Why putting a telescope in Space?
Since the telescope invention by Galileo, these instruments have been our most accessible and easiest mean of transport to the stars. Throughout the decades, science and technology have advanced in enormous steps and measurement instruments have become every time more and more sophisticated. Nowadays, professional telescopes utilized in astronomy are extremely large in comparison with the first ever telescope.
When we talk about dish antennas, the bigger the antenna then the better the quality in the sense that they are more directive, which means that can reach more power from a thinner region in the space.
Imagine for a moment that big ears allow you to hear better, big eyes to see further or big hands to figure out every material an object is made of; in telecommunications, the bigger the antenna, the deeper and finer it can “hear”, so the same occurs with a telescope, the larger it is the wider the area it can cover.
Among the several kinds of telescopes, radio telescopes for example, are analogous to a dish antenna. Big lenses allow to capture more light and so produce finer images, big dish telescopes cover wider areas and get sharper images, therefore a better quality is obtained because of collecting more light/energy, and more resolution for being able to distinguish further and thinner regions in space with sharper quality.
But where to place telescopes? Well, places like New York are not the best ones because too much light, the so-called city of lights contributes to what is known as light pollution. The darker the place, the better for the telescope.
This is important, but what about one of the most famous telescopes in the world, the Hubble telescope? This one is not even on Earth! So why placing telescopes on Earth when they can already be in space? Naturally, if there is the need of launching a rocket and building a special artifact to be placed in space, then the cost increases, however, there are still a lot of benefits from having a telescope in space rather than on Earth.
The reason for this is typically the limitations ground telescopes are exposed to, as light pollution. There are other limitations, such as the effect Earth’s atmosphere has on the incoming signals distorting them, although this can be compensated by adapting the telescope’s mirrors.
On the other hand, and more related to the frequencies of the desired signals to be received, along the whole and enormous frequency spectrum we can define some frequencies or, inversely proportional, some wavelengths, which are filtered out by our atmosphere, and that will be also a drawback from having a telescope on the ground, since these frequencies/wavelengths will not be perceived by the telescope.
This is similar to the reason why we see the sky blue, since all wavelengths except those corresponding to blue color are filtered out in the atmosphere. Yes, sunlight is composed of several frequencies and wavelengths, and the atmosphere allows us to see the blue light wavelength.
Signals coming from visible light which can be captured by imaging, or those which are invisible but can be received by radio telescopes, correspond to the portion of the spectrum that we can actually “see” or “listen” to.
However, some frequencies can only be reached through space, either because the Earth atmosphere blocks extremely high frequencies or because its gases just absorb incoming energy at certain frequency bands. Here is where space astronomy enters into the game. Furthermore, a sharper resolution is not only related with a big telescope, but also with an extremely small wavelength, which means an extremely high frequency, which are also those being blocked out by the atmosphere. These are reasons to put a telescope in space, because some astronomy studies just cannot be made from Earth due to physical reasons.
Before the frequency spectrum was mentioned. Regarding the spectrum regions beyond visible light, these are of extreme importance for astronomers, quite likely because the Universe is expanding and the furthest galaxies travel at faster speeds.
Recall that according to the Doppler effect, the faster the speed of an object escaping from us, then the smaller the received frequency.
Therefore we can expect to listen to the furthest part of the Universe by exploring the extremely small frequencies, this is relatively high wavelengths, also corresponding to non-visible light. Thinking about the Big Bang, the most distant places correspond to the very first moment, the starting point of the Universe as we know it, this is known as the Big Bang cosmic background.
I find telescopes a fascinating window to Space that make us feel closer to the furthest places of the Universe.
REFERENCES:
Academic and practical acquired knowledge in telecommunications, antennas and radio telescopes.
Space.com. Gallery: James Webb Space Telescope’s 1st photos.
Spacenews.com. NASA releases first color image from James Webb Space Telescope.
