A NASA orbiter set to start circling Mars later this month has tough shoes to fill — its predecessor exposed an unprecedented bounty of global data on the planet’s water history and suitability for human colonies. The earlier probe — Mars Global Surveyor — and its six scientific instruments have delivered more than 130 CD ROMS-worth of data during its primary mission which started in March 1999. The incoming spacecraft, called Mars Odyssey, will follow up with even higher quality data also aimed at paving the way for NASA’s goal to put humans on Mars.