"Egg Rock" is a smooth, shiny nickel-iron meteorite found sitting on the surface of Mars on Curiosity's Sol 1505, or 30-Oct-2016. It is described the next day in Arizona State University's Red Planet Report website: Curiosity: Egg Rock, a small meteorite

Did Curiosity's software flag it as potentially interesting (e.g. "hey, what's that?), or was it noticed/spotted first by researchers, who then directed Curiosity to take a closer look?

See also:

Images from EarthSky, credit NASA/JPL/ASU, captions "October 30, 2016 image via Curiosity rover on Mars" (click for larger size):

"Egg Rock" meteorite on Mars "Egg Rock" meteorite on Mars "Egg Rock" meteorite on Mars

  • $\begingroup$ See also Why doesn't the perchlorate on Mars' surface oxidize metallic meteorites? $\endgroup$
    – uhoh
    Jan 28, 2018 at 7:15
  • 1
    $\begingroup$ As interesting as Egg Rock is, looking at the color picture, I've just noticed the white material that looks like infill in the cracks of the rocks making up the surface of Mars. I'd be interested to know what that stuff is. I wondering if it's gypsum or something else. $\endgroup$
    – Fred
    Apr 30, 2021 at 9:02
  • $\begingroup$ @Fred the cause is described in my answer below, but exactly what it is and why it's white I don't know. So I really hope you post that as a new question! $\endgroup$
    – uhoh
    Apr 30, 2021 at 10:24

1 Answer 1


People did!

Re-reading the linked article in ASU's Red Planet Report, I noticed at the end it links to an additional article; "More on Egg Rock at redplanet.asu.edu/?p=21047".

That link says:

Laser-zapping of a globular, golf-ball-size object on Mars by NASA’s Curiosity rover confirms that it is an iron-nickel meteorite fallen from the Red Planet’s sky.

Iron-nickel meteorites are a common class of space rocks found on Earth, and previous examples have been seen on Mars, but this one, called “Egg Rock,” is the first on Mars examined with a laser-firing spectrometer. To do so, the rover team used Curiosity’s Chemistry and Camera (ChemCam) instrument.

Scientists of the Mars Science Laboratory (MSL) project, which operates the rover, first noticed the odd-looking rock in images taken by Curiosity’s Mast Camera (Mastcam) at at a site the rover reached by an Oct. 27 drive.

“The dark, smooth and lustrous aspect of this target, and its sort of spherical shape attracted the attention of some MSL scientists when we received the Mastcam images at the new location,” said ChemCam team member Pierre-Yves Meslin, at the Research Institute in Astrophysics and Planetology (IRAP), of France’s National Center for Scientific Research (CNRS) and the University of Toulouse, France.

The iron-nickel meteorite link above points to the same information as well as a further discussion of the meteorite.

below: cropped section of image of "Egg Rock" from redplanet.asu.edu/?p=21047 showing the spots where Curiosity's ChemCam laser has ablated material.

Egg rock on Mars showing the spots where Curiosity's ChemCam laser has ablated material.

  • $\begingroup$ If someone has more detailed information about the discovery, please consider posting another answer. $\endgroup$
    – uhoh
    Jan 29, 2018 at 9:44
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    $\begingroup$ Out if interest, how would a Curiosity discovery differ from a people’s discovery? How do you determine the two different discoveries? $\endgroup$
    – Edlothiad
    Jan 29, 2018 at 10:56
  • $\begingroup$ @Edlothiad the third sentence of the question explains what I mean by that. Through software upgrades, NASA has been adding more and more automation to Curiosity since it's been there. See for example the answers to How much can the Mars rover Curiosity do autonomously, after four years of operation? $\endgroup$
    – uhoh
    Jan 29, 2018 at 15:44
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    $\begingroup$ I totally glanced over that, thanks for pointing it out and the link! $\endgroup$
    – Edlothiad
    Jan 29, 2018 at 16:36

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