Why is it better to destroy the ISS than to elevate it to a graveyard orbit?

[farmerben]

Scott says the problem of space debris is more severe in higher orbits.  Micrometeors and such a likely to break off pieces of the station compounding the problem.  Too bad we can't push it past Earth's sphere of influence into it's own solar orbit.

[Spacescifi]

The ISS looks kind of flimsy. If one tried to push it into solar orbit using beefy chemical rocket engines I wonder if some of the solar panels would snap off from the stress of the multi-gees of acceleration.

In theory they could put in in a solar orbit if they used a nuclear boosted ion drive.

[kerbiloid]

The most important part of any activity is to cover all tracks in time.

Edited Sunday at 05:10 AM by kerbiloid

[RCgothic]

Because it can't be fixed or adequately preserved and will inevitably disintegrate, posing a hazard to all spaceflight in it's orbit and nearby orbits. 

Far better to end it decisively.

[AckSed]

I see it like this.

Imagine a high-altitude aircraft that has never landed. It flies around the world every three days. Tanker aircraft visit it to keep the fuel topped up. Other countries, working towards this grand endeavour, have contributed their own upgrades and even extra fuselages, despite the immense technical challenge of upgrading an airplane literally on the fly.

By now it appears simultaneously like a flying junkyard and a jet-age air-carrier ripped from the pages of Popular Mechanics. Advances in medicine, high-altitude flight, lightweight alloys, construction techniques and more have flowed out of this project since its inception. High-priority cargo is flown up and dropped off once it nears the destination.

It can no longer land. By now, there isn't an airfield on the planet that's prepared to accept it, unless a custom airfield was completed at immense cost.

It gets worse. The original airplane is still in there and... it was never designed for the amount of stress and fatigue hanging hundreds of tons of wings and engines would incur off it. Of course they contribute to its strength, but design decisions made 10, 20, even 30 years ago mean that fatigue kept accumulating.

It's going to crash sooner or later. The operators cannot land it, the fuel and maintenance bills are punishing, it's growing unsafe already (a crack formed in the windscreen!), so like deciding to switch off the ventilator on a coma patient, they make the call. It will be evacuated, drained of its fuel and, with the help of a custom autopilot, directed to crash in the South Pacific.

Edited Saturday at 08:44 PM by AckSed

[darthgently]

1 hour ago, AckSed said:

I see it like this.

Imagine a high-altitude aircraft that has never landed. It flies around the world every three days. Tanker aircraft visit it to keep the fuel topped up. Other countries, working towards this grand endeavour, have contributed their own upgrades and even extra fuselages, despite the immense technical challenge of upgrading an airplane literally on the fly.

By now it appears simultaneously like a flying junkyard and a jet-age air-carrier ripped from the pages of Popular Mechanics. Advances in medicine, high-altitude flight, lightweight alloys, construction techniques and more have flowed out of this project since its inception. High-priority cargo is flown up and dropped off once it nears the destination.

It can no longer land. By now, there isn't an airfield on the planet that's prepared to accept it, unless a custom airfield was completed at immense cost.

It gets worse. The original airplane is still in there and... it was never designed for the amount of stress and fatigue hanging hundreds of tons of wings and engines would incur off it. Of course they contribute to its strength, but design decisions made 10, 20, even 30 years ago mean that fatigue kept accumulating.

It's going to crash sooner or later. The operators cannot land it, the fuel and maintenance bills are punishing, it's growing unsafe already (a crack formed in the windscreen!), so like deciding to switch off the ventilator on a coma patient, they make the call. It will be evacuated, drained of its fuel and, with the help of a custom autopilot, directed to crash in the South Pacific.

You inspired me.  Stick with me here.  Envelope the entire ISS in a large enough helium gas bag that its surface area and volume will make reentry heating so spread out that it is negligible upon reentry.  The ISS would be tethered in the center by spherically radial cables.  Inflate with helium to full size such that the buoyancy is just right after deceleration to zeppelin speed.  Bring down in a controlled decent.

Starship can deliver the big gas bag and helium and the Polaris Sunset mission can install and deploy it.

If there are any other problems that need solving, let me know

 

[kerbiloid]

7 hours ago, darthgently said:

the entire ISS in a large enough helium gas

That's what they are doing right now, having started from inside.

[Piscator]

I was doing some quick back of the envelope math, fully expecting to kill the international space zeppelin idea right there, but the basics seem to check out. The ISS has a mass of about 450 metric tons. Helium has a buoyancy of about one kilogram per cubic meter at standard conditions. Therefore, you need about half a million cubic meters of helium to balance the mass of the ISS. This is equivalent to a sphere with a diameter of about 100 meters, which fits the dimensions of the ISS nicely. It's also well within the available helium budget of the world and would just cost about 10-20 million dollars (if I read the pricing information correctly).

So absolutely doable. Right? Right ..?

 

 

[kerbiloid]

24 minutes ago, Piscator said:

you need about half a million cubic meters of helium

In kiloboeings, please.

***

I see, what you were doing last summer.

Spoiler

 

[Dinlink]

23 minutes ago, kerbiloid said:

In kiloboeings, please.

6.25 kiloboeings

 

(A Boeing worth of Volume was calculated as the maximum cargo volume + the maximum fuel capacity of a Boeing 737-800, that gives about 80m^3)

[kerbiloid]

42 minutes ago, Dinlink said:

(A Boeing worth of Volume was calculated as the maximum cargo volume + the maximum fuel capacity of a Boeing 737-800, that gives about 80m^3)

I mean, the CST-100 helium tank, which is filling the ISS with helium right now.

(It was strange, as there is no buoyancy in vacuum, but after this thread got clear, why.)

ISS is already the first orbital station with artificial gravity (thanks, Nauka), and now it's becoming the first orbital airship ever.

Edited Sunday at 07:47 AM by kerbiloid

[cubinator]

6 hours ago, Piscator said:

I was doing some quick back of the envelope math, fully expecting to kill the international space zeppelin idea right there, but the basics seem to check out. The ISS has a mass of about 450 metric tons. Helium has a buoyancy of about one kilogram per cubic meter at standard conditions. Therefore, you need about half a million cubic meters of helium to balance the mass of the ISS. This is equivalent to a sphere with a diameter of about 100 meters, which fits the dimensions of the ISS nicely. It's also well within the available helium budget of the world and would just cost about 10-20 million dollars (if I read the pricing information correctly).

So absolutely doable. Right? Right ..?

 

 

Ok, so it floats. Now you need to make it not burn when it comes down. 

[Iapetus7342]

2 minutes ago, cubinator said:

Ok, so it floats. Now you need to make it not burn when it comes down. 

You'd need one big heatshield alright.

[farmerben]

In a way I'll be glad when we don't have a space station or a low orbit shuttle.  The priorities are the Moon and Mars.  Lets go already.  No more distractions.

[kerbiloid]

25 minutes ago, Iapetus7342 said:

You'd need one big heatshield alright.

To stop ISS from orbiting they need dV = 7.9 km/s, M ~480 t.

To make it falling slow until reaching the buoyancy altitude, a vertical set of engines should be providing ~480 tf of thrust.

So, a set of 12 NERVAs (40 tf) could do this, if mount them convertiplanenically.

Edited Sunday at 01:40 PM by kerbiloid

[PakledHostage]

2 hours ago, cubinator said:

Ok, so it floats. Now you need to make it not burn when it comes down. 

Since we're being silly, why not a scaled up version of the M.O.O.S.E?

[darthgently]

4 hours ago, cubinator said:

Ok, so it floats. Now you need to make it not burn when it comes down. 

The bigger, blunter, and less dense, the more the friction is spread out and the easier it is to decelerate.  It wouldn't heat as much as one would think as it would have slowed significantly in much thinner air higher up than a capsule.   

[magnemoe]

7 hours ago, farmerben said:

In a way I'll be glad when we don't have a space station or a low orbit shuttle.  The priorities are the Moon and Mars.  Lets go already.  No more distractions.

NASA still want access to an space station in LEO, but they don't want to run it, they want to rent place on an commercial space station, I assume an long term rent with an minimum rent and the option to add say 3 modules and have 4 astronauts on it for this rent, they can do more if they pay more. 
Benefit is that the owner is responsible for operation, maintenance and probably hotel services, who is likely to be cheaper as NASA is expensive and the owner will also provide services to commercial actors, other space agencies and tourists. 
Now this is already done with IIS but will be easier with an commercial station set up for this from the start than an station shared between multiple agencies. 

[Dinlink]

23 hours ago, cubinator said:

Ok, so it floats. Now you need to make it not burn when it comes down. 

Not quite...

The "sphere" that should contain the Helium must be structurally sound to resists the weight of the ISS and its own weight...

 

Comparing to the largest ever built airship ( the LZ-129 Hindenburg )... It had a capacity of 200k m^3 of Volume and had a dead weight of 118tons (stripping it out of fuel and other devices)... So it could have an available raw lifting of about ~100tons ... Then you would need about 5 Zeppelins to hold the ISS... Totalling a million m^3 of Volume, and an extra half a million tons of added weight... And all of extra engineering to make that monster structurally robust and capable of soft re-entry...

[kerbiloid]

They can fill it with vacuum. The vacuum is lighter than helium.

[darthgently]

2 hours ago, Dinlink said:

Not quite...

The "sphere" that should contain the Helium must be structurally sound to resists the weight of the ISS and its own weight...

 

Comparing to the largest ever built airship ( the LZ-129 Hindenburg )... It had a capacity of 200k m^3 of Volume and had a dead weight of 118tons (stripping it out of fuel and other devices)... So it could have an available raw lifting of about ~100tons ... Then you would need about 5 Zeppelins to hold the ISS... Totalling a million m^3 of Volume, and an extra half a million tons of added weight... And all of extra engineering to make that monster structurally robust and capable of soft re-entry...

I was taking the concept of an inflatable heat shield to the limit.  Make it spherical, full of  helium, and big enough to float the ISS and spread the plasma across a much larger blunt surface.  There is a point, perhaps beyond feasible, where it is still technically possible, by golly

[Dinlink]

45 minutes ago, kerbiloid said:

They can fill it with vacuum. The vacuum is lighter than helium.

Yes... But the reason that Helium is preferred over vacuum is because at standard temperature, it can excert pressure about the same as the atmospheric one with very low density... So it balances out with the external pressure and the structure of the airship only has to withstand its own weight and the weight of the load (ISS)... A vacuum airship would have to resists the stress of atmospheric pressure... And with known engineering materials, there's no structure that can withstand atm pressure while being lightweight enough to float... (at least that I'm aware of)

 

49 minutes ago, darthgently said:

concept of an inflatable heat shield

That sounds more plausible... But the main difficulty still stands, that is, to find a light weight, strong enough material that can hold a significant amount of a thin gas like helium without significant loses.

Strong enough to be able to sustain the stress of it own weight plus ISS weight plus internal gas pressure...

Light enough so that the added weight be insignificant relative to the provided lift capacity...

Another way to see it, is that the average density of the whole system must be less than the air density... And as I mentioned before, I'm not aware of any magical material that could do the job significantly better than the usual ones that leads to our five Zeppelins solution

[darthgently]

1 hour ago, Dinlink said:

'm not aware of any magical material that could do the job significantly better than the usual ones that leads to our five Zeppelins solution

And?  I didn't have a single problem with the 5 zepp sol'n.  It fits "technically possible".  Feasibility I'll leave for the money printers in DC to deal with

[Hi_123]

While we're being unreasonable you could just strap parachutes and heatshields to it and see what happens.

[Lisias]

58 minutes ago, Hi_123 said:

While we're being unreasonable you could just strap parachutes and heatshields to it and see what happens.

I would strap some deployable lifting surfaces on it, and then glide her into a nice and smooth splashdown...

Spoiler

(yeah, right )

Oukey, who will start the Thread for this Challenge?