The spacecraft's mass at launch was just over 13 tonnes, but some 10 tonnes of this was the fuel it expected to use in the course of its mission to the Red Planet's largest moon.
Some of the latest images from NASA's Global Surveyor mapping mission around the redplanet are making that abundantly clear, a group of scientists and engineers interested in NASA's Mars mission set for a 2001 launch learned recently.
The "car-sized" rover, set to touchdown on August 5th of this year at 10:31PM PDT, is currently journeying towards the RedPlanet on a suicide mission of sorts, with the success of its make it or break it EDL (enter, descent, landing) wracking the nerves of our Space Agency's greatest minds in advance.
And in case you missed the latest robotic resident arriving on Mars you can watch the action replay and view the very first pictures beamed back from the surface of the RedPlanet on Nasa's Mars Science Laboratory mission homepage.
Those overruns are partly to blame for leaving Mars exploration short of the multibillion-dollar commitment needed for another "flagship" mission of the scale it would take to fetch rocks and soil from the RedPlanet and bring them home.
With the first week on Mars behind them, the scientists and engineers who put Pathfinder on the RedPlanet say they have already met the major objectives set for the mission.