The DownlinkDec 24, 2021

Space is always worth the wait

Space Snapshot

Jupiter callisto voyager 1

While we wait as patiently as we can for JWST to launch, let’s look back at an equally awe-inspiring mission: NASA’s twin Voyager spacecraft. This image of Jupiter, with the small moon Callisto on its right, was taken by Voyager 1 on March 3, 1979 as it approached the gas giant. Jupiter is so enormous that this image, captured from 2.3 million kilometers (1.4 million miles) away, was the last full-planet photo taken before the spacecraft’s wide-angle camera could no longer fit the whole of the planet within its field of view. We highly recommend also checking out this jaw-dropping animation of Jupiter’s moving clouds, created from images taken by Voyager 1 as it approached the planet. Image credit: NASA/JPL/Ian Regan.

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Fact Worth Sharing

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Epic missions have equally epic timelines. JWST has been in development for 25 years. The Hubble Space Telescope has been in orbit for 31 years. And the twin Voyager spacecraft have both been in space for a whopping 44 years.

Mission Briefings

Jwst faring separation

Bah humbug: JWST is delayed again, hopefully for the last time. The NASA telescope has once again been bumped for launch, this time due to bad weather. JWST is now expected to blast off from the Guiana Space Center in Kourou, French Guiana on Dec. 25. You can watch the launch live at Pictured: An artist’s impression of the spacecraft being released from the rocket fairing.


SpaceX completed its 100th rocket landing and it was fittingly festive. On Tuesday, Dec. 21, the company launched a Dragon cargo capsule — containing astronaut supplies, scientific experiments and Christmas gifts — attached to a Falcon 9 rocket. The Falcon 9 took off from NASA’s Kennedy Space Center in Florida but clinched its milestone landing on one of SpaceX’s drone ships in the Atlantic Ocean called Just Read the Instructions.

From The Planetary Society

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5,000 years of Mars exploration and counting. A new book from space historian William Sheehan and planetary scientist Jim Bell traces the history of humankind’s relationship with Mars, stretching back more than five millennia. The authors of “Discovering Mars” join this week’s Planetary Radio to look at what we’ve learned about the Red Planet, from the earliest naked-eye observations to the most cutting-edge robotic exploration. Pictured: A composite of images taken by Mariner 4, one of the first missions to fly by Mars. Image credit: NASA/JPL. Bonus: If you liked the Jupiter approach animation, check out this animation of NASA’s Mariner 6 spacecraft’s approach to Mars in 1969.

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JWST demands patience, but there are good reasons for it. Even after it finally launches, we’ll have to wait six months for the first science images from the space telescope. The explanation, which JWST scientist and Planetary Society vice president Heidi Hammel outlines in a new article, reminds us just how magnificently complicated this instrument is. The wait will pay off; the first imaging targets have already been selected, each chosen to show off JWST’s impressive capabilities.

Epic missions don’t just happen. They need your support.

Hubble servicing mission

When you donate to The Planetary Society’s Planetary Fund, you help make historic missions happen. Make a gift today and support our mission to empower the world’s citizens to advance space science and exploration.

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What's Up

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People in the Northern Hemisphere can take advantage of the long winter nights this week, with great visibility of Venus low in the eastern evening sky. Saturn and then Jupiter can be seen to Venus’ upper left. Mercury shines dimly near Venus starting on Dec. 28th. Comet Leonard is still visible in that same part of the evening sky, but with better visibility from the Southern Hemisphere. Learn more at

Wow of the Week

Pluto before and after

NASA’s New Horizons mission was definitely worth the wait. After decades of development and near-cancellations, followed by nine years in transit, the spacecraft arrived at Pluto in 2015 and revolutionized our understanding of the dwarf planet. The image on the left was the highest-resolution photo taken of the tiny world prior to New Horizons’ arrival. On the right: a world finally brought into focus.

We love to feature space artwork in the Downlink. If you create any kind of space-related art, we invite you to send it to us by replying to any Downlink email or writing to [email protected]. Please let us know in your email if you’re a Planetary Society member!