Professor of Mathematics

Paata Ivanisvili

Department of Mathematics, University of California, Irvine

Candidate 26: Acheron Fossae region, beside a small crater

Strong · roughly 85%

Two CTX close-ups of the same 500 by 500 m in the Acheron Fossae region, from January 2012 and April 2023, with the sun in the same direction. A small old crater is in both; a dark dot beside it, at the arrow, is present only in the 2023 image. — The same 500 × 500 m in January 2012 and April 2023, with the sun in the same direction. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A compact dark dot about 50 m across appeared 70 m west of an old small crater in the Acheron Fossae region, between January 2012 and April 2023. It is in three images, from April 2023 to January 2025.

Why it may be a new impact. A January 2012 image, with the sun in the same direction, shows the old crater but no dot, and would have shown it clearly. The dot is a round disk beside the crater, not on its shaded side, so it is not the crater’s shadow; both key images are from northern spring, so it is not frost; and a dust-devil track would be a line.

Location: 33.289° N, 230.735° E (129.265° W)
Absent: 8 January 2012
Present: 12 April 2023, 11 June 2023 and 28 January 2025
Size: Compact dark dot about 50 m across
Confidence: Strong candidate; roughly 85% that it is a new impact.
Caveat: Only one earlier image exists, so it could have formed at any time in an eleven-year window. It lies outside every footprint of the high-resolution HiRISE camera. Like every candidate here, it is unconfirmed: see the caveat.

Four CTX images of the same 2 by 2 km patch, from 2012 to 2025. A dark dot beside a small old crater, at the arrow, is absent in 2012 and present in 2023 and 2025. — All four CTX images of the same 2 × 2 km patch, 2012 to 2025. NASA/JPL-Caltech/MSSS.

A 12 by 12 km CTX view from January 2025 of the Acheron Fossae region around the dot, with a dashed box around the 2 by 2 km patch and an arrow at the dot. — A 12 × 12 km view from January 2025. The dashed box is the 2 × 2 km patch. NASA/JPL-Caltech/MSSS.

The independent check: three columns of the same ground, 2 km wide above and 600 m wide below, with yellow ticks around the spot. The spot is missing in the earlier image, marked BEFORE, and present in the two later images, marked AFTER. — **Independent check.** A second, deliberately sceptical review downloaded every image again and found that the candidate passes every test. Each column is the same ground, north up, 2 km wide above and 600 m wide below. Columns marked BEFORE are earlier images in which the spot would have been visible had it been there; those marked AFTER show it. Each image keeps one contrast stretch in both rows, so the close-up cannot create a spot. NASA/JPL-Caltech/MSSS.