# 'Space ball' falls out of the sky in Namibia - what are these things? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [December 22, 2011, 10:58pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128 "2011-12-22T22:58:33Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [December 23, 2011, 6:03am UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/21 "2011-12-23T06:03:43Z")
> [@Leaffan](#): > > Google hydrazine tanks. > ETA: Specifically images thereof. Yep. [This](http://cs.astrium.eads.net/sp/spacecraft-propulsion/showcase/ariane5-attitude-control-system.html) shows the attitude control system of the Ariane 5 rocket. The spherical tanks are clearly visible in the main photo, and there is a close up photo of one of the tanks at the bottom of the article. Hydrazine is used as a propellant to control pitch and yaw. It’s toxic as fuck, though. I hope that thing that landed is empty. ---
**Author:** ![Taomist](https://avatars.discourse-cdn.com/v4/letter/t/53a042/32.png) [@Taomist](https://boards.straightdope.com/u/Taomist)\ **Post date:** [December 23, 2011, 6:33am UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/22 "2011-12-23T06:33:03Z")
This place is awesome, and I love you all, both for having the answer and reminding me of the Coke bottle movie. 😛 Time to go find that; haven’t seen it in AGES! ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [December 23, 2011, 1:42pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/23 "2011-12-23T13:42:51Z")
> [@Stranger\_On\_A\_Train](#): > > It would appear to be a small spherical pressure tank on launch vehicle upper stages, probably used for pressurizing liquid stage ignition systems or attitude/reaction control systems, or as an in-line accumulator on a liquid propellant feed system. Because the tank is spherical, it will tend to survive intact more frequently than other pieces. This is because they lack sharp edges or center of pressure offset from the center of mass, so they both act like blunt bodies, creating a sheathing layer that insulates against ram pressure heating, and tend to spin in flight further distributing incident heat flux. Pressure tanks are also inherently pretty strong and so tend to survive buffeting and impact. > > As for why they land more frequently in Africa, South America, and Australia, space launch vehicles are flown on trajectories that avoid re-entry ground tracks for expended stages pass over highly populated areas. It is virtually impossible, however, to have a trajectory that doesn’t pass over some land mass, so trajectories are selected that pass over mostly sparsely populated areas, hence why these appear frequently in land masses in the Southern Hemisphere rather than in North America or Europe. Hazards analyses are preformed to assure that the risk to populated areas is under an accepted threshold (usually \<10[sup]-4[/sup] chance of fatality) but it is impossible to build an expendable rocket launch system that is both robust enough to survive on the way up and will fragment into small enough or controlled enough pieces not to pose any threat on the ground. > > Stranger A pressurization tank from a rocket was my first though too, although I wonder about the stated weight of, I’m no rocket scientist, but I thought those tanks are very lightweight. Maybe it has been filled with mud and dirt since it fell? **A Monkey With a Gun** , that looks pretty much the same (and same size too). Could be from rocket launches from the Guyana site. ---
**Author:** ![Theophane](https://avatars.discourse-cdn.com/v4/letter/t/77aa72/32.png) [@Theophane](https://boards.straightdope.com/u/Theophane)\ **Post date:** [December 23, 2011, 1:44pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/24 "2011-12-23T13:44:18Z")
> [@Askance](#): > > No doubt he’s thinking of the invariable claim from UFO nuts that whatever they’ve just found couldn’t be of human origin as it’s made from some material “unknown to science” :rolleyes: Why the eye-roll? Science doesn’t know everything. ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [December 23, 2011, 1:48pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/25 "2011-12-23T13:48:50Z")
> [@Theophane](#): > > Why the eye-roll? > > Science doesn’t know everything. It’s one thing to discover a new substance or alloy or something. These things were obviously manufactured, so any claim that they were made of an alloy not known to science would have been extraordinary. Essentially it would have been a claim that they were built by aliens or some other non-human civilization. So yes, the eye roll makes sense. ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [December 23, 2011, 1:49pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/26 "2011-12-23T13:49:32Z")
> [@A Monkey With a Gun](#): > > Yep. [This](http://cs.astrium.eads.net/sp/spacecraft-propulsion/showcase/ariane5-attitude-control-system.html) shows the attitude control system of the Ariane 5 rocket. The spherical tanks are clearly visible in the main photo, and there is a close up photo of one of the tanks at the bottom of the article. Hydrazine is used as a propellant to control pitch and yaw. > > It’s toxic as fuck, though. I hope that thing that landed is empty. They say the fuel tanks hold 58 liters of hydrazine, but the Space Balls have a diameter of 35cm, they could hold about 22 liters at most, so it’s probably some other component. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [December 23, 2011, 1:57pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/27 "2011-12-23T13:57:51Z")
> [@A Monkey With a Gun](#): > > Yep. [This](http://cs.astrium.eads.net/sp/spacecraft-propulsion/showcase/ariane5-attitude-control-system.html) shows the attitude control system of the Ariane 5 rocket. The spherical tanks are clearly visible in the main photo, and there is a close up photo of one of the tanks at the bottom of the article. Hydrazine is used as a propellant to control pitch and yaw. > > It’s toxic as fuck, though. I hope that thing that landed is empty. Although there was an Ariane 5 launch (L561) on 21 September , it was to GTO, the tank was probably not an Ariane 5. The Ariane launches from Guiana Space Center in French Guiana near the equator, and so there would be no reason for a flight track to GTO to cross way south on the horn of Africa. It could have been from any of a number of launch vehicles as these tanks all look pretty much the same, but if I had to hazard a guess I would probably bet on it being the Delta II D357 launch of the [NPOESS Preparatory Project](http://www.nasa.gov/mission_pages/NPP/launch/npplaunchpreview.html) satellite, which was an eccentric polar orbit launch out of SLC-2 at VAFB on the California Central Coast. I haven’t looked in detail at the trajectory but that would have it overflying “The Horn”, and depending on what kind of coasting was planned for second stage and when engine cutoff occurred it could have flown down off the coast of Africa. Hydrazine is definitely toxic, which is why residual propellant is typically vented at altitude where it can disperse after engine cutoff and separation. Larger tanks are ofter cut open with linear or conical shaped charges so that they do not pose a shipping hazard (floating at or just under the surface), but with smaller tanks it is generally assumed that they pose little hazard and aren’t worth the weight of the cutting charge required. Stranger ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 23, 2011, 2:54pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/28 "2011-12-23T14:54:47Z")
A tank from a rocket was my first guess. There was a hydrazine spill at Edwards AFB when I was there, over by the F-16s. At least one of my coworkers was exposed (not much), but the things I was hearing about the long-term effects of hydrazine exposure was worrying. Anyway, there was quite the to-to about it. (I was in Mission Control, nowhere near the spill.) ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 23, 2011, 3:33pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/29 "2011-12-23T15:33:33Z")
> [@Theophane](#): > > Why the eye-roll? > > Science doesn’t know everything. Whether Ludik said “known” or “unknown” it seems obvious that it must have been said tongue in cheek. It’s just kind of dumb that the reporter quoted him so literally. Instead of: > [@](#): > > It was made of a “metal alloy known to man” and weighed six kilograms, said Ludik. You’d think it would read something like: > [@](#): > > Ludik said that it weighed six kilograms and jokingly added that it was made of a “metal alloy known to man”. ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [December 23, 2011, 4:01pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/30 "2011-12-23T16:01:24Z")
> [@davidm](#): > > Whether Ludik said “known” or “unknown” it seems obvious that it must have been said tongue in cheek. That’s not obvious at all. It’s relevant information in a story about a mysterious object falling out of the sky. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 23, 2011, 4:57pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/31 "2011-12-23T16:57:31Z")
> [@Marley23](#): > > That’s not obvious at all. It’s relevant information in a story about a mysterious object falling out of the sky. Don’t you think “made of an alloy known to man” is a little to close to the scifi cliche " made of an alloy _un_known to man" to be meant seriously? Wouldn’t he just say “it’s made of tungsten carbide steel” (or whatever, I don’t know alloys) or “it’s made of a known alloy”? But whatever, I don’t want to hijack this thread with a silly semantic issue. ---
**Author:** ![Marley23](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Marley23](https://boards.straightdope.com/u/Marley23)\ **Post date:** [December 23, 2011, 5:13pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/32 "2011-12-23T17:13:25Z")
> [@davidm](#): > > Don’t you think “made of an alloy known to man” is a little to close to the scifi cliche " made of an alloy _un_known to man" to be meant seriously? I don’t think that’s precisely the cliche. It’s in the ballpark and it’s unusual phrasing, but I wouldn’t assume it was a joke just based on the way he worded it. I think if he knew exactly what it was made of, he’d have just said so. Anyway I agree that I don’t want to hijack the thread over this. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [December 23, 2011, 5:26pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/33 "2011-12-23T17:26:22Z")
Sounds like the beginning of _The Blob_ with Steve McQueen. If it starts glowing. Don’t poke the thing with a stick. Run!!! ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [December 23, 2011, 6:23pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/34 "2011-12-23T18:23:52Z")
> [@Ale](#): > > They say the fuel tanks hold 58 liters of hydrazine, but the Space Balls have a diameter of 35cm, they could hold about 22 liters at most, so it’s probably some other component. Question I hope isn’t totally stupid: would being stored under pressure account for the difference? ---
**Author:** ![CaptMurdock](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/captmurdock/32/11736_2.png) [@CaptMurdock](https://boards.straightdope.com/u/CaptMurdock)\ **Post date:** [December 23, 2011, 6:47pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/35 "2011-12-23T18:47:19Z")
> [@cochrane](#): > > Spaceballs? > > [Oh, shit. There goes the planet!](http://www.youtube.com/watch?v=IS4aXCqzKgc&feature=youtube_gdata_player) Damn your eyes! :mad: 🆒 ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [December 23, 2011, 6:56pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/36 "2011-12-23T18:56:20Z")
> [@Mr.Accident](#): > > Obviously they’re test projectiles from the Martians. Now that they know they can hit Earth, the real bombs will soon be on their way. Come on, the chances of anything coming from Mars are…well it must be hundreds of thousands to one…if not more! ---
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [December 23, 2011, 8:33pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/37 "2011-12-23T20:33:27Z")
> [@KneadToKnow](#): > > Question I hope isn’t totally stupid: would being stored under pressure account for the difference? No, it wouldn’t. Hydrazine is a liquid under normal temp and pressure, and liquids are for all intents and purposes “incompressible”\*, i.e. no matter how much pressure a kilogram of a liquid like water is under, it is still going to take up the same amount of volume. Additionally, compressed gases, such as O2 or N2, are compressed to such a degree that they become liquids, so the same thing applies. In short, a liter of hydrazine is going to take up one liter of volume no mater what pressure it’s under. **Stranger on a Train** has the right of it. When I linked to the article on the Aries 5, I never said that this particular tank had to be from that particular rocket. **Stranger** correctly points out that the tanks do come in different sizes, and that they all pretty much look the same. So, it’s just a different sized tank from a different rocket. \*not 100% true, but the differences in volume under pressure are so tiny that they are frequently neglected and I think we can safely do that here. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [December 23, 2011, 8:56pm UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/38 "2011-12-23T20:56:39Z")
> [@A Monkey With a Gun](#): > > liquids are for all intents and purposes “incompressible” Dammit, I actually knew that somewhere in the back of my head. I learned it from, of all places, _Car Talk_. Thanks for not pointing and laughing. ---
**Author:** ![Marconi\_N.Cheese](https://avatars.discourse-cdn.com/v4/letter/m/57b2e6/32.png) [@Marconi\_N.Cheese](https://boards.straightdope.com/u/Marconi_N.Cheese)\ **Post date:** [December 24, 2011, 4:09am UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/39 "2011-12-24T04:09:00Z")
How long before this thing ends up on eBay or maybe even Etsy? And what would it be sold as, I wonder. Ben-wa ---
**Author:** ![Nunzio\_Tavulari](https://avatars.discourse-cdn.com/v4/letter/n/b9bd4f/32.png) [@Nunzio\_Tavulari](https://boards.straightdope.com/u/Nunzio_Tavulari)\ **Post date:** [December 24, 2011, 4:41am UTC](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128/40 "2011-12-24T04:41:02Z")
Does Santa’s sleigh have hydrazine tanks? He may have had to make a quick dash out to the Chinese factory to pick up some things that had been running behind schedule. [Previous page](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128.md?page=1) [Next page](https://boards.straightdope.com/t/space-ball-falls-out-of-the-sky-in-namibia-what-are-these-things/607128.md?page=3)