NASA's Mars chief frets over heat shield

July 10, 2012
A Vulcan joins the Red Arrow fly pass the airfield to mark the start of Farnborough International Airshow, Farnborough, England, Monday, July 9, 2012. (AP Photo/Sang Tan)

FARNBOROUGH, England (AP) — With weeks to go until its latest mission is due to arrive on the Red Planet, the head of NASA's Mars Exploration Program says his biggest worry is that the spacecraft's heat shield will not detach as planned.

Doug McCuistion cautioned Tuesday at the Farnborough Airshow south of London that many things can go wrong when the Mars Science Laboratory mission sets down a large, mobile laboratory on Mars.

He says the odds, historically, are against a successful outcome: of the 40 Earth missions to Mars, only 14 have succeeded. He predicted that this latest mission has a medium-to-low risk profile.

The spacecraft launched from Cape Canaveral last November and is due on Mars on Aug. 6.