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Optical Communications Challenges
October 29, 2012

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For all its benefits, optical communications still faces several challenges. Unlike radio communications, which can be sent out in a broad beam blanketing target areas with its signal, optical communication is sent in a relatively narrow beam pointed directly at a receiver. When broadcasting from thousands or millions of miles away, an optical communication telescope pointing must be extremely precise. A deviation of even a fraction of a degree can result in the laser missing its target entirely.

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To enhance the optical communications beacon-aided acquisition, SCaN is developing beacons near the receivers onto which spacecraft can lock-on to. Just like terrestrial lasers, the beam of space based optical lasers spreads out, or becomes dispersed. As this occurs, the light becomes less dense and the data is harder to retrieve. Special receivers called photon counting detectors are being developed to detect single photons as they travel in the optical beam from space to earth.

Even Earth's atmosphere interferes with optical communications. Clouds and mist can interrupt a laser. SCaN is investigating multiple approaches, like Disruption Tolerant Networking and satellite arrays to help deal with challenges derived from atmospheric means.

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Artist rendition of a ground based transceiver
Artist rendition of a ground based transceiver
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Clouds and mist can interrupt a laser
Clouds and mist can interrupt a laser
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Page Last Updated: August 8th, 2013
Page Editor: NASA Administrator