problems.........problems............problems.......15 years planing and 10 years travelling for this moment
(1) The spacecraft bumps three times unexpectedly and landed on far away from earlier planned site on comet (new site is covered by a small mountain or rock)
(2) The new site does have very little sun light (1.5 hr per day) and very little energy to power spacecraft using solar energy. Not sufficient to perform scientific experiments
(3) the spacecraft did not properly connected to the comet (any time it can throw away to empty space) . The mechanism did not work. The gravity is super weak in comet
(4) scientists try to fix it. The last option - move the spacecraft away from comet and try to land again (very risky)
from bbc and cnn