NASA shuttle launch video from the perspective of a solid rocket booster | Hacker News Reader

NASA shuttle launch video from the perspective of a solid rocket booster

pbs.org

77 pointsbhousel16 comments

Interesting that the parachutes are deployed 32 seconds before landing, and only fully expand 22 seconds before landing (as far as I can tell from the video).

Anyone know what the margins for a skydiving human are by comparison?

The minimum "safe" height for skydiving is 2000ft with most jumps between 2000-5000ft depending on the type of jump and experience of the skydiver.

In emergency situations it's possible to deploy at 200-300ft. and survive.

Basejumpers deploy way below 2000ft. with 200 or 300ft. not being uncommon but they have gear and techniques designed to open the chute very quickly.

Skydivers can fall at a rate of ~160 ft/sec. So in a worst case scenario you've got 2 seconds before impact.

at 4:28 is that the launch plume on the left, the moon in the middle and the spent rocket on the right?

Yes.

pretty amazing video indeed! the sound is kind of spooky during the space flight :-)

Yes! I love how the sound actually gets "quiet" as they reach the upper atmosphere. ("quiet" in quotes because I don't know that it's really correct to say that when all that's really happening is the sound-carrying medium is becoming less...)

The site says they used a "contact microphone," so I assume what we're hearing is vibrations in the rocket not so much the air.

I wonder when does it break the sound barrier when falling. It must fall pretty quickly - 7 minutes from start to landing.

Typically something in the far-upper atmosphere breaks the sound barrier by just falling - not as many molecules to produce drag - but I don't think the sound barrier "breaks" at that altitude for the same reason terminal velocity is greater than the speed of sound up there.

I may be mistaken in this, but I don't think without propulsion or an absurdly stable / aerodynamic falling that you can actually "break" the sound barrier in the traditional sense at the point in the air where density is high enough to produce the shockwave effect.

Edit: That second paragraph was entirely too convoluted on my first go at it.

It's not very difficult: the Tallboy Bomb was free-falling and exceeded Mach 3 at impact.

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

I guess what I'm now wondering is whether or not something requires a certain drag coefficient to, upon achieving trans-sonic speeds, create a shock wave in the air.

Obviously they probably didn't produce a shock wave at absurdly high altitudes, but were also probably falling at trans-sonic speeds.

What I was trying to mull over was for how long and at which point could something like that achieve enough drag to presumably both travel at trans-sonic speeds AND produce an audible shock wave as per an aircraft achieving the same speeds.

But that is also why I put in the disclaimer about high aerodynamic capability, because obviously the terminal velocity would be enough to surpass that pretty easily. I didn't know it would be Mach-3-easy, though.

Edit: That is pretty awesome though - traveling that fast would mean you wouldn't hear it coming...

Does it even produce a shockwave when there's nobody to hear it?

Not if they're already dead.

The part where he lost his brother was heart breaking.

Is there something I don't know here?

There are 2 SRB's, one on each side.

Reply on news.ycombinator.com