The New Space Race
alumni.hbs.edu
alumni.hbs.edu
0. https://www.quora.com/Why-were-Neil-Armstrong-Eugene-Cernan-...
https://www.reddit.com/r/IAmA/comments/2a5vg8/i_am_buzz_aldr...
This is quite a strange statement. Not even with multiple stages? Not even Saturn-V would be able to lift a cubesat - with necessary extra stages? I'd like to see numbers which support that.
Note that the 50% figure refers to escaping fat-Earth's gravity well with a single launch, as opposed to putting things into orbit.
The size, complexity, and costs of extra stages make it impossible once you add in the actual real-world constraints. As said in Terr_'s link: "Rockets at 85% propellant and 15% structure and payload are on the extreme edge of our engineering ability to even fabricate (and to pay for!). They require constant engineering to keep flying."
This is a link on a NASA website :) and that organization is known to err in questions related to space. Seriously, guys - Don Pettit wrote it for general audience, and skimming the article I spotted this -
> Hydrogen-oxygen is the most energetic chemical reaction known for use in a human rated rocket. Chemistry is unable to give us any more.
This can be understood in a certain way - but also can be argued, as here - http://yarchive.net/space/rocket/fuels/hydrogen.html
> The highest measured Isp ever achieved with chemical propellants was with LH2/LF2/LLi (yes, liquid lithium), at 542s in vacuum.
Next, 15% structure certainly doesn't apply to some first stages - particularly recent Falcons from SpaceX.
The point which I was trying to make is I doubt that big of a difference. Sure, it's pretty hard to get to orbit from, say, Jupiter-like planet. However orbital speed for a planet with constant density is linear by the planet radius, and to get to New Horizons' ~16 km/s delta V as orbital speed the Earth would have to be 2 times bigger - 8 times heavier. And New Horizon's ain't cubesat either.
And, on top of that, we still have other readily available tricks up our sleeve. So I think even with rather large variations of Earth size we'd get in time to the stars.
Besides, we aren't actually at the limit of even modern materials. Rockets were built decades ago - and comparatively slowly evolved ever since. SpaceX demonstrates the hidden opportunities.
Also, traditionally, external capital has sought out downstream opportunities. We've been focussing on upstream tech and it's much harder to prove the case given the long time horizon.
I've seen some incredible applications being pitched, but I think the real test will be whether they are able to generate significant exits. I, for one, hope that the next five years spells a period of immense productivity in the sector, generating profitability all along the value chain. If we're able to ride that wave, I think that there are many more applications that will pop up that make use of space infrastructure.