There are many things that are relevant to a decision like this, where to bulid your telescope, and whether it needs to be launched into space.
- Frequency - some frequencies are absorbed by the atmosphere.
- Sensitivity. You can build larger telescopes on the Earth, so they can spot fainter images for the same amount of exposure time. But on the other hand a space telescope like Hubble can look at the same spot for hours or days on end. Also, it has no background light from the sky as we have on Earth.
- Resolution. When they launched Hubble then there was no way to get the same level of resolution using Earth based telescopes. That's because of the fluctuations in the atmosphere - same reason stars "twinkle". But with development of adaptive optics we can now "untwinkle" stars. So now this is not such a big difference as it used to be.
- Field of view. Hubble has a very small field of view. We could build space telescopes with a larger field of view.
- Time and expense. For some kinds of observation you need lots of telescope time. Example, asteroid tracking, far too many to track. Even e.g. Jupiter no way that Hubble could observe Jupiter 24/7.
Space telescopes are currently usually much more expensive for the same capabilities, if itis an observation you can do on the Earth. - Where you observe from - some things - for instance the other side of the sun, asteroids between Earth and sun, can only be viewed from space. Also orbiters looking closely at other planets and moons. And on the other hand for observations of meteorites entering the Earth's atmosphere you can observe them best from Earth if lucky enough to be in the right place at the right time. As another example, observations of neutrinos are best done underground in deep mines or at the bottom of the sea to block out obscuring radiation from other sources. And cosmic ray showers also, high energy cosmic rays observed through their interactions with the atmosphere.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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