Since I started writing this blog I’ve found it hard to find things to talk about. To overcome this I’ve done something I haven’t done in a while, I started reading the news. Not the local paper or even the Australian, I spend a lot of my time online so finally used Google News to my advantage to find out new things about science. While I haven’t been able to make posts about most of the interesting things I’ve come across, yesterday something piqued my interest and I couldn’t help but just go with it. I’ve wanted to write a blog post about spacey stuff and now I’ve finally got my chance.
Image of the Hubble Space Telescope. Credit to NASA and STScI
The article that caught my attention was about an image from the Hubble Telescope. Now, I’ve heard of the Hubble Telescope, but to my shame I had always imagined it to be just some gigantic telescope in an observatory somewhere looking out into the sky. Instead what I’ve learnt that it is in fact a telescope that orbits around the Earth, taking pictures and relaying them back to us here on the ground.
Image of the Star-forming region LH 95 in the Large Magellanic Cloud, taken by the Hubble. Source: Hubblesite.org
It begs the question, why space? What’s wrong with the telescopes we have here on Earth? Well it turns out that Earth’s atmosphere can interfere and distort what we see through the telescopes here on Earth. Moving pockets of air in the atmosphere are one problem associated with this and the other is that the atmosphere can absorb or block out radiation from stars or other space objects, the different types of emitted radiation being the best way for scientists to study the space object. This is what happens with the greenhouse effect, our atmosphere blocks out the harmful UV radiation, or at least tries.
So how does this telescope work? As light comes into the telescope it hits one mirror, the primary mirror, and is then reflected towards a second mirror, which focuses the light into the instruments that sit just behind the primary mirror. This diagram is probably the best way to visualise it. The Hubble telescope has six different instruments that look at different types of light to gain different information, all except the ‘Fine Guidance Sensors’ which is used to keep the Hubble orientated the right way and also to measure the distance between stars.
Fun fact – when the Hubble was first sent up into orbit, scientists found that the quality of the images they were receiving was much lower than expected. This was due to a hugely minor flaw in the primary mirror that it was slightly the wrong shape, enough to cause the light to be focused in the wrong spot and distort the image received. This was fixed by installing a corrective optics instrument that, as the name suggests, corrects the images being seen by the other instruments. At this stage the instruments in the Hubble all have built-in corrections so the corrective optics instrument was removed on a servicing mission in 2009.
Image of Astronauts on the final servicing mission of Hubble in 2009. Image credit to NASA
Without getting into too much detail about each of the different instruments and how they work (though it’s pretty fascinating stuff) I’ll just mention that each one has a job to do in helping scientists learn a vast amount more knowledge about things across our universe, even remotely far away. If you would like to read about each of them here’s the place to go.
The Hubble is controlled by being given directions and commands via satellites from the engineers on the ground. This is also how we receive the data back, the Hubble sends the information it gathers back as data to the satellites which transmit it to the scientists on the ground. Similarly to the Australian Synchrotron, scientists who want to use the Hubble have to present their proposals to a review committee and then the ones that they believe will make the best use of the Hubble’s capabilities as well as addresses the most pressing astronomical questions gets the green light. Out of the approximate one thousand proposals that are reviewed each year, only about 200 of them are picked.
Image from the Hubble of a star-forming region in the Small Magellanic Cloud. Source: Hubblesite.org
Unfortunately the Hubble won’t last forever, its expected lifespan has already been extended with various servicing missions to it however its different parts will eventually degrade and cause the telescope to stop working.
But wait! A new telescope is in production to take over from the Hubble, it’s called the James Webb Space Telescope (JWST) and is looking at a 2018 launch date. It seems that we humans have come a long way since the days of believing that the Earth was the centre of the universe, but we’re still looking to the stars.
Image of a “storm” of turbulent gases in the Omega/Swan nebula (M17). Source: Hubblesite.org