Last updated on March 12, 2017
Spherical ooids on Earth are usually 0.25 mm to 1 mm in diameter (note 1). Ooids on Mars are often 0.2 mm to 0.5 mm in diameter (note 1). So, spherical ooids on Mars need to be crushed into fragments smaller than 0.15 mm in diameter in order to pass through the sieve for the SAM instrument aboard Mars rover Curiosity. Otherwise, SAM instrument may not be able to detect the organic matter preserved in the Martian ooids.