Jan 17, 2006, 23:48 GMT
Washington - Gusting winds at the launch pad prompted NASA officials to cancel Tuesday's liftoff of an Atlas 5 rocket carrying the first-ever New Horizons probe to Pluto and the Kuiper belt on the edge of the solar system.
New Horizons Spacecraft aboard a Lockheed Martin Atlas V rocket is viewed from a remote camera site in the middle of the lightning protection system on launch pad 41, Monday 16 January 2006. EPA/GARY I ROTHSTEIN
NASA officials kept delaying the launch from Cape Canaveral, Florida during the nearly two-hour departure window, citing communications problems and possible malfunctioning fuel valves.
Wind gusts up to 61 kilometres per hour prompted the final scrub of Tuesday's launch.
'We exceeded our wind limits at the pad - in excess of 33 knots, just two and a half minutes before launch,' officials said on NASA TV.
The launch window opens again on Wednesday at 1:16 p.m. (1816 GMT) for the 700-million-dollar mission. If the launch is successful, the spacecraft is expected to pass the moon's orbit within nine hours - a speed record for space launches.
NASA has until February 14 to launch the 438-kilogramme New Horizons spacecraft, headed for a 6.4-billion-kilometre trip of nine years past Neptune and across the debris-crowded Kuiper belt to the 'ice dwarf' Pluto.
Mission specialists are impatient to get the probe underway to make full use of a gravity assist from Jupiter that would boost its speed to 75,000 kilometres an hour and put it within 10,000 kilometres of Pluto by the summer of 2015.
But a later launch date would reduce Jupiter's shove, making the journey take another five years - 14 years total. Arrival is imperative before 2020, when Pluto's winter sets in and its atmosphere of methane and other gasses starts to freeze and 'fall as snow' again, mission scientists say.
On Sunday, NASA celebrated the year's first space achievement, when the Stardust probe returned to earth carrying stardust and particles from the Comet Wild 2 after a 4.6-billion-kilometre, seven- year journey. Analyzing the samples will keep scientists - and internet volunteers - busy for a decade.
NASA scientists hope that the Pluto and Stardust missions will shed light on the more than 4-billion-year history of the solar system.
Pluto, the only planet that routinely eludes amateur and even professional astronomers, is so far out on the cold, dark edge of the solar system that even the Hubble telescope fails to get clear images.
To reach Pluto, New Horizons must cross the Kuiper Belt, the collection of debris that rings the solar system and is believed to be left over from formation of the solar system. New Horizons' principal investigator Alan Stern compares the mission to an 'archeological dig into the history of the outer solar system'.
Pluto was discovered 75 years ago, by American Clyde Tombaugh, and his death day, January 17, 1997, was remembered Tuesday as scientists tried to launch New Horizons.
Pluto's moon, Charon, first sighted in 1978, is half the planet's size and pulls Pluto into an orbit around a centre outside its surface mass. That's why it's called a binary planet. Two smaller moons were discovered last year.
Before liftoff, environmentalists continued protests against the use of plutonium to power New Horizons. They fear that a malfunction or explosion during launch could release plutonium particles into the atmosphere, CNN reported.
New Horizons cannot fly on solar power because of Pluto's distance from the sun. The planet takes 248 Earth years to complete one solar orbit and has so little light that a camera on board is calibrated to read light levels 1,000 times fainter than daylight on Earth.
NASA's human space flight programme is on hold after a series of difficulties - the tragic destruction of Challenger and Columbia shuttles over the past 20 years, followed by last year's near glitch with heating tiles on Discovery.
Meanwhile, unmanned flight has racked up success after success since the 1970s. Like the projected journey for New Horizons, the Pioneer and Voyager missions to Jupiter and Saturn, the Mariner missions to Venus and Mercury, and other probes have all used gravity assists of Jupiter and other planets to reach their goals.
Pluto is the only known planet not yet reached by unmanned space probes.
Rockets designed before 1960 were unable to produce sufficient thrust to send spacecraft beyond Jupiter, and calculations put the travel time from Earth to Pluto at 40 to 50 years using conventional power, according to NASA. In comparison, New Horizons' journey will span nine to 14 years.
Your Talkback on this Story