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"I'm strictly an ivory-tower person. I can explain things but I can't do things."
- Isaac Asimov
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| Liquid Mirror Telescope on Mars | ||
| A large telescope using a spinning bowl of mercury as the mirror. |
Although Gallun did not invent the LMT, he makes good use of it as alien technology. Number 774, the Martian mentioned in the story, made great use of different exoskeletons to perform different tasks.
See if you can spot what appears to be an error in his use of the liquid mirror telescope in the quote below.
| Enigmatic forms of weird apparatus crowded in bewildering complexity against the walls. Tipped at a steep angle at the center of the floor was a vast cylinder of webby girders. Piercing the dome, opposite the upper end of the cylinder, was a circular opening through which a portion of the starlit sky was visible; and at the base of the cylinder a great bowl rotated rapidly, like a huge wheel.
The bowl contained mercury. As the container spun on its perfectly balanced axis, centrifugal force caused the mercury to spread in a thin, precisely distributed layer over the inside of the bowl, forming a concave surface that acted admirably as a mirror for Number 774's gigantic reflecting telescope. It's area, and its consequent light-gathering capacity, was many times greater than any rigid mirror that could have been constructed without flaws. |
| From Old Faithful,
by Raymond Z. Gallun. Published by Astounding in 1934 Additional resources -
|
He states that the cylinder was tipped at a steep angle; a real liquid mirror telescope has to remain fixed with the "bowl" perpendicular to gravity's pull.
In the story, Number 774 discovers people of the Earth using the telescope; he positions it to look at a particular part of the Earth during each observation session. Since an actual LMT cannot be "steered" (it can only look at the patch of sky directly above the instrument), the user cannot choose to focus directly on any object in the visible sky, as you can with a regular telescope.
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More Ideas
and Technology from Old Faithful
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and Technology by Raymond Z. Gallun
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Tech news articles related to works by Raymond Z. Gallun
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