The Red Planet may well be a dead planet, but deep down we all seem to want to find that extraterrestrial intelligence is (or at least was) present on Mars. From the Face on Mars through to Bigfoot on Mars, news stories continue to be written about photographic anomalies on our second-nearest planetary neighbour (no doubt assisted by the relatively large number of missions that have placed satellites in orbit and rovers on the ground there).
The latest anomaly creating a buzz is a ‘light on the horizon’ snapped by NASA’s Curiosity rover four days ago (April 3) soon after reaching a new study area known as the Kimberley (see the pic above – click for full-size image). But before you get too excited, there’s a problem: Curiosity takes stereo pictures with two different cameras, and the ‘light’ only shows up in the right hand camera, despite both taking pictures simultaneously. This suggests that the ‘light’ is not truly out there on the horizon, but is instead an imaging artifact of some kind. Indeed, Doug Ellison, visualisation producer at the Jet Propulsion Laboratory (JPL), explicitly stated on Twitter today that it was an artifact caused by “a cosmic ray hit“. Such glitches have caused Mars confusion before, such as this story about a Martian base.
What I found odd though is that another image taken by Curiosity, a day earlier, also showed this ‘light’ artifact – and this glitch too was precisely on the horizon line:
The camera is positioned differently, it was taken a day earlier, and yet the ‘light’ is on both occasions on the horizon. I thought perhaps that such glitches might manifest in areas of high contrast (e.g. where ground meets sky/distant mountain range) in an image, so I asked Doug Ellison on Twitter whether that was the reason for the similarity in location. His reply was that it was actually, quite simply, a coincidence that was bound to happen at some stage:
@DailyGrail Doesn't need a reason. Statistically over 100,000's of images, that will happen (and any other coincidence you fancy)
I bow to the experts on these matters, but I still find that explanation slightly unconvincing. Maybe there’s a better one: the Martians are trying to blind the rover…
(Caveat for the sake of those without a drop of humour: that last statement was a joke).
Update: Last night I checked Curiosity’s track maps and consulted Google Earth’s Mars view to get a feel for the direction the images are looking. What I found piqued my interest even further. The bottom image in my post was taken on Sol 588, the top image a day later on Sol 589. During that time the Rover moved slightly to the south, and in both cases is looking west(ish), firstly from the north-side of a mound in the foreground and subsequently on the south-side. If you look at where the light is in relation to the mountain range in the background (use the quite recognisable ‘two-level’ mountain directly behind the ‘light’ in the top pic for reference), you’ll notice that the ‘light’ would be in pretty much the same position on the terrain a couple of hundred metres away, if parallax is taken into consideration. Which tends to lift the possibility in my mind that it could very well be a physical object (shiny rock, electrostatic dust devil, Nephilim) rather than a cosmic ray camera artifact (though the issue of only being in one of the stereo cameras remains suggestive of a cosmic ray artifact).
Update 2: A few about-faces today on the cosmic ray artifact explanation. Doug Ellison, who in his reply to me was certain it was a CR, is now saying “I’ve done a complete 180. 589 could be a CR hit. 588 isn’t. It hides behind a hill behind the two eyes… if one triangulates between the two observations, one finds a point on a small ridge line. That point is also visible in Sol 580 MastCam imagery that shows a tall, thing [sic], bright rock at the exact same point”. And Justin Maki, lead scientist on Curiosity’s engineering cameras, has told Alan Boyle that it could be the light is the glint from a rock surface reflecting the sun.