“i-Heliograph” Can we make a low power data transmitter to send “lots” of data from the moon to the earth using a 19th century idea enhanced with 21st century technology? How does such a system compare to laser communication?

Replace this guy with a high speed optical modulator and an ethernet port. Replace this guy with a avalanche photodiode and an ethernet port..

Replacing the guy wiggling the mirror Voltage Controlled LCD displays (KHz Speeds?) Acoustic Optical Modulators (speeds up to 100 MHz)

Replacing the guy using his eye to see the signal on the receive end Avalanche Photo diodes

There should be a power savings compared to Laser Comm Lasers are ~10% efficient on producing optical output from electricity it gathers from ~25% efficient solar cells. –Total efficiency from sun = 0.25 * 0.1 = 2.5% Mirrors are ~90% reflective

Other factors in comparison Mass to moon –Do solar cells and power system with Laser weigh more than a mirror and heliostat? Reliability –Solar panels, motors, AOMs… –Is dust an issue?

2009 Olin Job Build a Heliostat to capture the sun Pipe the light from the Heliostat through either an accoustic optical modulator or a LCD retarder Build a simple pulse frequency modulator to drive the AOM or LCD retarder Build a demodulator to read the output of an APD Predict performance and compare to Laser Comm.

GSFC will provide A telescope base to make a heliostat An AOM to modulate light A Circuit design to produce a FM Pulse train A Telescope for the receive end An APD (maybe dual use the one for the MCA project) The demodulator design.