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lpetrich
2015-Jul-15, 12:05 PM
I've found these documents that mention the subject:
Warning! Firefox gave me warnings about security risks for these documents, something that seemed odd for their host: solarsystem.nasa.gov
WPP-263 - 07 - Space parachute system design Lingard.pdf (https://solarsystem.nasa.gov/docs/07%20-%20Space%20parachute%20system%20design%20Lingard.p df)
04_Parachute Development for Venus Missions_C. Kelley.pdf (https://solarsystem.nasa.gov/docs/04_Parachute%20Development%20for%20Venus%20Mission s_C.%20Kelley.pdf)
For Venus, they only mention the parachutes' having to survive the sulfuric acid in that planet's clouds, not the extreme heat of its surface.

These are NASA planning documents, and I've been unable to find out anything on the materials that the designers of the Venera landers had used for those spacecraft's parachutes. That detail may be buried in some technical report somewhere, and one that nobody has bothered to translate into English.

There are some plastics designed to survive high temperatures, notably Nomex: NomexTechGuide - nomextechnicalguide.pdf (http://www.nakedwhiz.com/gasketsafety/nomextechnicalguide.pdf), DPP_Nomex410_K20612-1.pdf (http://www.dupont.com/content/dam/assets/products-and-services/electronic-electrical-materials/assets/DPP_Nomex410_K20612-1.pdf), Nomex - Wikipedia (https://en.wikipedia.org/wiki/Nomex). Checking on its data sheets, I tried to estimate its maximum survivable temperature for a few hours' exposure. It was rather difficult, because most of the documents' temperature data is for 300 C or less. But it seems able to survive 300 C for a few hours, even if not for a few hundred hours. So a parachute made out of Nomex might be able to make it to Venus's surface.

The ultimate fate of a parachute in Venus's lower atmosphere? Getting charred (Pyrolysis - Wikipedia (https://en.wikipedia.org/wiki/Pyrolysis)), and likely carbonized, and ultimately disintegrating. It may someday be possible to watch this process from some future lander or rover.

ravens_cry
2015-Jul-16, 05:48 AM
Well, from what I know, the parachute was discarded before landing, with touch down being with atmospheric braking alone. What I am guessing is that in Venuses super thick lower atmosphere, the parachutes would provide *too* much drag.