Welcome back to What's Up?
The final servicing mission to the Hubble Space Telescope is planned for Oct. 14. This mission will repair and/or replace Hubble's instruments and components to allow it to operate into the year 2014.
Let's take a look at what the Hubble Space Telescope (HST) is, what it does, and why it is so important to astronomy.
The HST was first approved by NASA (National Aeronautics and Space Administration) back in 1969 and was referred to as the Large Space Telescope project. Due to budget restrictions, the original proposal was downsized a bit, decreasing the size of the main mirror and a few of the instruments aboard the telescope.
In 1975 the European Space Agency (ESA) joined the project and was to supply solar panels and various instruments with the promise that European astronomers would get a certain percentage of time on the telescope. In 1977 US Congress approved funding for this telescope.
In 1981 it was named after Edwin P. Hubble, an American astronomer (1889-1953). He's the person who confirmed the fact that the Universe is expanding and provided the foundation for the theory of the "Big Bang".
The Hubble Space Telescope was finally launched into space on April 24, 1990, aboard the space shuttle Discovery.
Why would anyone in their right mind want to put a telescope in space? The answer is simple: turbulence.
The Earth's atmosphere is always moving around and bending light. This causes objects viewed in a telescope to be blurry. This is what causes stars to twinkle and is similar to looking across the top of a car on a hot day and seeing the objects in the background to be bent around and giving a blurry image.
To fix this problem you need to get above the atmosphere where there is none of this annoying distortion. This is where the HST comes in.
The HST has a main mirror with a diameter of 2.4 meters (94.5 inches). This is considered small compared with today's giant, ground-based telescopes, but it still is at the forefront of research because of its unique observing location. This primary mirror was made to such great precision that if it were scaled up to the diameter of the Earth, the biggest bump would only be six inches tall.
After its deployment in space it was expected to take the greatest images of space ever taken. After the first few images came in and were examined, it was realized that Hubble's mirror was ground to the wrong curvature! This resulted in terribly blurry images. HST was called by some to be one of NASA's biggest financial blunders.
Luckily, this mistake was fixable. In December, 1993, a servicing mission was sent up to correct this error and upgrade a few instruments. After this "eye surgery", Hubble operated almost exactly like it was expected to!
Now operating to its full abilities, Hubble quickly became an essential component of modern astronomy. It began taking images of the very distant Universe, seeing faint objects never seen before and looking at objects that have been observed in the past except in greater detail than ever before. It has mapped out dark matter in 3D by seeing which way dark matter was tugging galaxies, pinned the age of our Universe at about 13.7 billion years old (much better than the previous estimate of between 10 and 20 billion years old), help us understand how galaxies form, that gamma-ray bursts come from distant galaxies when a giant star collapses in a supernova, and much more. That's just starting to scratch the surface of its many discoveries. All in all, more than 6,000 scientific articles have been published using data from the Hubble Space Telescope!
Hubble's successor, the James Webb Space Telescope, is scheduled for launch in 2013. It will have a special mirror made of many segments that will unfurl itself to the correct shape in space. It has an enormous main mirror, about 6.5 meters (21.3 feet) in diameter!
The James Webb Space Telescope will orbit the sun keeping its distance from Earth at about 1.5 million kilometers (1 million miles), so that it doesn't have to work as hard to keep itself locked on an object like the Hubble does. Since the Hubble flies around the Earth at a speed of 8 kilometers per second (5 miles/sec), it needs to be able to lock onto objects accurately. It can lock on to an object without deviating more than 7/1000th of an arc second (about the width of a hair seen at a distance of 1 mile).
To see where Hubble is orbiting above, go to: http://hubblesite.org/the_telescope/where.a.s_hubble_now/.
Once you're done checking that out, let's take a look at what's going on in the skies this month.
On Oct. 14 there will be a full moon, which will dwindle down to a new moon by Oct. 28.
On Oct. 21 will be the peak of the Orionids Meteor Shower. It will produce about 20 meters per hour at their peak but are very irregular and could give a good show on any morning between Oct. 20-24.
Until next month, just look up!
You can build your own model of the Hubble Space Telescope. Just go to http://hubblesite.org/the_telescope/hand-held_hubble/pvc.php for details on supplies and details on how to make it. Make sure to ask for help from parents when it comes to using the drill or the saw. It can be done in 1-3 hours for under $20. Have fun!