Professor of Mathematics

Paata Ivanisvili

Department of Mathematics, University of California, Irvine

Candidate 28: Plains north of Tithonium Chasma

Strong · roughly 85%

Two CTX close-ups of the same 500 by 500 m of plains north of Tithonium Chasma, from September 2008 and April 2025, under nearly the same sun. A very dark spot beside a small round feature, at the arrow, is present only in the 2025 image. — The same 500 × 500 m in September 2008 and April 2025, under nearly the same sun. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A very dark spot 30 to 35 m across appeared beside a feature about 100 m wide, probably a small old crater, on the plains north of Tithonium Chasma, between September 2008 and April 2025. It is still there in March 2026.

Why it may be a new impact. A September 2008 image under nearly the same sun shows nothing there and would have shown it clearly. The spot lies on flat ground outside the neighbouring feature under two sun directions 58 degrees apart, so it is not a shadow, and its compact, dark look is typical of a small new impact.

Location: 2.815° S, 268.360° E (91.640° W)
Absent: 17 September 2008
Present: 16 April 2025 and 4 March 2026
Size: Very dark spot 30 to 35 m across
Confidence: Strong candidate; roughly 85% that it is a new impact.
Caveat: Only one earlier image exists, so the window is 17 years long. It lies outside every footprint of the high-resolution HiRISE camera. Like every candidate here, it is unconfirmed: see the caveat.

Three CTX images of the same 2 by 2 km patch, from 2008 to 2026. A very dark spot at the arrow is absent in 2008 and present in 2025 and 2026. — All three CTX images of the same 2 × 2 km patch, 2008 to 2026. NASA/JPL-Caltech/MSSS.

A 12 by 12 km CTX view from April 2025 of the plains around the spot, with a dashed box around the 2 by 2 km patch and an arrow at the spot. — A 12 × 12 km view from April 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.