APOD: Falling to Earth (2014 Feb 10)

[geckzilla]

How did Felix stop the violent spinning?

Enquiring minds want to know. And no, Art, a Felix the Cat comic book cover with exegesis by Aldous Huxley is not an adequate physical explanation.

Felix explained this at a press conference. If clicking this link doesn't take you to the 10:15 mark, you'll have to set it there yourself.
http://www.youtube.com/watch?feature=pl ... T5mk#t=615

[Stendec]

Video? What video? I see nothing but a blank screen on the main page, and the click-through link ("above video") also has a blank screen with no video. There are no play buttons, no start buttons, no control buttons of any kind. Did I arrive late to the party after all the videos were taken down and everyone went home? From the comments it seems like a number of people saw the video; so where is it now?

[Chris Peterson]

Video? What video? I see nothing but a blank screen on the main page, and the click-through link ("above video") also has a blank screen with no video. There are no play buttons, no start buttons, no control buttons of any kind. Did I arrive late to the party after all the videos were taken down and everyone went home? From the comments it seems like a number of people saw the video; so where is it now? :?:

Sounds like you have some sort of browser configuration problem, or a plugin not installed (the APOD page requires Flash). However, if you view the video on the original YouTube page, http://www.youtube.com/watch?v=dYw4meRWGd4#t=3m42s, you don't need any plugins, just an HTML5 compliant browser (which all recent ones are), and which should also work on most portable devices of recent vintage.

If you're at work, there might be policies in place that block this media.

[Anthony Barreiro]

How did Felix stop the violent spinning?

Enquiring minds want to know. And no, Art, a Felix the Cat comic book cover with exegesis by Aldous Huxley is not an adequate physical explanation.

Felix explained this at a press conference. If clicking this link doesn't take you to the 10:15 mark, you'll have to set it there yourself.
http://www.youtube.com/watch?feature=pl ... T5mk#t=615

Thanks, I landed right at 10:15, and heard Felix say that he stuck his arm out in one direction and the spinning got worse, so he stuck his other arm out in the opposite direction and it got better. It sounds like he had a calm mind, good instincts, and very good luck! I wonder, if he had passed out, was there any sort of fail-safe mechanism to deploy the parachute automatically? A big splatter on the desert would not have been good advertising.

[Stendec]

Video? What video? I see nothing but a blank screen on the main page, and the click-through link ("above video") also has a blank screen with no video. There are no play buttons, no start buttons, no control buttons of any kind. Did I arrive late to the party after all the videos were taken down and everyone went home? From the comments it seems like a number of people saw the video; so where is it now?

Sounds like you have some sort of browser configuration problem, or a plugin not installed (the APOD page requires Flash). However, if you view the video on the original YouTube page, http://www.youtube.com/watch?v=dYw4meRWGd4#t=3m42s, you don't need any plugins, just an HTML5 compliant browser (which all recent ones are), and which should also work on most portable devices of recent vintage.

If you're at work, there might be policies in place that block this media.

Hi Chris, Thanks very much for your reply. It appears that the problem is Google, which is requiring that I sign up for an account to access YouTube videos. I have the latest Flash. I am at home, not at work. And I ran my cleaning software to eliminate problems from that area. Afterwards I went back to APOD, the APOD link I mentioned, and your link -- all with the same blank screen -- and all with a subscribe to Google button below the video. To further test my theory I went to a previous APOD -- 2013 August 27 at http://apod.nasa.gov/apod/ap130827.html -- this was a video I had no trouble running when it was posted. Now it is blank like today's post, and so is the sub-link within the explanation area. I did one final test. I went to YouTube directly, using my default browser, Firefox. Every video I tried, including new videos and videos I had accessed in months past, delivered the same blank screen with a Google signup button. Right now I'm a bit too irritated to offer Google my personal information for the privilege of viewing YouTube videos. I'm going to have to think this over a bit. -- Thanks again for your help. It enabled me to track down the problem.

[geckzilla]

Right now I'm a bit too irritated to offer Google my personal information for the privilege of viewing YouTube videos.

There must be another problem. I am easily able to open an alternate, rarely used browser on my own computer and any other computer in my house and there is no sign-in necessary to view any videos, either on the APOD page itself or at YouTube.

[Chris Peterson]

Right now I'm a bit too irritated to offer Google my personal information for the privilege of viewing YouTube videos.

There must be another problem. I am easily able to open an alternate, rarely used browser on my own computer and any other computer in my house and there is no sign-in necessary to view any videos, either on the APOD page itself or at YouTube.

Same here. I can connect using a private browser window, no cookies set and no Google login (with the sign in button visible) and I still get the video (and other YouTube videos) just fine, both in Flash and HTML5 modes.

[Nitpicker]

The heat is generated by the compression of the air in front of a falling object.

Is it, indeed? Please explain in a few words how does that work.

Nothing moving through the atmosphere is heated by friction. There is a heating process with some analogs to friction, but it's a collisional process that only applies when the moving body is small compared with the mean path between collisions. That means for small particles (<1 cm) at high altitudes (>50 km). Larger bodies simply compress the air in front of them, producing what can be very high ram pressures (megapascals). As always when you compress a gas, you increase its temperature.

In this case, the pressures were low and not much heat was generated. He reached a maximum velocity of only around 350 m/s. You need to be moving more than ten times faster to generate enough heat to start melting and ablating typical refractive materials. An astronaut trying to do this from an orbit would enter at over 8000 m/s, and would burn up with any current technology we have. Jumping from a balloon, which is stationary with respect to the ground, is a trivial problem compared with jumping from low-Earth orbit.

Thanks Chris. Of course, there are still drag forces, including skin friction components, which although not generating heat, are still something I'd want protection from, depending on the relative air speed.

I've never really thought about atmospheric heating arising from the air being compressed in front of the moving object. I've always considered it to be caused by the object slowing down the air within the boundary layer surrounding the object (which is necessary for continuity -- the speed of the air at the object's surface much be zero, relative to the object). Whenever you slow down a fluid, you increase its pressure, as per Bernoulli's principle (the same principle which explains aircraft lift and other cool stuff). And, as per the gas laws, by increasing the pressure, you increase the temperature, which is transferred from the boundary layer to the object via forced convection or possibly conduction (I'm not sure). Of course, both ways of looking at it amount to the same thing, but I believe one could argue that the heat is ultimately generated by viscous forces within the fluid, due to friction between neighbouring fluid particles. Edit: actually, I may be misunderstanding the gas laws. The relationship between pressure and temperature does not depend on viscosity, so I would appear to be wrong about viscous forces generating heat. It is rather that the heat increases the viscous forces. Poop.

[yellowbag]

can anyone tell me how he stopped himself from spinning, and why he started to spin in the first place?

[Nitpicker]

can anyone tell me how he stopped himself from spinning, and why he started to spin in the first place?

You can read the earlier posts about how he trialled sticking out one arm, and then the other, to control the spin.

As for why he spun in the first place, see:
http://en.wikipedia.org/wiki/Spin_(flight)

[SouthEastAsia]

LOL, at the comments all up in arms over this Not being a freefall, but a paidfall

One could only wonder how much this otherwise pretty cool jump would have cost taxpayers if it were a government run project instead...

3x as much???

Regardless of the sponsor (personally, I've never drank one and I never will, thank you very much), the imagery (I actually would consider buying a GoPro) and the stunt in and of itself, was pretty awesome and inspiring. So hats off to the dude (free-spirit guy <----) doing this absolutely, indisputably, incredible air-drop.

Next time... and regardless of whom the sponsor is... I'd vote to stitch a wing-suit on that pressure-suit and go for at least 41km up, with a goal to 'glide' supersonic and gradually pulling-up into a 100km down-range free-glide (sorry, paid-glide)!

[SolarofCalif]

Growing up around the NASA space industry my entire life, seeing real launches of weather balloons, 3 flights of the X-15, U-2's tree-topping over my house, etc., I thought what a GREAT VIDEO, then the Advertisement product placement of the Camera at the end, I changed my mind, THAT SUCKS NASA!
PERIOD!
You sold us out (explitive Noun)
nasa YOU BROKE YOUR OWN RULES, from RULE #8....
8.Advertising, Solicitation, and Spam
Do not post advertisements of any kind without securing the express consent of the administrators beforehand. Do not use this bulletin board as a vehicle to promote your own website, product, or forum, nor to sell merchandise. These are egregious offenses which will result in the deletion of the offending posts and immediate banning of the user(s) responsible.

[geckzilla]

SolarofCalif: That's a forum rule, not a NASA rule. The APOD page has its own guidelines to abide by.

[Nitpicker]

I was going to label all you purists as "space communists", but then I realised this "extreme sports" stunt was not performed close enough to space.

Personally, I'm more impervious to commercialism and advertising (I don't think I noticed the ads until I saw the complaints) than I am to overt nationalism. Regardless, it is always good to see humans pushing new limits.

[PiperJimB]

The original jump With Joe Kittinger was an amazing feat. With the technology available in the 1960's was a wonder it happened at all. With the technology available today a jump like this is much more safe and less subject to failure. The true hero I think is Joe who lead this out of duty and service to our country than out of duty to a high priced energy drink.

[Nitpicker]

The original jump With Joe Kittinger was an amazing feat. With the technology available in the 1960's was a wonder it happened at all. With the technology available today a jump like this is much more safe and less subject to failure. The true hero I think is Joe who lead this out of duty and service to our country than out of duty to a high priced energy drink.

FWIW, I believe Mr Kittinger participated in the 2012 jump as well, as "capsule communicator". Would you be happier with a sense of duty to a low priced energy drink? Coffee? OJ? Milk? Beer?

[Yoduh99]

Growing up around the NASA space industry my entire life, seeing real launches of weather balloons, 3 flights of the X-15, U-2's tree-topping over my house, etc., I thought what a GREAT VIDEO, then the Advertisement product placement of the Camera at the end, I changed my mind, THAT SUCKS NASA!
PERIOD!
You sold us out (explitive Noun)
nasa YOU BROKE YOUR OWN RULES, from RULE #8....
8.Advertising, Solicitation, and Spam
Do not post advertisements of any kind without securing the express consent of the administrators beforehand. Do not use this bulletin board as a vehicle to promote your own website, product, or forum, nor to sell merchandise. These are egregious offenses which will result in the deletion of the offending posts and immediate banning of the user(s) responsible.

If the jump was sponsored by the Bill and Melinda Gates Foundation would you be just as mad?

[Chris Peterson]

Personally, I'm more impervious to commercialism and advertising (I don't think I noticed the ads until I saw the complaints) than I am to overt nationalism. Regardless, it is always good to see humans pushing new limits.

I think I'm not overly influenced by it, but it does get old.

Had this been something of any value beyond an advertising stunt (it wasn't- no great engineering, no new science, very limited practical value) it would have bothered me. I do not want corporations sponsoring things that should be publicly supported. But this wasn't one of those things. This stunt would have been a waste of public funds were it conducted by NASA or the Air Force. But it was nothing different than a corporate sponsored athletic event.

[neufer]

Growing up around the NASA space industry my entire life, seeing real launches of weather balloons, 3 flights of the X-15, U-2's tree-topping over my house, etc., I thought what a GREAT VIDEO, then the Advertisement product placement of the Camera at the end,

At least it was After the Fall.

[Rollover Mikey]

Absolutely stunning.