NASA engineers have taken on the challenge and formed a plan to build a lunar radio telescope. But what is it, why are they building it, and what are the challenges they’re encountering?

Most likely you’ve seen a radio telescope before, whether in movies, shows, or in person. They look quite stunning, definitely the bigger they get, perhaps leaving a lasting impression or wandering imagination. Well, if you already find them stunning you’re in luck, because they get more interesting the more you know about them. 

Radio telescopes are made up for the most part of a big circular reflector, used for reflecting electromagnetic waves, specifically; radio waves. Radio waves are electromagnetic waves within a given frequency, the lower frequency levels of the electromagnetic spectrum. So just like traditional (optical) telescopes study light waves, those frequencies from the electromagnetic spectrum which we can observe with the naked eye, emitted by astronomical bodies and objects, radio telescopes are used to observe astronomical emitted radio waves. Because of the bowl-like shape, more specifically the paraboloid shape of the reflector, the waves are reflected back to one focus point where all the reflected waves have been calculated to cross. At the focus point there is either a secondary reflector, reflecting the waves back to the observation point, often in the middle of the ‘bowl’, or the focus point will also serve as an observation point.

What do radio telescopes really help us ‘see’? Just like traditional telescopes make it possible for us to look at distant astronomical bodies, which we’re not capable of seeing with the naked eye, radio telescopes make it possible for us to observe distantly emitted radio waves. The difference is that the observation of radio waves can’t be done solely with our senses, for the observed waves must be ‘translated’ by machinery to something we can perceive.

Why is it important to observe distantly emitted radio waves? In the vastness of our cosmos the further we look, the further back in time we will be looking too. This cool phenomenon opens many doors for astronomers, for it’s given us the chance to look at the earlier stages of our universe. Through the observation of very distant radio waves, further in space and time than we’ve ever looked, astronomers and scientists can make better predictions regarding the earlier stages of our universe.

You might wonder, if we have plenty of radio telescopes already here on earth, why build one on the moon, except for the fact that it sounds super cool? On Earth, our radio telescopes are limited because of earthly radio waves interfering with incoming radio waves or because of incoming radio waves being reflected when reaching Earth’s atmosphere. The moon does not face these problems as it barely has an atmosphere and seeing that the telescope would be built on the far side of the moon (facing away from the Earth), further decreasing man-made radio waves interfering with astronomical incoming ones, the interfering radio waves are greatly reduced. The moon will shield the telescope from the Earth.

Although a radio telescope on the moon is theoretically more convenient for researchers and scientists, in practice the engineers will have to overcome many hardships! One of the biggest headaches when it comes to building on the moon is transporting the necessary materials to the moon first, therefore the engineers at NASA must try to keep the necessary materials light. Easier said than done when planning to construct the biggest radio telescope in ‘the world’. So much of the construction plan is focused around conserving energy and resources by having to use and transport as little materials as possible and avoiding any difficult construction methods on the moon. Therefore, the engineers will be making use of the lunar craters, by suspending a circular thin wire mesh over the crater, hanging from the edges of the crater. Similarly, the focus point and observation will also be suspended, but higher so it finds itself at the cross-point of the reflected radio waves. 

There are still doubts about how NASA will set up the radio satellite without the use of any humans on the moon. The leading idea would be to use robots/rovers to plant the tethers for the mesh reflector. The development of the robots is in process but their success can’t be guaranteed yet. Although, to lessen cost and resources it was suggested to land the moon lander, supplied with the mesh, in the middle of the crater and then shooting the tethers in a circular projectile path over the craters edge, to avoid the use of robots.

There is no certainty to whether NASA or any other space organization will take the task of being the first to build on the moon. Although the development of this plan surely is a statement of our technological advancements. Interesting times, with many innovations and plenty more crazy ideas, but how long will it take before these ideas stop sounding crazy.

Alexander van der Velden

Sources:

britannica.com – radio wave

education.nationalgeographic.org – Atmosphere

en.wikipedia.org – Parabolic antenna

en.wikipedia.org – Parabolic reflector

en.wikipedia.org – Radio telescope

nasa.gov – Lunar Crater Radio Telescope: Illuminating the Cosmic Dark Ages

nasa.gov – Radio Waves