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Laser ranging retro-reflector: continuing measurements and expected results
Science (New York, N.Y.)
|January 30, 1970
Summary
Scientists precisely measured the Earth-Moon distance using laser pulses reflected off the Apollo 11 retro-reflector. This lunar laser ranging (LLR) technology achieved sub-meter precision, advancing our understanding of the Earth-Moon system.
Area of Science:
- Lunar Laser Ranging (LLR)
- Geophysics and Astronomy
- Space Geodesy
Background:
- The Apollo 11 mission deployed a laser ranging retro-reflector (LRRR) on the Moon.
- Precise measurement of the Earth-Moon distance is crucial for understanding celestial mechanics and relativistic effects.
Purpose of the Study:
- To report on the successful acquisition of reflected laser pulses from the Apollo 11 LRRR.
- To demonstrate the performance and precision of lunar laser ranging measurements.
- To contribute to ongoing monitoring of the Earth-Moon system dynamics.
Main Methods:
- Utilized telescopes at Lick and McDonald observatories for laser pulse acquisition.
- Measured the round-trip travel time of reflected ruby laser pulses.
- Implemented and refined instrumentation at McDonald Observatory for enhanced precision.
Main Results:
- Achieved initial range precision of +/-2.5 meters in September.
- Demonstrated LRRR performance during lunar night and sunlit conditions.
- Reached a precision of +/-0.3 meter by October, with further improvement to +/-0.15 meter anticipated.
Conclusions:
- The Apollo 11 LRRR is performing effectively for precise distance measurements.
- Lunar laser ranging offers a robust method for monitoring Earth-Moon distance variations.
- Continued measurements will enhance our knowledge of the complex Earth-Moon system.
