Cheap ways of getting to space.

[phlogistician]

But 125 tonnes... they make bridges that can easily hold that kind of weight, so why not a circular track? Especially if it's set into the ground.

Sure, out of concrete, but we're talking about a maglev here. We can't have rails, or wheels, or any contact, as the velocity required far exceeds any capability we have to use traditional chassis,....

So we need to make a maglev that can support and guide 125tonnes at 7000ms, that requires it to be enclosed I think, to safeguard the satellite from any debris that could be blown onto the track. That starts to sound rather expensive,... 50Km of enclosed maglev. Nearly twice the length of the LHC,....

 

[phlogistician]

But on a serious note...I seem to remember talk a decade or so ago about mounting a reusable re-entry vehicle to a large airliner, like a boeing 777, flying it up to maximum altitude for the "parent vehicle" and then launching from there. It would alleviate the cost of massive SRB systems and the huge fuel tank that current shuttle missions use. Come to think of it I thought they (being NASA) were going to begin testing of the idea sometime in the past five years or so... Of course with the flood of accidents and budget cuts it may just be a pipedream at this point.

Er dude, that's exactly the design being used by Burt Rutan. Except it's all custom made.

 

[Pete]

Sure, out of concrete, but we're talking about a maglev here. We can't have rails, or wheels, or any contact, as the velocity required far exceeds any capability we have to use traditional chassis,....

So we need to make a maglev that can support and guide 125tonnes at 7000ms, that requires it to be enclosed I think, to safeguard the satellite from any debris that could be blown onto the track. That starts to sound rather expensive,... 50Km of enclosed maglev. Nearly twice the length of the LHC,....

4km radius means 26km of track, not 50.
Wikipedia say maglev costs around $40 million per km including trains and stations, so about a billion. Double that to make it enclosed and evacuated, I guess.

Maybe doable?

 

[phlogistician]

4km radius means 26km of track, not 50.

oops, I did a quick Pi r^2 in my head,... 2Pi R,.. oops!

Wikipedia say maglev costs around $40 million per km including trains and stations, so about a billion. Double that to make it enclosed and evacuated, I guess.

Maybe doable?

At those numbers,... maybe doable,.... but I guess it's only suitable for non-manned flight,.... but then manned flight is a waste of money anyway, so I'd defo think this is worth a feasibility study,... although the velocities bother me, it's a bit quick.

 

[Pete]

Let's go extreme!

Say a 10km radius for 63km of track, and wind a 1000 kg load up to 12km/s for interplanetary launch capability, or a 1200kg load up to 8km/s for LEO.

That's really simplistic of course, because it completely ignores how our launch vehicle is supposed to cope with exiting the atmosphere at 12km/s, and it still needs to carry fuel to change from launch trajectory to orbit, but I don't know how to figure those parts out. I'll just wave my hands and call it 'minor details' .

So anyway, that's maybe 1500 tonnes weight on a small section of our maglev track, which is going to bump up the engineering challenge. Our costs are also going to be significantly higher than base maglev, because we're running at much(!) higher speeds, which again makes engineering fun.

So, let's say $200million per km, plus padding, for a nice total of $15 billion, or 3 years of space shuttle budget.

Would it be worth it?

A Falcon 1e can lift 1000kg to LEO for about $10million per launch.

So if this system could reduce that cost to $1 million per launch, then we can recoup costs in 1500-2000 launches.

Since there will be few launch windows each year, and the market for LEO launches isn't that great... we should break even in about 100 years. Hmm. Will definitely have to keep construction costs at around that $2 billion mark after all.

 

[Pete]

Cool conference paper from IEEE:
Low-cost propellant launch to LEO from a tethered balloon

 

[kwhilborn]

Surprised nobody has mentioned an obvious real world approach.

http://en.wikipedia.org/wiki/Space_elevator

Yes! Build an elevator into space. Basically a cable has one end in the taxpayers pocket and the other end in outer space.

See the wikipedia link I have posted. This idea has been around for over 100 years and is seen as practical, although building materials for such a cable seem to be a problem at the moment. Not practical for us, but Nasa maybe.

 

[kx000]

Giant catapult?

 

[chimpkin]

Giant catapult?

I've wondered if they could build a giant railgun with some sort of supercapacitor banks, use a wind turbine to build charge?

Basically a giant space cannon to shoot things into orbit.

I kind of assume that would be for launching large amounts of cargo only. Assuming anything alive would go all red and squishy under acceleration.

 

[Nasor]

So if this system could reduce that cost to $1 million per launch, then we can recoup costs in 1500-2000 launches.

Since there will be few launch windows each year, and the market for LEO launches isn't that great... we should break even in about 100 years. Hmm. Will definitely have to keep construction costs at around that $2 billion mark after all.

I suspect that such a system would have very high fixed costs and very low marginal costs per launch, so the average "cost per launch" would depend very heavily on how often you used it.

 

[phlogistician]

I've wondered if they could build a giant railgun with some sort of supercapacitor banks, use a wind turbine to build charge?

Basically a giant space cannon to shoot things into orbit.

I kind of assume that would be for launching large amounts of cargo only. Assuming anything alive would go all red and squishy under acceleration.

I think you'd pretty much break anything you launched that way! You'd need a really long barrel to spread out the acceleration, hence the discussions of maglevs and tracks tens of kilometres long.

 

[hombre]

I bet it's possible to blast objects into space from the tops of tall mountains.

 

[phlogistician]

I bet it's possible to blast objects into space from the tops of tall mountains.

Wow, why have none of the eggheads at NASA thought of this?

Is it because it's a stupid idea? Everest is just under 9km tall. The low part of an LEO is about 160km, so hauling everything up Everest still means you need to be able to climb 151 kilometres, so you've not saved much fuel. Plus there's no road, it's really cold, and the weather can close it off, making launches impossible.

You could try and pick a place with infrastructure,... near a city, at least there would be roads and services, ... somewhere like La Paz in Bolivia, or Quito, in Ecuador, but they are around 3000m, so you are gaining even less altitude. At least Quito is near the Equator though, so you'll get a boost from the rotation of the Earth.

 

[hombre]

Why do forums have to be this way? I guess they do, they're all the same. This is why adults stay away.

Why not estimate how much atmosphere mass-wise is in the lower 9km? Why not estimate how much risk and rocket mass is eliminated by traveling up the low 9km?

Also I did not say 'Everest'. Also I did not mean a rocket. I meant a projectile, from a shooter, at a high elevation.

 

[billvon]

I bet it's possible to blast objects into space from the tops of tall mountains.

Sure it is. It's also possible to blast them into space from the bottom of Death Valley. It's just that neither one has significant advantages over (for example) launching them near the equator.

 

[billvon]

I've wondered if they could build a giant railgun with some sort of supercapacitor banks, use a wind turbine to build charge?

I think you'd pretty much break anything you launched that way!

Hmm. Artillery shells experience accelerations of 13,000 G's - and yet they build guidance systems and telemetry systems into them.

You probably wouldn't be able to launch anything living that way. But electronics/propulsion/fuel - I bet you could design a vehicle that could survive those accelerations.

 

[Pincho Paxton]

I bet it's possible to blast objects into space from the tops of tall mountains.

I was thinking about the neutrinos in the mountain today. Funny.

 

[phlogistician]

Why do forums have to be this way? I guess they do, they're all the same. This is why adults stay away.

I am an adult, and I used to work with a bunch of Astronomers and engineers, so retain an interest in Rocketry.

Why not estimate how much atmosphere mass-wise is in the lower 9km? Why not estimate how much risk and rocket mass is eliminated by traveling up the low 9km?

You think hauling a rocket up to the freezing heights of 9km is going to eliminate risks? You are aware of the Challenger disaster? That it was a frozen 'o' ring that caused that? Familiar materials behave in less than optimal ways at low temperatures. I've had equipment fail on me at -23degC/3500m that works just fine when it's simply chilly.

Also I did not say 'Everest'.

No, I did. To illustrate that if you go to the highest point on Earth, you only shorten your journey of 160km, by 9km. Now, do you drive? Would you drive up Everest, to shorten your overall car journey by 9km?

I then gave some other options, cities that are at elevation. Cities, that have roads leading to them, so you could at least transport your rocket and staff to the launch site,... but they are only around 3000m up, so of even less gain.

Also I did not mean a rocket. I meant a projectile, from a shooter, at a high elevation.

'from a shooter', .. such a technical exposition! Are you labouring under the impression that it's nearly feasible, bar the last few Km?

 

[phlogistician]

Hmm. Artillery shells experience accelerations of 13,000 G's - and yet they build guidance systems and telemetry systems into them.

That is true, but Satellites are far more complex, so I don't think it's a fair comparison. Weight is the enemy or rocketry, so satellites are engineered to be as light as possible, and therefore there are limits on how robust they can be made. I don't see mechanisms that unfurl solar panels surviving that kind of acceleration for one. While artillery shells are heavy, they aren't complex, when compared to a satellite, and are much smaller and more dense.

I also kinda think if it could be done, we'd be doing it already. There have been many 'super gun' projects, and while they got close to the numbers required, never (unless it's classified, but I doubt that, as they are energetic events when they go off, and are hard to conceal) managed to get anything into orbit. The last attempt at building such was the 'Iraqi Super Gun' in the 90's, but they never managed to get the parts to build the full sized version, as the international security community realised what they were up to.

 

[adoucette]

Why not estimate how much atmosphere mass-wise is in the lower 9km? Why not estimate how much risk and rocket mass is eliminated by traveling up the low 9km?

Why not consider where the Shuttle is at SRB separation?

It's 2 minutes into the flight.

It's at an altitude of 150,000 ft (46 km)

But more importantly, it has increased its velocity by over 3,000 mph

In comparison, being a mile or so up and having zero velocity is pretty much nothing.