There are three ways for Curiosity, to broadcast data back to Earth – but it’s only the UHF transmitter that can be used for transmitting the amounts of data required for sending back images. ‘The UHF antenna transmits to two spacecraft orbiting Mars, which relay the results back to Earth. That’s where most of the data is coming from. It gives us on the order of 250 megabits per day, and that’s got to be shared between a bunch of instruments, so there’s not much bandwidth for the cameras.’ Ravine explains.
250 megabits per day. Convert that to megabits per second and you get: 0.00289 Mbps or 2.89 Kbps. You don’t even get all of that because that bandwidth is shared with data being sent by other instruments. Imagine trying to download a 2 megapixel image with a connection that slow.