NASA

Searching for Spherules to Sample

Written by Denise Buckner, Postdoctoral Fellow at NASA’s Goddard Space Flight Center Over the past few weeks, Perseverance has been investigating some curious spherules peppered across the “Witch Hazel Hill” region along the rim of Jezero crater. A striking cluster of the small bubble-shaped stones were first spotted by the Mastcam-Z instrument on Sol 1442 […]

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May 6, 2025 - 03:00

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Searching for Spherules to Sample

A color close-up photo of the Martian surface shows a pale yellowish-tan rock, with grooves or lines emanating from a center point like rays, with scattered black spots and small indentations throughout its surface.

Subsurface spherules: This image of the Hare Bay abrasion patch was acquired by the WATSON camera on Sol 1480 (April 19, 2025), showing dark-colored spherules set in a fine-grained light-toned matrix. These spherules appear to be smaller versions of similar structures that have been found in numerous rocks in the vicinity. Perseverance is currently working to collect a sample of these spherules to return to Earth. WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) is a close-range color camera that works with the rover’s SHERLOC instrument (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals); both are located on the turret at the end of the rover’s robotic arm.

NASA/JPL-Caltech

Written by Denise Buckner, Postdoctoral Fellow at NASA’s Goddard Space Flight Center

Over the past few weeks, Perseverance has been investigating some curious spherules peppered across the “Witch Hazel Hill” region along the rim of Jezero crater. A striking cluster of the small bubble-shaped stones were first spotted by the Mastcam-Z instrument on Sol 1442 (March 11, 2025) at “Broom Point,” in a rock named “St. Pauls Bay.” A few sols later, a similar assemblage was discovered by the SuperCam instrument at the “Mattie Mitchell” outcrop near “Puncheon Rock.” As the rover continued along its traverse, spherules continued to appear. At the targets St. Pauls Bay and Mattie Mitchell, the spherules are densely packed and almost look like bunches of grapes. Elsewhere, similar smaller spherules were found intermixed with other grains within the rock. At a target called “Wreck Apple” at the “Sally’s Cove” outcrop, individual spherules were set in a matrix of coarse, dark grains. Even more of these circular features are embedded in finer-grained, layered bedrock at a nearby area called “Dennis Pond.”

A color photo from the Martian surface shows pale brownish-orange fine soil with several small and medium sized rocks poking above the surface, lighter-toned than the surrounding soil, mostly flat with varied edges and cracks. One exception is a rock that stands out at the middle right of the image, dark gray and slightly larger than everything else around, vaguely diamond-shaped — from the viewer’s vantage point — and covered everywhere on its surface in tiny bumps.

Spherules at St. Pauls Bay: NASA’s Mars Perseverance rover acquired this image, a striking cluster of spherules, on March 11, 2025 – Sol 1442, or Martian day 1,442 of the Mars 2020 mission – at the local mean solar time of 11:12:40. Perseverance used its Left Mastcam-Z camera; Mastcam-Z is a pair of cameras located high on the rover’s mast.

NASA/JPL-Caltech/ASU

A close-up of jagged, bumpy, grayish-orange rocks on the Martian surface. In several spots the rocks are pockmarked, or have bubble-like protrusions.

Spherules at Wreck Apple: NASA’s Mars Perseverance rover found smaller spherules in a coarse-grained matrix. The rover captured this image using the WATSON camera on March 27, 2025 – Sol 1458, or Martian day 1,458 of the Mars 2020 mission – at the local mean solar time of 15:36:04. WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) is a close-range color camera located on the turret at the end of the rover’s robotic arm.

NASA/JPL-Caltech

Although the team was intrigued by the spherule-rich layers at Sally’s Cove and Dennis Pond, these outcrops were challenging for the rover arm to access. After some searching to find an accessible target, the team decided to perform an abrasion at a neighboring outcrop, called “Pine Pond,” which contained an extension of the Dennis Pond layers. The team picked the target “Hare Bay” in hopes of finding spherules within a rock interior, and conducting proximity science observations with PIXL and SHERLOC to investigate their composition and internal structure. Images of the abrasion patch taken by WATSON show that Hare Bay contains light-toned medium-sized grains, with millimeter-sized spherules dotted throughout the rock! Leading hypotheses for the origin of these spherules include formation by volcanic activity or impact-related processes.

Having found an accessible spherule-bearing rock, the team is currently hard at work collecting a spherule-filled sample! Combined with the information already gathered by Mastcam-Z, SuperCam, PIXL, SHERLOC, and WATSON, future laboratory analyses could help solve the mystery of when, where, and how these spherules formed, which can in turn detangle the geological events that formed and transformed the surface of Mars over billions of years!