The Pluto mission launch to the edge of the solar system hit another hold pattern Tuesday afternoon, until 1910 GMT, due to concerns over gusting winds and other problems, NASA television said, according to DPA. The 438 kilogramme New Horizons payload atop the Atlas 5 rocket is headed for a 6.5 billion kilometre trip past Neptune and across the debris-crowded Kuiper belt to the "ice dwarf" Pluto, first discovered in 1930. Tuesday's launch window opened at 1824 GMT and closes at 2023 GMT. Mission managers were checking to make sure a problem with the "fill and drain valve", which was not opening and closing as required, had been solved, and were making minor adjustments, according to NASA TV. If the launch goes off as planned, it will mean a speedier trip for the ambitious Pluto project by making use of a gravity assist past Jupiter. It could mean New Horizons will arrive as early as 2015 at Pluto after crossing the debris-crowded Kuiper belt. The launch window extends until February 14, but a later departure could delay arrival to as late as 2020, when the onset of Pluto's long winter could cause snowy atmospheric conditions on Pluto. Liquid oxygen and hydrogen were loaded into the fuel tanks Tuesday morning. The 700-million dollar project is expected to reveal new insights into the formation of the solar system some 4.5 billion years ago. After travelling 6.5 billion kilometres, the probe is expected to approach the "ice dwarf" - as Pluto is known - as close as 10,000 kilometres to Pluto.
