Today's episode — S05E183, Wednesday September 2, 2026: Main story: A thermal anomaly beneath Mars's south pole. Writing in Nature on August 27, a team led by Alexander Berne (Caltech PhD '26, now University of Arizona) reports that the interior of Mars's southern hemisphere is 200–400 °C hotter than the northern hemisphere and partially molten. The team used tidal tomography — measuring how much the solid body of Mars flexes under the Sun's tidal pull by tracking minute velocity changes in three orbiters (Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter) across roughly 25 years of radio tracking data. Hotter, softer rock deforms more, so the degree of flex reveals interior temperature. The result offers a deep-interior explanation for the Martian crustal dichotomy — the sharp division between the smooth low northern plains and the ancient, thickly crusted southern highlands, unexplained since the Viking era — and also accounts for the concentration of crustal magnetic anomalies in the south and the unexpectedly strong seismic-wave damping seen by InSight. The cause of the asymmetry remains open: a giant early impact, lopsided mantle convection, or a heat-trapping compositional layer. Co-authors span Brown University, NASA Goddard, the University of Arizona, Academia Sinica, the University of Rome, TU Delft, UCLA, UT Austin, CU Boulder and UC Santa Cruz. Crew-13 stands down. NASA and SpaceX announced on August 29 that an oxidizer leak had been found in the Dragon spacecraft's propulsion system during standard prelaunch processing, delaying the Crew-13 launch from its September 12 target. Teams are performing additional tests and data review and will complete any necessary rework before flight; a new target date will be announced once available. The crew is commander Jessica Watkins (NASA), pilot Luke Delaney (NASA), and mission specialists Joshua Kutryk (CSA) and Sergey Teteryatnikov (Roscosmos), flying an approximately seven-month increment with significant station maintenance and several spacewalks planned. Swift is observing again. NASA's Neil Gehrels Swift Observatory restarted science operations on August 26, with two of its three instruments back online and the third expected within weeks. Swift's telescopes had been powered down progressively — the ultraviolet/optical and X-ray telescopes in February, the Burst Alert Telescope in April — to reduce power draw and atmospheric drag while awaiting a boost from Katalyst Space's LINK spacecraft, launched in July. NASA announced on August 19 that LINK would not attempt the capture after developing attitude-control problems. With no rescue coming, NASA has restarted the instruments to extract as much science as possible. NASA expects Swift to fall below roughly 300 km (185 miles) — where telescope operations become impractical — within the next one to two months. Katalyst will still fly proximity operations to demonstrate in-orbit servicing techniques. An 80,000-year mission to Alpha Centauri. The Seattle-area nonprofit Fermi Explorer Mission announced plans to launch a 100–200 kg probe toward Alpha Centauri (4.4 light-years away) at the end of 2029, most likely on a SpaceX rideshare. Solar electric propulsion plus repeated perihelion pumping manoeuvres would build a cruise speed of 24.2 km/s (about 54,000 mph) — faster than New Horizons at Pluto — for a journey of roughly 80,000 years: 12 years of active operations followed by around 79,500 years of coasting. Budget is under $15 million, with $10 million verbally pledged. Payload is at least 1 kg in a shielded 10 cm cube, including a digitised Voyager Golden Record, messages from children worldwide, and cosmic-ray detectors. Co-founders Philip Johnston, Ezra Feilden and Adi Oltean are behind the space computing company Starcloud; the advisory board includes Rob Meyerson (former Blue Origin president) and Jeff Thornburg (former SpaceX propulsion lead). Johnston: "We'll be the first to leave, and the last to arrive." It would be the first spacecraft deliberately aimed at a specific star. Tonight's sky and the month ahead: Five naked-eye planets are in play through September. Venus dominates the early evening, low in the west/west-southwest about 14° up an hour after sunset (Sydney sunset ≈ 5:34pm AEST), still close to Spica after last night's conjunction, and building to maximum brilliance on September 18 — with a thin crescent Moon alongside on the 14th. Saturn is up most of the night at magnitude +0.4 with its rings tilted just 8° from edge-on, the narrowest in about a dozen years, and rides far higher for Southern Hemisphere observers than for northern ones. Mars rises around 1:40am and is slowly brightening; Jupiter rises east-northeast around 3:50am, and on September 8 the Moon occults Jupiter for much of North America. Mercury appears low in evening twilight in the final week, about 1° above Spica on the 25th. The Moon is a waning gibbous heading to last quarter on September 4....
