How the hell do i put this up there?

[MC.STEEL]

So we all know that chemical rockets just arent going to cut it and the space-a-vator seems a little far from reality.So is there a (less loony) way to send things to orbit?

fusion rockets

advanced plasma propulsion(V.A.S.M.R.)/crazy powerfull ion engines like the one in ksp (it has about 0.50 rl ones have even lower than that) [dont quote me on this]

blimps?

also does VSMR have a higher TWR than 1

[N_las]

Why do you think that chemical rockets just arent going to cut it? The work perfektly fine...

[MC.STEEL]

Why do you think that chemical rockets just arent going to cut it? The work perfektly fine...

oh they work perfect but the small detail there is that they are just too expensive

[Seret]

oh they work perfect but the small detail there is that they are just too expensive

Cheaper and more reliable than anything else though. That's why we use 'em.

I do agree though that we need a cheaper route to space. I don't think incremental improvement of current rockets is going to bring about a revolutionary reduction in cost, it's going to take a breakthrough technology. Where that comes from is anybody's guess.

[Superfluous J]

This calls for a big rail gun going up the side of a mountain.

[sgtscuba]

This calls for a big rail gun going up the side of a mountain.

Actually that would be a semi good idea, and has been sort of done during project HAARP

[Charlie089]

Most of the cost in a rocket is NOT the fuel. It's the rocket itself. If I remember correctly, 90% of the cost of the rocket is assembly and parts, with a few percent as fuel. Enter SpaceX and reusable rockets stage left.

[Nibb31]

oh they work perfect but the small detail there is that they are just too expensive

Not really. They are pretty cheap for what they do. The problem is pesky physics. You have a payload, and you want to accelerate that payload from 0 to 24000km/h. However you look at it, it's always going to take a lot of energy and that is always going to be expensive and complicated.

[MC.STEEL]

idk a saturn V doesent look to cheap to me

and its not just cost its efficency why lift all that rocket fuel when you can have a cars fuel tank full of xenon for instance

[Nibb31]

Because a car's tank fuel of xenon can't be converted into the amount of kinetic energy that is needed to push a 100t payload to orbital speed.

F=ma. Newton sucks.

The kinetic energy required to accelerate 100 tons to 8km/s is 3,200,000,000,000 joules or 3.2 Terajoules. That's just for the payload. You also need to move whatever device is necessary to produce that amount of kinetic energy and usable thrust (i.e. the rocket itself), which in most cases will have to weigh several times the mass of the payload.

Edited November 13, 2013 by Nibb31

[J.Random]

Because a car's tank fuel of xenon can't be converted into the amount of energy that is needed to push a 100t payload from 0 to 24000 km/h.

F=ma. Newton sucks.

Gravity sucks. And sir Isaac Newton is the deadliest SoB in space.

[Ralathon]

Funnily enough, putting the payload on top of gigantic ongoing explosion is the least crazy way we've managed to think up to get into space...

The problem with engines like VASMR, ion and fusion is that they require near vacuum to operate and they have horrible thrust to weight ratios. The reason for that is simple: Isp is based on exit velocity. So if you spew out matter twice as fast you get twice the Isp. Thrust is based on exit velocity times mass flow, so twice the exit velocity means twice the thrust. But, energy scales with velocity squared, so you'll need 4 times the energy to double your Isp.

Your spacecraft only has a limited amount of energy at its disposal. It can only draw so many watts from its power source. So you have to pick between pumping out a lot of mass at low speeds (high thrust, low Isp) or pumping a small amount of mass at high speed (low thrust high Isp). In the high thrust - low Isp area chemical engines win by a landslide. The reason is that they use their reaction mass as energy source, this way they don't need to drag a heavy nuclear reactor around.

Blimps wouldn't really help either, the main hurdle to get into space is getting up to orbital speed, not exiting the atmosphere.

The spacehook could be an idea here. You essentially have a long rope with a counterweight in low earth orbit and make sure that it spins in such a way that the tip dips into the atmosphere and moves slowly relative to the surface. You could then 'catch' the tip using an aircraft when the hook is at it's lowest point and the spacehook would lift you into space. Then you just have to release the cable when you picked up enough lateral velocity and circularize.

Obviously the skyhook would start to deorbit after a while thanks to atmospheric drag and the spaceships leeching momentum, so you'd have to occasionally grab an asteroid or container with heavy stuff and lower it down to earth to maintain orbit. The space elevator is actually a special case of the skyhook, but thanks to the enormous length the elevator is much harder to build than a space hook would be. It still has some serious downsides though, the physics of long cables in orbit are really weird and difficult to predict. Not to mention you have to grab a hook moving at immense speed in the upper atmosphere.

Other ideas could be a giant cannon, a maglev train suspended above the atmosphere via centripetal force and ablating a block of metal remotely with a giant array of ground based lasers. All of these ideas are absolutely bonkers and have major technological hurdles. So, until we manage to get more efficient energy storage/generation or we have some major breakthroughs in material science that makes one of the above ideas possible we're stuck with rockets I'm afraid.

[Dunbaratu]

This calls for a big rail gun going up the side of a mountain.

The problem with those sorts of suggestions is that the G forces involved would ruin most payloads. You have to get up to orbital velocity in just a few kilometers. The amount of acceleration that takes is enormous. Even if you have the technology to make the rail gun that can do that, you then have the problem of making the payload, be it people or computerized probes, survive it.

[Tommygun]

There are several ideas that involve laser propulsion for lower cost launches.

I think it may be a more cost effective way to go.

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

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

[NASAFanboy]

So we all know that chemical rockets just arent going to cut it and the space-a-vator seems a little far from reality.So is there a (less loony) way to send things to orbit?

fusion rockets

advanced plasma propulsion(V.A.S.M.R.)/crazy powerfull ion engines like the one in ksp (it has about 0.50 rl ones have even lower than that) [dont quote me on this]

blimps?

also does VSMR have a higher TWR than 1

Grammar, spelling, and capitalization, my dear friend. That's very important....

Currently, we have two options. Chemical rockets, or nuclear pulse propulsion, the latter which would send the Presidential poll ratings down to the single digits and make Greenpeace attack the NASA HQ with oversized branches from local trees.

VASMIR can work, and so can ion engines...but they are impossible to use in a atmosphere. Hell, one large ion engine might be enough to float a piece paper on it for a couple seconds, until it runs out of battery/Xenon (And the KSP ones, at most, might float a paper for a full hour.) Fusion cannot be *practically* achieved as of today (But yes, it can be achieved, and we DO have experiential reactors throughout the world), and NERVA will also send Greenpeace attacking NASA HQ with oversized tree branches and picket signs. Blimps are a possibility, but not proven. Laser propulsion seems a little promising, but I wouldn't bet on it...it simply seems "too optimistic", even for me (Though might work in a

vacuum and be used for direct ascent from the Moon..bring your own air)

Our best hope is something similar to a SSTO (Hurry up, SABRE!).

Let's stick with Chemical for now....Newton can be a real ***** sometimes, can't he? Just hold still and hope.

Edited November 13, 2013 by NASAFanboy

[Monkeh]

Adam Roberts speculated an idea in his excellent novel, Gradisil. Here he explains it..a bit...kinda.

Adam Says:

With Gradisil I wanted to find a way in which ordinary people could start to colonise space under their own steam. Up until now, after all, getting into orbit has been so ruinously expensive that only national governments (and latterly very wealthy corporations) have been able to manage it. You can't extrapolate colonisation from that premise: it'd be as if getting across the Atlantic to America in the 19th century had cost so much that only European Governments and the Rothschilds could afford to send settlers - and they'd be a select group of ex-military team-thinkers who'd execute government orders and then sail home after a couple of months. Under those circumstances there would never have been an America.

The problem is that rockets are expensive. No way round that. So I needed a plausible means of getting into orbit that didn't involve rockets. I imagined a technology you could fit to any regular jet-plane or private flier that used resistance to the Earth's magnetic field to 'fly' into orbit. When I ran the idea past Stephen Baxter he did not say that it was not without the possibility of never working in real life. At all. I took this to be a ringing endorsement

Great book by the way, most here would find it interesting I would think.

From here btw: http://www.adamroberts.com/writing/gradisil/

Edited November 13, 2013 by Monkeh

[Nibb31]

I imagined a technology you could fit to any regular jet-plane or private flier that used resistance to the Earth's magnetic field to 'fly' into orbit.

Whatever you do, you can't get around that pesky F=ma equation. Therefore, extreme amounts of kinetic energy will always be required to achieve orbital speed. You will always need an extremely high power energy source and a means to convert that power into thrust. There will always be inefficiencies in that conversion. You will always need some sort of consumable to be expelled if you want to produce thrust and you will always need to carry that consumable with you.

We might one day manage to pack high energy into small packages. We might even make those packages relatively cheap. But I doubt that such packages will ever be available to private individuals because of safety issues and the devastation that they could cause if they were misused. How would you feel if every car on the road had the explosion potential of a tactical nuke?

In the meantime, high output energy sources require heavy equipment. It's as simple as that.

[Monkeh]

I think in the book he described the planes almost climbing magno bars, (my name for magnetic isobars), like rungs on a ladder.

Obviously this is science fiction but if Stephen Baxter says it could be so, then I'm not arguing. Baxter is a boss.

[Idobox]

The JAXA is looking into blimps. the idea is to go very high, where air resistance is much smaller, and use a low thrust, highly efficient drive (not sure if they chose one) to accelerate to orbital speed over a long time.

Railguns are impractical, but maglev have been proposed (startram), as well as ram guns (a tube fuel of fuel-oxydizer mix, with a projectile speeding through it, looking a lot like a ramjet). You can either have short tracks and insane accelerations (impossible with maglev, no way to store enough electricity), or longer tracks (more expensive). In both cases, you have projectiles travelling at orbital speeds at low altitude.

The is also the launch loop, which could work, but that we'll never build.

I love the idea of beam powered scramjets, but I don't think they're very realistic either.

Rotovators and other space tether concepts are probably our best bet for the foreseeable future, but you will still need to get suborbital.

I remember reading a proposal to build a rotovator in LEO, and another in low Moon orbit. The idea being to send moon rocks to Earth to "charge" the rotovators with kinetic energy (the Moon surface is on a higher potential energy level than Earth) and use it to accelerate spacecrafts from Earth to wherever you want them.

[Nibb31]

There's a difference between "ringing endorsement" and "not bothering to contradict science fiction technobabble". IMO, that Adam Roberts quote is quite presomptuous.

[NASAFanboy]

I think in the book he described the planes almost climbing magno bars, (my name for magnetic isobars), like rungs on a ladder.

Obviously this is science fiction but if Stephen Baxter says it could be so, then I'm not arguing. Baxter is a boss.

While Stephen Baxter is a good hard sci-fi novel writer, I do not believe that magnetic currents are strong enough to hoist ANYTHING to orbit, and even he will take liberties with physics (Titan. Going to Saturn on a Saturn V with a space shuttle...space does not work that way)

It's a novel, not a textbook.

Blimps are are a probability, but they probably won't come to light in the near future. SSTOs are the way.

[Monkeh]

Yeah, Adam Roberts wrote a book where people who committed one of three crimes had their heads chopped off but we're kept alive. The obvious and blatant sign of their disgusting past causing much social leprosy.

I should have known not to trust his work! I love Adam Roberts and Land Of The Headless is an AMAZING book.

[Ralathon]

I think in the book he described the planes almost climbing magno bars, (my name for magnetic isobars), like rungs on a ladder.

Obviously this is science fiction but if Stephen Baxter says it could be so, then I'm not arguing. Baxter is a boss.

Stephen Baxter might be a good scifi writer, but he is still that, a writer.

The earth's magnetic field is:

A) Very weak, maximum of about 1e-4 T on the surface.

Very uniform, because the planet is simply very big.

This makes it useless for levitation or propulsion. In a uniform magnetic field it doesn't matter how you move something, the energy stored in the combined magnetic field will be the same regardless. No change in energy = no force = nothing to hold on to. For example, for magnetic levitation to occur the following threshold needs to be satisfied:

B*(dB/dz) = u₀*density*(g/X).

For a perfect superconductor X (How easy it is for the magnetic field to penetrate it) will always be -1. This means perfect deflection, no magnetic field can ever enter the material, so this is the best possible case. Let's be kind and say the earth's magnetic field extends 1000km from the surface and uniformly decays over that distance. So dB/dz = 1e-10 T/m. u₀ is defined as 4*pi*10^-7 so we know a superconductor needs a density of 8.1e-10 kg/m^3 or less to keep itself afloat in the earth's magnetic field at sea level (it gets worse when you go higher up).

Considering that the same volume of air at sea level weighs 1.4 billion times more, I reckon that's a bit of a tall order. If you wanted to levitate a payload of 1kg and you had magical superconductors that weighed nothing at all, you'd need a sphere with a diameter of nearly 1.3 km to keep it levitated. Not very practical...

Science fiction is fun and all, but don't take what they say at face value. It is meant to entertain, not inform.

[NASI Director]

Don't quote me on this, but I think that there is certain ratio with payload:rocket depending on the type of rocket. To achieve the minimum altitude to orbit for a 10 tonne object, the launcher would be (please don't quote me on this!) a lot more, increasing predictably as the mass of the payload increases. An SSTO would have a smaller ratio than a 5 stage rocket. An antimatter propulsion system would have a smaller ratio than the SSTO, and so on and so forth as the efficiency increases.

[magnemoe]

Don't quote me on this, but I think that there is certain ratio with payload:rocket depending on the type of rocket. To achieve the minimum altitude to orbit for a 10 tonne object, the launcher would be (please don't quote me on this!) a lot more, increasing predictably as the mass of the payload increases. An SSTO would have a smaller ratio than a 5 stage rocket. An antimatter propulsion system would have a smaller ratio than the SSTO, and so on and so forth as the efficiency increases.

Payload faction mainly on the efficiency of the fuel but also the dry mass of the ship. The last is why SSTO has bad payload rations you has to bring all the dry mass and cargo up and the dry mass down again.

You can cheat, say you use an hotol plane to deploy an satellite to GEO or other high orbits you need an transfer stage anyway. Now if you don't take the hotol into orbit but just go suborbital you need less fuel and oxidizer so you can carry an larger transfer stage, this large transfer stage only has to carry the satellite and the fuel needed from LEO to GEO in addition to the fuel needed to reach orbit so you can increase the payload a lot.