How the hell do i put this up there?

[Moon Goddess]

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

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

Honestly when I read that quote it rings of total sarcasm. The double (triple?) negatives, the weasel words, it's obvious to him that it's not a ringing endorsement, that's why he said it was, it's hyperbole.

[Monkeh]

Now you mention it, Moon Goddess, I think you may be totally correctamundo. I shall retire to the dark and nurse my battered intellect whilst worshipping my new favourite deity.

[Savage117]

I personally like the StarTram idea the most because it sounds the most feasible compared to many other ideas, it's still got it's hurdles but it is technically doable right now, we have all the right technical skills and building materials available. The cons being: it would require enormous amounts of power very quickly for the short and fast track version, also the payload is put under a lot of stress making Personnel transport impossible with the short track version. The long track version sounds like the best bet but it would require a huge amount of high tensile strength materials for the upper parts of the track which would be in the thinner parts of the atmosphere several miles up, so yeah almost prohibitively expensive.

But according to the Wiki, and we all trust the Wiki blindly right? It would take the average cost of a rocket, it says $10k USD, all the way down to, I'm just guesstimating here, to about $100 USD per launch, that’s a huge cost savings, but you spent an awful lot of money building the thing, so not sure when you would start making your money back. 50 years maybe.

The wiki also had this, which is some other ways thrown about on how one would achieve orbit without rockets, StarTram included.

[Idobox]

I like the starstram too, but its difficulty is grossly underestimated.

Building a 300km tunnel with hard vaccuum, at a slope, in mountains is something nobody knows how to do today.

Storing the energy in supraconductors is a project at least on the scale of LHC.

And the thing cannot be used anywhere close to human habitation or endangered wildlife because of the shockwave when entering the atmosphere.

Other types of space guns, like ram guns for example, are more realistic. Of course the acceleration will be much higher, but electronics can survive that if designed properly, and storing energy in chemical form is easy. You still have the issue of dealing with projectiles traveling at orbital speed in dense atmosphere though.

[AeroEngy]

Nothing is going to replace conventional rockets in the near future ... or in the intermediate future ... maybe in the distant future when something total unexpected comes around. The way to make it cheaper is to go the way of SpaceX. Reusable stages, vertically integrated supply chain, common components that are easier to manufacture & assemble. You would be amazed at the extra cost of outsourcing rocket components which most companies do to various degrees.

Although this does make it much cheaper to get stuff into space it is still really expensive. I believe they have a target of around $1000/lb to LEO for their Falcon 9 Heavy ... which is much cheaper than say a Delta IV-H which is around $6,000/lb to LEO. However, they set those prices under the assumption that they would be able to recover and reuse the first stage's engines. As they have not actually been able to do that yet we will have to wait and see if they can maintain those prices.

[3_bit]

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.

This is the exact reason the Proton, with several modifications over the years, is used today: It's mass produced, has a good track record, and is pretty reliable. That's why it is arguably the best launch system today, and is used for so many commercial launches.

[Nibb31]

Mass production is also the rationale behind Ariane 6. The first and second stages use identical solid boosters (3 on the first stage, 1 on the second stage). They are aiming for over 10 launches per year, which requires 40 units per year. Vega and Ariane 5 will use variants of those boosters, and so do the French ICBM M51. SRBs are hard to design, but pretty simple to make, so these should turn out being pretty cheap to produce.

SpaceX actually has a bit of a contradictory plan. On one hand, they are pursuing mass production of Merlin engines, claiming to be able to churn out 400 Merlin engines (or 40 Falcon 9 core stages) per year. On the other hand, they are actively working on reusable first stages. But mass production goes against reusability, because the cheaper they can actually produce those Merlins, the less viable a reusable Falcon becomes.

Edited November 15, 2013 by Nibb31

[TheGeoninja]

From what I have read it is possible with current technology to build a space-elevator on Mars but it would be a bit useless at the moment.

[Ralathon]

From what I have read it is possible with current technology to build a space-elevator on Mars but it would be a bit useless at the moment.

Yea, it's possible to build one out of Kevlar from the moon to L1 as well. The problem with building space elevators is that earth has such a deep gravity well. If we evolved on mars instead we would probably already have one.

[Idobox]

I think space tether to accelerate from sub-orbital to orbital velocities could happen within my lifetime. At least I hope.

If your rockets only 2000m/s of deltaV, everything becomes much cheaper.