Professor of Mathematics

Paata Ivanisvili

Department of Mathematics, University of California, Irvine

Candidate 32: Plains north-west of Echus Chasma

Strong · roughly 80%

Two CTX close-ups of the same 500 by 500 m of knobby plains north-west of Echus Chasma, from May 2008 and May 2025, under a similar sun. A dark spot with a soft halo at the arrow is present only in the 2025 image. — The same 500 × 500 m in May 2008 and May 2025, under a similar sun. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A compact dark core about 55 by 45 m, inside a soft halo, appeared among small knobs north-west of Echus Chasma, between May 2008 and January 2025. It is in images from January and May 2025, taken on two orbits.

Why it may be a new impact. A May 2008 image under the same sun, with every knob lined up, shows nothing there and would have shown it clearly, so the spot is not a shadow. A compact dark core with a halo is the classic look of a small fresh impact.

Location: 6.888° N, 276.316° E (83.684° W)
Absent: 9 May 2008
Present: 20 January 2025 and 5 May 2025
Size: Dark core about 55 × 45 m, inside a soft halo
Confidence: Strong candidate; roughly 80% that it is a new impact.
Nearby: Candidate 29, about 220 km away, and candidate 36, 296 km away. All three are near Echus Chasma, but they are separate events: no single meteoroid scatters craters that far apart.
Caveat: It has been followed for only three and a half months, so a short-lived dark patch made by wind is not excluded, although the core-and-halo look favours an impact. The window is 17 years long because no image was taken in between. 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 2025. A dark spot among small knobs, at the arrow, is absent in 2008 and present in both 2025 images. — All three CTX images of the same 2 × 2 km patch, 2008 to 2025. NASA/JPL-Caltech/MSSS.

A 12 by 12 km CTX view from January 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 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.