NASA's Moon Orbiter Finds Record Crater While Yale Team Rewrites Early Solar System Chemistry

Two space science papers landed within days of each other this month, and both undercut assumptions scientists had held for years.

A Crater That Formed While We Were Watching

NASA's Lunar Reconnaissance Orbiter (LRO) has been circling the Moon for more than 17 years. The long dataset recently paid off.

Robert Wagner, an image-processing specialist with Arizona State University who works on LRO's camera data, was doing a routine data-quality check when he spotted an unusually bright spot ringed by a dark halo, according to NASA Science. He stopped and dug in. What he found, first identified in 2025 according to Space.com, was the largest newly formed impact crater ever documented anywhere in the solar system.

NASA named it McGetchin crater, after lunar scientist Tom McGetchin. It formed on the Moon's eastern edge sometime between April 11 and May 22, 2024, when a comet or asteroid the size of a three- to six-story building slammed into the surface. The crater measures 728 feet across, about the length of two football fields, and 141 feet deep, deep enough to stack three school buses. NASA scientists estimate an impact this size happens on the Moon only about once a century.

Two papers describing the find were published September 16 in the journal Science Advances. One, led by Mark Robinson of Arizona State University, mapped the crater and the huge apron of ejected material thrown across the surrounding surface. The second, led by Tyler Powell, used LRO's Diviner thermal instrument and found a 4.3-mile-wide zone around the crater running about 16 degrees Fahrenheit cooler at night than the surrounding terrain, evidence the impact physically disturbed a much wider area than the crater itself.

"McGetchin crater is exceptional because it is the largest newly formed impact crater that has been identified to date," Powell told Space.com. He added that scientists were "extremely lucky" the impact happened during LRO's operational life, giving them before-and-after data on a fresh strike before weathering and micrometeorite bombardment start erasing it.

LRO's team has now flagged more than 1,000 new craters and 100,000 surface changes over the mission's run, according to NASA Science. A 17-year-old spacecraft still generating first-of-its-kind science represents a reasonable return on a government space program that critics often flag for cost overruns elsewhere.

Rewriting the Solar System's First Million Years

The second story is older in subject matter but just as new in method. A team led by Damanveer Grewal, an assistant professor of Earth and planetary sciences at Yale and an assistant curator at Yale's Peabody Museum, published findings September 18 in Nature Astronomy showing the solar system's very first solid bodies were built almost entirely out of dry rock, not ice.

Grewal worked with Zhongtian Zhang at Princeton and Joanna Drążkowska at Germany's Max Planck Institute for Solar System Research, according to Yale University. Their target was planetesimals, the asteroid-scale building blocks that later grew into planets and moons, from within the first million years of the solar system's roughly 4.6-billion-year history.

The problem: none of those original bodies survive intact. They absorbed so much radioactive aluminum-26 that they melted completely, according to Yale, destroying any direct record of what they were made of. What's left are iron meteorites, fragments of those melted cores that eventually landed on Earth.

Grewal's team used two independent chemical tracers, sulfur content and iron oxidation state, both tied to a fine, cold dust called matrix that carries water ice and organic molecules, to reverse-engineer the original composition. The result: these earliest bodies were 83% to 92% chondrules, the heat-forged rocky beads found in primitive meteorites, and only 8% to 17% matrix, according to the study as reported by Times of India, Earth.com, Space Daily and time.news.

"Our work shows that this assembly process was remarkably selective from the very beginning," Grewal said, according to Yale University.

Prior research had only documented this rock-over-ice sorting in objects that formed two to four million years after the solar system's origin, according to Yale. Grewal's team pushed the evidence back to the first million years, meaning the disc of gas and dust around the infant Sun was aerodynamically filtering rocky grains from icy dust almost immediately, not gradually over millions of years as material cooled.

None of the seven sources reviewed dispute the study's core numbers, and none report a competing analysis. The open scientific question, as Yale's own writeup frames it, is what specifically drove the sorting mechanism this early and how far it extended across the outer disc, something the current iron-meteorite record can only partially answer since no intact body from that first million years survives to check the reconstruction directly.