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Could a "simple" inflated party balloon be dropped from space entering an atmosphere? The first case at orbital speed, the second case just outside the atmosphere and the third interplanetary?

The balloon would shrink as it falls but still would have a little air inside. Maybe a hard plastic balloon that equalizes on descent?

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Would the balloon pop when entering an atmosphere? What is the terminal velocity of a balloon?

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    $\begingroup$ Is the balloon at near-orbital velocity or at rest when it's released? $\endgroup$ – Russell Borogove Mar 23 '18 at 14:11
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    $\begingroup$ Dropping something from orbit is impossible. The something will orbit as well as the satellite being dropped from. If the drag to mass ratio is bigger than that of the satellite, it will sink from LEO faster and reentry earlier. $\endgroup$ – Uwe Sep 25 '18 at 20:27
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    $\begingroup$ Why should the balloon burst when the pressure outside is rising? If there is no fast reentry from orbit but only a slow ballistic drop and no heat is destroying the balloon will just get smaller and smaller. $\endgroup$ – Uwe Sep 25 '18 at 21:33
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    $\begingroup$ I wonder what sort of baloon would be sturdy enough to be buoyant at 100ft and not burst in vacuum of space... $\endgroup$ – SF. Sep 27 '18 at 0:09
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    $\begingroup$ Useful calculations: ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/… $\endgroup$ – Hobbes Jan 7 at 15:14
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Special high-altitude balloons are used to do research or other measurements (weather balloons) in the higher atmosphere, by carrying sensors. Those are especially made to expand much more that your usual party balloon. They usually burst between 30 and 50 km in altitude. At the ground there appears to be almost no gas inside them, because it expands and fills the balloon more with decreasing surrounding pressure:

deflated balloon image Credit: NASA

inflated balloon image Credit: NASA

However NASA is developing a new parachute system (LDSD) for Mars, in wich a kind of balloon is used for braking at Mars, however it is pressurized at much less pressure than your everyday party balloon, due to lower pressure at higher altitudes and even lower pressure at Mars. This is however only used in the first stage of deceleration and later replaced by a parachute, since it provides enough drag and rigidity to slow it from supersonic speeds, but not bring it to a smooth landing. Here is a great nasaspaceflight article about the test flight

So it would be feasible to use a balloon to break when dropping from space, but you could only fill it with very little helium and need a different system for the final deceleration and landing.

LDSD Credit: NASA

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    $\begingroup$ @Muze if you fill the balloon in space it would probably completely deflate and crumble due to atmospheric pressure before the point where you even reach atmospheric heating. You’d either continuously fill more gas in or inflate it at a lower altitude, at that point you have something similar to the LDSD in the post above, which works, at least to some degree, but still requires some sort of heatshield for hotter parts of the reentry. $\endgroup$ – Hans Mar 23 '18 at 19:12
  • $\begingroup$ updated question $\endgroup$ – Muze Jan 7 at 16:34
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Well, a party balloon could definitely be dropped into an atmosphere, but it's tricky to find a way for it to survive the experience.

At orbital or interplanetary velocity, the balloon would burn up in the atmosphere. It doesn't matter whether it starts out inflated or not. At those speeds the balloon has a lot of kinetic energy that is going to be converted to heat, and rubber is less heat-resistant than many other materials that also burn up in the atmosphere.

If you dropped it from a rocket platform hovering at 100 km, then I am not sure if it would pick up enough speed while air resistance was negligible to burn up in the slightly thicker part of the atmosphere. After 20 km it would be going around 1400 mph. I am thinking that as the atmosphere got thicker there would be heating at those speeds and likely destruction of the balloon, but I am not sure.

You also ask what the terminal velocity of a balloon is. The terminal velocity always depends on the medium. In air at sea level, the terminal velocity is something you have observed directly; I am guessing less than one m/s. But that is not very relevant to what happens when the balloon is initially moving very fast.

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  • $\begingroup$ If the balloon is lower than the terminal velocity of the atmophere even at 100 km should it not remain at terminal velocity all the way to the ground. I should have asked would a fether burn up on rentry? $\endgroup$ – Muze yesterday
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So rather then changing a risk down votes or invalidating the question's answer I iterate here in the form of an answer if this is ok? Should I add another question about flexible but not necessarily stretchy and light weight material that can be used in place of rubber? Not sure if the new question is on topic here?

Solar radiation heats objects in LEO to 393 kelvins (120 degrees Celsius or 248 degrees Fahrenheit) or higher, while shaded objects plummet to temperatures lower than 173 kelvins (minus 100 degrees Celsius or minus 148 degrees Fahrenheit).

Answer: Reentry aside, No simple balloon would last very long in space while inflated if even seconds before rupturing. Must rubber in simple balloons would either melt and pop or freeze brittle breaking from the atmopheric pressure from within. I did not take in temperature in account and was focused on the frictional heat and pressure change impressed on the balloon under its own weight and reentry speed. I am interested the right material to make a balloon as stated by S.F. in comments.

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  • $\begingroup$ To expose a balloon to a vacuum it should be inflated to a very, very low pressure before, It is the pressure difference between inside and outside that would let the balloon rupture. $\endgroup$ – Uwe yesterday

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