These telescopes are huge (E-ELT, OWL, VLT)

Hi,
today I will write more about telescopes. In a previous post I already mentioned why radio telescopes like Arecibo are so huge, its because of the long wavelength. Today though I will concentrate on another type of telescopes and those are the ones that sit on Earth and collect information from visible light (those are called optical telescopes).

Comparison of various telescopes. Note OWL, the big circle in the background and even bigger white Arecibo.


I already mentioned Hubble telescope and James Webb Telescope (JWT) that is planned for launch next year. Those are in space so they have quite limited size. Down here we can build bigger ones. Right now in building phase is the E-ELT (European Extremely Large Telescope). Its primary mirror will have 39 meters [1] making it the largest optical telescope. It has to be so big because otherwise it could not match the ones in space. This is because we have our lovely atmosphere in the way and it makes harder for telescopes to distinquish small objects (though these days we have software that is able to account for that).

VLT aka Very Large Telescope is already working optical/infra-red telescope. It consists of 4 telescopes each of them with primary mirror of 8.2 meters in diameter. They can work together to make images of angular resolution 0.001 arcsecond. In one post I said that we are not able to take an image of star other than just point like source of light but apparently that is not true so I apologize for it:

First Direct Photo of Alien Planet Finally Confirmed

First confirmed image of an exoplanet. The ones that we can see are bigger than Jupiter and usually quite far away from their star. Credit: Gemini Observatory

VLT is second, right behind Hubble in the amount of scientific papers that its work produced (in the field of visible light/infrared telescopes).

There are many other telscopes that I might mention in the future like Thirty Meter Telescope but I will end it with OWL – Overwhelmingly Large Telescope. It was supposed to be the largest telescope ever, with primary mirror of 100 meters! The price was estimated to be about 1.5 billion euro and because of that it was decided that its not worth it. If we do not kill ourselves we might see giants like those in the future though I have no idea how the scientists, or whoever does it, will name them (UGHT – Unimaginably Giantic Huge Telescope).

Dragallur

[1]Just as JWT, the mirror is made from smaller segments. In the case of E-ELT it is because the mirror would be too heavy and we do not have the technology to build it and in the case of JWT it is because you have to somehow get it into orbit.

Comparison of telescopes: By Cmglee – Own workiThe source code of this SVG is valid., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=33613161

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Telescope of this generation

Hi,
this title is kind of weak, I know that, but I did not want to write “rusty, old piece of metal”. First because rusty could be a little bit misleading, rust only occurs when there is oxygen and there is only little of that in space, more accurately there is 1% of all the atoms in the Universe which is quite few tons but at the same time Hubble Space Telescope is flying in near vacuum when there are just a couple of hydrogen atoms per cubic meter, maybe in his lifespan he even touched few oxygen atoms. Second because he just does not deserve it. (Check out the post about James Webb Space Telescope)


His lifespan? Well it has been a long for such an instrument which are usually meant to work for much less years. For now the telescope has been working for 25 years, 9 months and 29 days. It is assumed that it might work for another 20 years or so, it could be even longer but it is slowing down and as I explained in post about orbits, it will eventually fall down and burn up in atmosphere. Not that this space telescope would be half immortal or so, but it was able to work for so many years because there were actually missions to repair some of its tools and power systems, otherwise it would not work by now [1].

When Hubble was launched and first images sent to NASA they were good, but not good enough which was because of the mirror. It was polished to a little bit wrong shape so they had to repair that. Before they did it NASA used some complicated image processing to get the best out of those pictures.

The repair itself was very complicated since replacing mirror was simply impossible and to bring the telescope back was too expensive. They solved it by making the same mistake but “of opposite direction” on another part of the telescope so it was totally canceled out, you can check out on the next picture to see how much it made a difference:

 

One of the images taken during the misson for some repair.

Pillars of creation, by Hubble

NASA even decided to borrow some of Hubble’s time for amateur astronomers, of course it was not easy to get that time but it was definitely worth it I am sure.

Hubble is not justing taking those beautiful pictures but it also helped to measure Hubbles constant on whole next level and also through his data we found out that the expansion of Universe is actually increasing, phenomenon which is not well understood but most people think that it is because of dark energy.

This is monstrosity, almost all of those bright points are galaxies, galaxies which we will most probably be never able to search through.

Hubble also helped with some observations of black holes and also as you can see above, Hubble made a whole new picture of the youngest parts of Universe, so extremely far away.

Depiction of progress in the detection of the early Universe

How far can we actually see?[2]

Dragallur

[1]Actually it is the first such thing in space that was repaired by humans which is actually pretty cool.

[2]Check out this post to read about red shift, the x axis on the picture.

All pictures from here and here

 

Telescope of new generation

Hi,
today I would like to mention new kind of telescope which is right now being build. It is quite amazing piece of human technology, The James Webb Sp Telescope.


Named after James E. Webb who was leading NASA about 50 years back. First they wanted this telescope to name Next Generation Space Telescope but then they decided to give James Webb the honor.

Labeled Spacecraft

Above you can see how it should look like when we will launch it. It is telescope which should work instead of Hubble’s Space Telescope which even that it did great work, is not good enough right now. James Webb Space Telescope should have even better view in the vastness of Universe. Also more details which means that for example, we could get much more information about exoplanets, we could even start to analyze more of their atmosphere and learn more about stars and so on.

Still Hubble’s telescope has some time since James will be launched in 2018 in French Guiana. Here you can browse some pictures for sun shield testing, this is the part that is turned towards Sun and protects all the fragile tools that are on the telescope because in space, radiation could easily destroy transistors and other equipment.

https://i1.wp.com/jwst.nasa.gov/images/JWST-HST-primary-mirrors.jpg

The most kind of shocking part, which you can see above is the primary mirror. You can see that James Webb has upgraded a lot from Hubble. This mirror is actually too big so it had to be made from separate pieces, hexagons. It was quite fun to watch as they for months placed those plates on the structure. The mirror is made from beryllium because it is strong and light element and the top is covered in gold for protection from radiation. This kind of mirror is used on optical telescope and the bigger the mirror is the better the image which is formed. This is why they must be so polished, it is also important to have the working area clean so this is how the engineers usually look like:

JWST Team Photo with Completed Flight Instrument moduleThere are few more instruments that collect the light in various spectrums. For now we must wait before they finish whole work, and there is nothing more to do than admire the work that Hubble has done for us (and is still doing (actually the work of engineers and scientists)).

Dragallur

Pictures from here here and here.