An exciting discovery on Mars

Space Snapshot

NASA’s Perseverance rover has identified a potential biosignature on Mars — the most promising potential hint of ancient life ever discovered on the red planet. On Wednesday, NASA announced that a rock discovered on Mars last year, called “Cheyava Falls,” continues to show signs consistent with past microbial life, though alternate explanations still remain. Patterns on the rock, nicknamed “leopard spots,” could have formed through chemical reactions known to fuel life. Further study is required to know for sure, and Perseverance now carries a sample of the rock to be brought back to Earth as part of NASA’s Mars Sample Return mission. However, that initiative remains in limbo as NASA’s budget is under threat of dramatic cuts. Image credit: NASA / JPL-Caltech / MSSS.

Fact Worth Sharing

Cheyava Falls may be the first single place on Mars known to show signs of once hosting all three of life’s main ingredients: liquid water, energy, and organic molecules. Billions of years ago, this rock could have met all the conditions life needs to thrive.

Mission Briefings

A total lunar eclipse graced the skies of Africa, Asia, Australia, and Europe last Sunday. The next one won't be visible until 2026, but another great time to moon-gaze is coming up sooner: International Observe the Moon Night, scheduled for Oct. 4. On this week's Planetary Radio, host Sarah Al-Ahmed speaks with two of the event’s organizers about how looking to the Moon connects people around the world — just as this week's lunar eclipse did.

Debris from ancient asteroid impacts may survive deep inside Mars. According to a new analysis of Marsquakes measured by NASA's Insight lander, the red planet's mantle could be scattered with fragments leftover from rocky impacts billions of years ago. That would mean Mars has never gone through the sort of internal churning that would have erased these shards — and that other hints about its past may lurk underground.

Astronomers have finally found auroras on Jupiter related to all four of its largest moons. For years, scientists have wondered why Jupiter’s moons Io, Europa, and Ganymede seemed to cause bright glows on the gas giant while Jupiter’s second-largest moon, Callisto, did not. Now the telltale glow has been spotted by NASA’s Juno spacecraft, thanks to a massive stream of particles buffeting Jupiter in just the right way. The discovery reveals more about Callisto and how it interacts with the rest of the Jupiter system.

From The Planetary Society

This week marked Bill Nye’s 15-year anniversary as CEO of The Planetary Society. Bill’s vision, strong leadership, and unwavering commitment to space science and exploration has carried us through some of the most successful years in our organization's history. Whether advocating tirelessly for planetary science on Capitol Hill or fixing the garbage disposal at Planetary HQ, Bill has come to stand for the dynamic culture of care, support, and plain, simple fun that has made The Society into what it is today. Thank you, Bill, for 15 years of inspiring leadership!

A decades-old Uranus mystery has been solved. Since 1986, scientists have wondered why — unlike the Solar System’s other giant planets — Uranus appears to emit less heat than it receives from the Sun. Now astronomers have flipped this picture upside-down. On last week’s Planetary Radio, host Sarah Al-Ahmed spoke with Michael Roman, atmospheric scientist at the Universidad Adolfo Ibáñez in Chile, about what this news means for one of the most mysterious and overlooked planets around the Sun.

Learn about the size of the Universe with our newest children’s book. “The Size of Space” brings the mind-boggling scale of the Universe down to Earth, combining the wonder of a cosmic perspective with easy-to-understand examples. It’s the latest installment in our series created in partnership with Lerner Publishing, which also includes books on the planets of the Solar System and the search for life.

Is NASA declining as SpaceX rises? On Planetary Radio: Space Policy Edition, host Casey Dreier speaks with Franklin Foer, staff writer at The Atlantic, as Foer traces the history of NASA and argues that the agency has accidentally contributed to its own downfall.

Alien life on Mars is not a new idea. Next month, The Planetary Society’s book club will take you back to a time in U.S. history when many — including some scientists — believed that an alien civilization was thriving on Mars. Join Mat Kaplan and David Baron for a live virtual event to discuss Baron’s new book, “The Martians: The True Story of an Alien Craze that Captured Turn-of-the-Century America,” in our Book Club Q&A. Members can join the event in the online member community and participate in discussions with the author. Not yet a member? Join today. Image credit: Liveright Publishing.

Space Advocate Update

It’s been a busy week:

• The U.S. Senate Commerce Committee held a hearing on NASA exploration plans, declaring the U.S. to be in a new “space race” with China.
• Our Chief of Space Policy, Casey Dreier, published a joint op-ed saying that, if the Congress is serious about this new space race, we must continue to invest in space science.
• CEO Bill Nye made the rounds in Congress, meeting with multiple Members of Congress, including Senator Mark Kelly (D-AZ) and Representative Jay Obernolte (R-CA), to talk about the importance of investments in NASA science.

Join us next week for a special briefing on the status of NASA’s 2026 budget. The new fiscal year is rapidly approaching, and with Congress likely to miss the October 1st deadline, Congress must pass a stop-gap funding bill to prevent a government shutdown. What does this mean for NASA and for our efforts to Save NASA Science? On Sept. 17 at 1:00 PM PST, we’ll provide a detailed update on the state-of-play and the likely scenarios facing space science.

We’re also delighted to introduce our first AAAS Policy Fellow. Ari Koeppel, a planetary geoscientist who has previously served on the science teams for NASA’s Curiosity and Perseverance missions, is joining our policy team’s operations in Washington, D.C., for the coming year. This is The Planetary Society’s first fellow hosted through the prestigious American Association for the Advancement of Science (AAAS) Science & Technology Policy Fellowship. Welcome, Ari!

What's Up

This week, look for super bright Venus in the predawn east. Very bright Jupiter is above it, getting farther away in the sky as the weeks pass. Yellowish Saturn rises around sunset in the east and is up most of the night. Reddish Mars is in the evening west and getting lower as the weeks pass. Find out what else to see in September’s night skies.

Carl Sagan. Bill Nye. You.

The Planetary Society was co-founded by Carl Sagan to give you an essential role in space exploration. Not already a member? Join today! When you become a member, you join a global community of space advocates who make a critical difference in supporting a future full of space exploration. Join CEO Bill Nye and become part of the world's most effective independent space advocacy nonprofit!

Wow of the Week

Your name can fly around the Moon as part of NASA’s Artemis II mission. Sign up for the agency’s “Send Your Name with Artemis II” initiative before Jan. 21, 2026, and your name will go on an SD card inside the spacecraft that will carry four astronauts around the Moon and back. The mission, slated for April 2026, will mark the first time that humans have journeyed beyond low-Earth orbit in over 50 years. Image credit: NASA.

Send us your artwork!

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!