Iss

[Mutley]

http://www.ibtimes.c...ebris-space.htm

 

Why dump it in the sea? Any space nerds able to explain why it can't be put on a course into the sun to burn up?

[Alias]

Would take a lot of fuel, even if it's possible. This is because relatively speaking, the ISS isn't actually that high up (because it was designed for use with the Shuttle).

[Mutley]

Would take a lot of fuel, even if it's possible. This is because relatively speaking, the ISS isn't actually that high up (because it was designed for use with the Shuttle).

 

Would it take much fuel? Point it in the direction of the sun, give it a push and let a frictionless vacuum and the suns gravity do the rest. Or slingshot it around the moon.

[GD4ELI]

Would it take much fuel?

 

Yes, it's in a low earth orbit, getting it out of orbit just can't be done.

 

Drop it on Ramsey I say

[Tweek]

Would it take much fuel?

 

Yes, it's in a low earth orbit, getting it out of orbit just can't be done.

 

Drop it on Ramsey I say

Yeah, Ramsey or Uranus - much the same thing really.

[VinnieK]

Would it take much fuel? Point it in the direction of the sun, give it a push and let a frictionless vacuum and the suns gravity do the rest. Or slingshot it around the moon.

 

Friction isn't really the main concern, it's the Earth's gravitational field (and remember, the ISS isn't really very far from the Earth). The danger being that the ISS would just end up plumetting back to Earth at some point. It's also very expensive to deorbit something properly , so the preferred solutions are either to ditch it in the ocean, or move it to a further orbit (which isn't always successful, and it's better to try and limit the amount of junk we have orbiting us).

 

To slingshot it around the moon would similarly be expensive. Ditching it in the ocean is generally the simplest and cheapest option.

[pongo]

I hope they build another. It's a wonderful thing.

[Alias]

I hope they build another. It's a wonderful thing.

For sure, if it was more valued. But when the science budget is so small and each Shuttle cost $1 billion to launch, there are better things to spend money on.

[Bobbie Bobster]

Would take a lot of fuel, even if it's possible. This is because relatively speaking, the ISS isn't actually that high up (because it was designed for use with the Shuttle).

Would it take much fuel? Point it in the direction of the sun, give it a push and let a frictionless vacuum and the suns gravity do the rest. Or slingshot it around the moon.

 

Some have suggested putting it into a geostationary orbit & using it there. Problem is that that would involve a plane change as it's in an inclined orbit at the moment (in order for it to be accessible from Russian launches). [Never mind that it would be then above the van allen belts and exposed to deep space radiation levels, and we don't currently have a man-rated transfer vehicle to reach GEO]. Plane changes are the expensive things to do in terms of fuel, rather than altitude changes. Similar issues for dumping it into the sun as you would need to do a plane change to the ecliptic.

 

The trusses were only designed to handle relatively gentle station keeping, boosting it regularly using a "tug" to counteract for atmospheric drag. Major changes of delta v would probably require significant re-engineering.

 

It does weigh 400 tonnes. That's 4 x Saturn V launches to LEO, or about 9 Protons. IIRC you need very roughly the same order of magnitude to go from LEO to GEO (very roughly...) so that's about USD1bn for the launchers not counting other engineering changes.

[pauld]

Would it take much fuel?

 

Yes, it's in a low earth orbit, getting it out of orbit just can't be done.

 

Drop it on Ramsey I say

 

is that right, so how much percentage wise is the gravitational pull on the space station now, i will tell you, virtually zero, the station only needs repositioned once every 2 months maximum..

the shuttles orbit in low orbit 150 miles, the space station is alot higher, its height only restricted by shuttle re-supply range.

 

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 278 km (173 mi) and a maximum of 460 km (286 mi).

The normal maximum altitude is 425 km (264 mi) to allow NASA Shuttle rendezvous missions. It is likely that, with the retirement of the shuttle, the nominal orbit of the space station will be raised in altitude.[105] As the ISS constantly loses altitude because of a slight atmospheric drag, it needs to be boosted to a higher altitude several times each year.[32][106] This boost can be performed by the station's two main engines on the Zvezda service module, a docked space shuttle, a Progress resupply vessel, or by ESA's ATV. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed.

 

They certainly could remotely boost the baby out into space if thats what they wanted to do.

It is what they planned to do with it, by fitting it with russian experimental plasma propulsion engines.

[Stavros]

It does make me wonder about the environmental implications of dropping something as large and as complex as the ISS into the ocean. If the maritime rules and regulations prohibit the disposal of the Solway Harvester by towing it back out to sea and sinking it, what regulations are there that would prohibit the dumping of an international space station in the sea. Something the size of 2 football fields and weighing in excess of 450 metric tons with an orbital speed of around 17,227 miles per hour. That can't be good, can it?

[Tempus Fugit]

can the MEA put in a bid for the solar panels ?

[pongo]

what regulations are there that would prohibit the dumping of an international space station in the sea

 

Whatever regulations Mr Putin decrees.

[Chinahand]

Yes, it's in a low earth orbit, getting it out of orbit just can't be done.

 

is that right, so how much percentage wise is the gravitational pull on the space station now, i will tell you, virtually zero, the station only needs repositioned once every 2 months maximum.

Pauld, I think you aren't really understanding the issues here - the earth's gravity is acting strongly on the ISS, but the ISS isn't falling to earth - why - because of the centripetal (erm - VinnieK, Dr Dave should that be centrifugal?*) force produced by it orbiting the earth. These two forces balance each other out leaving the ISS in microgravity.

 

Because the ISS is so low it is still in the top of the earth's atmosphere and though this is incredibly thin it produces drag which slows the ISS down - as it slows down it orbits less quickly and so produces less centrifugal force. The forces are no longer balanced - the force of gravity is stronger then the centrifugal force and starts to pull it lower. But this doesn't cause the ISS to crash down to the earth - as it gets lower it takes less time to make a complete orbit of the earth even though its going at the same speed - the orbit is smaller - this shorter orbital period results in a larger centrifugal force (than when it was orbiting at the same speed, but a higher orbit) which now once again balances the force of gravity making the orbit stable again.

 

The time between it being repositioned is due to the thinness of the earth's atmosphere not the weakness of the earth's gravity acting on it. If you sucked all the atmosphere away from the earth you could get something to orbit it only 10 feet above Mount Everest - it would just have to go really really fast. Once it was going fast enough to orbit at such a rate so as to produce a centrifugal force equal to gravity you could cut the engines and it would continue orbiting effectively for ever - as long as it doesn't slow down it's orbit is stable. Air resistance stops this happening in reality, so you can only get stable orbits well out of the earth's atmosphere - the ISS isn't far enough up and so needs to be boosted up every so often.

 

 

See this Xkcd cartoon to see how low in Earth's gravity well the ISS is.

 

 

*My understanding is that gravity is the centripetal force pulling it down and round in a circle - the opposite and equal reaction to this the inertial centrifugal force - is that right?

[guzzi]

 

 

is that right, so how much percentage wise is the gravitational pull on the space station now, i will tell you, virtually zero, the station only needs repositioned once every 2 months maximum..

the shuttles orbit in low orbit 150 miles, the space station is alot higher, its height only restricted by shuttle re-supply range.

 

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 278 km (173 mi) and a maximum of 460 km (286 mi).

The normal maximum altitude is 425 km (264 mi) to allow NASA Shuttle rendezvous missions. It is likely that, with the retirement of the shuttle, the nominal orbit of the space station will be raised in altitude.[105] As the ISS constantly loses altitude because of a slight atmospheric drag, it needs to be boosted to a higher altitude several times each year.[32][106] This boost can be performed by the station's two main engines on the Zvezda service module, a docked space shuttle, a Progress resupply vessel, or by ESA's ATV. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed.

 

They certainly could remotely boost the baby out into space if thats what they wanted to do.

It is what they planned to do with it, by fitting it with russian experimental plasma propulsion engines.

 

Pauld you obviously didn't pay attention in Physics. The gravitational pull of the earth is what holds the ISS in orbit around the Earth, as it does for all satellites, including the Moon. When Apollo went to the moon, they had to use a huge rocket to place it in a very high, elliptical orbit, that would eventually be intercepted by the orbit of the moon and allow Apollo to be captured by the moons gravity. They did not point the rocket at the moon and shoot.

 

The reason the ISS needs to be boosted occasionally to maintain it's present orbit is nothing to do with gravity. It is because where it orbits, there is a small amount of drag caused by traces of the Earth's atmosphere. If left, it's orbit would eventually decay, and it would fall back to Earth.