The DownlinkNov 20, 2020

Atmospheres that intrigue, protect, and obscure

Space Snapshot

Mars atmosphere viking

This vintage space image from NASA’s Viking Mars orbiter shows the veil-like Martian atmosphere. Every planet in our solar system has some kind of atmosphere, even if extremely thin and tenuous. As we discover and study exoplanets, there is much we can learn about the nature and diversity of atmospheres in the cosmos.

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Fact Worth Sharing

Jupiter illustration

On Jupiter, there is no clear boundary between the atmosphere and the liquid interior of the planet. Likewise, there is no sudden boundary as the atmosphere ends and the vacuum of space begins. A gas giant is a continuum between nothingness and density.

Mission Briefings

Hot exoplanet

A new exoplanet mission is one step closer to reality. The European Space Agency’s Ariel mission has moved into its implementation phase. Ariel will survey about 1,000 exoplanets, measuring the chemical makeup of their atmospheres as they cross in front of or behind their host stars. This mission will give scientists a better idea of the possible types of worlds around other stars. Pictured: An artist’s impression of an exoplanet transiting in front of its star. Image credit: ESA/ATG medialab.


Europa’s plumes are complicated. Jupiter’s icy moon has a subsurface ocean and water plumes that vent into space. It’s easy to imagine those plumes are all linked to the ocean, but new research suggests some may originate from pockets of water within the crust, formed by comet or asteroid impacts. Not all of Europa’s plumes can be explained this way, which bodes well for missions like Europa Clipper that aim to sample ocean plumes, looking for signs that those subsurface waters could support life.


SpaceX successfully launched 4 new astronauts to the International Space Station. The Crew-1 mission marks the start of regular astronaut flights by SpaceX to the International Space Station, following a successful crewed test flight in mid-2020. The astronauts will stay aboard for about 6 months.


That’s no moon—it’s an old rocket booster! Scientists at NASA’s Jet Propulsion Laboratory were puzzled over Earth’s newest moon: an object in orbit around the Earth, temporarily captured by our planet’s gravity. Tracing the object’s trajectory back through time, they discovered it came from Earth itself in 1966, when NASA launched Surveyor 2 to the Moon. The object is likely the rocket’s upper stage.


NASA released a new selfie from its Mars Curiosity rover. The rover captured the images needed for the selfie at a location named Mary Anning where scientists suspect conditions on Mars were once favorable for life. The site is named after a 19th-century English paleontologist whose discovery of marine-reptile fossils was ignored for generations because of her gender and class. Learn why the mission matters.

From The Planetary Society

Mars impact crater mro
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The surface of Mars is a beautiful place. We know this very well, thanks in part to two extraordinarily productive NASA spacecraft. On this week's Planetary Radio, Jeffrey Plaut and Richard Zurek, project scientists for Mars Odyssey and the Mars Reconnaissance Orbiter (MRO) respectively, chat with host Mat Kaplan about studying the Red Planet from above. You can also learn all about how the results of the recent U.S. elections might affect NASA in the most recent episode of Planetary Radio: Space Policy Edition. Pictured: MRO captured this image of a newly formed impact crater in 2019. If Mars had a thick atmosphere like ours, fewer asteroids would reach the surface. Image credit: NASA/JPL/University of Arizona.

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Cast your vote for the best of 2020! As the year comes to an end, we’re looking back at the amazing advances that have happened in space science and exploration. What were the highlights for you? Cast your vote today to choose 2020’s best space images, mission milestones, and feats of exploration, and help us celebrate a fantastic year in space. Voting ends on 30 November.

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The next chapter of Mars exploration is upon us, and we’re getting ready to celebrate! In February 2021, three missions will arrive at Mars: Perseverance, Tianwen-1, and Hope. To mark these exciting arrivals, we’re throwing a party. Planetfest, our signature festival for major exploration milestones, will bring together Planetary Society members and supporters from around the world for a virtual event. To deliver the best celebration possible, we want to hear from you. Tell us in this quick form: What would make Planetfest ’21 a valuable experience for you?

What's Up

Mars illustration

In the early evening, look for bright Jupiter with slightly dimmer Saturn to its left. Further to the east, Mars shines bright and reddish. In the predawn sky, Venus is unmistakable in the eastern sky. Learn more at

Wow of the Week

Titan through atmosphere

Atmospheres can shroud a world in mystery, but they’re no match for modern scientific instruments. This near-infrared image of Saturn’s moon Titan peers through its extremely thick atmosphere to see the surface below. With lakes of liquid ethane and methane, Titan’s surface is one of the most unique and intriguing in our solar system.

Do you have a suggestion for the Wow of the Week? We’re looking for space-related art, music, gadgets, quotes, fashion, burning questions, brief sci-fi passages, or anything else that will make our readers go “Wow!” Send us your idea by replying to any Downlink email or writing to [email protected], and please let us know if you’re a Planetary Society member.