1. Outbound pulse start out 3.5 metres in diameter, 2 cm thick
2. Atmosphere causes beam to diverge by one arcsecond or more
3. At the moon, 1 arcseconds is 1.8 km, so beam at moon is about 2 km across
4. Only about 1 in 30 million photons in this 2 km beam hit the suitcase-sized reflector
5. Each outgoing laser pulse contains 300 quadrillions photos