Professor of Mathematics

Paata Ivanisvili

Department of Mathematics, University of California, Irvine

Candidate 20: Arabia Terra, north of Schiaparelli crater

Strong · roughly 70%

Two CTX close-ups of the same 600 by 600 m north of Schiaparelli crater, from October 2023 and July 2025, under the same sun. A faint compact dark spot at the arrow is present only in the 2025 image. — The same 600 × 600 m in October 2023 and July 2025, under the same sun. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A compact dark spot about 40 by 60 m appeared north of Schiaparelli crater between October 2023 and September 2024, a window of 11 months. It is in images from September 2024 and July 2025.

Why it may be a new impact. Three earlier images, from 2013, 2014 and October 2023, show nothing there, and each of them would have shown it; the last was taken under the same sun as the July 2025 image. The two images that show it have the sun in directions 57 degrees apart, so it is not a shadow.

Location: 10.375° N, 12.946° E
Absent: 19 December 2013, 30 November 2014 and 10 October 2023
Present: 7 September 2024 and 13 July 2025
Size: Compact dark spot about 40 × 60 m
Confidence: Strong candidate; roughly 70% that it is a new impact.
Caveat: It is faint, and it sits on a bright slope beside a dark scarp, where new slope streaks (small dust avalanches) are common. It looks compact in both images, ten months apart, rather than drawn out downslope, but the head of a short streak cannot be excluded at this resolution, so the confidence is lower. 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 2013 to 2025. A faint compact spot at the arrow is absent in 2013 and October 2023 and present in 2024 and 2025. — Four of the five CTX images of the same 2 × 2 km patch, 2013 to 2025. NASA/JPL-Caltech/MSSS.

A 12 by 12 km CTX view from July 2025 of the ground north of Schiaparelli crater, with a dashed box around the 2 by 2 km patch and an arrow at the spot. — A 12 × 12 km view from July 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.