@S1-A.ARPA,@MIT-MC:TENCATI@JPL-VLSI.ARPA (05/03/85)
From: Ron Tencati <TENCATI@JPL-VLSI.ARPA> Henry S. F. Cooper Jr. in his book "The House in Space" quoted one astronaut as saying that he had faced the dilemma of getting "stuck" in the middle of a room in zero G. He said that all his "swimming" attempts succeeded only in causing his body to gyrate in the opposite direction of the force, and that he had to have help to get to the other side of the room. This same astronaut then did an experiment where a small amount of velocity was introduced into the experiment. He was still unable to control his own destiny, but he did get to the other side of the room a half hour later. I wonder if a change in the ship's velocity would affect the hapless astronaut who is hanging in mid-air. Ron Tencati JPL-VLSI.ARPA ------
barnett@ut-sally.UUCP (Lewis Barnett) (05/04/85)
> From: Ron Tencati <TENCATI@JPL-VLSI.ARPA> > > Henry S. F. Cooper Jr. in his book "The House in Space" quoted one astronaut > as saying that he had faced the dilemma of getting "stuck" in the middle of > a room in zero G. He said that all his "swimming" attempts succeeded only > in causing his body to gyrate in the opposite direction of the force, and > that he had to have help to get to the other side of the room. I remember reading a story long, long ago that suggested that it should be possible to produce some velocity by throwing an object in the opposite direction one wanted to move. It sounded reasonable to me then, but I was young and impressionable at the time. And, of course, it _was_ science fiction... Lewis Barnett,CS Dept, Painter Hall 3.28, Univ. of Texas, Austin, TX 78712 -- barnett@ut-sally.ARPA, barnett@ut-sally.UUCP, {ihnp4,harvard,seismo,gatech,ctvax}!ut-sally!barnett
@S1-A.ARPA,@MIT-MC:TENCATI@JPL-VLSI.ARPA (05/04/85)
From: Ron Tencati <TENCATI@JPL-VLSI.ARPA> I guess I forgot to mention that Cooper's book "A House in Space" was a documentary on the Skylab missions. It was not a science fiction novel. I read the book several years ago, but it is still on my bookshelf. As I recall the hapless astronaut was not stuck with velocity=0, but he was in the middle of the room, drifting VERY slowly, and he was unable to affect his velocity or course. He then repeated the experiment with a little more velocity. Flapping one's shirt or trunks will may work in the shuttle where there is an atmosphere and wind can be generated. In the vacuum of space, however, nothing will induce velocity unless the astronaut puctures his/her space suit and causes some kind of thrust. Henry Cooper only gave this topic about 1 page in his book, so I shouldn't take up more room than that. I can dig up the book and provide the name of the astronaut, who can then be contacted for the "real scoop"... ------
steve@siemens.UUCP (05/06/85)
If you're fortunate enough to have a ball, you can throw it at the wall away from where you want to go, giving yourself some momentum (mv, isn't it?) and then catch it when it bounces back, getting teh same amount of momentum again (less friction loss, inelasticity of bounce, etc.)
brent@phoenix.UUCP (Brent P. Callaghan) (05/06/85)
How about jet propulsion !!!
Theory: Take deep breath in desired direction of travel.
Rotate head 180 deg
Blow out with puckered lips
(whistle tune if other crewmembers don't mind)
Repeat until either:
- feeling dizzy (breathe in paper bag)
- enough delta V
- destination reached (could use retro technique to soft land)
Skillful lip control would gimbal the thrust vector to maintain
attitude and thrust direction.
I'll experiment in 2D next time I go ice skating.
--
Made in New Zealand --> Brent Callaghan
AT&T Information Systems, Lincroft, NJ
{ihnp4|mtuxo|pegasus}!phoenix!brent
(201) 576-3475maurice@nmtvax.UUCP (05/06/85)
>I wonder if a change in the ship's velocity would affect the hapless astronaut >who is hanging in mid-air. Yes, it would. It has been noticed that objects that are floating in mid air will start to drift, or change directions when the control rockets fire to keep the shuttle pointed the right way, or just change directions. If it does happen to an object, it should be the same for an astronaut. Roger Levasseur
@S1-A.ARPA:HQM@MIT-MC (05/08/85)
From: Henry Minsky <HQM@MIT-MC> I belive that the rocket-propulsion schemes (throwing a ball, blowing a balloon) are all much much less efficient than something that involves taking advantage of pushing off of the air itself. (i.e., heavier than air flight with wings and propellors can be done with a lot less power than a plain reaction rocket-engine) The suggestion of swim fins seems like about the best idea. Maybe in a pinch you could grasp your shirt in two hands and wave it back and forth the the tail of a fish. (In sailing, if you are becalmed, and you pump your tiller back and forth, you get some forward motion)
karn@petrus.UUCP (05/11/85)
> Yes, it would. It has been noticed that objects that are floating in > mid air will start to drift, or change directions when the control rockets > fire to keep the shuttle pointed the right way, or just change directions. > If it does happen to an object, it should be the same for an astronaut. Of course, what's REALLY happening is that the objects remain stationary in their inertial reference frame, while the ship accelerates "around" them. I recall seeing a brief but amusing clip from one of the shuttle missions. Whenever one of the astronauts would release a roll of duct tape, it would slowly accelerate towards the right and bounce off the wall. If the astronaut let go of the handle he was holding, he'd also drift to the right and hit the wall. Obviously, an orbit maneuver was going on, but the orbiter is so massive that the acceleration given by the OMS is pretty small (1/2 m/sec/sec, depending on fuel and cargo load, seems about right from memory). Phil
throopw@rtp47.UUCP (Wayne Throop) (05/14/85)
In article <478@nmtvax.UUCP> maurice@nmtvax.UUCP (Roger M. Levasseur) writes: > >>I wonder if a change in the ship's velocity would affect the hapless astronaut >>who is hanging in mid-air. > > Yes, it would. It has been noticed that objects that are floating in >mid air will start to drift, or change directions when the control rockets >fire to keep the shuttle pointed the right way, or just change directions. >If it does happen to an object, it should be the same for an astronaut. > >Roger Levasseur Well, if you ignore air resistance and such, a change in ship's velocity would NOT affect the floating astronaut. Which of course means that as the vehicle accelerates, it bangs into the floating astronaut. In other words, it doesn't much matter whether an astronaut is inside the spacecraft or not, s/he stays put and the craft accelerates. The nice thing about being inside is that no matter which way the craft departs, a wall eventually collides with the occupant and takes him/her along. -- Wayne Throop at Data General, RTP, NC <the-known-world>!mcnc!rti-sel!rtp47!throopw
dbb@aicchi.UUCP (Burch) (05/17/85)
> > Yes, it would. It has been noticed that objects that are floating in > > mid air will start to drift, or change directions when the control rockets > > fire to keep the shuttle pointed the right way, or just change directions. > > If it does happen to an object, it should be the same for an astronaut. > > Of course, what's REALLY happening is that the objects remain stationary > in their inertial reference frame, while the ship accelerates "around" them. > > I recall seeing a brief but amusing clip from one of the shuttle missions. > Whenever one of the astronauts would release a roll of duct tape, it would > slowly accelerate towards the right and bounce off the wall. If the astronaut > let go of the handle he was holding, he'd also drift to the right and > hit the wall. Obviously, an orbit maneuver was going on, but the orbiter > is so massive that the acceleration given by the OMS is pretty small > (1/2 m/sec/sec, depending on fuel and cargo load, seems about right from > memory). > > Phil Well... What really would happen (assuming no orbital maneuver and the air blowers are all off) is that the astronaut will reach a wall! This is because of the fact that the astronaut and the spacecraft are unlikely to share a centre of gravity, and therefore are in different orbits around the earth. Quite likely there are tidal and other effects which would cause the standed fellow to reach a wall eventually... -Ben Burch, AIC
swift@reed.UUCP (Theodore Swift) (05/17/85)
> I belive that the rocket-propulsion schemes (throwing a ball, >blowing a balloon) are all much much less efficient than something >that involves taking advantage of pushing off of the air itself. >(i.e., heavier than air flight with wings and propellors can be done >with a lot less power than a plain reaction rocket-engine) > The suggestion of swim fins seems like about the best idea. In considering "efficiency" you might consider that swim fins push against water, and your proposed "air fins" work against air (at a reduced pressure of something like 10 psi to boot, if what I've heard is correct). I believe air is something like 1/20 as dense as air (at 14.7psi), so to get the "same effect" you'd need fins 20 times bigger, i.e., big mongo butterfly wings! This might be OK in Heinlein's big flying chamber on the moon (see, I believe, _The Moon is a Harsh Mistress_) but it's downright lethal in a space station. If you brush the wrong switch with your multicolored wings (made by Hobie, no doubt :-)) you're liable to do something irreversibly bad. (see Niven's stories about Belters- people who live in small ships in the Asteroid belt.) The idea of a balloon is good, as long as you take care where and how you inhale. I'd suggest inhaling through both sides of your mouth, then exhaling into the balloon. Better yet, don't get into the situation of being stuck out there in the first place. It would be hard to do, anyway since you'd have to leave your last wall with SOME velocity. If the ship fired it's rockets while one was floating in "midair", of course the ship would accelerate "at you" at whatever rate the engines were giving it. This could hurt. A lot. Most of these questions can be answered by taking a good squint at Sir Isaac's three laws.
nessus@nsc.UUCP (Kchula-Rrit) (05/21/85)
> In considering "efficiency" you might consider that swim fins push > against water, and your proposed "air fins" work against air (at a > reduced pressure of something like 10 psi to boot, if what I've heard > is correct). I believe air is something like 1/20 as dense as air (at > 14.7psi), so to get the "same effect" you'd need fins 20 times bigger, > i.e., big mongo butterfly wings! This might be OK in Heinlein's big > flying chamber on the moon (see, I believe, _The Moon is a Harsh Mistress_) > but it's downright lethal in a space station. ... *** REPLACE THIS LINE WITH YOUR MESSAGE *** Wasn't the story by Heinlein called "The Menace From Earth"? Then again, maybe my memory is saturated from read science-fiction since age 12. I agree with the rest of the article. From the alter ego of-- Kchula-Rrit