Slashdot Mirror
HD Video From the Edge of Space, On the Cheap
SoundDoc75 links to a page describing the motivations and problem-solving behind "a 10-minute HD video taken on August 24th with a Canon Vixia HF20 HD camera suspended from a 1500g hydrogen balloon and launched near Edmonton, Alberta. This is the first known amateur video taken from this height — 107,145 feet."
Woah did anyone watch that movie? I'm about ready to vomit on my keyboard. My eyes are still spinning. DO NOT WATCH THAT IF YOU GET MOTION SICKNESS! Woah, just ruined any desire I had to fly in a balloon. Gives new meaning to the words vomit comet.
Qxe4
So clearly you didn't look at either article (I know, this is slashdot).
Completely different projects.
100Km is about 328,000 feet. That's why Space Ship One had a tail number of N328KF.
Also, the North Texas Balloon Team and the South Texas Balloon Project routinely (with launches approximately annually) send balloons with video cameras to altitudes in excess of 100,000 feet. Those are just the two balloon projects I'm familiar with. I am sure there are others because it's not particularly hard to do.
So, this is pure ho-hum to me. Let me know when they've done it a couple of dozen times.
That Show would be http://en.wikipedia.org/wiki/Salvage_1
When we find God, maybe we can get him to stop the Slashdot editors from posting so many dupes?
I mean honestly. I logged in, looked down the page, and had to check the date thinking I'd somehow slipped back into last week.
The last one was a team from MIT, with normal digital stills which is getting fairly routine, this one has hi-def video... Same Idea, different beast...
Weight restrictions vs performance. The envelope is filled to 25% capacity with helium, then released. As the balloon ascends, the gas expands, filling the envelope completely. Once it reaches altitude, it will stay there until either the membrane fails or programmed cutter severs the the tether, letting the payload descend back to the ground. A release valve would prolong the flight, but with amateur rides like this, they usually let it ride up until it bursts at a calculated altitude from the overpressure. 100K feet is impressive and the video is stunning.
First rule of holes; When in one, stop digging.
The Apollo astronauts were trained by a professional photographer on how to use the custom (Hasselbak or something close to that.) cameras for use on the moon.
They were modified Hasselblad cameras (a very nice medium format film camera). They brought the film back but left the cameras on the moon.
I am a member of the Tennessee Balloon Group. We had a parachute failure on one of our flights. TABEL-5 if I remember correctly. It burned in at a whopping 55 MPH and landed in a tree. We only launch if the predicted burst and landing is over a rural area.
--fatboy
It's an exponential decay. There is no sharp cutoff. Nothing special happens at 100 km. The scale height of the earth's atmosphere is about 7 km, so the pressure at 107,000 ft (32 km) is about 10^-2 of what it is at the surface, while the pressure at 100 km is about 10^-6 of surface pressure. It's not like somewhere in between 10^-2 atm and 10^-6 atm there's a mystical barrier that suddenly makes balloon flight impossible. It just gets harder and harder; to stay aloft with a given volume of hydrogen, a balloon at 100 km would have to have 10^-4 of the weight of a balloon that's neutrally buoyant at 32 km. It just happens to be difficult to make a balloon with sufficiently thin walls, high strength, and low surface-to-volume ratio.
If you watch the (very cool) video, the sky is black, there is no sound, and the curvature of the earth is extremely obvious. I would call that the "edge of space" -- for some definitions of "edge of space." There's not some international standards body that defines terms like "edge of space."
Find free books.
Except that the atmosphere isn't a smooth medium; 100,000 ft. is still inside the stratosphere. To go to 100 Km, you're going through the stratopause (the boundary between the stratosphere and mesosphere) and the mesopause (the boundary between the mesosphere and the thermosphere.) All three layers have different characteristics as far as temperature and circulation.
Achieving orbit would be impossible for such a project. Most of the energy in spacefaring rockets is spent on gaining velocity, not altitude. This balloon would give a lot of altitude "for free", but virtually no velocity. Gravity is pretty much as strong at 30 km as it is here on the ground, so it's not like the rockets would have an easier time lifting the payload than they do at ground level.
Don't whistle while you're pissing.
It's an exponential decay. There is no sharp cutoff. Nothing special happens at 100 km.
Yes it does. At around that height the theoretical speed that would be required to generate enough lift to stay in the 'air' surpasses orbital speed in vacuum.
Look at 'Karman line'.
Thank you. I blame YouTube in part for the jerky video, as well yes, there were MANY things we COULD have done in order to try to stabilize the camera, Gyro's, Fins, etc..etc..etc... Don't think that many wern't considered (you don't go sending a $1000 camera & spending the time/money doing this on a whim) but when it comes down to it KISS won out. at 107K feet fins don't help, no real air to push against, a gyro might have helped though, but the package was kept small for a reason. External fins might also have gotten tangled in the parachute lines after burst, so we kept this one nice and simple. Looking at the video after recovery, I never knew the decent was so rough! I'm actually suprised it survived. Some of our previous launches have gone higher, some lower, each one is a little different and unique. The next one will have more stable video, the wings will help with that... More into on this and our other flights at: http://bear.sbszoo.com/bear3-4/bear4.htm and http://bear.sbszoo.com/