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Re: John Did It.
Date: 11/25/13 3:25 pm
In Response To: Re: John Did It. (scarab)

: His absolute velocity is much greater than that of someone standing on the
: surface.

: We can see this by looking at the two circles: The circle that someone
: standing on the earth's surface sweeps out as he/she rotates around the
: Earth's center once a day the circle that someone orbiting 35,786
: kilometers above the Earth's surface sweeps out in a day

: One circle is much larger than the other - the circumference is much greater
: - therefore the orbiting person has to be traveling faster in order to
: complete his circle in the same time as the person on the ground.

: Somehow this excess velocity has to be shed so that the orbiting person can
: reach the ground and end up traveling at the same velocity as a person
: standing on the ground.

: I don't know how 6 managed this. I think that we assume that he shed a lot of
: velocity as heat caused by atmospheric breaking. I don't know how much
: delta-V is required to get down low enough for atmospheric breaking to
: have a significant impact. What I mean is that he probably required
: rockets just to get low enough for the atmosphere to get hold of him.

: Otherwise it may have taken months or years to deorbit him - years of
: drifting before the atmosphere got a good grip on him.

: I liked Quirel's suggestion that the ship was in a Star Trek style,
: "standard orbit" - an 'orbit' where you aren't going fast enough
: to remain in orbit once your engines are switched off.

: I also liked his description of the reentry pack and how it worked.

: As Cody points out - it may not be enough. It bugged me at the time but I've
: moved on a long time ago. I don't care these days.

You know, this is interesting. I always thought of it the way loftus had... geostationary means that if you're at a higher altitude orbit, you can still look down and see that you essentially remain above the same location on Earth, all the time.

But you're right, at that height, your actual speed (by the time it takes to travel your greater orbital circumference around the Earth being the same as at sea level for instance) is much greater than at a lower altitude - even though your relative location remains steady.
(sort of like angular velocity; picture the same effect as the twirling skater, speeding up as she brings her arms in... or a smaller tire having to rotate faster than a larger one in order to keep a vehicle moving the same speed)

So as your orbital height decreases, your position relative to the Earth location will accelerate, as the difference between sea-level orbital speed and speed your altitude becomes more apparent.

However, you then factor in the increased friction of entering the atmosphere, which would slow you down. I would think that with a HEO jump from geostationary orbit you would at first see the effect of 'speeding up' (relatively speaking to the surface of the Earth), and then as friction increases so would the heat (this would be where the re-entry pack kicks in), followed by slowing of your relative speed to the surface. Your final speed on arrival at the surface I think would entirely depend on how much heat friction your re-entry pack could sustain based on how fast you want to slow down your velocity.

...if that makes any sense.

I would think, given a sufficient package, you could slow your relative velocity sufficiently to enter a freefall within the earth's atmosphere (ie, where your orbital velocity has slowed to match that of the earth's surface, or a relative speed of 0).

The question is, would 26th century tech have a re-entry pack with sufficient protection to defend against that amount of speed reduction during atmospheric re-entry? (based on a geostationary orbit starting point)

I say yes. Because Halo. :P

Messages In This Thread

Noble Six's jump reduxCody Miller11/21/13 2:58 am
     Re: Noble Six's jump reduxQuirel11/21/13 3:58 am
           AlsoZackDark11/21/13 8:09 am
                 RE: AlsoQuirel11/21/13 12:15 pm
                       Fantastic! *NM* *NM*asa11/21/13 1:08 pm
     Nope, it'd be moving fasterpadraig0811/21/13 9:33 am
     Re: Noble Six's jump reduxRagashingo11/21/13 8:57 pm
           Re: Noble Six's jump reduxCody Miller11/22/13 2:42 am
                 Re: Noble Six's jump reduxRagashingo11/22/13 6:17 pm
                       I was hoping he was trying to be funny there... *NM*ZackDark11/22/13 8:47 pm
                       Re: Noble Six's jump reduxCody Miller11/22/13 11:31 pm
                             Re: Noble Six's jump reduxRagashingo11/22/13 11:38 pm
                             John Did It.Morpheus11/23/13 12:21 am
                                   Re: John Did It.Stephen L. (SoundEffect)11/23/13 10:57 am
                                         Re: John Did It.scarab11/23/13 12:12 pm
                                               Re: John Did It.uberfoop11/23/13 12:36 pm
                                                     Re: John Did It.scarab11/23/13 5:01 pm
                                                           Re: John Did It.Cody Miller11/23/13 6:00 pm
                                                                 Re: John Did It.Quirel11/23/13 6:07 pm
                                                                       Re: John Did It.Stephen L. (SoundEffect)11/23/13 9:21 pm
                                                           Re: John Did It.uberfoop11/23/13 6:21 pm
                                               Re: John Did It.Stephen L. (SoundEffect)11/23/13 9:27 pm
                                                     Re: John Did It.Quirel11/24/13 12:45 am
                                                     Re: John Did It.scarab11/24/13 8:18 am
                                                           Re: John Did It.thebruce011/25/13 3:25 pm
                                                                 Re: John Did It. *img*thebruce011/25/13 3:54 pm
                                                                 Re: John Did It.Stephen L. (SoundEffect)11/26/13 11:26 am
                                                                       Re: John Did It.ZackDark11/26/13 11:37 am
                                                                             Re: John Did It.Stephen L. (SoundEffect)11/26/13 7:06 pm
                                                                                   Re: John Did It.ZackDark11/26/13 7:43 pm
                                                                                         Re: John Did It.Ragashingo11/26/13 9:54 pm
                                                                                               Re: John Did It.Stephen L. (SoundEffect)11/26/13 10:08 pm
                             Apollo 13's problem wasn't quite the sameZackDark11/25/13 6:04 pm
     They Have A Point...Morpheus11/22/13 12:11 am
     He wouldn't even make it to burningGeneral Battuta11/23/13 9:33 am
           Re: He wouldn't even make it to burningGeneral Battuta11/23/13 9:35 am
     Re: Noble Six's jump reduxCHa0s11/24/13 2:27 pm

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