Professor of Mathematics

Paata Ivanisvili

pivanisv@uci.edu · x.com/PI010101

Department of Mathematics, University of California, Irvine

Paata Ivanisvili

← Possible new impact sites on Mars

Candidate 33: Western Arabia Terra, about 700 km west of Pasteur crater

Strong · roughly 95%

Two CTX close-ups of the same 500 by 500 m in western Arabia Terra, from March 2014 and May 2023, under nearly the same sun. An older small crater is in both; a dark patch on its rim, at the arrow, is present only in the 2023 image.
The same 500 × 500 m in March 2014 and May 2023, under nearly the same sun. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A dark patch about 40 m across appeared on the north-west rim of an older crater 80 m wide in western Arabia Terra, between March 2014 and May 2023. It is still there in three images from January to March 2025. A fainter dark band that runs about 70 m south-south-east from it, along the old crater’s rim, is partly new too, perhaps a small dust avalanche set off by the impact.

Why it may be a new impact. Images from 2010 and 2014 show nothing there, and both would have shown it; the 2014 image was taken under nearly the same sun as the 2023 one, so the patch is not a shadow. By chance, NASA’s HiRISE camera photographed the spot in March 2025, on the same orbit as a CTX image. It shows a pit about 2.5 m wide at the centre of the dark patch, shaded like a small bowl (dark on the side facing the sun, bright on the far side): just what a small fresh impact leaves.

Location
19.143° N, 12.188° E
Absent
17 February 2010 and 18 March 2014
Present
4 May 2023, 6 January 2025, 3 February 2025 and 25 March 2025 (CTX and HiRISE)
Size
Dark patch about 40 m across, with a pit about 2.5 m wide at its centre
Confidence
Strong candidate; roughly 95% that it is a new impact.
Caveat
The HiRISE image was aimed at the surrounding terrain, not at the spot, but the HiRISE team may have noticed it. Like every candidate here, it is unconfirmed: see the caveat.
Six CTX images of the same 2 by 2 km patch, from 2010 to 2025. A dark patch on the rim of an older small crater, at the arrow, is absent in 2010 and 2014 and present in the four images from 2023 and 2025.
All six CTX images of the same 2 × 2 km patch, 2010 to 2025. NASA/JPL-Caltech/MSSS.
A 12 by 12 km CTX view from February 2025 of the cratered 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 February 2025. The dashed box is the 2 × 2 km patch. NASA/JPL-Caltech/MSSS.
Three HiRISE panels from March 2025: a 300 m view with a dark patch on the north-west rim of an older crater, inside a red dashed circle; a 70 m enlargement of the dark patch with a small pit at its centre; and a 16 m close-up of the pit, black on its side towards the sun and bright on the far side.
HiRISE view of the spot (25 March 2025, 0.5 m per pixel), taken by chance on the same orbit as a CTX image: 300 m wide, then a 70 m enlargement, then the central 16 m. The dark patch lies on the north-west rim of the older crater; at its centre is a pit about 2.5 m wide, dark on the side towards the sun and bright on the far side. The red dashed circle marks the CTX position. NASA/JPL-Caltech/UArizona.
The independent check: four 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 CTX images and the HiRISE image, all 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, the last in HiRISE. Each image keeps one contrast stretch in both rows, so the close-up cannot create a spot. CTX: NASA/JPL-Caltech/MSSS; HiRISE: NASA/JPL-Caltech/UArizona.
The independent review’s HiRISE close-ups, 600 m, 150 m and 40 m wide, with yellow ticks around a small pit at the centre of the dark patch, and a graph of brightness along the sun line through the pit: a dip on the side towards the sun and a peak on the far side.
The independent review’s HiRISE close-ups, 600 m, 150 m and 40 m wide, and the brightness along the sun line through the darkest point: dark on the side towards the sun and bright on the far side, the shading of a small pit rather than a boulder. NASA/JPL-Caltech/UArizona.

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