Mars Mystery Spheres Mystify Scientists

Using its Microscopic Imager, the Opportunity rover photographed these small spherical objects on Sept. 6, 2012. The view covers an area about 2.4 inches across at an outcrop called “Kirkwood” on the western rim of Endeavour Crater. Credit: NASA

So what are these things? If you follow Mars news, you might guess they’re Martian “blueberries”, those BB-sized concretions that form when water dissolves minerals inside rocks which precipitate as hard little pellets. Concretions, excellent indicators of formerly wet environments, are found both on Earth and Mars.

Nope, these are different.

“This is one of the most extraordinary pictures from the whole mission,” said Opportunity’s principal investigator, Steve Squyres of Cornell University. “Kirkwood is chock full of a dense accumulation of these small spherical objects. Of course, we immediately thought of the blueberries, but this is something different. We never have seen such a dense accumulation of spherules in a rock outcrop on Mars.”

BB-sized “blueberry” concretions in the tracks of Opportunity rover on Mars They weathered out of a rock formation. Credit: NASA

The spheres are just 3 mm in diameter or just over a tenth of inch in diameter. If you look closely, you’ll see some of them have a concentric structure where the wind has eroded away the exteriors. According to Squyres, they’re crunchy on the outside and softer on the inside. Kind of like chicken nuggets. Well maybe not exactly like nuggets, but you get the idea.

Accretionary lapilli from the Gunflint Trail area north of Grand Marais. Notice the concentric or ringed structure inside the little balls. Credit: Mark Jirsa

While scientists are working out various hypotheses as to their origin, allow me to suggest one. Fair warning, this is only a hunch. Up north of Duluth on the Gunflint Trail near Grand Marais, Minn., geologist Mark Jirsa discovered outcroppings of rock composed of layers of small spheres with concentric structures several years ago. After analysis, Jirsa determined they were created in the fiery maelstrom following the impact of a small asteroid that created the Sudbury Impact feature in nearby Canada. In the rising cloud of ejected material ash and vapor coalesced to form small spherical rocks with concentric layering, much the same way hailstones form. These fell back to Earth in Minnesota (and other places) and over time became cemented into a layer of rock. Other types of lapilli are released during volcanic eruptions.

It’s possible that one or both of these two scenarios happened on Mars. I can’t wait to see what further studies of the new spheres will show. If you’re interested in Jirsa’s research, please check out this short, readable paper on the topic.

7 Responses

  1. Dennis Zogbi

    Theory: Ferromanganese Micro-nodules: A nodule commonly forms around a nucleus such as a shark’s tooth or volcanic fragment. Nodules grow in concentric layers that may represent changes in seawater composition during growth. Rates of nodule growth are 1-4 mm/106 years. They commonly occur where sedimentation rates are less than 5 mm/1000 years. Apparently, sporadic movement by benthic organisms burrowing through the sediments is sufficient to keep most nodules at the sediment surface, where they can grow. The greatest area of manganese nodule development occurs in the Pacific, where 75% of the equatorial and North Pacific deep sea floor is covered with nodule patches. Fields of nodules develop in areas swept clean of fine detrital sediments by bottom currents. Where nodules cover 100% of the sediment surface, the area is called a manganese nodule pavement. In some cases, nodules join to form a solid surface. Such pavements are found on deep plateaus including the Blake Plateau in the western North Atlantic and the Agulas Plateau south of South Africa.

  2. Tony J Carey

    In the bottom left corner there is what looks like a fossil of a juvenile coral [can send arrowed image on request] and the spheres themselves might well be fossilised amoeba. It could just be that this the real ‘smoking gun’ to confirm that there was, and probably still is [at least microbially] life on Mars!

    1. astrobob

      Thanks Tony for your observations. The concentric structure would probably rule out amoebas and more likely point to a mineral process, but we’ll just have to wait and see. Very exciting either way.

  3. Tom

    We have investigated that topic thoroughly in our team and came to some quite disturbing conluclusions. Based on digital analysis of the recent pictures and some additional calculations we expect that at least one of those round objects (esp. in the upper right corner of the picture) resembles a coin. Those are damn smart amoebas with own currency.

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