The European Space Agency (ESA) has landed a robot probe on a comet, but an anchoring system problem may hamper planned investigations into the origins of the Solar System.
The "Philae" probe touched down on the surface of comet 67P in a space exploration milestone on November 12, seven hours after separating from the "Rosetta" spacecraft.
ESA said the landing was a "big step" for humans, and the U.S. space agency NASA described it as a "breakthrough moment."
But initial data from the 100-kilogram explorer indicated that harpoons designed to anchor it to the comet failed to deploy properly.
More information is expected on November 13, when "Philae" is scheduled to make contact with "Rosetta."
"Rosetta" traveled 6.5 billion kilometers over more than 10 years to reach the comet, a 4-kilometer wide lump of dust and ice.