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It seems there are many scientific laser ranging stations around the globe and some are mobile.

Scientists Bounce Laser Off Soviet Lunar Rover
Scientists Bounce Laser Off Soviet Lunar Rover Lost On Moon Decades Ago. Source

Questions

  • How dangerous are those scientific laser beams for passengers and crew, and for the aircraft?
  • Is there a NOTAM or a temporary flight restriction associated with scientific laser activity?

Background

For satellite laser ranging:

In satellite laser ranging (SLR) a global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of millimeter level precision which can be accumulated to provide accurate measurement of orbits and a host of important scientific data.

International Laser Ranging Service
International Laser Ranging Service - Map of stations. Source.

and for the Moon:

Laser beams are used because they remain tightly focused for large distances. Nevertheless, there is enough dispersion of the beam that it is about 7 kilometers in diameter when it reaches the Moon and 20 kilometers in diameter when it returns to Earth. Because of this very weak signal, observations are made for several hours at a time. By averaging the signal for this period, the distance to the Moon can be measured to an accuracy of about 3 centimeters.

For astrophysics purposes:

Adaptive optics systems require a wavefront reference source in order to correct atmospheric distortion of light. Sufficiently bright stars are not available in all parts of the sky [...], one can create an artificial guide star by shining a laser into the atmosphere.


See also

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    $\begingroup$ Just a comment because it's hearsay, but: I worked with a guy who had a degree in astrophysics. He said that observatories that use artificial guide stars for their adaptive optics employ interns whose job it is to lay on a cot in the parking lot and hit a remote kill switch when an aircraft approaches. $\endgroup$ – Kevin Krumwiede Jul 14 '15 at 19:45
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    $\begingroup$ Yes, I read that too, and Frederico good answer also mentions (sorry for the caps): "THE AREA WILL ALSO BE MONITORED BY OBSERVERS AND THE LASER BEAM WILL BE TERMINATED IF NONPARTICIPATING AIRCRAFT ARE DETECTED". Pretty boring job. Also read that small radars start to be coupled with the laser source. Thanks for the confirmation anyway. $\endgroup$ – mins Jul 14 '15 at 20:07
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    $\begingroup$ If the issue is the beam itself, why not just have a sensor that watches in the area the beam is projected and automatically shut it off when movement is detected, no need to worry about a shivering intern losing focus for a moment. Or is it just that the telescopes are so expensive they don't want to spend money on extra equipment like that? $\endgroup$ – JAB Nov 17 '15 at 14:35
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    $\begingroup$ @mins You could use a high-resolution video camera with good nighttime capabilities, a good-quality motion-detection algorithm, and a computer to run it on and trigger the kill switch when it detects point motion in the camera's field of view. There would likely be some expense involved, but it seems like it might be slightly more effective than a freezing-cold intern having to stay constantly alert. $\endgroup$ – JAB Nov 18 '15 at 18:53
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    $\begingroup$ @mins Nope, and neither do I know the specifications of individual observatory telescopes for their high-quality imaging. I do know, however, that telescopes of that scale are quite expensive, so even a lesser system of similar quality for detection of motion near the path of the telescope's direction would likely be quite pricey as well. Hence my initial comment about cost. Though if a human can spot the planes moving, an equivalent camera probably wouldn't need anywhere near the same amount of sensitivity as an advanced telescope to accomplish the same task anyway. $\endgroup$ – JAB Nov 18 '15 at 19:41
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Is there a NOTAM or a temporary flight restriction associated with laser ranging activity?

Apparently yes:

The lasers on the telescopes are in the range of 15-40 watts. The FAA calls a no-fly zone over the area when a laser is in use, and two people have to stand around outside in the freezing temperatures and watch for airplanes. Each of them has a kill switch to turn off the laser in case an airplane comes near. [...]

To clarify, the FAA does not have a no-fly zone, but instead issues a “Notice to Airmen” or NOTAM about the laser operations.

I also worked on an Adaptive Optics project and it was given for granted that NOTAMs would be issued by the people in charge of the experiments.

Example of NOTAM:

FDC 0/7651 ZDC .. SPECIAL NOTICE .. LASER OPERATIONS EFFECTIVE 1005010001 UTC UNTIL 1112312359 UTC. SCIENTIFIC AND RESEARCH LASER OPERATIONS WILL BE CONDUCTED AT THE NASA GODDARD SPACE CENTER IN GREENBELT, MARYLAND, LOCATED AT 390113N/764939W. THE SYSTEM IS INTERMITTENT, WITH POSSIBLE OPERATIONS HAPPENING 24 HOURS A DAY, 7 DAYS A WEEK. THE LASER BEAM MAY BE INJURIOUS TO PILOTS/AIRCREWS AND PASSENGERS EYES FOR A DISTANCE OF 98,000 FEET ABOVE GROUND LEVEL. HOWEVER, THIS SYSTEM USES A LASER HAZARD REDUCTION SYSTEM RADAR THAT IS SLAVED TO THE TELESCOPE MOUNT TO ENSURE THE LASER IS DEACTIVATED IN THE EVENT AN AIRCRAFT APPROACHES. THE AREA WILL ALSO BE MONITORED BY OBSERVERS AND THE LASER BEAM WILL BE TERMINATED IF NONPARTICIPATING AIRCRAFT ARE DETECTED. LASER IRRADIANCE LEVELS WILL NOT EXCEED THE MAXIMUM PERMISSIBLE EXPOSURE LEVELS WITHIN THE LASER FREE, CRITICAL FLIGHT, AND SENSITIVE FLIGHT ZONES. OTHER VISUAL EFFECTS, E.G., FLASHBLINDNESS, AFTER IMAGE, GLARE, AND DISTRACTION MAY OCCUR AT GREATER DISTANCES. THE POTOMAC TRACON /PCT/ PHONE NUMBER 540-349-7541 IS THE FAA COORDINATION FACILITY.


How dangerous is a laser beam for passengers and crew, and for the aircraft?

For the aircraft (meaning the hull) it is no danger, 40 watts of unfocused power (astronomers do not need laser beams in the sky as focused as the beams in an optics lab) do not affect the hull.

For the eyes of pilots and passengers it can instead be extremely dangerous, see Why is laser illumation of a cockpit an emergency?

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    $\begingroup$ "At one telescope, planes get close enough to the beam to cause a shutoff once every year or twin". Well! -- I'm adding a link to the Mauna Kea timelapse which is a pure beauty. $\endgroup$ – mins Jul 14 '15 at 12:02
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    $\begingroup$ @mins note that that is not used for ranging, but for Adaptive optics systems: en.wikipedia.org/wiki/Adaptive_optics $\endgroup$ – Federico Jul 14 '15 at 12:08
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    $\begingroup$ I WISH THEY WOULD STOP WRITING IN ALL CAPS SO THAT WE COULD ACTUALLY READ THE NOTAMS. :) $\endgroup$ – Doug McClean Jul 14 '15 at 17:17
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    $\begingroup$ Teletype machines were caps only. Aviation habits change quite slowly. $\endgroup$ – Wirewrap Jul 14 '15 at 21:26
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    $\begingroup$ So the area around these laser ranging sites basically becomes a "controlled firing zone"; not marked as a potential hazard area on sectionals (though the observatories themselves, typically placed on mountains in the middle of nowhere, are common VFR landmarks) and non-participating aircraft don't have to avoid them, but it would be nice if you did. $\endgroup$ – KeithS Jul 15 '15 at 16:44

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