Recently in Astro 201, we learned a bit about the physics of light and how it applies to the instruments we use to view the sky. Over the years, NASA and other space agencies have employed a variety of telescopes and instruments in order to better understand the universe. Of these, perhaps the most famous is the Hubble Space Telescope. The telescope was launched in 1990 and orbits at an altitude of 353 miles, well above the Earth’s atmosphere. This allows it to view the heavens without having to deal with the distortions of light that occur when light travels from space to an observatory on the Earth’s surface. Equipped with instruments that can peer into the far regions of space and take images at optical, infrared, and ultraviolet light wavelengths, the Hubble has been crucial in the advancement of astronomical knowledge over its lifetime (Bennett et al., 2010).
Interestingly, the Hubble Project nearly faced a premature, and disastrous, ending. Just weeks after its launch, the first pictures were relayed back to the astronomers on the ground. They were shocked to see that those images, while better than ones taken by observatories on the ground, were far less pristine than expected. This was the result of Hubble’s primary mirror being slightly misshapen… by about 1/50th the thickness of a sheet of paper. This incredibly small error was enough to throw off the path of light as it entered the telescope, and illustrates how crucial attention to minute details is when dealing with incredibly advanced astronomical technologies. The flaw in the mirror was enough to render the telescope a $1.5 billion sitting duck.
Thankfully, NASA figured out a way to fix the problem. Space Shuttle Endeavour STS-61’s crew fitted the telescope with COSTAR, an instrument which compensated for the original aberration. The results were stunning:
Hubble is slated to be replaced by the James Webb Space Telescope in the near future. Until then, it will continue doing its job of shaping our cosmic perspective, just as telescopes have done for hundreds of years. And, with regards to that, I leave you with this animation (you might need to click on it to see it):