Red Bull Stratos project: 23 miles, Mach 1, free fall

[destrekor]

Anyone excited to see this so close? Felix Baumgartner is hoping to be the first man to reach Mach 1 during freefall, jumping from a balloon around 23miles off the surface of Earth, jumping from space.

It's a publicity stunt, but also potentially chock full of scientific and medical data that could be used in the near future.

It'll be interesting to see if Baumgartner can survive and beat Kittinger's record that has stood for nearly 50 years, with quite a few failing at attempts to break them, some even having died.

Red Bull Stratus

 

[El Guaraguao]

 

[FelixDeCat]

Didnt someone try this a few days ago over Australia?

 

[GodlessAstronomer]

Mach 1 in free fall? My immediate reaction to that is "that sounds physically impossible", but I'm sure some smart person will tell me why it's not.

 

[Bateluer]

Its been done.

http://en.wikipedia.org/wiki/Project_Excelsior

 

[destrekor]

Its been done.

http://en.wikipedia.org/wiki/Project_Excelsior

In case you missed it, Kittinger is working with the team preparing Baumgartner for the jump.
Kittinger made the records that still stand today. He is helping prepare Baumgartner to try and break those records.

edit:
To add more to the conversation, Killinger never broke the speed of sound at any altitude his speed was measured.
Mach 1 at sea level is approx. 760mph, and at an altitude of around 100k ft, it's about 670mph.

Killinger's jump reached a top speed of 614mph.

The capability for a body to reach Mach 1 in free fall is essentially based on how long they can sustain terminal velocity in a region of minimal drag. Baumgartner will be jumping from over 120k feet, and will have a longer sustained free fall at terminal velocity with low drag. His terminal velocity will continue to decrease as he descends through the atmosphere, increasing more resistance due to the drag from increased air pressure.
But the team is actually worried about Baumgartner reaching more than Mach 1.2, with hopes he/they can prevent reaching that speed.

 

[DrPizza]

Any astronaut that has gone out on a space walk has been in free fall WELL in excess of Mach 1.

 

[destrekor]

Any astronaut that has gone out on a space walk has been in free fall WELL in excess of Mach 1.

when there's no atmosphere, of course they're in excess of Mach 1.

Plus are they truly considered to be in free fall? Can anything in orbit be considered free fall?
Sure, orbiting at a height that also means a continually degrading orbit might be considered falling, but is it free falling?

 

[GodlessAstronomer]

Plus are they truly considered to be in free fall? Can anything in orbit be considered free fall?
Sure, orbiting at a height that also means a continually degrading orbit might be considered falling, but is it free falling?

Absolutely. They are being pulled towards the Earth by gravity with no other significant forces acting on them. That's pretty much the definition of free fall.

 

[destrekor]

Absolutely. They are being pulled towards the Earth by gravity with no other significant forces acting on them. That's pretty much the definition of free fall.

By pure definition I guess I agree.

But I would consider free fall to be an act of falling with terminal velocity.

A degrading orbit has a body falling far short of terminal velocity, wouldn't you agree?

The point being, that the technicalities of this matter here don't really matter.

The feat of Killinger's records apply to free fall within atmosphere essentially.

If we really want to question the record, should we throw up a few astronauts in a space walk, and then have them maneuver to enter a pure free fall from the height of LEO?
Well... could they survive is another question. And actually, that's part of what this team hopes to find out. Some of the medical and scientific data to be collected is wrapped around the notion of surviving an emergency escape from a craft far above the surface.

 

[JRich]

Any astronaut that has gone out on a space walk has been in free fall WELL in excess of Mach 1.

Rocket assisted :awe:

 

[DrPizza]

when there's no atmosphere, of course they're in excess of Mach 1.

Plus are they truly considered to be in free fall? Can anything in orbit be considered free fall?
Sure, orbiting at a height that also means a continually degrading orbit might be considered falling, but is it free falling?

Absolutely. If they weren't falling, they'd go in a line tangent to their orbit. Heck, even Isaac Newton came to the realization that the reason the moon orbits the earth is that it's falling. Orbit *IS* freefall. And, technically, there IS atmosphere at the altitude the space shuttle & space station are in orbit at.

 

[silverpig]

Any astronaut that has gone out on a space walk has been in free fall WELL in excess of Mach 1.

Actually that's probably not true. While they're travelling faster than mach 1 at sea level, because sound doesn't travel at space shuttle altitude, there's no speed of sound, no mach speed, and so the measurement is useless.

 

[silverpig]

By pure definition I guess I agree.

But I would consider free fall to be an act of falling with terminal velocity.

A degrading orbit has a body falling far short of terminal velocity, wouldn't you agree?

The point being, that the technicalities of this matter here don't really matter.

The feat of Killinger's records apply to free fall within atmosphere essentially.

If we really want to question the record, should we throw up a few astronauts in a space walk, and then have them maneuver to enter a pure free fall from the height of LEO?
Well... could they survive is another question. And actually, that's part of what this team hopes to find out. Some of the medical and scientific data to be collected is wrapped around the notion of surviving an emergency escape from a craft far above the surface.

It's not a degrading orbit problem. Orbit is free fall.

Picture a satellite orbiting the earth from the north pole south along the prime meridian to the south pole, then back over the international date line. If you look at the orbit, you will notice that at one point the satellite is directly above the north pole, and half an orbit later, it's directly over the south pole. The satellite has fallen down from above the north pole, past the earth, and through to above the south pole. The only thing that keeps it from splatting into the arctic is the fact that it's travelling "sideways" and misses the earth as it falls past.

 

[DrPizza]

Actually that's probably not true. While they're travelling faster than mach 1 at sea level, because sound doesn't travel at space shuttle altitude, there's no speed of sound, no mach speed, and so the measurement is useless.

Agreed. And, this same argument applies to the person attempting this in the OP.

 

[silverpig]

Agreed. And, this same argument applies to the person attempting this in the OP.

Not really. He starts off virtually in space to get enough velocity built up such that when he "hits" the atmosphere he's going faster than the speed of sound at that level of the atmosphere.

 

[KingGheedora]

In case you missed it, Kittinger is working with the team preparing Baumgartner for the jump.
Kittinger made the records that still stand today. He is helping prepare Baumgartner to try and break those records.

edit:
To add more to the conversation, Killinger never broke the speed of sound at any altitude his speed was measured.
Mach 1 at sea level is approx. 760mph, and at an altitude of around 100k ft, it's about 670mph.

Killinger's jump reached a top speed of 614mph.

The capability for a body to reach Mach 1 in free fall is essentially based on how long they can sustain terminal velocity in a region of minimal drag. Baumgartner will be jumping from over 120k feet, and will have a longer sustained free fall at terminal velocity with low drag. His terminal velocity will continue to decrease as he descends through the atmosphere, increasing more resistance due to the drag from increased air pressure.
But the team is actually worried about Baumgartner reaching more than Mach 1.2, with hopes he/they can prevent reaching that speed.

Why does it matter how long he can sustain terminal velocity? I thought the definition of terminal velocity was when the sum of forces (e.g. gravity vs. drag) was zero, causing constant velocity. Once you reach terminal velocity you don't go any faster. In fact wouldn't he slow down once reaching TV, since the air gets thicker as he gets closer to the earth?

 

[destrekor]

Agreed. And, this same argument applies to the person attempting this in the OP.

Negative, because there will be atmosphere to conduct sound.
Like I said, there is Mach measurements for his altitude. And Mach 1 is still fast at that altitude.

100,000ft above sea level, Mach 1 is roughly 670mph.

Regardless of whether there is atmosphere at the point he jumps out of the balloon, his velocity should have enough time to reach Mach 1 within atmosphere. Though at sea level, I do not believe the terminal velocity is faster than Mach 1, I believe the drag would cap the terminal velocity below that of Mach 1.

and to everyone:

Orbit is also not a guaranteed fall to the surface. Everyone is arguing semantics as only nerds know how to best.

In fact, free falling in the atmosphere is technically a misnomer, and thus imho, deserving of a different definition. Free fall implies no resistance, movement due to gravity without drag.

Take the moon, it's orbit is doing the opposite - falling away from the Earth.

Falling without use of an attached device in the atmosphere is technically not free fall in physics nomenclature.

But it's also the only type of free fall in which one can break Mach 1, because Mach 1 requires atmosphere to provide said drag, which as noted earlier, is technically a disqualification for the term free fall anyhow.

y'all just want to spoil an obvious advance in what we feeble humans can do.
Breaking Mach 1 with the body and only the body, and surviving to tell the tale (Baumgartner hopes), would certainly be quite an achievement.

 

[destrekor]

Why does it matter how long he can sustain terminal velocity? I thought the definition of terminal velocity was when the sum of forces (e.g. gravity vs. drag) was zero, causing constant velocity. Once you reach terminal velocity you don't go any faster. In fact wouldn't he slow down once reaching TV, since the air gets thicker as he gets closer to the earth?

heh whoops, kind of mangled that in translation between my thoughts and ability to type them as words.

You are absolutely right, I really don't know what the hell I was trying to explain. That was a few hours ago and my brain didn't hold onto that thought.

But essentially the higher up he starts, the more time he has to reach terminal velocity in lesser atmosphere, the more of a chance he has to attain Mach 1, considering the terminal velocity of a human within atmosphere thick enough to breathe is roughly 2/5ths of Mach 1 at that same breathable atmosphere.

 

[AMCRambler]

Mach 1 is the speed of sound. If there's no air, there's no sound. So I'd say there's no way for an astronaut to hit mach 1.

 

[FelixDeCat]

Ive never been skydiving. This saddens me. :'(

 

[silverpig]

Orbit is also not a guaranteed fall to the surface. Everyone is arguing semantics as only nerds know how to best.

In fact, free falling in the atmosphere is technically a misnomer, and thus imho, deserving of a different definition. Free fall implies no resistance, movement due to gravity without drag.

Take the moon, it's orbit is doing the opposite - falling away from the Earth.

Falling without use of an attached device in the atmosphere is technically not free fall in physics nomenclature.

Sorry, but this is all wrong. Orbit is basically the DEFINITION of free fall. You don't ever have to reach the surface.

The moon is always falling TOWARDS the Earth, not away from it.

And yes, it is free fall in physics nomenclature

<--- physicist.

 

[rockyct]

lol, this thread reminds me of the plane vs. a conveyor belt thread.

 

[RU482]

mach 1 is the speed of sound. If there's no air, there's no sound. So i'd say there's no way for an astronaut to hit mach 1.

omfg

 

[KillerCharlie]

Sorry, but this is all wrong. Orbit is basically the DEFINITION of free fall. You don't ever have to reach the surface.

The moon is always falling TOWARDS the Earth, not away from it.

And yes, it is free fall in physics nomenclature

<--- physicist.

I disagree. I define freefall as moving toward something. I don't know what you're trying to say, but the moon isn't getting any closer to earth, it's moving around it. It's acceleration vector is pointing toward the earth, but it's velocity vector is NOT.

<--- Aerospace Engineer (you know, the ones that put us on the moon)