I have some questions about Messenger's communication subsystem, could anybody help?
1. It is said that the advantage of phased array antenna is that they can be electronically steered - which mean Messenger can keep communicate with the Earth even while moving/rotating without using its thrusters to stabilize?
2. What is the gain for this antenna compared to a parabolic one? It is said that phased array antennas have lower gain than parabolic ones at the same power, is it correct?
3. As I saw in the s/c design diagram at http://messenger.jhuapl.edu/the_mission/sp...aft_design.html, Messenger has 2 phased-array antennas mounted on opposite sides of the s/c. Are they simply providing redundancy or are both required for the s/c to have full sky coverage?
4. Regarding the above question, what is the sky area (in degree) that one antenna can cover?
5. Do you know of any planned deep-space mission that's going to use the same antenna as Messenger's?
6. Having to know about the phased array antennas, I see they're really magnificent things. But do they have any major drawbacks for use in a deep-space mission? Do they require any special requirement on the ground station?