Space telescopes and their applications in astronomy

Space Telescopes

Ever since its launch in 1990, the Hubble telescope has been orbiting the Earth at 600 kilometers above, bringing valuable information and photos from space. Its history goes back to 1977, when the Congress approved the project funds. However, operations didn't take off until 1981, when the Space Telescope Science Institute was founded, designed especially for the production and research of the Hubble Space Telescope.

In 1990, on April, 25th, the telescope was deployed into orbit. Several problems appeared during the first years of use. An aberration in one of the mirrors was soon discovered and needed to be changed later in 1993. A new computer was installed in 1999 and the telescope was placed in "safe mode" after "the failure of a fourth gyroscope." However, it continued to produce generously relevant data on the Universe and its components.

One can never underestimate the importance and the extent of Hubble's accomplishments. Some facts and figures are relevant in this case. We should mention, for example, the fact that Hubble sends everyday 10 to 15 gigabytes of data to Earth. In total, up to the year 2000, Hubble has taken 330,000 separate observations, traveled close to 1,500 billion miles, created an archive of 7.3 terabytes and has observed close to 25,000 astronomical targets.

The initial cost of the telescope was $2 billion. However, one may wonder what the costs of keeping it running every day are. According to Ed Weiler, NASA's chief Hubble scientist, "each American is paying less than $1 a year in taxes for the telescope - less than 2 cents a week." This calculation is a result of the $230 million needed to operate and maintain the Hubble.

2. The James Webb Space Telescope (JWST) may be considered Hubble's successor in space, in case the latter is bound for retirement. The JWST is scheduled to be launched in 2011 and contains some last hour technologies. These include the Integrated Science Instrument Module (ISIM), the Optical Telescope Element (OTE) and the Space Support Module (SSM).

The Science module integrates some extremely performing instruments, such as the near infrared camera, the near infrared spectrograph and the detectors. Given the fact that its primary mission, initially, will be to study early galaxies that are better seen in infrared, as well as the birth and formation of stars and the origins of our planetary system, the telescope's detectors are of extremely high quality.

Further more, the telescope itself uses a new type of mirror, aimed at being able to perceive characteristics of galaxies billions of light years away. The primary mirror will be 6.5 meters in diameter. Compared to Hubble's 2.4 meters main mirror, the differences are obvious. The problem, however, is the fact that one needs to be able to build a 6.5 meter mirror that will also be light enough to be carried on board of the launching shuttle and, on the other hand, it needs to be strong enough.

The technology that JWST will be using is much more performing than the Hubble technology, simply because there is a 15-20-year generation gap between the two. Despite the four repairs that Hubble has sustained, it remains a telescope of the 90s. If we compare strictly in the area that JWST was conceived for (early galaxies, etc.), the Hubble could see up to 400 million years after Big Bang, while JWST will go back just 100 million years after the Big Bang. On the other hand, Hubble seems to have had a less specific mission, being predisposed to gathering general information on the Universe. JWST is at the moment being strictly used for studying early galaxies. In this sense, we may state that JWST is more than able to replace the Hubble, but only in one area of competency.

3. Given the fact that the last servicing mission has been cancelled, in my opinion, Hubble is approaching an end. This is not necessarily because it is not doing its job anymore, but simply because time and use is already taken a toll on its equipment. Even initially it was only designed to be used until more than 2006, which is quite a long period of time. The fact that the servicing mission was cancelled entitles me to believe that there will be no further investments in the Hubble.

It is to be expected that NASA will wait a year or two and then will end Hubble's period of activity. The $350 million a year I have mentioned do not seem reasonable in this case. The JWST, for example, has cost an overall $1.6 billion. This means that five years of not working on the Hubble are enough to build an ultra- performing, last generation telescope. It does not seem cost effective anymore to invest in the Hubble. However, its accomplishments until now and the fact that it is still gathering important information should be enough arguments in favor of prolonging Hubble's life as long as possible.

4. In my opinion, we should, first of all, state again that there are several conceptual differences between Hubble and JWST, related to the objectives each has. JWST is much more focused on gathering information on early galaxies and the Big Bang. As such, it would probably be beneficial if both could be held in place and be used.