Question about machines in space

[Paratus]

Your forgetting that there is no air in space, that's why things that look"flimsy" do just fine, 20K MPH, 40K MPH is irrelevant, there is no wind resistance because there is no air..

You are right and wrong.

You are right that from a structural loading perspective there's not enough air resistance to really be a concern. But from attitude control and altitude air resistance plays a big part.

We do reboosts several times a year to combat drag. Plus we normally fly in a torque equilibrium attitude where air resistance and gravity gradients are the biggest torques.

 

[BUTCH1]

I see. Then, what exactly is a solar wind?

It's charged particles emitted from the sun, not like the wind here on earth, geez, did you have a science class at your school??..

 

[sunzt]

I see. Then, what exactly is a solar wind?

that or when the sun passes gas...

 

[AeroEngy]

they're designed to withstand debris that are usually under 10 cm diameter, which accounts for most space debris. ...

That is not accurate. There is very little chance to survive an impact of an object anywhere close to 10 cm in diameter.

Basically stuff less than a 1 cm a satellite might survive depending on where it hits. If it hits a solar panel it will most likely just punch a hole right through it and take a cell or two.

Anything bigger than about 1 cm can cause some pretty heavy damage. The real danger zone for debris is the stuff that is between around 1 cm and 10 cm. That is because > 10 cm you can track and avoid < 1 cm you might survive.

Take a look at this photo from an impact test. That is the results from a 1.2 cm aluminum sphere impacting I believe an 8 cm aluminum plate at approximately 7km/s.

 

[NikolaeVarius]

Could you (or somebody else) rephrase this in layman's terms?

Space is very hot and very cold simultaneously.

Cooling is a massive issue in space.

 

[Dari]

It's charged particles emitted from the sun, not like the wind here on earth, geez, did you have a science class at your school??..

I got a B in Astronomy. It was an easy out for a science requisite. Sorry.

 

[Dari]

That is not accurate. There is very little chance to survive an impact of an object anywhere close to 10 cm in diameter.

Basically stuff less than a 1 cm a satellite might survive depending on where it hits. If it hits a solar panel it will most likely just punch a hole right through it and take a cell or two.

Anything bigger than about 1 cm can cause some pretty heavy damage. The real danger zone for debris is the stuff that is between around 1 cm and 10 cm. That is because > 10 cm you can track and avoid < 1 cm you might survive.

Take a look at this photo from an impact test. That is the results from a 1.2 cm aluminum sphere impacting I believe an 8 cm aluminum plate at approximately 7km/s.

So then what is the probability of a satellite getting hit with a device in that range? Also, how long do these satellites stay up there?

 

[Paratus]

That is not accurate. There is very little chance to survive an impact of an object anywhere close to 10 cm in diameter.

Basically stuff less than a 1 cm a satellite might survive depending on where it hits. If it hits a solar panel it will most likely just punch a hole right through it and take a cell or two.

Anything bigger than about 1 cm can cause some pretty heavy damage. The real danger zone for debris is the stuff that is between around 1 cm and 10 cm. That is because > 10 cm you can track and avoid < 1 cm you might survive.

Take a look at this photo from an impact test. That is the results from a 1.2 cm aluminum sphere impacting I believe an 8 cm aluminum plate at approximately 7km/s.

As I mentioned before the ISS pressurized modules have a dual layer gapped design. The first thin layer causes the debris to vaporize at which point it spreads out the debris as I crosses the gap to impact on the thicker inner layer. Effectively this spreads the energy out over a much larger area.

The ISS uses a Whipple shield design. Which is nominally good for impacts of upto 1 cm depending on velocity and impact angle. If I remember correctly.

 

[AeroEngy]

So then what is the probability of a satellite getting hit with a device in that range? Also, how long do these satellites stay up there?

The service life of a satellite can vary quite a bit. I would say typical is 5-10 year. Mid and High orbits could last longer. Luckily ... sort of ... most of the debris is in Low Earth Orbit. I say "luckily" because that means its orbit will decay quicker and eventually clear itself out. I say "sort of" because LEO has a lot of stuff in it like the ISS. Debris in higher orbits could last centuries.

I saw a study awhile ago that listed over 10 Million pieces of debris less < 1 cm, ~20,000 objects > 10cm and about 1/2 Million or so objects in that >1 cm but <10 cm range. So it is a real problem that could get out of hand if unmitigated. Luckily Space is big and the orbits are not to crowded ... yet. The worry is in a cascade scenario where if the orbits get to crowded and a satellite gets destroyed creating more debris ... destroying more satellites. Eventually rendering large chunks of desirable orbits unusable.

 

[AeroEngy]

As I mentioned before the ISS pressurized modules have a dual layer gapped design. The first thin layer causes the debris to vaporize at which point it spreads out the debris as I crosses the gap to impact on the thicker inner layer. Effectively this spreads the energy out over a much larger area.

The ISS uses a Whipple shield design. Which is nominally good for impacts of upto 1 cm depending on velocity and impact angle. If I remember correctly.

You are absolutely correct about the Whipple shields. However, not all satellites have them and as I mentioned they are not that effective if you get hit by say a 5 cm chunk of something.

 

[Paratus]

You are absolutely correct about the Whipple shields. However, not all satellites have them and as I mentioned they are not that effective if you get hit by say a 5 cm chunk of something.

Yes, which as I said earlier, for impacts above the range the ISS can handle but smaller than we can detect we have procedures in place to protect the crew from depressurization.

Ever since the Chinese did that satellite missile test we've been having a lot more potential conjunctions with the station.

As for the other satellites I don't have to worry about them, just the ISS. 😉

 

[AeroEngy]

Yes, which as I said earlier, for impacts above the range the ISS can handle but smaller than we can detect we have procedures in place to protect the crew from depressurization.

Ever since the Chinese did that satellite missile test we've been having a lot more potential conjunctions with the station.

As for the other satellites I don't have to worry about them, just the ISS. 😉

The Chinese satellite missile test was completely retarded. At least when we did the same thing it was at a lower altitude so the debris would degrade quickly and not screw up usable orbits.

 

[Paratus]

The Chinese satellite missile test was completely retarded. At least when we did the same thing it was at a lower altitude so the debris would degrade quickly and not screw up usable orbits.

I remember that. I also think we had an upper stage of something breakup about the same time. The ISS is in a bit of a shooting gallery which sucks because we end up doing a ton of work to prepare for a debris avoidance maneuver and the most times it's called off once the trajectory is refined a bit better.

 

[Red Squirrel]

The IIS is equipped with MMDS (Multiple Missle Defense System) and it will just shoot away anything that comes at it. They added that system a bit after 9/11 to be prepared for the worse. I just made all that up.

I think it's just a luck thing. While there is tons of debris in space, space is so vast and the debris is so spread out that the odds of one hitting one of our objects... or even our planet, is very very small.

Though what I always wondered is why the satellites don't have a fuel cap like a car would. To refuel them they actually have to take them apart somewhat. At least that's what they were showing on TV. They only have to refuel like every 10 years or so, but still, you'd think they'd make it easier. Some kind of plug that the fuel ship hooks to.

 

[clamum]

The only issues in space are debris and radiation. Give this mother fucker head of NASA!

Probably off topic, but I can't believe NASA administrators haven't read "The Case for Mars".

 

[The Boston Dangler]

That is not accurate. There is very little chance to survive an impact of an object anywhere close to 10 cm in diameter.

Basically stuff less than a 1 cm a satellite might survive depending on where it hits. If it hits a solar panel it will most likely just punch a hole right through it and take a cell or two.

Anything bigger than about 1 cm can cause some pretty heavy damage. The real danger zone for debris is the stuff that is between around 1 cm and 10 cm. That is because > 10 cm you can track and avoid < 1 cm you might survive.

Take a look at this photo from an impact test. That is the results from a 1.2 cm aluminum sphere impacting I believe an 8 cm aluminum plate at approximately 7km/s.

that picture reminded me of this guy from doctor who:

 

[BUTCH1]

You are right and wrong.

You are right that from a structural loading perspective there's not enough air resistance to really be a concern. But from attitude control and altitude air resistance plays a big part.

We do reboosts several times a year to combat drag. Plus we normally fly in a torque equilibrium attitude where air resistance and gravity gradients are the biggest torques.

There probably bits of atmosphere where the ISS orbits but I always thought any orbit not in geo-sync is subject to degradation..

 

[BUTCH1]

The IIS is equipped with MMDS (Multiple Missle Defense System) and it will just shoot away anything that comes at it. They added that system a bit after 9/11 to be prepared for the worse. I just made all that up.

I think it's just a luck thing. While there is tons of debris in space, space is so vast and the debris is so spread out that the odds of one hitting one of our objects... or even our planet, is very very small.

Though what I always wondered is why the satellites don't have a fuel cap like a car would. To refuel them they actually have to take them apart somewhat. At least that's what they were showing on TV. They only have to refuel like every 10 years or so, but still, you'd think they'd make it easier. Some kind of plug that the fuel ship hooks to.

Communication satellites orbit very high, too high to be "re-fueled", they carry enough hydrazine propellant at launch to do maneuvering when needed

 

[sandorski]

If Space is a vacuum, where's the bag and who empties it?

 

[Fayd]

I see. Then, what exactly is a solar wind?

energy.

 

[BUTCH1]

I remember that. I also think we had an upper stage of something breakup about the same time. The ISS is in a bit of a shooting gallery which sucks because we end up doing a ton of work to prepare for a debris avoidance maneuver and the most times it's called off once the trajectory is refined a bit better.

Is the ISS equipped with a thruster system to bump it around to avoid debris?

 

[The Boston Dangler]

energy.

matter

 

[Paratus]

Is the ISS equipped with a thruster system to bump it around to avoid debris?

The Russian Segment has thrusters on the Service Module. However we normally use the Russian Progress vehicles or Europeant ATV vehicle to perform attitude maneuvers or reboots to save life on the SM thrusters. Those vehicles are disposable.

The US segment has the 4 big control momentum gyros to hold attitude without using fuel.

We maneuver this thing about once a week for dockings, undockings, reboosts, thruster tests, and debris avoidance maneuvers.

 

[ichy]

Is the ISS equipped with a thruster system to bump it around to avoid debris?

Yes. They also need to do periodic reboosts or the ISS would eventually pull a Skylab and go crashing to the ground. Low Earth orbit is not a perfect vacuum.

 

[96Firebird]

If Space is a vacuum, where's the bag and who empties it?

Its a canister model, and obviously a woman empties it.