It would be amazing if they let you do that, but is very unlikely that NASA would let you control a real Mars rover using an iPhone app but if they do, it would look something like what is demonstrated over here.
Eclipse open source community (EclipseCon 2010) in collaboration with NASA JPL, organized the e4-Rover Mars Challenge where attendees supposed to create a robotic control system to drive a NASA-provided robot across a “prototypical Mars landscape”. To win Participants could do one of the two: Prove e4 programming skills by creating the very best e4-Rover client OR Use an e4 client to operate the Rover through a series of tasks to collect points.
As it can see in the video, iPhone app works by exclusively using the iPhone accelerometer. The prize is a visit to the NASA robotics lab in Los Angeles, a Lego Mindstorms NXT 2.0 robotics set and $500 credit for Amazon Web Services, it’s very understandable.
Jon Dearden’s wont the award for Best client, which was constructed using an e4 client and was used to operate the Rover through a series of tasks to collect points.