Is this image from Mars showing an artificial light source — an alien beacon perhaps — or is there something else going on here?
Unfortunately for anyone excited about a possible Martian sighting, or the discovery of ancient alien artifacts, or busting wide the whole 'conspiracy' that NASA's Curiosity rover is actually driving around in the desert somewhere in U.S. Southwest, there are some much more mundane explanations for what we're seeing here.
According to Justin Maki, of NASA's Jet Propulsion Laboratory, the bright spot, seen on Mars Sol 589 (April 3, 2014 here on Earth), is most likely due to a cosmic ray particle hitting the camera's CCD or it's sunlight glinting off a particularly shiny rock.
"In the thousands of images we've received from Curiosity, we see ones with bright spots nearly every week," he said in a JPL statement.
In an email to NBC News reporter Alan Boyle, Maki put forward another idea as well: that it could be light from the sun shining directly on the camera's CCD through a vent in the camera housing.
One unusual factor to this is that the light only shows up in one side of the 'stereo vision' provided by Curiosity's navigational cameras (Navcams). The above image is from the right navcam, while the left navcam image (below), taken just one second later, doesn't show the same bright spot.
"Normally we can quickly identify the likely source of a bright spot in an image based on whether or not it occurs in both images of a stereo pair," Maki said in the statement. "In this case, it's not as straightforward because of a blocked view from the second camera on the first day."
As Maki said, these two images from the previous day, at roughly the same time of day as the April 3 images, show the bright spot in the right-side navcam view, but the terrain is blocking the left navcam's view. In the days after, Curiosity's images of the same area didn't show any bright spot at all, from either the right navcam or the left navcam. However, those images were taken later in the day.
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With the bright spot visible in the same camera two days in a row, that would probably rule out a cosmic ray hit, since it would be quite the coincidence for two to hit the camera almost exactly one day apart ... not to mention in exactly the right place on the camera's CCD both times to cover the exact same point of the Mars terrain. However, with the bright spot showing up in one camera and not the other, that would skew the odds back towards cosmic rays, since it would be unlikely (but not necessarily impossible) for one navcam to see light glinting off a rock and the other to miss it.
One thing we can be pretty sure of though ... just as with all the previous mysteries that Curiosity has spotted since it landed, the answer to this mystery is not aliens.
An in-depth discussion of the images and what the spot could be is still going on right now on UnmannedSpaceflight.com.
(Images courtesy: NASA/JPL-Caltech)
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