next generation lunar laser ranging
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Next Generation Lunar Laser Ranging. Alix Preston * , Stephen Merkowitz, Jan McGarry, Thomas Zagwodzki LUNAR Steering Committee Meeting April 12, 2011. - PowerPoint PPT PresentationTRANSCRIPT
Next Generation Lunar Laser Ranging
Alix Preston*, Stephen Merkowitz, Jan McGarry, Thomas Zagwodzki
LUNAR Steering Committee Meeting
April 12, 2011
*supported in part by an appointment to the NASA Posdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through contract with NASA
2Lunar Ranging – LUNAR Steering Committee Meeting – 9/21/09
Hydroxide Bonding and Hollow Cubes
• GSFC has been investigating in-house hollow corner cube development
• Attempting to use Hydroxide-Bonding techniques to bond mirrors– Easy: only need a small amount of hydroxide
solution (typically KOH or sodium silicate)– Strong: >1 MPa in shear– Can bond large surface areas– Works with a variety of materials– Can survive large temperature changes
• Currently understanding how the hydroxide bond cures– How much does it change the angles between
surfaces? Two 1” mirrors bonded using the hydroxide
bonding method
3Lunar Ranging – LUNAR Steering Committee Meeting – 9/21/09
Current Work
6-axis piezo positioners that will be used to construct hollow
corner cubes
1” corner cube produced using the piezo aligners and
hydroxide bonding
• Fabricated fixture to make corner cubes– Can accommodate larger facets already
• 2” fused silica facet flats have been ordered (arrive in May)– Alignment procedures/test protocols will
be established once the cubes are made– Zerodur facets will be ordered when this is
completed
• Optimizing the bonding process is underway– a few variations have been found already
• Improvements were made to the far-field test bed– Transmit /receive optics simplified, fiber
replaced spatial filter, larger off axis parabola with longer focal length, others
4Lunar Ranging – LUNAR Steering Committee Meeting – 9/21/09
Future Work Plan• Finish improvements to far-field test bed
(almost done)
• Make and test 2” cubes– Attempt to have first cube made in June– Determine how the FFDP changes after
thermally cycling– Compare cubes using different bonding
methods
• Prepare report on 2” cubes
• Procure 5”-6” facets– Currently looking into possible vendors
• Make and test larger corner cubes
• Prepare report on larger cube results
FFDP of an optical flat (left) and spare LAGOES 2 corner cube
(right) using the improved setup. Quality is limited by air currents
and vibrations
Construction of the light-tight enclosure to reduce air
turbulence