Re: Mars in two weeks?

From: Doug Jones (
Date: Mon Jan 08 2001 - 01:18:05 MST

Jeff Davis wrote:
> Additional problems include: High Pressure Nervous Syndrome (HPNS), which
> results from an overly fast rate of compression; and, of course,
> decompression complications.

Nah, even at 70 g, the max hydrostatic pressure is only about 3 bars-
the total N2 saturation would be modest, and limited by the lower
pressure in the upper portions of the body.
> For a diver, HPNS is bad news because he has to function as a worker, not
> to mention survive in a hazardous environment, but for an astronaut just
> laying back for the trip, it's not so critical. I'm not a hundred percent
> certain, but as I recall the theory of HPNS attributes it to mechanical
> distortion--due to compression--of neural cell membranes, and that it can
> be prevented or reversed by administration of anesthesia, which, absorbed
> by the membranes, causes them to swell. First it restores normal nerve
> function, then, with additional absorbtion and swelling, it puts you to
> sleep. So to prevent our astronaut from becoming wired to the point of
> seizures--that's what HPNS does to you--we have to medicate him.

No, HPNS is adequately countered by adding a small amount of N2 to the
breathing mix. That's how the 2000+ fsw dives were done, and is used in
routine saturation diving at lesser depths.
> What with the escalting complexity of life-support with increasing G
> forces, I conclude that one G, a good book, some videos, and a bucket of
> McNuggets will do just fine. Two days one hour and fifty minutes (at
> mars-to-earth closest approach) is less time than it takes to cross the
> Atlantic by boat, even today.

Perzackly- and engine mass is typically proportional to thrust, so it
would probably be the best trade of speed vs performance to drop the
acceleration to 1 m/s and take 3x as long to get there- using 1/3 the
propellant. A few weeks is still far better than nine months.
> And one last comment. The rotary rocket engine, the spinning wheel,
> exhaust nozzles at the periphery, dynamic geometric simplicity replacing
> complex and expensive turbopumps, remains for me a concept of breathtaking,
> dazzling elegance. I am bereft and inconsolable at the thought that it is
> not to be. Rather, I choose to believe that persons of venality and small
> vision, the spawn which curseth humanity by their abundance, have simply
> postponed the day when that beauty of engineering shall grace the skies.
> Tell me Doug--lie if you have to--that there is still hope.

Oh, there *is* hope but the rotary engine is not the be-all and end-all
of efficient and simple propulsion. It has a certain elegance, true,
but it has its own can of worms also. I can't talk about our activities
at XCOR, but we *are* making progress.

Doug Jones
Rocket Plumber, XCOR Aerospace

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