If the fuel had run out before the probe reached the comet, the navigational thrusters would not have been able to make the numerous course corrections needed to meet the comet and then establish a stable orbit from which to launch the Philae landing module. Throughout the decade-long journey, the pressure sensors monitored the fuel consumption continuously to ensure that Rosetta arrived with enough fuel to make the final corrections to put the probe into orbit.
The key selection criteria for the sensors included longevity and reliability despite high levels of vibration at lift-off and years of zero gravity conditions.
The mission is the most ambitious by the European Space Agency. Rosetta's cargo includes the Rosetta Disk – a nickel alloy disk with information etched onto it in image form. The disk contains about 13,000 pages of text in 1,200 languages, and it should still be readable after 10,000 years.