The local team in charge of the Curiosity rover project on Mars found themselves on the defensive Thursday when reporters grilled them about a NASA report questioning the project's return on investment.
Instead, several reporters asked JPL's John Grotzinger and NASA's Director of Planetary Sciences Division, Jim Green, to respond to a recent senior review that criticized the team's extended mission.
The report from earlier this summer called Curiosity's new objectives "a poor science return for such a large investment." The rover is budgeted for $59.4 million over the next fiscal year.
Specifically, the panel argued that the six-wheeled rover will be doing too much driving and not enough sample gathering during the next phase of its explorations.
Currently, the rover is scheduled to take eight drill samples from four locations over the next 24 months.
The panel also said the rover's extended mission "lacked specific scientific questions to be answered, testable hypotheses, and proposed measurements and assessment of uncertainties and limitations."
Curiosity's main project scientist John Grotzinger defended the rover's stated goals by saying the team specifically chose to drill less in order to help preserve key parts of the $2.5 billion machine.
"We do worry about overuse, and the vehicle is a consumable. Every instrument is a consumable, the wheels are a consumable, the drill is a consumable," he commented.
The rover's six wheels are badly damaged from two years of driving on the rocky surface of the Red Planet, according to Grotzinger.
He also noted that while the rover will only perform eight drill samples during its extended mission, those samples will come from a wide variety of locations.
"The important thing for us is that this not become a 'rander' mission, which is a rover that lands in one spot and then just noodles around."
Instead, his team hopes to sample, analyze and then cruise to the next distant location.
In total the rover is will travel about 5 miles to reach the four locations that NASA thinks contain rocks from different periods in Mars' history.
NASA's Jim Green stressed that the senior review panel still believes in the importance of the mission, despite the harsh comments.
"That's what we asked them to do, to be critical," Green emphasized.
So far, NASA headquarters has not directed the Curiosity team to alter plans in any substantial way.
The one-ton rover landed on Mars in August 2012. Its primary mission was to determine if Mars was ever the type of place life could exist.
In June, it ended that mission, claiming success. The rover is now embarking on EM1, or Extended Mission 1. This phase is expect to last until Sept. 25, 2016.