Deep Space Tuesdays

From The Decisional Pass · your weekly dispatch from the far reaches

This week, a visitor from another star system is still giving up its secrets — and a fleet of our own probes is quietly coasting toward the outer planets.

☄️ An interstellar comet keeps surprising us

3I/ATLAS is only the third interstellar object we've ever caught passing through the solar system — after 'Oumuamua in 2017 and Borisov in 2019 — and unlike those, we got a long, good look. It rounded the Sun in October 2025 and is now on its way back out to the stars, but the data is still landing. Using the James Webb Space Telescope, astronomers found ratios of carbon and heavy hydrogen (deuterium) in its coma that don't match any comet born in our own system — chemical fingerprints of a world that formed around a different star, possibly one far older than the Sun. Webb also clocked an unusually high carbon-dioxide-to-water ratio, and Europe's Very Large Telescope pinned down more of its makeup. A rock from somewhere else, briefly close enough to read.

References: NASA — Webb finds clues to 3I/ATLAS's origin · Sky at Night · ESA — 3I/ATLAS FAQ

🪐 The quiet cruisers

Most of deep space exploration is patience. Right now, three flagships are simply en route, and one of them has a big moment coming:

• Europa Clipper — NASA's mission to Jupiter's ocean moon is coasting through the inner solar system and lines up an Earth gravity assist in early December, the slingshot that bends its path toward a 2030 arrival. It will make dozens of close passes of Europa to probe the ocean beneath the ice.
• Psyche — running on solar-electric propulsion toward the metal-rich asteroid 16 Psyche, a possible exposed planetary core, with arrival in 2029 after a Mars gravity assist.
• JUICE — ESA's Jupiter Icy Moons Explorer, Clipper's counterpart, is on the long road to a 2031 arrival and a focus on Ganymede.

None of them make headlines most weeks. All of them are exactly where they should be — which, in deep space, is the whole game.

Track every planetary mission across the solar system on the Orbital Roster dashboard.

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