Astronomy from Space

Ken Tapping, November 14, 2007

Last month NASA engineers shut down FUSE, an orbiting telescope that has been producing valuable astronomical information for over eight years. FUSE, which stands for Far Ultraviolet Spectrum Explorer, was a project in which Canada was a participant, and has produced some important astronomical discoveries regarding the youth of the universe and the formation of galaxies.

In these days of important international partnerships to build new ground-based optical and radio telescopes, why do we want to put telescopes in space? At the moment Canada is involved in international partnerships to build state of the art instruments. Examples include Gemini, which consists of two 8 metre optical telescopes in Chile and Hawaii, and ALMA, the Atacama Large Millimetre Array, a state of the art radio telescope under construction on the high, dry Atacama Plateau in Chile. If we are working on such projects, why do we also want to put telescopes in space, where they have to be much smaller and less sensitive, and are a lot harder to get at if they go wrong?

Here on the Earth we have to look at the universe through our turbulent atmosphere, which is like looking at a penny on the bottom of a stream. It is a terrible shame that information is traveling to us over up to millions or billions of light years only to get horribly degraded over the last few kilometres. Lifting our telescopes above the atmosphere avoids that. The stunning images recorded by the Hubble Space Telescope are living proof of that.

There is another reason. On the ground we can observe cosmic light and radio waves. However, there are other waves coming in from space, all carrying unique information about the objects producing them. These include gamma rays, X-rays, ultraviolet and infrared rays. Our atmosphere blocks these. This is a good thing for us and the other life forms with which we share our world, because some of these waves are very dangerous. However it is not so good for astronomy. Fortunately we can get around this problem by lifting our telescopes above the atmosphere, into orbit. Orbiting telescopes have advanced astronomical knowledge in many important areas, from black holes to the beginning of the universe.

With all these things we can discover by making astronomical observations from space, why bother doing it from the ground? In fact the ground-based telescopes are complementary to the space-borne ones. On the ground we can make much larger instruments, and whereas orbiting telescopes are hard to modify during construction or in orbit to meet new astronomical needs, ground-based ones can easily be adapted to meet new challenges. There are whole areas of astronomy that do not need to be made from orbit. In addition, ground-based facilities are technical development sites and places where we train the next generation of astronomers who understand instruments and engineers who understand astronomy. If we don't do that, we will lose our ability to have a say in where astronomy is going, and will simply become borrowers of what others choose to build.  

Comet Holmes is still in the Perseus area. Mars rises about 8 p.m.  Saturn rises about 1 a.m., Venus about 3 a.m. The Moon will reach First Quarter on November 17.

Ken Tapping is an astronomer at the National Research Council Herzberg Institute of Astrophysics (NRC-HIA), and is based at the Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9 Tel (250) 493-2277, Fax (250) 493-7767, E-mail: ken.tapping@nrc.gc.ca