On March 1, 2020, the only human spacecraft orbiting Venus – Japan’s Akatsuki – saw a mysterious flame in the planet’s alien sky. The twinkling could provide vital evidence in a 40-year effort to solve a turbulent planet puzzle: Is there a world of lightning with clouds?
Lightning is found throughout the solar system. A spacecraft has discovered external lightning strikes in the clouds of Jupiter, Saturn, and Uranus. Covered in thick clouds, “we expect to have lightning on Venus” too, says Noam Izenberg, planetary geologist at Johns Hopkins University and vice chairman of the Venus Research Group.
The flame seen by the Akatsuki spacecraft, which means “Dawn” in Japanese, was unveiled by planetary scientist Yukihiro Takahashi of Hokkaido University at this year’s gathering of the American Geophysical Union. Takahashi’s team suspects it was a powerful lightning strike, about 10 times more dynamic than lightning on Earth, or a giant meteor that exploded in the planet’s atmosphere.
The flame was spotted by the craft’s Lightning Camera and Airglow, a device that has been scanning Venus clouds for five years – just now picking up the first flame of light. This is one of the most promising signs of lightning on Venus, but the team is still analyzing the data, and members have refused to discuss the research until it is published in a peer – reviewed paper.
“Lightning has been controversial in Venus for many decades,” Takahashi said in his speech.
Surprising evidence of Venusian lightning has been seen in the past, from electromagnetic impacts measured by a spacecraft to pulses of light seen from Earth. But each time, scientists have questioned whether the signals came from lightning or another source, such as flashes of grains from a deep space called cosmic rays, or from sound created by the scientific instruments themselves.
To mark the source of the recent flash, astronauts are hoping to see another one. “It’s interesting, and they’re doing the work to eliminate other things,” said Izenberg, who is not involved in the new research. But “the proof is going to be in the mud to see it again. ”
If the lightning were lightning, it would be a huge step towards the mysterious nature of Venus’ thick clouds – giving an idea of whether such an environment could support life. “[Lightning] it can break down atoms, and give you free radicals that propagate and form molecules that you wouldn’t expect to receive, ”says Colin Wilson, a planetary scientist at Oxford University.
Whistles in the maelstrom
Scientists have been searching for lightning on Venus for nearly fifty years, searching through telescopes and monitoring for electromagnetic pressure by a spacecraft. NASA’s Cassini spacecraft, which was easily found lightning on Earth, was flown by Venus twice in the late 1990s on its way to Saturn and did not pick up any missiles.
But there are earlier advertisements. Some Venera landowners of the Soviet Union, launched between the 1960s and 1980s, recorded suspicious recordings of magnetic and acoustic sensors. The United States’ Pioneer Venus Orbiter triggered energetic explosions in the 1980s, as did the radio attached to the Galileo probe when it went down in 1990 on its way to Jupiter. An earth-based telescope saw several light-emitting splotches on Venus in the mid-1990s.
“None of that has been absolutely certain,” said Karen Aplin, a physicist at the University of Bristol who studies planetary lightning. “In general, it was difficult to block other interpretations. ”
The European Space Agency’s Venus Express spacecraft, which orbited the planet from 2006 to 2015, heard many “whistling” radio waves emanating from the planet. On Earth, these signals – named by World War I radio operators who heard whistling sounds on the radio and worried that they could be incoming grenades – could be generated by lightning. .
However, “whistling mode waves can be generated by any kind of instability or turbulence in the atmosphere,” says Shannon Curry, planetary physicist at the University of California, Berkeley. They regularly hear them coming from Venus and Mars, and it is possible that these signals are coming from unseen lightning, but astronomers cannot be sure.
Seeing is believing
Most of the optical searches did not come for lightning – look for the visible flavors. One possibility, Wilson says, is that “the source of the lightning is under the roof of the clouds, which means that the radio waves are emitted, but much of the light is blocked.”
The Akatsuki spacecraft can detect faint flashes of light escaping from the clouds of Venus. However, since the craft suffered a bad engine and did not go into orbit around Venus in 2010, it had to orbit the solar system and try again in 2015. Although Akatsuki succeeded in entering Venus’ orbit on the second attempt, he had to settle for too long an orbit that will keep the craft far away from the planet most of the time.
After half a decade, however, Akatsuki saw a flash of light. “I’m surprised they never saw him again,” Curry says. “The fact that they only saw it once bothers me,” because lightning should appear in collections. But “I find the truth I believe.”
The flash doesn’t look like it could have been caused by a cosmic ray, although Akatsuki’s team thinks it may have been a bolide – a meteor that explodes into the atmosphere with a bright flame. Those like Akatsuki see bolide, based on what we know about how often they hit planets, however, is very unlikely.
For now, lightning is the main explanation.
“An isolated case of an instrument error that occurs as a real signal would be a remarkable coincidence,” said Ricky Hart, a graduate student at the University of California, Los Angeles, who studies signals from a potential electronics. on Venus. The shower, he said, “well supports the case for lightning on Venus. ”
Mystery in thick clouds of alien
If the lightning is lightning, what does it do? Hunting astronauts for the answer to this question believe it could transform what we know about Venus’ skies.
The planet’s sulfuric acid clouds are unique in the solar system, so traditional models of lightning generation do not belong to Venus, Aplin says. One issue is that its clouds are thought to carry relatively little electricity, which could prevent electricity from accumulating in one place to the place where lightning is triggered.
Earth’s clouds separate droplets of water with electricity and ice crystals through communication – when warmer clouds move up and colder clouds sink – resulting in lightning. But it’s not clear how much direct mixing will occur in the clouds of Venus, says Paul Byrne, a planetary scientist at North Carolina State University. And Akatsuki can’t put the height of the flash, so if it were lightning, it could have struck from anywhere between the high atmosphere and the main cloud deck tens of miles deeper.
One chance is that a lightning strike on Venus will follow volcanic eruptions. Although an explosion has not been observed directly through the hidden clouds of the planet, there is evidence around many planetary scientists to prove that an explosion does occur nonetheless. Explosive events could result in the unplugging of an electrical, lightning-bolted plug.
Whether this discovery is true or not, planetary scientists will continue to search for more flavors, wanting to find out if alchemic lightning power is working on Venus.
“Lightning is attractive, as a process. It’s active, ”Izenberg says. It could “be one of the potential engines for prebiotic chemistry on Venus,” meaning the explosions could bring together molecular energy needed for life. If this process occurs in parts of the atmosphere that are known to be watery, medium and sunny, it could create a potential space for photosynthetic microbes.
Lightning may be responsible for the production of the phosphine gas, a fertilizer recently discovered on Venus – although some experts have questioned whether the discovery is valid – and it is known that produced by microbes on Earth. If this gas is actually in the Venusian clouds, some of it can be created by lightning interacting with the atmosphere.
Dual observations made with terrestrial telescopes and Akatsuki would go a long way in convincing the public that lightning is a sign, Curry says. But until humanity sends a new mission to Venus to dive through the atmosphere or fly near the tops of the clouds, lightning is likely to remain an open issue, Byrne says.
Little wonder about Venus, a world that is about the same size and size as Earth but whose evolution has been very different. This flash, Izenberg says, is “another argument that says we need to go back.”