Venus Science |
Venus Science |
Feb 10 2006, 10:18 PM
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Sunspot, NM (Feb. 7, 2006) -- The planet Venus is best known for the thick layers of clouds that veil its surface from view by telescopes on Earth. But the veil has holes, and a New Mexico State University scientist plans on using a solar telescope to peer through them to study the weather on Venus.
"Observations of Venus from a nighttime telescope at a single location are very difficult because Venus is so close to the Sun in the sky," said Dr. Nancy Chanover, a planetary scientist at NMSU in Las Cruces, NM. "You can observe it for about two hours at most." Then the Sun rises and blinds the telescope (or Venus sets, depending on the time of year). http://www.nso.edu/press/venus06/ -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Feb 13 2006, 10:15 AM
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
Something in my infinitely long list of "would love to do" is create a version of the "image" of Venus that Mariner 2 took.
Yes. I know Mariner 2 didn't carry an imaging system. Not entirely true. Both the microwave radiometer and infrared radiometers were mounted on a scan platform. Each had 2 channels: 2 different wavelengths. (going from memory) The design was for the platform to scan back and forth at a high slew rate till the brighness temperature sensed by the microwave radiometer got above a threshold, then scan back and forth in a zig-zag slow scan pattern, reversing direction every time the signal dropped below a threshold. This would have generated a 4 crude zig-zag raster scanned images of Venus' disk: 2 microwave, 2 IR. During launch, the microwave radiometer was probably damaged -- some of it's thermal shielding may have been disturbed. Output signal was lower than designed and the second channel's data was actually reversed! When scanning past a calibration "warm plate" on the edge of the scan range it put out a LOWER signal than when pointed at black space! As a result, the instrument couldn't do the fast "search" scans it was designed to do. During the encounter, which was at about twice the nominal pre-launch distance (they didn't take the risk of a second midcourse just to get closer than the acceptable result of the first), they got 3 slow rate scans across the planet's disk, one by accident when the scan got confused by the reversed signal, sped up, hit the end of the stop and reversed direction. There were about 15 total microwave measurements (and IR) on the limb and disk of the planet and they could be turned into very crude "sparse" images. The microwave channels basically showed limb darkening caused by the atmosphere attenuating the heat from the surface. The IR (one in a CO2 window) both showed cloud top temperatures with no breaks in the cloud, one measurement apparently hit the cold polar collar and was lower than expected for it's emission angle. |
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