Science

Telescopes team up to predict extraterrestrial storm on Titan

Telescopes team up to predict extraterrestrial storm on Titan

Two views of Saturn’s moon Titan taken by the James Webb Space Telescope. The image on the left uses a filter sensitive to Titan’s lower atmosphere, and the image on the right is a color composite. At the bottom is an annotated version indicating several features captured in each image. (NASA, ESA, CSA, A. Pagan (STScI), JWST Titan GTO Team via The New York Times)

It was a cloudy day on Titan.

This became clear on the morning of November 5, when Sébastien Rodríguez, an astronomer at the Université Paris Cité, downloaded the first images of Saturn’s largest moon taken by NASA’s James Webb Space Telescope. He saw what looked like a large cloud near the Kraken Mare, a 1,000-foot-deep sea in Titan’s northern polar region.

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“What a wake-up call this morning,” he said in an email to his team. “I think we see a cloud!”

This caused a sort of weather emergency among the Al Rockers in space, causing them to scramble for more coverage.

Titan has long been a jewel of astronomers’ curiosity. Less than half the size of Earth, it has its own atmosphere, thick with methane and nitrogen – and even denser than the air we breathe. When it rains on Titan, it rains gasoline; when it snows, the snow is as black as coffee grounds. Its lakes and streams are full of liquid methane and ethane. Beneath its frozen sediment-like crust lies an ocean of water and ammonia.

Prospective astrobiologists have long wondered whether the chemistry that prevailed during Earth’s early years is being recreated in Titan’s slushy mounds. The potential progenitors of life make the smog-clogged world (where the surface temperature is minus 290 degrees Fahrenheit) a long-term hope for the discovery of alien chemistry.

To that end, missions to Titan are planned, including sending a nuclear-powered drone called Dragonfly to orbit Saturn’s moon by 2034, as well as more conventional trips such as sending a submarine to explore the oceans.

Meanwhile, however, despite observations by Voyager 1 in 1980 and the Cassini Saturn orbiter and its Huygens lander in 2004-5, planetary scientists’ models of Titan’s atmospheric dynamics were still tentative. But the Webb telescope, which launched almost a year ago, has infrared eyes that can see through Titan’s haze.

So when Connor Nixon of NASA’s Goddard Space Flight Center received Rodriquez’s email, he was thrilled.

“We’ve been waiting years to use Webb’s infrared vision to study Titan’s atmosphere,” Nixon said. “Titan’s atmosphere is incredibly interesting, not only because of its methane clouds and storms, but also because of what it can tell us about Titan’s past and future, including whether it always had an atmosphere.”

That same day, Nixon contacted two astronomers—Imke de Pater of the University of California, Berkeley, and Catherine de Clear of the Caltech Institute—who were associated with the twin 10-meter Keck telescopes on Mauna Kea in Hawaii and called themselves the Keck Team Titan. He asked for immediate follow-up observations to see if the clouds were changing and which way the winds were blowing.

As de Pater explained, such last-minute requests are not always possible because telescope time is a precious commodity.

“We’ve been extremely lucky,” she said.

The observer on duty that night, Carl Schmidt of Boston University, was their collaborator in other planetary studies.

The Keck staff, de Pater added, is also eager to support the Webb telescope observations.

“They love solar system objects,” she said, “because they’re just neat and always changing with time.”

With visible-light images from Keck and infrared pictures from the Webb Telescope, Nixon and his colleagues were able to probe Titan from Earth elements through the various layers of its atmosphere—everything a long-term weather forecaster might need.

And there is more to come.

In an email, Nixon said his team is especially excited to see what happens in 2025, when Titan will reach its northern fall equinox.

“Shortly after the last equinox, we saw a giant storm on Titan, so we’re excited to see if the same thing happens again,” he said

© 2022 The New York Times Company

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