Football star Rob Gronkowski set a world record for catching a football dropped 600 feet from a helicopter.
At some point, the terminal velocity of a football is the same no matter what height you drop it from, but I think if properly designed, it could withstand the temperatures of re- entry from orbit, 17,000 MPH and get down to the same speed the Gronk caught that ball at.
So the contest would be set out in the desert, contestants would spread out over a hundred square miles or so ready to try their luck and skill. An astronaut would be seen on live video in his spacesuit outside the spacecraft ready to throw the ball when in position.
The throw would have to be incredibly precise so there would be a hoop put about 100 yards in front of the astronaut/quarterback that he would have to hit precisely.
After a few minutes, the ball re-enters the atmosphere turning white hot in the process, slows down and eventually cools off and slows down to a catchable speed.
I think.-- doctorremulac3, Apr 26 2021 Take this to an insane extreme. https://www.cnn.com...ld-record-spt-intl/I'd try my hand at this if I was wearing proper body armor, helmet etc. I'd certainly watch in on TV. [doctorremulac3, Apr 26 2021] Slightly relevant? Pizza_20Satellite [pocmloc, Apr 26 2021] Wood ablative heat shield https://en.wikipedi.../Fanhui_Shi_Weixing [bs0u0155, Apr 27 2021] Super lightweight stuff https://inhabitat.c...dense%20than%20air.How does this behave during re-entry? [doctorremulac3, Apr 28 2021] Chalkboard spaghetti. https://penntoday.u...-math-meets-physics [doctorremulac3, Apr 28 2021] You think your spaghetti is impressive? http://www.mhs.ox.a...mbnails=on&irn=9738 [pocmloc, Apr 28 2021] Steak Drop https://what-if.xkcd.com/28/Mr Munroe doing it his way... [neutrinos_shadow, Apr 28 2021] Starlite https://en.wikipedia.org/wiki/Starlite [bs0u0155, Apr 29 2021] All that money they spend on the hi-tech ceramic tiles to protect spacecraft from burning up on re-entry. They could just use deflated footballs to coat the leading edge of the shuttle and other returning craft.-- pocmloc, Apr 26 2021 I think this would be an interesting design challenge.
How do you get something to survive a couple of thousand degrees and incredible pressure then be light enough to get down to a slow terminal velocity while being cool enough and slow enough to catch?
That's the interesting challenge right there.-- doctorremulac3, Apr 26 2021 Magnus Forces might make this particularly tricky if the ball goes into any kind of spin on the way down.-- zen_tom, Apr 26 2021 The trajectory issue would be difficult even if a machine did it, but to have the astronaut throw it, even tricker. A few inches in one direction or another is a few hundred miles by the time it got to the impact point.
There's other stuff you could do with this as well. Just dropping stuff that anybody could catch. Goodwill sort of stuff like, I don't know, what could you catch falling from the sky that would make you happy?
God, the only thing that came to my mind is money. Silicon Valley really has warped my soul.
By the way, scratch the term "impact point", something like "Happy funtime catch zone." might be better.-- doctorremulac3, Apr 26 2021 There's been some discussion of re-entry heating on here before, related to pizzas I think, but I'm struggling to find much-- pocmloc, Apr 26 2021 I'd rather they tossed Gronk out and we could go looking for him, (and his parachute of course.) hahahaha.-- blissmiss, Apr 26 2021 A snowball, in August A letter from my son Hot stew when I'm hungry A crispy buttered bun The sky has its limits No largess by the ton But surely some trifle My favorite team's home run?
The things that we wish for could fill a Scrooge's home But listen, dear reader Allow your thoughts to roam to things that we're blessed with before our pains bemoan The sky grants us blessings it gave us all we own.
When rain falls remember the fruit out in the field how richly the harvest that rain and sun will yield. The brightness, the comfort the smiles that are revealed It's not just the sunshine but from the bad, a shield.
From there in the vastness the comet and asteroid the gamma, the beta the power of the void against the flares and nova our world a guard employed The air and the magnet leaving us undestroyed
When life gives you lemons at least you have the tree Snow storms bring their danger but watch your children's glee! An angel or a snowfort A mountain you can ski. Dark clouds have their lining So gratitude is key.-- Voice, Apr 27 2021 Wow V, that's beautiful. You wrote that?-- doctorremulac3, Apr 27 2021 //All that money they spend on the hi-tech ceramic tiles to protect spacecraft from burning up on re-entry// //I think this would be an interesting design challenge//
It's the friction of the atmosphere against the object achieving re-entry of course, which leads me to wonder, surely if you could match that orbit to the speed of the atmosphere's rotation while lowering the object through it slowly enough you could avoid that friction entirely?-- Skewed, Apr 27 2021 You mean drop it from geosynchronous orbit?
Yes, that's a great idea but don't you have to be pretty far out to do that? I think you have to have enough speed to stay in orbit so to achieve that you have to be really far away. If you're geosynchronous any closer you just fall with the football you're trying to drop. You'd just be traveling at whatever the Earth rotates at, 3,500 MPH or something? (I'm probably totally off) but definitely not fast enough to stay in orbit which has to be 15,000 MPH I think.
So you could drop it from way out there where we put the satellites that stay over a set point on Earth, but not much chance of predicting where it lands.
You could slow it down by shooting it out of a cannon or attaching rockets to it, but to slow it down to a standstill over a spot on Earth means accelerating it to 15,000 MPH relative to the spacecraft going that fast in the other direction, so only rockets would do that. Not even a railgun can get much beyond 5,000 MPH I'm reading. At some point it gets pretty pointless. Good luck getting the taxpayers to foot the bill for that.
So I think you're stuck with engineering a football that can survive thousands of degrees then be light enough, slow enough and cool enough to catch when it reaches terminal velocity.
Let me know when you come up with the design. I'll be in my office.
By the way, correct me if I'm wrong, but didn't Arthur C Clark, the 2001 author invent geosynchronous orbit? I think he did.-- doctorremulac3, Apr 27 2021 I don't know one way or the other [any atmospheric & orbital mechanics experts out there?] but I can't help suspecting that geosynchronous with the atmosphere 'might' not be (entirely) geosynchronous with the planets surface? if you have a smooth ball floating & spinning in a bowl (made of frictionless material for the purpose of this thought experiment) of water does the water spin at the same speed as the ball or is some of the energy lost to heat dissipation in the friction transferring the motion to the water & it spins a bit slower than the ball?-- Skewed, Apr 27 2021 //How do you get something to survive a couple of thousand degrees and incredible pressure then be light enough to get down to a slow terminal velocity while being cool enough and slow enough to catch?//
The key is to go for an ablative heat shield like the Chinese oak version <link>. Then, you can throw a re-entry capable spacecraft but catch a football, if you get your calculations exactly right. Otherwise Gronk might have to catch a 50lb lump of scorched wood.-- bs0u0155, Apr 27 2021 I thought about that, and you're right. 1% off in your calculation and the Gronk's got a pretty sizable hole clear through his chest.
Guess you could do some kind of staging thing like they do with other delicate stuff being de-orbited. Heat shield separates and drops the football after all that nasty re-entry stuff. Sort of cheating though, I think the challenge of having one object that fills all the criteria is what's interesting.-- doctorremulac3, Apr 27 2021 // I thought about that, and you're right. 1% off in your calculation and the Gronk's got a pretty sizable hole clear through his chest.//
What you'd want is an ablative heat shield that continues to ablate when the football is pretty slow in thick-ish atmosphere. Something like dry ice might do it, frozen alcohol? Water ice isn't a good candidate because big hailstones make it down OK.-- bs0u0155, Apr 27 2021 //You wrote that?//
yup ^_^-- Voice, Apr 27 2021 //is some of the energy lost to heat dissipation in the friction transferring the motion//
Remember, the atmosphere has had 4 billion years to spin up to the rotational velocity of the earth.-- Voice, Apr 27 2021 Hey V, just read that again, kind of speechless. Please publish that someplace or something. That needs to be shared.-- doctorremulac3, Apr 28 2021 Share it, copy it, rewrite it, publish it. Information wants to be free.-- Voice, Apr 28 2021 ^ nice.
You could make the football from aerogel. Should withstand the heat, be light enough to maintain a slower terminal velocity... and I like aerogel. It's funky.-- 2 fries shy of a happy meal, Apr 28 2021 The question is, what is meant by orbital velocity. After all ANY height or vector above a point of gravity will be some kind of orbit. Is it "an orbit that clears the atmosphere in all phases"? That would give a minimum and maximum velocity, but the minimum would be much, much lower than he maximum. If that's your definition you'll do best to have a circular orbit at the minimum permitted height. If you do that, though, the orbit will not re-enter except by slowing to a suborbital velocity. And if you're defining it as a suborbital velocity, well, it's tautological.-- Voice, Apr 28 2021 Why am I thinking of a turtle called tortoise right now, something about the style I think.-- Skewed, Apr 28 2021 2fries, aerogel, hmm.
Dumb question: how do the lightest substances (link) behave during re-entry? I assume you need some mass to actually drop into the atmosphere instead of just bouncing off right?
Is this a correct assumption? So you're going to need to generate some push against that atmosphere to get the friction going.
I assume something like a feather would burn up during re- entry eh? What about this super light stuff?-- doctorremulac3, Apr 28 2021 [Voice], I love your poem. I would like to put it on my home page. May I? I may also share it elsewhere where we speak of gratitude's importance daily. This is incredible.-- blissmiss, Apr 28 2021 Hmm, sounds like a job for somebody fluent in spaghetti, which is my name for what superbrainiacs put on a chalkboard or whiteboard when they're designing something I can't begin to comprehend. (link)-- doctorremulac3, Apr 28 2021 //I would like to put it on my home page. May I? //
Of course. Information wants to be free. I'm happy you guys like it. It seemed average to me.-- Voice, Apr 28 2021 I put the last line on my homepage, but to make up for being so reverent (very bad form) I took the liberty of matching up the rhythm in the lines a little bit. (I know, even worse form!)
When life's giving you lemons, at least you have the tree. Snow storms may bring their danger, but watch your children's glee! An angel or a snowfort, a mountain you can ski. Dark clouds all have their lining, so gratitude is key.
— Voice, Apr 27 2021-- doctorremulac3, Apr 28 2021 xkcd did a What If about dropping steak (linky), which covers some of the questions here.-- neutrinos_shadow, Apr 28 2021 That kind of makes sense to me, so I'm thinking 2fry's aerogel football would do it.
I'm going to contact some scientists to find out.
Anybody want to place bets? Or want to submit another design to go up against 2fry's? We have the ablative shield but that would be too unpredictable I think.-- doctorremulac3, Apr 29 2021 I'm going standard football covered with Starlite <link>.-- bs0u0155, Apr 29 2021 So cornstarch, baking soda and glue. OK, sounds like I'm being sarcastic but I've seen a video of the guy demonstrating the stuff and if it's a farce it's a damn good one. Looks pretty amazing. Hate that it's not being used for anything. Sounds like he was overly protective of his invention maybe.
Aerogel vs Starlight but a thin enough layer that you're not adding much mass.
I'll add my design suggestion now. The ball is football shaped only at sea level. In the vacuum of space it expands to say... the size of a Volkswagon. This very large but low mass for its size object would aerobrake with a great deal of area high up but shrink as the atmospsheric pressure increased. By the time it's at sea leval it's just a catchable football.
If that wasn't enough to slow it down, you could have bits of heat shield glued all over it that would pop off as it shrunk but guess that's just another heat shield so yea, just the expansion thing then.
I'll contact some sciency types at Stanford, MIT and Oxford etc. I've done it once before regarding a subject discussed here and was surprised at how eager these guys were to assist if it's an interesting enough question.-- doctorremulac3, Apr 29 2021 Satellites in low Earth orbit go round in around 90 minutes whilst we are fixed on the Earth and go round in 24 hours. So we can definitely say low Earth orbit satellites are going about 16 times faster than we are, relatively speaking.
The radius of the Earth is about 6400000 metres so with a bit of 2.Pi.R action we can calculate satellites move at around 7500 metres per second. On the Earth we are moving round at around 470 metres per second.
So all we have to do is slow down the football by around 7000 metres per second; around 25000 miles an hour. That's a lot of speed to lose and I'm sure it can be solved. Satellites in geostationary orbit go round in 24 hours but given their distance above the Earth, something like 36000000 metres, they are travelling at around 3000 metres per second. A bit less speed to lose but the wait as those footballs make the 36000 kilometre journey might make it a dull spectator sport and we do have to think about how to monetize the business model.
I suggest an alternative. We should speed up the Earth's rotation.
If we increase the spin of the Earth so a day is now a cheeky 90 minutes, the problem reduces somewhat. No more rapid delta-v changes now. Low Earth satellites with hopeful throwers can aim with more confidence and there should only be a few minutes between throw and impact. Plenty of time for some revenue generating adverts as well as a nice cup of tea.
There would be some second order problems to solve but I think it's do-able. We would have to change the working day to fit into 90 minutes. Frankly, it's about time we changed this. There might be tricky climate impacts but surely nothing too serious. People at the Equator would feel centripetal forces that are likely to counteract gravity completely so there would be a whole new market for weight loss holidays in the Tropics. The oceans might escape into space and the planet might spin apart but these feel like low risks so I'm not worried.-- DenholmRicshaw, Apr 29 2021 I think a football that could be blown up to the project echo size thing is possible. That's an interesting engineering challenge right there.
//the wait as those footballs make the 36000 kilometre journey might make it a dull spectator sport and we do have to think about how to monetize the business model.//
Good looking cheerleaders. Problem solved.-- doctorremulac3, Apr 30 2021 [DenholmRicshaw]; rotating the Earth at 1 rev in 90 minutes is dangerously close to falling-apart speed: my calculations (correct me if I'm wrong) put the "centripetal acceleration = gravity" speed at 1 rev in 84.42 minutes (1h 24m 26.3s).-- neutrinos_shadow, Apr 30 2021 Yes, so we might need to strengthen the Earth a bit but worth it for those weight loss holidays.-- DenholmRicshaw, Apr 30 2021 Same result but easier is to slow down the clocks.-- pocmloc, Apr 30 2021 //my calculations (correct me if I'm wrong) put the "centripetal acceleration = gravity" speed at 1 rev in 84.42 minutes //
That's no coincidence: after all, it's orbital velocity.-- Voice, Apr 30 2021 //Earth so a day is now a cheeky 90 minutes//
I expect that would have a fairly dramatic effect on the Coriolis force and therefore hurricanes. Florida is in real trouble.-- bs0u0155, Apr 30 2021 It seems to me shorter days (in a fantasy world where gravity isn't effected) would lead to calmer weather, as the cold and hot air meet each-other more frequently and therefore don't have as much time to build up volume and large temperature differences.-- Voice, May 01 2021 //beetles the size of cars//
Not unless you unleash the terrifying Genetic Engineers and give them lungs.-- Voice, May 01 2021 //Genetic Engineers// or... raise them in a total-O2 atmosphere, then attach some solar-powered case fans before releasing them.-- FlyingToaster, May 01 2021 //a 21 tone rocket booster// I would pay to listen to that-- pocmloc, May 04 2021 random, halfbakery