Slashdot Mirror
"Slingatron" To Hurl Payloads Into Orbit
cylonlover writes "People have been shooting things into space since the 1940s, but in every case this has involved using rockets. This works, but it's incredibly expensive with the cheapest launch costs hovering around $2,000 per pound. This is in part because almost every bit of the rocket is either destroyed or rendered unusable once it has put the payload into orbit. Reusable launch vehicles like the SpaceX Grasshopper offer one way to bring costs down, but another approach is to dump the rockets altogether and hurl payloads into orbit. That's what HyperV Technologies Corp. of Chantilly, Virginia is hoping to achieve with a 'mechanical hypervelocity mass accelerator' called the slingatron."
Out of curiosity, why aren't mass drivers feasible for this sort of thing? You could build one up a mountainside near the equator - something like Mt. Chimborazo (6200+ meters) and drastically reduce the amount of fuel needed to get anything into space. By making the thing several kilometers long, you'd also massively lower the material strains on any craft (you probably still couldn't send humans up, but you'd have far less limits on how sensitive your cargo could be.)
The slingshot sounds like an extremely limited tool - you'd still need a high degree of complexity for things like guidance systems and engines, because of drag you probably couldn't launch anything right into space without at least a partial boost. A mass driver would only get your cargo up to equivalent speeds once it got to the "muzzle", which would ideally be located at very high altitudes with thin air...
Cole's Law: Thinly sliced cabbage
They're going to launch it from the surface at orbital velocity? It would burn up from the air friction inside the Slingitron itself before hitting orbital velocity. If it didn't (i.e. it was a vacuum inside the Slingitron) - it would as soon as it hit the outside air. Meteorites and returning spacecraft do this (in the opposite direction) when the reenter the Earth's atmosphere. Watch how much the atmosphere slows them down (and burns them up). Why wouldn't this happen from a Slingitron launch? This issue was never even addressed in the video.
Have they actually studied physics? This project is so bogus on multiple levels:
1) It's much easier to use a linear accelerator. It won't have to deal with tremendous loads from centrifugal forces, for one thing.
2) Acceleration will be murderous for anything that's not a solid material.
3) And finally, it still won't work even if a payload is accelerated to orbital speed. That's because the payload would re-enter the atmosphere and return to the point where it left the accelerator at the end of its first orbit - that's simple freaking orbital mechanics. And you need quite a bit of delta-v to lift the perigee high enough to avoid it, which requires a rocket with an engine, see 2) why it's not feasible.
A surprisingly large amount of stuff sent into low earth orbit and even geosynchronous orbit consists of fuel and oxidiser. The Shuttle launched with over 14 tonnes of manoeuvering fuel and oxidiser on board for the OMS and RCS motors. That's 14 tonnes that couldn't be dedicated to payload, food, water etc. Similarly a geosynchrononous satellite weighing 6 tonnes will be carrying two or three tones of fuel and oxidiser so it can maneuver into its final orbit and allow it to maintain station for a decade or more. Some GEO birds have been decommissioned when they nearly ran out of fuel, not because they broke down or became obsolete.
Using a slingshot or other brute-force technique to put tanks of fuel and oxidiser into orbit cheaply could well be worthwhile; robot tugs could collect them into a tank farm of some kind in a higher orbit and then deliver fuel and oxidiser to various vehicles as needed rather than them having to lift their entire fuel and oxidiser loads along with delicate electronics, structural components for Mars landers, fleshy meatbags etc.
The maximum exhaust velocity of a Space Shuttle engine is approximately 10,000 mph, they are shooting for a velocity much higher than this. Why not use the Slingatron as a direct propulsion device once in space? You could use solar or nuclear to generate the electricity then your fuel could be anything. You can use all your waste as propellant, just fling it away, or cannibalize unneeded (spent) portions of your ship as you go. You could use BB sized objects as the propellant so I imagine this thing could be scaled to a something easily within current launch capabilities.
Letter To Iran
Sorry, but given a "plurality rules" voting system, that won't work. If a majority of votes were required, that would be a defensible tactic. This is why I favor either Condorcet voting or IRV (Instant Runoff Voting.).
I will agree that there is no perfect way of counting votes, but plurality rules is worse than most of the options. In fact I would consider it significanlty worse than slection by lottery.
I think we've pushed this "anyone can grow up to be president" thing too far.
1 and 5, sure. 3 is iffy. 2 and 4 are out of the question.