Space lasers fired at the Moon! It sounds like something from an Austin Powers movie – do you mean a “Space Laser” <air quotes> 🙂
The truth is even more interesting. Astronomers at observatories in new Mexico, Italy and Germany have been firing lasers at the Moon for 50 years as part of a long-ranging experiment that has yielded data on the tidal behaviour of Earth’s oceans, the surprising flex of the elastic lunar surface (up to 15 cms), the gradual movement of the Moon away from the Earth, and confirmation of Einstein’s gravitational theories.
Arrays of hundreds of prisms left on the lunar surface by Apollo missions receive the incoming laser beams and bounce them back to Earth. The Apollo 11 and 14 arrays have 100 quartz glass prisms each, while the array left by Apollo 15’s astronauts has 300! The accuracy in measurement these prism arrays allow is stunning — and the experiment just keeps yielding data year after year because the arrays require no power or maintenance.
The returning signals have allowed the orbit, rotation and orientation of the Moon to be very accurately determined, and have confirmed that he the distance between the Earth and Moon is increasing by around 4 cm a year.
The experiment has highlighted the behaviour of Earth’s ocean tides, but also has shown that the lunar crust also rises and falls in a solid lunar “tide”. It has also confirmed that the Moon has a fluid core! This really surprised me, having thought (like many others) that the Moon was a “dead” rock. In fact the prevailing theory, even among scientists, was that the core would be cool and solid. The Moon’s fluid core affects the position of its north and south poles, which the experiment was sensitive to pinpoint.
The experiment has also confirmed Einstein’s theory of gravity, which assumes that the attraction between bodies is independent of their composition – proven true for the gravitational affects between the Sun and Moon, and Sun and Earth, despite the higher iron content of the Earth.
And that’s not the end for lunar reflectors. NASA has recently approved a new generation of reflectors to be positioned within the next ten years. These would be spread over a larger area, allowing more extensive analysis of lunar geography and further verification of Einstein’s gravitational theory.
Studies like this are invaluable in understanding new worlds. As a SF writer, they provide invaluable insights when it comes to building your own planets. Check out my own world-building in my SF novel, The Tau Ceti Diversion.
With the crew dead, and the starship’s jury-rigged fusion threatening a lethal explosion, Karic and the surviving officers finally reach a habitable planet. It’s a miracle, but the last thing they expected was to find that planet already occupied . . .