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0.2 microradians. That's the

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angle of pointing stability of the ATLAS laser. If you

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placed a silver dollar 28 miles away from ATLAS, the laser's center

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would stay on the coin. That kind of stability is absolutely

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critical for the spacecraft to measure the height of Earth from orbit.

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To ensure pointing stability, ATLAS uses the Beam Steering Mechanism,

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which is a motorized mirror that moves to compensate for thermal changes

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that happen in orbit and prevents the ATLAS beams from bending as they head

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for Earth.
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