I heliograph
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“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 avalanche photodiode and an ethernet port.

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“i-Heliograph”

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“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 avalanche photodiode and an ethernet port..

Replace this guy with a high speed optical modulator 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.


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