What is the maximum data transmission rate the MRO achieves when relaying data down to Earth?

Up to 6 megabits per second (Mbps)

The efficiency gained by using the relay architecture is highlighted by the impressive data rates achievable during the downlink from orbit to Earth. When the Mars Reconnaissance Orbiter (MRO) serves as an active relay, it is capable of transmitting collected information back to the Deep Space Network at speeds reaching as high as 6 megabits per second (Mbps). This significant rate allows mission controllers to receive substantial volumes of operational telemetry and numerous high-resolution images daily, which is crucial for keeping complex, long-duration missions operating on schedule and maximizing scientific return within limited communication windows.