to detect seismic activity. Now, this research shows that the technology to detect infrasound on Venus is also possible. In fact, since the atmosphere of Venus is much denser than the Earth, sound waves travel more efficiently.
“According to calculations, the acoustic coupling of earthquakes on Venus into the atmosphere is 60 times stronger than that on Earth, which means that it should be easier to detect Venus earthquakes from a low temperature layer of 50 to 60 kilometers from the atmosphere of Venus,” JPL technology Siddharth Krishnamoorthy, the principal investigator of the research and the researcher, said, “While determining the activity level, we should be able to detect Venus earthquakes, volcanic activity, and outgassing events.”
Krishnamoorthy paired flying on Venus. What is of greatest interest to balloons is that scientists can use them to drift over seismically active areas observed by satellites and find out if they are really active. . “If we drift over a hot spot or look like a volcano from the orbit, the balloon will be able to listen to the sound to determine whether it looks like a terrestrial volcano,” said Krishnamoorthy, one of the technical leaders of Ridgecrest Balloon Sports. “In this way, Balloons can provide real ground data for satellite measurements.”
While the Venus balloon team continues to explore these possibilities, NASA colleagues will continue to advance the agency’s recently selected 2028 to 2030 Two missions to Venus in 2009: VERITAS and DAVINCI+. Among them, VERITAS will study the surface and interior of Venus, while DAVINCI+ will study its atmosphere. The European Space Agency (ESA) also announced its Venus Vision mission. These missions will provide new clues to explain why this once-earth-like planet has become so uninhabitable.