Despite their economic troubles, people are beginning to focus in on just what is happening up in space, 350 miles above their heads, and it really is incredible what the Shuttle crew is doing.
Launched in April 1990 by the Space Shuttle Discovery, the 24,000 pound Hubble Space Telescope (HST) is already very old in terms of space and even telescope technology.
But as image sensor technology has improved over the years, the HST has been updated with new instrument packages which vastly improved the quality of the data it gathers. This was envisioned from the first to some extent – that is why some parts were made to be easily removed and replaced – each time the HST gets new sensors and cameras the image quality improves by about a factor of 10.
But this is an ancient piece of space junk by now – just imagine our advances; today we can watch over the repair crew’s shoulder every second, live on almost any computer in the world!
The HST’s exceptional long life means that components such as the gyroscopes that keep it oriented on objects it is photographing are wearing out; even batteries are getting too old – those and other parts of HST were never intended to be repaired or replaced, and that is what is now being done.
The best analogy I can think of is this. Consider that you are in a blizzard, all bundled up with heavy gloves and coat. You can probably change a flat tire if you are tough enough and can’t get a tow truck because your cell phone is dead.
Now consider that, as hard as that is, you are expected to be able to change a tire as a routine matter – your car came with the tools for that simple replacement and even the spare tire!
That is mostly what the Shuttle crew has been doing up until now and some of those old fasteners are just as difficult to get off as the wheel on an old car.
But, starting today especially, they are doing the equivalent of changing the carburetor on that same old car, in a blizzard, with little room to work, wearing a heavy coat and very thick snowmobile gauntlets.
Most incredible of all, YOU can watch while this is going on – do your kids a favor and try to get them to watch some of this. Also, try to give them some idea how difficult the task is.
You can go to www.space.com and use their viewer to watch the live feed, or go directly to www.nasa.gov and pick up the feed there; one may work better than the other for some users.
As I am writing this, John Grunsfeld and Andrew Feustel are suiting up and preparing to start today’s spacewalk which was scheduled to begin at a quarter past 9 a.m. EDT (1316 GMT).
For older children, you might remind them that the repair crew is doing all this while being shot at by random snipers firing space junk at them at speeds of thousands or even tens of thousands of miles/hour.
The HST, named for famous American astronomer Edwin Hubble, uses a telescope design similar to the one invented by Sir Issac Newton – a reflector. (Technically the HST uses a modification of the plain reflector, a Ritchey-Chretien design which “corrects” the tiny optical distortions found in plain reflectors – See http://en.wikipedia.org/wiki/Ritchey-Chretien.)
Hubble is basically a 7.9 ft diameter curved mirror at the end of an empty tube (by way of comparison, I have what is considered a pretty large amateur telescope and it is 12 inches in diameter); that mirror focuses incoming light on various sensors, making it possible to image space objects such as nebulae (gas clouds) and galaxies (large groups of stars such as what we call the milky way) which would otherwise be far too faint to detect.
The reason for having a telescope in space is twofold – first, it eliminates all the interference from dust, light pollution, and the jittery images caused by moving air.
The second reason is because the atmosphere absorbs some frequencies of light, making them invisible from the surface.
