Current Mars rovers collect large amounts of data and image sequences on Mars and store them in memory, and usually they then transfer the data to a spacecraft in Mars orbit for rebroadcast to Earth at scheduled times.
But is it possible for a rover like Curiosity, to transmit 'live' HD video from the surface of Mars to an orbiter which, at the same time, will rebroadcast the images to Earth ?
Curiosity is equipped with significant telecommunication redundancy by several means – an X band transmitter and receiver that can communicate directly with Earth, and a UHF Electra-Lite software-defined radio for communicating with Mars orbiters.
[...]Curiosity can communicate with Earth directly at speeds up to 32 kbit/s, but the bulk of the data transfer should be relayed through the Mars Reconnaissance Orbiter and Odyssey orbiter. Data transfer speeds between Curiosity and each orbiter may reach 2000 kbit/s and 256 kbit/s, respectively, but each orbiter is able to communicate with Curiosity for only about eight minutes per day (0.56% of the time).