The DownlinkFeb 05, 2021

The ISS in perspective, and bad news for Venusians

Space Snapshot

Moon from iss

A full Moon looks down on Earth’s beautiful blue and white atmosphere in this photo taken from the International Space Station in 2019. Scroll down to this week’s “Wow” to see things from another perspective. Image credit: NASA.

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Fact Worth Sharing

Earth illustration

The ISS is 109 meters (356 feet) end-to-end. That’s one yard shy of an American football field, including the end zones. If you watch this weekend's Super Bowl, take a moment to appreciate just how big this marvel of engineering really is.

Mission Briefings

Venus upper clouds

Two new papers challenge the discovery of phosphine in Venus’ atmosphere. The original announcement of the detection of phosphine—a chemical associated with life—came in September 2020. Since then, other scientists have challenged the findings. One of the new papers argues that sulfur dioxide could be producing the phosphine signal. New observations of Venus are planned in the coming weeks and months. Pictured: Venus’ upper clouds imaged in infrared by JAXA’s Akatsuki spacecraft. Image credit: JAXA/DARTS/ISAS.


The first 2 of 3 new Mars missions arrive next week. The United Arab Emirates’ Hope spacecraft enters orbit on Tuesday, and China’s Tianwen-1 enters orbit Wednesday. Both launched in mid-2020. Tianwen-1 includes a rover; the rover will remain attached for now with a landing planned for May. For the latest news, see our Mars 2021 Missions Arrival Guide.


SpaceX plans to launch 4 private astronauts into orbit on a 4-day mission in late 2021. Tech entrepreneur Jared Isaacman purchased the flight at an undisclosed price. His fellow passengers will be a healthcare worker, the winner of a charity raffle, and a contest winner from a pool of people who use his company’s software to launch an online store.


SpaceX’s big Starship rocket flew again, but didn’t stick its landing. The company, which plans to use Starship to send humans to Mars, is conducting high-altitude test flights in Texas. This one ended the way the first did, with a spectacular crash-landing. Another test vehicle is already waiting in the wings. Learn how NASA and SpaceX rely on one another for success.


NASA astronauts Michael Hopkins and Victor Glover completed a second spacewalk outside the International Space Station. The crew members, who arrived at the ISS via SpaceX’s second astronaut flight in November, wrapped up battery replacement work that began in 2017 and installed a new high-definition camera.


The Space Launch System will conduct a second test-firing of its engines. NASA says a faulty wire harness and overly conservative test parameters stopped the first test of the big rocket. The second test is scheduled for the week of 21 February.

From The Planetary Society

Hale dome trails
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Every discovery has a story behind it. This week on Planetary Radio, astronomer Linda Schweizer shares some of the best ones. She’s spent countless hours interviewing the explorers who revolutionized astronomy at California’s Palomar Observatory, all documented in her new book Cosmic Odyssey: How Intrepid Astronomers at Palomar Observatory Changed our View of the Universe. Pictured: The Hale Telescope and its dome at Palomar Observatory. Image credit: Palomar/Caltech

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With Hope nearing Mars, its team is relying on more than just high hopes. In a recent webinar moderated by Planetary Radio host Mat Kaplan, the U.A.E.’s Minister of State for Advanced Technology Her Excellency Sarah Al Amiri discussed the skill and preparedness that the Hope team is bringing to every stage of the mission. Education in science, technology, engineering, and mathematics has played a big role in realizing the nation’s space exploration ambitions. Hope will conduct the difficult maneuvers necessary to enter Mars orbit on 9 February.

What's Up

Mars illustration

Mars is fading, but still looks like a bright reddish star in the evening sky. You can find it near the constellation Orion, although nearby reddish star Aldebaran could be mistaken for the Red Planet. Learn more at

Wow of the Week

Iss moon transit

Dubai photographer Florian Kriechbaumer captured this photo of the International Space Station passing in front of the Moon, an event that took less than 1 second. You can find more of Florian’s photography work at

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.