Scene Context: Les receives a video message from Talani on the 118th day of the flight to Mars and is forced to wait at least 8 minutes for a reply. Communication occurs exclusively through asynchronous video file exchange.
Essence of the Phenomenon: Deep space communication fundamentally differs from the terrestrial internet. Information is transmitted via radio waves, the speed of which is limited by the speed of light in a vacuum. Therefore, an unavoidable physical delay arises between sending a message and receiving it.
Scientific Basis: On the 118th day of the flight, the spacecraft is tens of millions of kilometers away from Earth. A 4-minute one-way delay means the distance between the Sagan and Earth is approximately 72 million kilometers. Communication utilizes the Deep Space Network (DSN)—a system of giant parabolic antennas on Earth. The signal from the spacecraft is extremely weak and is sent not as a continuous stream, but as fragmented data packets, which the computer on Earth reassembles, decrypts, and checks for data loss.
Current Limitations: No technologies based on classical physics are capable of transmitting information faster than the speed of light. A live communication regime becomes physically impossible just beyond lunar orbit.