European scientists are still not certain whether a space lander that reached Mars yesterday touched down on the Red Planet in good working condition.
"The landing test still gives us some open questions we have to analyse," European Space Agency Director General Jan Woerner said this morning.
He added that he could not say whether the disc-shaped Schiaparelli probe was still in one piece.
Scientists said data had been received showing the lander's heat shield and parachutes deployed successfully, but that it was unclear what happened in the final seconds before landing and no data had yet been received from the surface.
Schiaparelli, which is testing technologies for a rover due to follow in 2020, represents only the second European attempt to land a craft on Mars.
Earlier, Paolo Ferri, ESA head of missions operations, said: "We saw the signal through the atmospheric phase, the descent phase - at a certain point it stopped.
"This was unexpected but we couldn't conclude anything from that because this very weak signal picked up on ground was coming from an experimental tool.
"We waited for the Mars Express measurement which was taken in parallel. It was of the same kind, it was only recording the radio signal.
"The signal came through at 6.30pm and confirmed exactly the same. The signal went through the majority of the descent phase, but it stopped at a certain point that we reckon was before the landing".
Schiaparelli separated from its own mothership, the ExoMars Trace Gas Orbiter, on Sunday after a 500 million kilometre seven-month journey through space.
