Hubble
Why launch a telescope into space when the ones on the Earth aren’t limited by launch weight restrictions? There are many reasons, but the biggest one is that Earth’s atmosphere and pollution get in the way. When you get to the sort of deep field imaging the Hubble is doing, any infrared fuzz from other sources at all will blur the photo and reduce the telescope’s range. The atmosphere contains and reflects a lot of radiation, all across the spectrum, so it naturally obscures quite a bit of what you’d see if you were just outside of it.
As a result, NASA uses satellite telescopes to see the farthest reaches of our universe! While Hubble was not the first of its kind (the 60s had the Orbiting Solar Observatory) it is one of the most technologically advanced, and it remained the pinnacle of space-based telescope tech for most of its life so far, receiving regular upgrades and repairs until 2009. It consists of the same ‘mirrors reflecting lights onto a central point’ that many long distance telescopes do, but without all the fuzz of the atmosphere in the way, it was able to catch an astonishing amount of detail and distance not previously seen by telescopes on Earth! While this is no longer the most powerful telescope in space thanks to the James Webb, it’s still provided tons of valuable, useful research material. It’s central mirror can capture 40,000 times more light than a human eye could. You may notice that stars in Hubble’s pictures have a distinct halo with four points of light – that’s thanks to how the side mirrors are arranged around the central one.
Cassini and the Golden Disk
Most of the stuff people send into space isn’t expected to make it back to Earth, at least in one piece – there’s not a great way to retrieve large objects from space. However, most of the objects we send out are expected to stay in orbit, or burn up. James Webb and Hubble are in orbit (although the Webb telescope is actually orbiting the sun).
The Cassini space probe, launched in 1997, is not in orbit, at least not anymore. Cassini’s original goal was to learn about Saturn and its moons. It maintained an orbit around Saturn from 2004 to 2017 when it’s orbit decayed (on purpose) so it could descend into Saturn and hopefully learn a little more on its way out of this material realm. And learn it did!
Even more far-reaching are the Golden Records, sent out on the Voyager spacecraft in 1977. Voyager was not launched towards one particular star; the closest it’s going to get, barring any encounters with space debris on the way, is a lightyear and a half away from a star in 40,000 years. The records contain sounds and sights from the planet Earth, intended as a message in a bottle, for anyone or anything that finds it. It uses pulsars, long-lived remnants of stars that ‘flash’ or ‘pulse’ EM waves at a constant rate, to orient the map, since anything complex enough to spot Voyager would also be able to see them, thus providing a reference point.
Did you think the Mars Curiosity probe singing happy birthday to itself was sad? We’ll never see Voyager again. There’s no promise anything will.
James Webb
The James Webb telescope is one of the most technologically impressive things humankind has ever managed to make. It took several hundred millions of dollars and years of hard work to make it happen. The images coming back right now (as of this article, July 14th of 2022) cover an area of the sky approximately the size of a grain of sand from our perspective on Earth. The universe is huge! That one little point shows an enormous amount of galaxies, including ones whose light has been warped as it traveled to us by something in between us and them, all different angles and distances away from us. It also captured higher-quality images of planetary nebulas and the like that we had from Hubble, but even more detailed! None of this, of course, would have been possible without Hubble coming first, and the images Hubble captured are equally impressive – the Webb scope’s design simply allows it to see further and gather more light in order to actually ‘see’ the things out there in space. Webb’s images of stars also have halos, but it has six points of light instead of four like Hubble, a result of a different and improved mirror focusing design.
When you’re dealing with such huge distances, your telescope has to begin compensating for something known as ‘Red-shifting’ – especially with things that are moving away from you or your telescope. Red-shifting means that the waves of light will begin stretching out. Wider wavelengths of light are redder than narrower ones, and so everything begins trending towards infrared light when it gets far enough away from us. If those galaxies have aliens looking back at us, they’d see us as redder than we are, too! As such, both Webb and Hubble captured information from Infrared all the way up to X-Ray bands. We can’t see X-Rays either, and have to compensate there as well.
Technology on Our End
Not all of that compensation is happening in the telescope itself – a lot of it is happening in the data processing back on Earth. The same thing goes for the Hubble. Many of the complex images of planetary nebulas or gas clouds are the result of weeks’ worth of light catching and data combining. Some celestial bodies are bright, others are dim, some gasses that compose nebulae are not visible to the human eye, etc. and so all must be visually adjusted so that we, on the other side of that enormous void, can actually put together an image we understand. This doesn’t mean the images are ‘fake’, although they’re not always the pretty colors shown in the images by NASA. NASA often color codes things to indicate where one kind of gas cloud ends and another begins, for example, or differences in density and temperature that the telescope could see in X-Ray but we couldn’t.
Just as the telescopes have gotten better, so too has the technology receiving the images back on Earth.
