Mars and Planetary Missions: Rovers, Probes, Sample Return — 2026-09-25

Top developments

Perseverance finds evidence of ancient hot water at Jezero Crater

NASA announced this week that its Perseverance rover, working in the Margin Unit region on the inner edge of Jezero Crater, has found evidence revealing how groundwater, surface water, and heated fluids shaped Mars billions of years ago. The agency described the finding as revealing "complex water systems on early Mars," noting that scientists were surprised by what the rover found when it reached the crater's inner edge. The results strengthen the case that the samples Perseverance has been collecting are scientifically exceptional — a key argument in the ongoing debate over Mars Sample Return, whose NASA-led architecture was cancelled by Congress backing the administration's efforts earlier this year.

Curiosity reflects on 5,000+ sols of Mars science

EarthSky published a fresh retrospective this week on Curiosity's milestone of more than 5,000 Martian days (sols) on the Red Planet, recapping the rover's key discoveries to date. Curiosity, which recently gained a kilometer of elevation climbing Mount Sharp in Gale Crater, remains NASA's longest-running mobile Mars laboratory. With Perseverance focused on the Jezero water story, Curiosity's continued operation provides complementary geochemistry from a very different Martian environment.

JUICE prepares Earth gravity-assist flyby on September 28

ESA's JUICE (Jupiter Icy Moons Explorer), launched in April 2023, is approaching Earth for a gravitational-assist flyby scheduled for Monday, September 28, 2026, at approximately 13:45 local time, passing at a distance of about 8,640 kilometers. The spacecraft has already performed flybys of the Moon, Earth, and Venus; this maneuver adjusts its trajectory for the long cruise to Jupiter, where it will study Europa, Ganymede, and Callisto. The flyby comes as Europa Clipper, Jupiter's other incoming ice-moon explorer, continues its own cruise toward Jupiter orbit in April 2030.

Local view

French-language media are heavily focused on ESA missions this week. Le Soir (Belgium) detailed JUICE's upcoming Earth flyby on Monday at ~13:45, at roughly 8,640 km altitude, noting the probe has already bypassed the Moon, Earth, and Venus since its April 2023 launch. Nouvelles du Monde similarly highlighted the September 28 Earth gravity assist en route to Jupiter. French outlets also continue to follow BepiColombo's high-risk approach to Mercury following the September 3 separation of its transfer module (covered in previous issues). No recent local-language commentary on Mars rover science was available in this week's research.

Context & numbers

• JUICE Earth flyby: about 8,640 km from Earth, around 13:45 on September 28, 2026
• Curiosity: more than 5,000 sols (Martian days) on Mars
• Perseverance: has driven the equivalent of a full marathon, 26.2 miles (42.195 km), across Jezero Crater in five years and four months as of July 2026 — background to this week's new science
• Europa Clipper: launched October 14, 2024; Jupiter orbit insertion planned for April 2030; its Earth gravity-assist flyby is scheduled for December 2–7, 2026, at roughly 3,140–3,450 km altitude
• Mars Sample Return remains effectively cancelled by Congress in January 2026, raising the stakes of Perseverance's in-situ discoveries

On the radar

• JUICE Earth flyby, Sept 28, 2026 — expect trajectory-confirmation updates and possible opportunistic science observations during the pass.
• Europa Clipper Earth flyby, Dec 2–7, 2026 — its final major gravity assist before the cruise to Jupiter orbit in April 2030.
• BepiColombo Mercury orbit insertion — following the September 3 transfer-module separation, the dual ESA/JAXA probes (MPO and Mio) are on final approach after eight years and more than 10 billion km of travel; separation and orbit milestones warrant monitoring.
• Venus program churn — rumors continue around Europe proceeding without NASA's radar payload on EnVision after an instrument pull, while NASA's DAVINCI works toward an early-2030s launch; treat details as unconfirmed pending fresh agency statements.