Side-by-side images show the Phoenix Mars Lander's robotic arm on the craft's first and second days on Mars after touchdown on May 25, 2008.
The folded arm had been protected from Earthly contaminants by a "biobarrier" since just before launch last August. Upon landing, Phoenix snapped a shot of the arm so that scientists could see whether the barrier had retracted.
The images show that on the first day, known as sol 0, the shield was not 100 percent deployed, but by the next day, sol 1, it had moved enough out of the way that the arm could be extended safely.
However, a communications problem on May 27, 2008, between Phoenix and the Mars Reconnaissance Orbiterwhich relays signals between Earth and the landermeans that NASA was not yet able to extend the arm.
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Image by NASA/JPL-Caltech/University of Arizona