8 ms·
The Nuclear Potato Cannon, Part 2 (2006)
- BartSaM 9y agoFor me, this story, showing up here and there, is to discredit Russian Space Program in some part. There are so many unknowns... Do we even know if Russian had a situation like this with their nuclear tests? Most data is classified anyway, so how can we know? This is not science, this is just "we cannot find a part that could have to reach the space".
- ajmurmann 9y agoWhy do you assume this is a anti Russia story? To me this really was just a cute story that someone wants to believe in because it's fun and fascinating.
- BartSaM 9y agoThis story is surfacing every few months on many major outlets. The story itself is fun, but the fact that it often tries to "prove" that the US was first in space without any proof is misinformation. A lot of non-technical people will take this story and pass it as a fact.
- flashdance 9y agoDr. Brownlee himself (the guy who designed the experiment) said that the plate was vaporized by the atmosphere and never got to space. Sorry for the buzzkill, folks. https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_...
- paulsutter 9y agoYou're misquoting the article: > Dr. Brownlee believes that the plate did not leave the atmosphere, as it may even have been vaporized by compression heating of the atmosphere due to its high speed.
- lotu 9y agoWell it sounds like the the only reasonable, responsible course of action is to replicate the original test but use modern high speed recording equipment to determine what would happen to that steel plate.
- gambiting 9y agoHow critical is the nuclear explosion in this experiment? Could you use an equivalent traditional explosive? 1KT explosion can be achieved without going nuclear.
- flashdance 9y agoAccording to the wiki page the Pascal-B test was the equivalent of 300 tons of TNT.
- solotronics 9y agohold my beer
- evan_ 9y agoI'm not a physicist but as far as I know a nuclear explosion releases its energy much more quickly than e.g. TNT, so just releasing the same number of joules wouldn't exactly duplicate the test unless you were able to release them in the same number of nanoseconds.
- deleted 9y ago[deleted]
- careersuicide 9y agoThis video https://www.youtube.com/watch?v=T2orn6T2QFM https://www.youtube.com/watch?v=T2orn6T2QFM is a good DIY experiment along those lines and is interesting if not necessarily correct at the nuclear scale.
- 9y ago
- NegativeLatency 9y agoInterestingly those kind of speeds could put it on the speed record list (if it was a vehicle) https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#Relative_to_Earth https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#...
- mikeash 9y agoI'm familiar with this incident, but never saw this article before. I've seen articles such as http://nuclearweaponarchive.org/Usa/Tests/Plumbob.html#PascalB http://nuclearweaponarchive.org/Usa/Tests/Plumbob.html#Pasca... and http://nuclearweaponarchive.org/Usa/Tests/Brownlee.html http://nuclearweaponarchive.org/Usa/Tests/Brownlee.html (the latter being written by Dr. Brownlee, the scientist who designed the test in question). This article seems like an independent telling of these events, along with an independent recalculation of the results in the first link, but based on conversations with the same person, which is kind of interesting. As far as the first man-made object in space, there's no real question that this was not it. There are two major problems: one is that the steel plate pretty much certainly vaporized in the atmosphere before it reached space. The second, even bigger problem is that the first man-made object in space was a V-2 rocket launched in 1944.
- flashdance 9y agoThat V-2 rocket was indeed the first thing in space, but there's a distinction to be made: it only went suborbital. If our big steel friend wasn't tragically vaporized in the atmosphere, it might just have left the earth's gravity well--maybe even the solar system's well (escape velocity of 44km/s), which is in part why that incident is so cool! Fun fact: the first ever picture taken from space was from a v-2 rocket launched in 1946. This is what it looked like: https://thumbs-prod.si-cdn.com/nnJLv8axPAJI3nScxyDExEeTQLk=/800x600/filters:no_upscale()/https://public-media.smithsonianmag.com/filer/33/d1/33d15156-47cd-4307-9c23-e3c8498539f5/1stphotofromspacejpg__600x0_q85_upscale.jpg https://thumbs-prod.si-cdn.com/nnJLv8axPAJI3nScxyDExEeTQLk=/...
- mikeash 9y agoSure, but the phrasing used here was "...the first man made object shot into space." This whole story is awesome, no doubt. That's just not quite the right question to ask. In any case, sweet picture.
- flashdance 9y agoTotally, I was just trying to be extra pedantic.
- SOLAR_FIELDS 9y agoThe term potato cannon got me interested enough to look up the Wikipedia page for it, where I learned that they are also amusingly colloquially referred to as "spud guns". There's also a vacuum variant known as the "vacuum bazooka".
- anfractuosity 9y agoI always thought 'spud gun' referred to this kind of toy gun - https://en.wikipedia.org/wiki/Spud_gun#/media/File:Spud_Gun.jpg https://en.wikipedia.org/wiki/Spud_gun#/media/File:Spud_Gun.... which fires small parts of a potato. The vacuum bazooka, looks really neat, I'm surprised that according to wiki, they can apparently project the potato at 650mph.
- SOLAR_FIELDS 9y agoApparently according to Wikipedia the term is used in both contexts: to specifically refer to the toy, and more generally as another term for potato cannons.
- damnfine 9y agoIf the fov was a 1/4 mile, and the plate near the center, wouldnt that halve the calculated velocity? I feel like I am missing the actual data here.
- NegativeLatency 9y agoThere isn't enough data to know the real velocity of it. Since the plate only appeared in one frame, only a lower bound for it's speed can be given with observational data. A minimum of 2 frames with the plate visible would be required for determining its speed.
- GlenTheMachine 9y agoIn grad school my advisor (who was teaching "Launch and Entry Systems") told us this story. A few lectures later he went over rail guns as a launch system, and mentioned that by his back-of-the-envelope calculations, a slug of titanium the size of a telephone pole, launched at earth escape velocity by a rail gun at sea level, would ablate approximately a third of its length away in the first thousand meters, or something close to that (it's been a long time). Actually calculating the heating of a steel plate launched at that speed is a significantly nontrivial problem, because its aerodynamics are unstable. In other words, it would almost certainly tumble in flight, in an unpredictable manner. There's no guarantee that it would even fly in anything approximating a straight line. Even figuring out the effective coefficient of drag would be really hard. Figuring out the thermal profile would be even harder. But, as several other comments have mentioned - no matter how you slice it, it would be subject to a hell of a lot of heating, and it's a pretty safe bet that it ablated completely away and did not reach space.
- gene-h 9y agoIt has been proposed that we could construct one of these nuclear potato guns to launch things into space[1]. One digs a multi-kilometer deep borehole in say a salt dome(easy to drill), lines that with steel, puts a bomb at the bottom, some reaction mass(essentially trash that will vaporize in the explosion), and a projectile we wish to launch into space. So this solves several problems over other nuclear bomb based propulsion methods like Project Orion[0]. Foremost, we can contain almost all of the fallout. Second, we aren't accidentally triggering nuclear war by lobbing a bunch of nuclear bombs into orbit. In addition, if the nuclear charge is 150 kilotons or less and that charge is detonated underground then it's in full compliance with certain treaties. So aside from the shear political impalatibility of using nuclear bombs, there are a couple problems. Namely, even if we use a very long shaft, the acceleration is still on the order of thousands of Gs. So no launching humans. Second, it's impossible to get into earth orbit purely with a cannon launch. And because it's difficult to make stuff that can withstand thousands of Gs of acceleration, orbital circularization will be difficult. So one suggested use case is to literally shoot the moon. One fills the projectile with things that can withstand the high acceleration like water, construction materials, MREs, propellant, and carbon(extremely rare on the moon, but extremely useful for refining silicon for solar cells). We launch this projectile, which should mass ~3000 tons or so, to the Moon and then harvest everything we need to bootstrap a Moon base from the impact site. Perhaps we can even save money on our MREs by letting the acceleration do the food processing. For example, for apple sauce, all we need to is put cored apples in a plastic bag. The thousand G acceleration of the launch and lunar impact should be more than enough to reduce them to pulp. Now, while we can't get into Earth orbit easily, if the projectile velocity is sufficiently high we can put the projectile into solar orbit. It is a questionable proposal, but interesting nonetheless. [0]https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls... [1]https://www.nextbigfuture.com/2010/03/150-kiloton-nuclear-verne-gun.html https://www.nextbigfuture.com/2010/03/150-kiloton-nuclear-ve... [2]https://www.nextbigfuture.com/2010/12/sea-based-launch-option-for-nuclear.html https://www.nextbigfuture.com/2010/12/sea-based-launch-optio...
- NegativeLatency 9y agoI saw a talk about something similar (non nuclear) a few years ago. Could have made building up a supply of fuel in orbit cheaper. https://en.wikipedia.org/wiki/Quicklaunch https://en.wikipedia.org/wiki/Quicklaunch
- lord_jim 9y agoWith the nuke mania of the early Cold War, I'm surprised that the military never tried creating a nuclear version of Project HARP: https://en.m.wikipedia.org/wiki/Project_HARP https://en.m.wikipedia.org/wiki/Project_HARP (I've also always enjoyed the parallels of this story with "From the Earth to the Moon")
- DanielBMarkham 9y agoThis -- or a rail gun similar to this concept -- in my mind is the key to true low-cost LEO cargo. The investment wouldn't be that great in comparitive terms, and it promises to bring an order of magnitude more cargo to space at an order of magnitude less cost.
- ChuckMcM 9y agoAll of the 'all impulse at the start' ideas for putting things into orbit die on the fact that air is a fluid. Further that fluid is very dense at the surface of the earth. What that means in practical terms is that the harder you push something to go through the air, the harder the air pushes back. If you plot the air resistance as a function of energy applied, you see that the long before your payload has achieved orbital velocity + the amount you expect to slow down going up through additional air, you are dumping so much energy into the air that your payload vaporizes. "But we'll shoot it straight up to minimize the time in the air!" Now you'll have an orbit who's perigee intercepts the earth again (aka highly elliptical). The ideal trajectory can be calculated, (easiest at the equator but there are solutions for latitudes above and below the equator, to accelerate into an orbital plane such that on your first orbit you can "bounce" (trade excess velocity for altitude) into something that is lies entirely out of the atmosphere. But in that trajectory you spend more time at lower altitudes and that means more energy to get past that air and that makes you vaporize that much more quickly. "We'll start from a higher altitude!" is another avenue to explore, the ideal altitude to start from is > 65,000' (20 km) which is defined as 'near space' but still 80km from the Kármán line. And we're still unable to build a 20km tall tower.
- DanielBMarkham 9y ago
- xiphmont 9y agoDuring my time at MIT, we referred to several explosions in the service and steam tunnels (caused by aging infrastructure) that launched street-level manhole covers into the air as the 'People's Republic of Cambridge Unmanned Space Program'. Seems the PRoCUSP got several-upped.