The main imaging cameras on the Mars Curiosity rover have only 2-megapixel sensors with 8 GB of flash memory — compare that to a maxed-out iPhone 4S with an 8-megapixel sensor and 64 GB of flash memory (not to mention 30-fps 1080p video). Planning timeframes and communications bandwidth contributed to the chosen camera size.
‘There’s a popular belief that projects like this are going to be very advanced but there are things that mitigate against that. These designs were proposed in 2004, and you don’t get to propose one specification and then go off and develop something else. 2MP with 8GB of flash [memory] didn’t sound too bad in 2004. But it doesn’t compare well to what you get in an iPhone today.’
The cameras were also supposed to be outfitted with zoom lenses but that part of the project was scrapped.