What would have happened if Joe Kittinger, Felix Baumgartner and Alan Eustace had opened their parachute right after jumping off the capsule (respectively releasing oneself from the balloon in case of Eustace)? At first it probably wouldn't matter as the chutes would be needless in the near-vacuum the balloonists jumped from, but how exactly would an open parachute have altered their falls? And would something happen to the parachute itself?
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asked Feb 17, 2022 at 17:24
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8$\begingroup$ If it were the Loony Tunes world, the jumper would float at the same height as the platform until they pulled out some old-school bellows to inflate the parachute. Only then would they start to fall. $\endgroup$– CriggieFeb 18, 2022 at 2:45
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4$\begingroup$ All these 3 were high-altitude balloons, not space ones. $\endgroup$– Quora FeansFeb 18, 2022 at 2:57
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3$\begingroup$ If it took any longer they might have had to amputate his hand. $\endgroup$– MazuraFeb 18, 2022 at 5:31
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2$\begingroup$ @QuoraFeans The Space Shuttle wasn't a space shuttle either, it was a high-altitude shuttle. The Earth's atmosphere extends until 6,200 or more miles from the surface, hence the only literal spacecraft was the Apollo, the only crewed vehicle having gone beyond 6,200 miles so far. $\endgroup$– Better not tellFeb 18, 2022 at 6:41
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2$\begingroup$ @Betternottell: Some define the boundary of space (the Kármán line) as beginning 100 kilometres above Earth's sea level. The space shuttle went to space according to this definition (but it was not a shuttle, since a shuttle operates at frequent intervals non-stop between two places). For advertisement purposes, of course, Baumgartner claimed it was a space jump. $\endgroup$– Quora FeansFeb 18, 2022 at 13:27
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1 Answer
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tl;dr Opening too high will kill you.
As you note, the parachute would just hang next to them immediately after leaving the balloon -- there's too little air that high to even drag the shroud lines out straight.
Later on, there would come a point when the canopy would fill, probably while the jumper was near Mach 1: the air would become thick enough to drag the parachute out to the end of the shrouds and pressure inside the canopy would build enough to shape the parachute. Assuming it doesn't tangle and fail in one of several ways (this is a real hazard if the lines are slack at any point), there's still the danger of the canopy opening abruptly. Even in the thin air above 40 km (25 mi), a canopy sized for a man in a pressure suit is capable of generating an opening shock -- the G force from the sudden deceleration as the canopy shapes and its drag force becomes measurable in tons -- sufficient to deal severe injury. Historically, this has caused broken necks and backs even with parachutes opening at a mere 100-150 m/s (330-490 ft/s) in denser air.
This is why it's normal even with a bail-out at jet altitude to free fall to within a couple kilometers of ground level -- because the lower you get, the slower you fall. Rising air density reduces your terminal velocity from, in the case of Baumgartner, at least, near Mach 1 to only 50-60 m/s (160-200 ft/s).
Of course, with opening shock that high, there's also the possibility (nay, likelihood) that some part of the parachute system will fail under loads tens of times what they were designed to take. Shroud lines can snap, canopy fabric rip, etc. This can lead to an open parachute that doesn't provide the low fall speed it should, or a streamer -- potentially with a badly injured jumper who isn't functional enough to cut away and open his reserve.
Bottom line, these men had a very carefully thought out system to get them down safely: their drogue to stabilize their fall when there was barely enough air to make a self-inflating drogue pull its line straight, and their long, long fall under drogue before opening their main low enough that the opening shock wouldn't break anything.
From comments, there's a question whether there's a midway opening altitude where the parachute can fill, but the air is too thin to produce injurious opening force. I don't know that this has been studied in detail, but there are altitudes within the envelope of various aircraft (high altitude interceptors and the SR-71 they were designed to try to intercept) at which it might be possible to open safely -- perhaps between about 18 and 20 or so kilometers (59-65,000 ft) -- but doing so would be a bad idea for another reason: there's a limited supply of breathing oxygen in the "bail-out bottle" attached to a pilot's pressure suit, and a parachute descent from above some altitude (guessing, but it's probably lower than 15 km (49,000 ft)) will result in depletion of this oxygen reserve and hypoxia well before descending into air thick enough to breathe directly.
answered Feb 17, 2022 at 17:41
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6$\begingroup$ Much as I enjoy the green checkmark, it's usually recommended to allow 24 hours or more -- an accepted answer tends to discourage other answers, and you might prevent a better answer than mine from being written. $\endgroup$ Feb 17, 2022 at 18:33
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1$\begingroup$ @Bohemian It's a fail-safe. Stable freefall needs you to hold a particular body position. If you're a mass suspended under a drogue, you can pass out and still come down stably. $\endgroup$– GrahamFeb 18, 2022 at 9:02
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6$\begingroup$ The other function of the drogue is to reduce the tendency to spin. This is well documented in multiple high altitude fighter bail-outs; it's almost impossible to prevent spinning one direction or the other at rates that can induce loss of consciousness. IIRC Baumgartner had this as well. And if you pass out due to spin, you might well die (G/pressure induced stroke etc.) before you get low enough to control the spin. $\endgroup$ Feb 18, 2022 at 12:05
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2$\begingroup$ @LorenPechtel A specially designed parachute might permit this -- NASA has parachutes that can open at supersonic speeds without destroying themselves or their payload, using reefing lines and staged opening in a heavily vented canopy, but this is a large drogue, not the parachute that will give final descent velocity. Carrying this kind of drogue and its reserve, plus your main and reserve, would become an impractical load just for exiting the balloon capsule. $\endgroup$ Feb 20, 2022 at 11:09
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2$\begingroup$ @Jpe61 The issue is that at the point the air gets thick enough to fill the canopy, the jumper is likely still superonic, so the opening will be catastrophic -- it'll go from not enough pressure differential to open the canopy to full open at Mach 1+ in a second or less -- and that's a force increase roundly a thousand-fold, from an unopened wad of parachute material to a fully open canopy. Delay panels as used on modern flat canopies aren't designed to deal with this, and such don't generally exist on a round parachute. $\endgroup$ Feb 21, 2022 at 12:47