Squyres said his team had two theories on how the rock got there – that there\u2019s \u201ca smoking hole in the ground somewhere nearby\u201d and it was caused by a meteor, or that it was \u201csomehow flicked out of the ground by a wheel\u201d as the rover went by.<\/p>\n
\u201cWe had driven a metre or two away from here, and I think the idea that somehow we mysteriously flicked it with a wheel is the best explanation,\u201d Squyres said.<\/p>\n
Yet the story got even stranger when Opportunity investigated further. Squyres explained: \u201cWe are as we speak situated with the rover\u2019s instruments deployed making measurements of this rock.<\/p>\n
\u201cWe\u2019ve taken pictures of both the doughnut and jelly parts, and the got the first data on the composition of the jelly yesterday.<\/p>\n
\u201cIt\u2019s like nothing we\u2019ve ever seen before,\u201d he said. \u201cIt\u2019s very high in sulphur, it\u2019s very high in magnesium, it\u2019s got twice as much manganese as we\u2019ve ever seen in anything on Mars.<\/p>\n
\u201cI don\u2019t know what any of this means. We\u2019re completely confused, and everyone in the team is arguing and fighting (over what it means).<\/p>\n
\u201cThat\u2019s the beauty of this mission\u2026 what I\u2019ve realised is that we will never be finished. There will always be something tantalising, something wonderful just beyond our reach that we didn\u2019t quite get to – and that\u2019s the nature of exploration.\u201d<\/p>\n
Squyres was speaking at an event marking the 10th anniversary of the arrival of Opportunity and Spirit on the surface of Mars.<\/p>\n
While Spirit lost contact with Earth and was later declared \u201cdead\u201d in 2010, Opportunity has now roamed the planet far in excess of what was originally planned as a three-month mission. Nasa said that with its maximum speed of just 0.05mph, as of \u201cSol 3547\u201d (15 January 2014) Opportunity had covered just over 24 miles (38km).<\/p>\n