We've seen our planet from the perspective of Mars before, but this one's a bit different. It's an image of our pale blue dot as seen by the Mars Express Orbiter. It may not look like much, but getting this shot was no easy task.
The European Space Agency recently captured a chance image of Jupiter using the MEO's onboard VMC camera. This gave the researchers hope that a similar shot could be taken of Earth. But imaging Earth from a Mars-orbiting spacecraft using a camera with no specialized optics presented some challenges.
As noted by Daniel Scuka at the ESA blog, they had to determine the optimal time to take the photo; they had to pinpoint the exact time when the Mars-Sun-Earth angle was large enough such that a sufficient amount of Earth was illuminated, but not so large that the Sun was to close to the camera's field of view. The JPL's HORIZONS solar system ephemerides computation service was able to help.
Another major challenge was getting the MEO spacecraft to point its instruments at Earth (and in a way that didn't peril the mission). Once these and other hurdles were overcome, the team was able to snap the picture — the Earth at a distance of 150,031,705 km taken on 3 July 2014 at 15:52 CET. Scuka writes:
The bright patches you can see are sunlight hitting the top of the recess VMC sits in and then being reflected off the camera lens.
However, on the 2-second exposure, this glare is reduced sufficiently to leave Earth clearly visible in the middle left of the image (Note: the colours here are the result of the processing tool we run the VMC images through).
At first glance it doesn't look like a particularly exciting photo. Some lens flare and a small faint dot are visible.
However, remember: there are 7 billion people living on that small faint dot!
More details here.
Credit: ESA/Mars Express/VMC