Loss of mass of an object falling through air

In summary, the conversation discusses the potential danger of a spacecraft falling to Earth and the complexities of simulating reentry and predicting where it will land. The participants also discuss the possibility of intentionally destroying a falling satellite and the potential dangers of toxic chemicals being dispersed upon impact.
  • #1
Sumit Adhikari
2
0
Hello All,

I am an electrical engineer and hence quite far away from mechanics of masses.

I just came to know that a spacecraft got crazy and might fall on earth.

I did a simple math using MATLAB considering no atmosphere with h and m of the object as input and Nagasaki Bomb scale energy release upon contact as output.

But there will be atmosphere which will lead to loss in mass. How do I do that (assuming the falling object is as Iron)

Regards,
Sumit
 
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  • #2
There is no man-made object in space that would release as much energy as the Nagasaki bomb. Even the kinetic energy of the ISS is just at ~4000 tons of TNT and it won't fall on Earth in an uncontrolled way.

Simulating how things break up into smaller pieces on reentry is very complex.
Satellites reach terminal velocity in the atmosphere before they (or their pieces) hit the ground - might be deadly if something happens to fall onto your head, but without any effect if it does not directly hit anything (and the Earth is huge and mainly empty). Satellites deorbit all the time, so far nothing hit anything. Space stations get deorbited in a controlled way.
 
  • #3
Thanks for the reply!

I understand that very well.

My question is out of curiosity and not out of scare. You can sat a fun timepass at office :)
 
  • #4
The spacecraft is already traveling much faster than terminal velocity (around 15,000 mph). As the atmosphere sucks energy out of the orbit, the orbit is getting smaller (losing potential energy), with a lot of that potential energy being turned into kinetic energy (velocity). So, ironically, the spacecraft is speeding up in spite of the thickening, but still thin atmosphere, until, eventually, the atmosphere is thick enough to actually start slowing the spacecraft .

Hence the heating and the break-up of the spacecraft long before reaching the surface. Only the strongest of spacecraft parts have any chance of reaching the surface (titanium spherical fuel tanks from Delta II boosters are notorious for surviving re-entry).
 
  • #5
What is the safe altitude to blow up a falling satellite with a missile such that no space debris is created ? I remember the US did it few years ago and China did it too.
 
  • #6
Monsterboy said:
What is the safe altitude to blow up a falling satellite with a missile such that no space debris is created ? I remember the US did it few years ago and China did it too.
It's not possible to do it without space debris, the trick is to make that debris stay up there for as short of time as possible. The atmosphere doesn't stop, it just kinda fades away as you get higher up. The lower you are, the more drag and the faster it'll be slowed enough to crash down. Any object in Earth orbit will eventually either be sucked into Earth or be thrown off into space, any satellite is by default in a death spiral and will come down if left up there long enough. Remember interplanetary space isn't a vacuum, the sun's heliosphere has it's own friction.
 
  • #7
Just don't blow up deorbiting satellites - there is no point in that (unless you expect some hostile mission of the satellite).
 
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  • #8
mfb said:
Just don't blow up deorbiting satellites - there is no point in that (unless you expect some hostile mission of the satellite).
http://edition.cnn.com/2008/TECH/space/02/20/satellite.shootdown/index.html
Without intervention, officials say, the satellite would have fallen to Earth on its own in early March. However, since it malfunctioned immediately after it was launched in December 2006, it had a full tank -- about 1,000 pounds -- of frozen, toxic hydrazine propellant.
The fuel tank probably would have survived re-entry if the satellite had fallen to Earth on its own. That could have dispersed harmful or even potentially deadly fumes over an area the size of two football fields. Hydrazine is similar to chlorine or ammonia in that it affects the lungs and breathing tissue.

The danger seems to be only with new satellites with their tanks full.
 
  • #9
Hmm okay, dangerous chemicals can be an issue if you lose control over the satellite.
 

1. What causes an object to lose mass while falling through air?

The main cause of mass loss in an object falling through air is air resistance or drag. As the object moves through the air, it collides with air molecules, causing a transfer of momentum and energy. This transfer results in the object losing some of its mass as it falls.

2. Does the mass loss of an object affect its acceleration?

Yes, the mass loss of an object falling through air can affect its acceleration. As an object loses mass, its weight decreases, resulting in a decrease in the force of gravity acting on it. This, in turn, can lead to a decrease in the object's acceleration.

3. Is the loss of mass constant or does it change over time?

The loss of mass of an object falling through air is not constant and can change over time. As the object falls, the amount of air resistance it experiences may change, leading to fluctuations in the rate of mass loss. Additionally, the shape and composition of the object may also affect the rate of mass loss.

4. Can the loss of mass be prevented?

It is difficult to prevent the loss of mass in an object falling through air, as air resistance is a natural force that cannot be completely eliminated. However, certain materials and shapes can be designed to minimize the effects of air resistance, resulting in less mass loss.

5. How does altitude affect the loss of mass in an object falling through air?

The altitude at which an object is falling can affect the rate of mass loss. At higher altitudes, the air is less dense, resulting in lower air resistance and therefore, a slower rate of mass loss. As the object falls to lower altitudes, the air becomes denser, leading to a faster rate of mass loss.

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