6. External Communication System

DL4 must have a communications system that is capable of two-way audio and visual communication between Earth, transport vehicles, miners on asteroids or the Moon and DaedalusaL4.  Communications will be used to:

1.       Avoid complete isolation from Earth,

2.       Communicate with vehicles docking or manoeuvring around the settlement,

3.       Allow miners working on asteroid or lunar sites to contact DL4,

4.       Communicate research findings to Earth-bound sponsors/scientists and

5.       Enable a tele-education system for those third level students who remain onboard (see 19 Education System).

The external communications system will be a relatively simple operation involving a number of communications satellites. Today, the launch of such satellites is very expensive because of the high cost per kilogram of Earth launch (see fig. 3.2a).  With no commercial construction and assembly capability in space, satellites must fit into one launch payload.  Hence, their capabilities are limited.  However, use of a Solar Orbit Transfer Vehicle to transport satellites from DL4 would be far cheaper. There is no apparent reason why the satellites used would have any dramatic differences to communications satellites used today, however they will be easier to launch and cheaper to construct from DL4, using lunar and asteroid materials.

An S-band system will be used for audio communications and file transfer between DL4 and Earth (ref. 68). It involves a movable antenna, which can transmit radio frequencies among other signals.  An ultra-high frequency system can also be used to communicate with Earth, and also with various vehicles.  Both of these systems involve a transmitting antenna, like those used by today’s satellites, and a ground receiver, if the signal is to be sent to Earth.   All vehicles will be equipped with a receiving antenna and transmitting antenna for communications purposes.