Communications
This page will discuss the work on the communications systems.
Radio communication of sensor data and images is critical for the success of the Mars balloon project. There are three parts to the system as implemented with the new Mars Science Laboratory and Mars Reconnaissance Orbiter. First, a UHF radio on the rover communicates with the orbiter. The orbiter collects the data and saves it to nonvolatile storage. The Orbiter (MRO or Odyssey) sends the data via Xband radio to the Deep Space Network which is run by NASA. The data is sent from the DSN to whatever sites need access to the information.
For the first prototype balloon, there is no need to bundle an orbiter if the UHF radio function can be included in the balloon and allow it to talk to the existing orbiters.
Per NASA information, MRO and Odyssey can give at most an 8 minute window per orbit. Bandwidth for MRO can be up to 2 or 4Mbits/second. For the Odyssey, the figure maxes out at 256kbits/second. For the balloon, it must blast the image data to the orbiter as soon as the window starts to enable any reasonable amount of data to get sent. For example, the 8 minutes equates to 480 seconds. Time 4M bits gives a max of 1920 megabits per window. With overhead, a 5 megabyte images file (cell phone quality) becomes 50 megabits. This gives us a figure of 38 images per window max. For a slow moving balloon taking a picture every half an hour or so during the day time (24 images) this is sufficient. If the MRO synchs at a lower speed, we can only upload half or even less than the max, which could mean 18 or so pictures. That could mean just one per hour.