Mars 3 (Various Topics Merged) |
Mars 3 (Various Topics Merged) |
Dec 29 2004, 10:36 PM
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#1
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
On my website sometime back, I added a page on the image fragment sent back by the Mars-3 Lander. I released serveral versions, including the best quality processing using othodox techniques I would use on other images plus colorization here:
http://pages.preferred.com/%7Etedstryk/fragmentc.jpg However, I released another image, which I called a "What if" image. This image can be seen here http://pages.preferred.com/%7Etedstryk/m3s5b.jpg It was produced via extreme processing of the original data to make a Mars-like scene, but I made it clear on my website it was only a speculative image. I strongly doubt if the raw data even shows Mars at all - it could be all noise. But since this mode of processing looked strangely Viking-like, I figured I would put it on the web. I was warned by several, who said that while fun, some kooks might take it seriously. My response was that I really don't care what kooks think. Then I noticed this web page: http://en.wikipedia.org/wiki/Mars_2 They used the overprocessed image. I feel like it is being presented as a true photograph. This is of concern. -------------------- |
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Feb 6 2009, 11:50 AM
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#2
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Solar System Cartographer Group: Members Posts: 10226 Joined: 5-April 05 From: Canada Member No.: 227 |
Way off course by a few hundred km maybe, not half way round the planet.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Feb 7 2009, 04:51 AM
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#3
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Member Group: Members Posts: 236 Joined: 5-June 08 From: Udon Thani Member No.: 4185 |
Way off course by a few hundred km maybe, not half way round the planet. I agree on you with that. I have often wondered how the autonomous navigation prior separation/EDL worked on Mars 2-3. They had quite a big problem due to inaccurate ephemeris data on Mars, that's why they needed an orbiter around Mars prior to both landers, when that launch went wrong they had to rely on the untested autonav function from the landers. The landers had a solid propellant retro-engine, so their retro-impuls was more or less fixed (they could change the orientation but not the duration of the impuls) and from the various accounts it reads like the whole entry sequence was mostly completely fixed and not much could be changed on the spot (even orientation engines were partly 'gunpowder' engines, so fixed impuls). Entry and landing was a parabolic trajectory. Thus everything relied on the mothership releasing the lander on exactly the correct trajectory and in the correct orientation. The latitude of 45 degrees south for both landing sites corresponds more or less with the inclination of the final orbits of both motherships, and might thus have been a pre requisite of the automatic entry-sequence. With uncertain ephemeris, the mothership had to update its own statevector prior to release of the lander (using Mars and Sun?), then calculate its final course correction in order to steer to the correct trajectory. Afterwards the mothership had to place itself in the correct orientation, and release the lander (sounds like lander was spin-stabilized afterwards till firing of its retro engine, and then steered into correct entry-orientation). By the sound of it, this was all done automatically and pre-programmed, quite a feat for 1971 technology. It is unclear whether there were any communications from the lander after release, on Mars 6 it is stated that an extra transmitter was added to transmit data during the parachute descent, and this sounds like Mars 2/3 did not have such a transmitter or maybe only very basic telemetry was send. The fact that the landingsites were chosen from mariner 6/7 images is very interesting and makes sense as these images were freely available at the time and were the best there was to have, but without accurate ephemeris data and with pre-programmed entry-sequences it sounds landing accuracy must have been very low, which makes finding those probes almost impossible. Regards, Geert. |
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