OLSG Report_Final_06_05_12 - Interagency Operations Advisory ...

Optical Link Study Group (OLSG) Final Report
IOAG.T.OLSG.2012.V1
7. Are there any decommissioned telescopes at your site that could be used for optical
communications? What types and diameters? Who owns each? When was each last used
and what is its mechanical and optical state?
8. Are there requirements for EMI shielding of ground equipment at the site?
9. Do you gather any statistics about clouds, seeing, etc., for your site? Do you monitor
any statistics on a real-time basis?
10. Are there any other factors we need to consider? (e.g., Are there any foreseen
difficulties regarding the addition of a structure at your site due to local laws/regulations?
Are there additional organizations with facilities/telescopes at the site with whom we need
to coordinate?)
11. What “rent” would we be charged if we located our transmitter and receiver on the
site (could be either one or two structures)? What does the rent cover?
Below is some information that you may find useful in answering these questions:
Each optical communications ground terminal would consist of two telescopes (which could
potentially be combined into one): an uplink transmitter and a downlink data receiver. The
two telescopes would not necessarily have to be on the same structure and the allowable
distance between the two structures would depend on the type of mission supported. We
are considering uplink transmission (ground to space) at 1550±20 nm, 1030 nm, and/or
1064 nm and downlink transmissions (space to ground) at 1550±20 nm and/or 1064 nm.
The OLSG is considering optical communications support for several types of space missions,
including spacecraft in Low Earth Orbit (LEO), in Geostationary Earth Orbit (GEO), in Lunar
orbit, at the Sun-Earth L1 and L2 points, and in deep space (e.g., in Mars orbit). For the
purposes of this questionnaire, optical ground terminal parameters can be categorized as
follows:
• To support LEO spacecraft: The receiver (downlink) telescope would be ~ 50 cm
and the transmit (uplink) telescope aperture would be ~ 40 cm. The spacecraft
transit over the site would be on the order of minutes. The elevation and
azimuth tracks could vary widely depending upon the orbit of the spacecraft.
• To support GEO spacecraft: The receiver telescope would have a diameter up to
1 m and the transmit telescope would be ~ 40 cm in diameter. Tracking would be
limited to basically transmitting and receiving continuously at a fixed point in the
sky above Earth’s equator, with the azimuth and elevation dependent upon the
orbital slot of the spacecraft.
• To support spacecraft beyond the geostationary orbit, e.g., Lunar, Sun-Earth L1
and L2, Mars, etc.: The receiver telescope aperture would be ~ 1 -12 m, and the
transmit telescope aperture would be ~ 1 m. The tracking rate would be
equivalent to the rotation rate of the Earth and the elevation and azimuth of the
track would depend upon the location of the spacecraft in the Solar System.
Depending upon the orbital location of the target spacecraft, optical
communications would occur in daytime only (for L1 missions), nighttime only
(for L2 missions), or during the day and night (for Lunar, Mars, and other deep
space missions).
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