Boost ISS into geosynchronous orbit?

[DaleBrown]

Would it be possible to boost the ISS into GEO orbit? It takes 1K Newtons to adjust the ISS's orbit 3 miles every month or so, so I think it would take about 8M N to accelerate the ISS to GEO. A single STS SRB can put out 12.5M N.

I think you'd want to have a throttleable engine to avoid tearing the ISS apart, or perhaps use several smaller boosters arrayed around the ISS to equally distribute the force.

 

[MeteorWayne]

Not even close. How are you going to get the required amont of propellant up there? What would be the purpose, since no spacecraft could reach it to service the station? No supplies, no astronauts coming in or leaving, etc...

Welcome to Space.com, a reality check.

 

[JonClarke]

Plus GEO is in the van Allan belts and the spacecraft would require additional shielding.

Plus it takes more energy to reach GEO than it does to achieve Earth escape. None of the current support craft could reach the station.

And what would be the point? What could the ISS do in GEO that you can't do more easily in LEO?

Jon

 

[DrRocket]

Would it be possible to boost the ISS into GEO orbit? It takes 1K Newtons to adjust the ISS's orbit 3 miles every month or so, so I think it would take about 8M N to accelerate the ISS to GEO. A single STS SRB can put out 12.5M N.

I think you'd want to have a throttleable engine to avoid tearing the ISS apart, or perhaps use several smaller boosters arrayed around the ISS to equally distribute the force.

You don't even have the physics correct. The thrust level (Newtons) has nothing whatever to do with what it takes to reach GEO. GEO, like any orbit is characterized by a velocity, and direction and a location. To get to GEO you need to provide sufficient energy to reach the required altitude with the speed needed to maintain that orbit and a velocity vector directed in the correct direction. Basically you need to supply a certain amount of kinetic energy.

It takes LOT of energy to go from a low earth orbit to GEO, nearly as much as to to reach escape velocity. That would take a lot. And once you reached there it would be difficult to get astronauts to the ISS on a regular basis. Heavy payloads, like the shuttle orbiter, can't get that high.

This is your basic bad idea.

 

[Saiph]

possible or not (though it ain't, as mentioned above), I'm not sure what the overall goal would be. What can you do in Geo Synch that you can't do in LEO? And does it justify the additional risks, costs and effort? I can't think of anything myself, other than to reduce the need for re-boosts...which could actually be done by moving it just further out than LEO. Granted, that means we couldn't really ship people there regularly....

 

[silylene]

There are only two benefits of geosynchronous orbit that I can think of:
- near freedom from risk of collision from space trash
- the ISS would become a fixture in the sky that people on the correct location on earth could easily find it every night.

In additon to all the many disadvantages mentioned in the prior two posts, there would be a higher risk of radiation being above the Van Allen belts, and the additional risks astronauts would have to take going through the belts to travel to the ISS.

 

[CalliArcale]

Would it be possible to boost the ISS into GEO orbit? It takes 1K Newtons to adjust the ISS's orbit 3 miles every month or so, so I think it would take about 8M N to accelerate the ISS to GEO. A single STS SRB can put out 12.5M N.

I think you'd want to have a throttleable engine to avoid tearing the ISS apart, or perhaps use several smaller boosters arrayed around the ISS to equally distribute the force.

You don't even have the physics correct. The thrust level (Newtons) has nothing whatever to do with what it takes to reach GEO. GEO, like any orbit is characterized by a velocity, and direction and a location. To get to GEO you need to provide sufficient energy to reach the required altitude with the speed needed to maintain that orbit and a velocity vector directed in the correct direction. Basically you need to supply a certain amount of kinetic energy.

It takes LOT of energy to go from a low earth orbit to GEO, nearly as much as to to reach escape velocity. That would take a lot. And once you reached there it would be difficult to get astronauts to the ISS on a regular basis. Heavy payloads, like the shuttle orbiter, can't get that high.

This is your basic bad idea.

What he said. While it has a certain cool factor, it's kinda pointless.

The factor DrRocket's referring to is delta-vee. Delta of course means change, and the V stands for velocity. Remember, of course, that velocity is different from speed -- velocity also includes direction. So it takes energy to change from 17,500MPH in one direction to 17,500MPH in a different direction. How much requires math that I don't know the equations to. ;-)

But it is basically just a math and engineering challenge when you get right down to it, and when it comes time to figure out how to achieve the desired delta-vee, the newtons put out by a rocket will become significant. You'll also want to look at specific impulse (the change of momentum per unit of propellant expended), which will tell you how big your gas tank is gonna have to be.

 

[DrRocket]

What he said. While it has a certain cool factor, it's kinda pointless.

The factor DrRocket's referring to is delta-vee. Delta of course means change, and the V stands for velocity. Remember, of course, that velocity is different from speed -- velocity also includes direction. So it takes energy to change from 17,500MPH in one direction to 17,500MPH in a different direction. How much requires math that I don't know the equations to. ;-)

But it is basically just a math and engineering challenge when you get right down to it, and when it comes time to figure out how to achieve the desired delta-vee, the newtons put out by a rocket will become significant. You'll also want to look at specific impulse (the change of momentum per unit of propellant expended), which will tell you how big your gas tank is gonna have to be.

This is only partially correct. Delta-V is indeed change in velocity, but the language as used in the industry is somewhat imprecise and the rocket equation that provides the Delta-V calculation in terms of specific impulse and the log of the ratio of final mass to initial mass really calculates delta speed. It is a one-dimensional analysis that produces that equation.

In any case the orbital parameters are reflective of velocity and position, or equivalently speed, direction and position at any point in the orbit determines the entire orbit. It is speed and not velocity that determines energy, which is what one might expect from the observation that speed adn energy are both scalars, while velocity is a vector. A change in direction in orbit does not require an increase in speed, and hence does not require any increment of energy. What it does require is a change in momentum, momentum also beintg a vector quantity, just velocity times mass. However, as a practical matter the only way to change momentum is to burn rocket fuel and by doing that you also increase speed and gain energy.

If you go from 17500 mph in one direction to 17500 mmph in another direction your kinetic energyis the same before and after. But the momentum before and after are precisely opposite vector quantities, and the maneuver that it takes to make that change will consume propellant and hence require expenditure of chemical energy. How much fuel is expended depends on the precise maneuver performed, hence so does the energy expenditure. Optimal (minimum fuel) maneuvers are impulsive burns.

But in either case the actual force or thrust is secondary to the calculation. You get energy from force times distance (really the dot product of two vectors which produces a scalar), not force alone, and you get momentum from force times time which produces the vector quantity "momentum". Orbital changes are commonly accomplished with rockets of quite low thrust but high Isp, which as you noted tells you how much fuel you need. Isp is measured in terms of momentum per unit mass of fuel expended, or what is equivalent the speed of the exhaust gasses. .

 

[michaelmozina]

Plus GEO is in the van Allan belts and the spacecraft would require additional shielding.

Plus it takes more energy to reach GEO than it does to achieve Earth escape. None of the current support craft could reach the station.

And what would be the point? What could the ISS do in GEO that you can't do more easily in LEO?

Jon

I guess petet addressed the possible reasons for wanting to do it, but I had the same question you had about why you'd want to waste all that additional energy to reach GEO everytime we wanted to visit the station. I also remember the shuddering experienced by one of the recent maneuver operations and it seems unlikely to me that it would be a good idea try to move it that far.