Scientists said the Philae spacecraft, which had landed on a comet last year, may have shifted in its position, making it difficult to communicate with the space probe. Philae's project manager, Stephan Ulamec, explained on Monday that the pattern of sunlight on the lander's solar panels appeared to have changed, possibly due to a shift in position.

"We have observed signs that Philae could have moved and that its antennas are thus perhaps more concealed or their orientation may have changed," Ulamec said.

No communication in two weeks

Philae had touched down on comet 67P/Churyumov-Gerasimenko on November 12 last year, and went into hibernation mode three days later, waking up again on June 13 for intermittent contact with Earth via its orbiting mothership Rosetta. The last time Philae communicated with ground controllers was on July 9, when it uploaded data. The European Space Agency confirmed that it hadn't received any signals from the lander since then.

The German Aerospace Center (DLR) Lander Control Center team has been "working hard to get back in contact with the lander and operate it to conduct scientific measurements," DLR said in a statement.

Not the first interruption

Scientists enlisted in the project plan to send further commands to the lander and said they hoped that it would respond again, as had happened before. The mission also planned to examine communication options originating from the mothership Rosetta.

"At the moment we have some concerns about this," DLR spokeswoman Manuela Braun said. "We are trying to understand."

The space project had undergone various challenges and uncertainties before.

ss/kms (AFP, AP)