The spacecraft on a nine-year cruise to Pluto has spent its first 100 days getting warmed up for the scientific mission ahead.
NASA's New Horizons spacecraft launched from Earth on 19 January 2006. On 7 April, sailing along at 111,960 kilometres per hour, it passed the orbit of Mars – the first planet to overtake on its way to Pluto. By 7 May, it will be twice as far from the Sun as is the Earth.
After spending the early part of the mission testing the spacecraft sub-systems, managers spent March and April checking on some of the spacecraft's scientific instruments and tweaking its software.
The team successfully beamed up a new version of command and data handling software. Every time a new version is sent up, the spacecraft's main computer has to be rebooted. "You can imagine how much care, how many design reviews, how much event simulation, and how much nail-biting was involved in planning for this," says Alan Stern, the New Horizons principal investigator at the Southwest Research Institute in Boulder, Colorado, US, in an online update.
The instrument checks have also gone according to plan. The Ralph instrument, which will map the surface composition of Pluto, and REX, a radio science experiment, both performed flawlessly in their initial functional checks. The SWAP solar wind detector has also successfully turned on its detectors, Stern says.
Three instruments will open their detector doors for the first time in May – Ralph, the Pluto Energetic Particle Spectrometer Investigation and Alice, an ultraviolet imaging spectrometer. This will enable the instruments to take "first light" measurements, although Ralph's door has a window, meaning initial calibrations can be done earlier.
"These will each be big milestones - we are opening up our 'eyes' to space," says Stern.
The mission team will also spend the next few months practicing for New Horizons' flyby of Jupiter in February 2007. The spacecraft will use the giant planet's gravity to fling it like a slingshot into the outer solar system. The boost provided by Jupiter will slash about three years from the spacecraft's flight time.
The probe will approach Jupiter to within 16 times the diameter of the planet – three to four times closer than the Saturn-bound Cassini mission did. It will take some measurements but its priority will be instrument testing and calibration. Scientifically valuable observations of Jupiter's atmosphere, moons, rings and magnetosphere will be of secondary importance.
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18:00 07 October 2008
17:56 07 October 2008
