With the onset of the space age, scientists have the opportunity to take various instruments to other planets in order to multiply the accuracy of measurements and obtain new types of data. One such instrument is the surprisingly simple laser reflector – nothing is more accurate when you need to measure something over a very long distance. The Perseverance rover will take the latest version of such a reflector to Mars for missions not even conceived yet.
The first reflectors for laser beams were installed on the Moon as part of the Apollo 11 and Apollo 14 missions. They turned out to be so convenient and useful that they are still used today. Thanks to minute changes in the speed of the reflected laser beam, scientists have discovered that the moon changes shape, contracting under the gravitational influence of the Earth. If you have a reflector on a space object, you can aim at it with a laser from the Earth laboratory and collect a lot of useful information about the behavior of that object.
Reflectors on the moon are shaped like bulky flat panels to make aiming easier. The reflector on board the Perseverance is a small hemisphere with a diameter of only 5 cm. Behind each hole in it there are three tiny mirrors at an angle of 90 degrees to each other, which ensures that the laser is reflected exactly to the source of its radiation. The design is so successful that it has already been decided to put analogs on the NASA InSight lander and the ESA rover Rosalind Franklin, which is scheduled to launch in 2022.
The small size of the reflector is not a hindrance, because they will not aim at it from the Earth, but from the orbit of Mars itself. In the future, when new ships fly there, they will be able to orient themselves on this reflected signal and accurately calculate their actions. Due to the fact that the radio signal from Mars to Earth takes more than 4 minutes, now we have to land platforms with rovers in automatic mode and at great risk. But when a reliable “beacon” appears on the surface of the Red Planet, everything will become much easier.