Evidence of Vessel-Element-Like Morphology in a Martian Rock (Mastcam-Z Sol 1639)

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Image source: NASA/JPL-Caltech/ASU – Mastcam-Z (Sol 1639, Sept 29 2025)

Enhanced image: https://www.flickr.com/photos/fossil_lin/54831355453/

Enhancement: Zeke color filter, × 8 enlargement
Date of analysis: Oct 5 2025

Abstract

An enhanced Mastcam-Z image acquired by the Perseverance rover on Sol 1639 displays a rock slab bearing millimetre-scale, vessel-like structures. Each red-arrowed feature measures roughly 1–2 mm across and exhibits a bounded, circular-to-polygonal outline resembling a single xylem vessel element in petrified wood. Yellow arrows mark smaller circular and square spots that could represent cross-sections of subsidiary structures. This paper documents the morphology, assesses possible geological and biological analogs, and identifies questions that require higher-resolution data.

1  Introduction

2  Image Description

The enhanced frame shows a flat slab surrounded by smaller clasts. Across its centre run several parallel ridges, each 1–3 mm wide and nearly uniform in spacing. Within those ridges occur discrete oval to angular cavities about 1–2 mm across, the ones labelled by red arrows. Illumination geometry demonstrates real topographic relief: the bright edges are raised, shadows recessed. Yellow-arrowed points highlight faint circular and square depressions, possibly end or cross-sections of similar cavities.

3  Morphological Observations

1. Shape: Most red-arrowed units have smooth, continuous boundaries, neither jagged nor dendritic.
2. Isolation: Each appears self-contained rather than merging into a vein or fracture.
3. Orientation: Their long axes align roughly with the ridge direction, implying a coherent fabric.
4. Scale: Measured from Mastcam-Z calibration, diameters average ≈ 1.5 mm.
5. Relief: Edges stand slightly above surrounding matrix, suggesting differential hardness or cementation.

4  Comparative Analogues

The morphology shows partial similarity to several terrestrial materials:
– Petrified wood: circular or rectangular lumina bounded by wall-like rims, though Martian features are larger.
– Fibrous mineral veins: parallel arrangement, but usually crystalline and reflective.
– Laminated mudstone: millimetre spacing, but geological layers seldom form isolated, bounded cavities.
– Concretions or vesicles: single circular cavities, similar in size but random in placement.

5  Discussion

The geometry invites comparison with secondary xylem tissue, especially a single vessel element or vessel-ray complex. Morphologically, the red-arrowed objects mimic the lumen and wall outline of such elements, though they are larger than any known living or fossil vessel cells. Hence, while the pattern is tissue-like, it cannot be called biological without compositional or microscopic confirmation.

Alternative geological explanations—laminated erosion or fibrous mineralisation—account for the parallel background ridges but not easily for the discrete circular forms. The feature thus occupies an interpretive middle ground: a structured geological texture with biological resemblance.

6  Implications and Next Steps

- Microscopic imaging (≤10 µm px⁻¹) is needed to test for internal partitioning or cell-wall microtextures.
– Elemental mapping could reveal whether ridge interiors differ chemically from the matrix.
– Field context should be checked for repetition of identical morphologies.
– Terrestrial simulation—wind abrasion of laminated silicates or mineral growth in constrained cracks—may determine if such forms can arise abiotically.

7  Conclusion

The Sol 1639 Mastcam-Z image documents a Martian rock containing one or more vessel-element-like structures approximately 1–2 mm across. These features are tissue-like in morphology—bounded, oriented, and internally coherent—but too large to represent individual biological cells. No confirmed Earth analog reproduces the same combination of scale and shape. Whether they record an unusual geological fabric, a fossilised bio-template, or another process entirely remains an open question that merits further investigation.

Acknowledgements

Image data courtesy of NASA/JPL-Caltech/ASU (Perseverance Mastcam-Z). Color enhancement and annotations by Liangtai Lin (Flickr user Fossil_Lin).

Figure 1. Mastcam-Z (Sol 1639) image enhanced by Zeke filter (×8). Red arrows mark vessel-element-like structures approximately 1–2 mm across; yellow arrows indicate smaller circular or square features possibly representing cross-sections. Source: NASA/JPL-Caltech/ASU/Kevin M. Gill; enhancement and annotations by Liangtai Lin.

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Source: https://wretchfossil.blogspot.com/2025/10/evidence-of-vessel-element-like.html