The BBC aired a show sometime in the recent past depicting an interplanetary expedition on a tour of the solar system. The part I have watched featured a crew of two landing a vessel on the surface of Venus, with one of them performing an EVA outside the craft. First of all, the atmosphere of Venus is highly corrosive. A couple of acidic compounds in the Venusian air would dissolve equipment quite rapidly, and the BBC show depicts this well by showing in the scenario that the EVA can only last an hour or something like that. They show them losing different cameras as they dissolve and corrode away, etc. Here, though, is the problem I see: weve set the standard for measuring atmospheric air pressure with the Earths at sea level to be 1 bar. Astronauts have pressurized their spacesuits at slightly below that for work in vacuum conditions, this is to help with the depressurization process and to help prevent decompression sickness or to help prevent problems with repressurization. The astronaut will do a round of prebreathing to purge nitrogen from the blood stream, then they are fitted into the suit where it is inflated to the desired pressure. Now, the problem with the Venus scenario is that on the surface there, the pressure is a staggering 92 bars! The show (while not being based on actual events) claims the Venus EVA suit is made of some kind of Titanium alloy which is supposed to hold up to the pressure, but the internal pressure of the suit is still only within the human threshold of tolerance. I am not the expert on fluid dynamics, but it seems to me that high pressures will always overtake areas of lower pressure. The show depicts the crewman doing the EVA slowly traversing the surface with elevated breathing and heart-rate, but overall, hes upright and walking. I would think that in Venus thick, high-pressure atmosphere, a person would not be able to move much at all. It would be like swimming in maple syrup. With temperatures above 900 degrees Fahrenheit, pressure at 92 bars, and corrosive chemicals--Venus is nothing short of a hell for humans and we would not be able to survive a landing and especially not an EVA.
Posted on: Tue, 15 Jul 2014 16:17:48 +0000
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