Nanotechnology, nuclear fusion, imaging a life-bearing exoplanet, an interstellar mission (unmanned or manned).
SolarKinetic Pulse Propulsion could provide cheap access to space, if the sailbots are cheap enough. Not just LEO, but really the entire Solar System.
Quote from: IsaacKuo on 06/02/2011 04:37 pmSolarKinetic Pulse Propulsion could provide cheap access to space, if the sailbots are cheap enough. Not just LEO, but really the entire Solar System.About the cost of the sailbots--the 30cm square of aluminized kapton costs almost nothing, so the main cost is the control chip.If the control chips can be mass produced at a cost of under $1 per chip, this adds up to under $100 per kg to GTO, or under $70 per kg to LEO.
I'm interested in perfecting the process to increase the purity of fused silica. The windows on the shuttle are made of a composite of aluminum silicate glass and fused silica glass, in 3 separate panes; an outside thermal pane, a center optical pane that is approximately 3 & 1/2 inches (89 mm) thick and an interior pressure pane that is part of the cockpit pressurization system. So there is plenty of precedent for its use in spacecraft.Fused silica, if pure enough, would enable the practical development of the nuclear lightbulb NTR engine, using uranium hexafloride gas as the reactant and LH2 as the propellant. This engine would be safe enough for ground launch and would provide *enormous* thrust and an isp in the tens of thousands of seconds. That would be a true game changer in propulsion.
Quote from: clongton on 06/02/2011 08:50 pmI'm interested in perfecting the process to increase the purity of fused silica. The windows on the shuttle are made of a composite of aluminum silicate glass and fused silica glass, in 3 separate panes; an outside thermal pane, a center optical pane that is approximately 3 & 1/2 inches (89 mm) thick and an interior pressure pane that is part of the cockpit pressurization system. So there is plenty of precedent for its use in spacecraft.Fused silica, if pure enough, would enable the practical development of the nuclear lightbulb NTR engine, using uranium hexafloride gas as the reactant and LH2 as the propellant. This engine would be safe enough for ground launch and would provide *enormous* thrust and an isp in the tens of thousands of seconds. That would be a true game changer in propulsion.Chuck,Is this because any impurities in the quartz/silica would not be transparent to the UV radiation and hence heat up uncontrollably and damage the window?-Jim
Quote from: IsaacKuo on 06/02/2011 04:37 pmSolarKinetic Pulse Propulsion could provide cheap access to space, if the sailbots are cheap enough. Not just LEO, but really the entire Solar System.This reminds me a bit of my slightly kooky "beamed regolith propulsion" launcher The idea was to deliver cargoes of super fine regolith dust from the moon to LEO. The dust is dispersed like a long column of smoke in the path of a suborbital craft. Because this dust is moving at orbital velocity, or even faster if it still retains its velocity from the trip from the moon, it can apply a force against the heatshield of the craft accelerating it to orbital velocity.
It is also a lot like the overhead magnetic monorail idea. I can't really claim that because it is just an orbital ring without the elevator/tower. It really only differs from the solar kinetic idea in that the chain of satellites apply force magnetically, like a magnetic train track, so they are reusable but I guess must be much more massive.
I've always liked the Scifi idea of force fields. Have no idea how to start the construction of one but a force field having the strength of a steel cylinder with no or very little mass would sure improve the mass ratio of solid rockets. Of course Vasimr already uses a magnetic field for its rocket nozzle so that is a kind of force field.
Yes, it needs to be MUCH more massive. It requires a huge initial investment of many orders of magnitude launch mass compared to the payload. Like any other scheme involving a huge initial investment, it only makes sense if there are going to be an extremely high number of launches.SolarKinetic is unique in that its initial investment is an order of magnitude LESS mass than its payload capacity. The incredibly high impact velocities mean that 1 ton of sailbots can lift 10 tons of payload to GTO, or 14 tons of payload to LEO.
Quote from: IsaacKuo on 06/06/2011 10:44 amSolarKinetic is unique in that its initial investment is an order of magnitude LESS mass than its payload capacity. The incredibly high impact velocities mean that 1 ton of sailbots can lift 10 tons of payload to GTO, or 14 tons of payload to LEO.Good points.. I know what Jim would say about the suborbital rendezvous though. Version 1.0 could just be about raising orbits.
SolarKinetic is unique in that its initial investment is an order of magnitude LESS mass than its payload capacity. The incredibly high impact velocities mean that 1 ton of sailbots can lift 10 tons of payload to GTO, or 14 tons of payload to LEO.
I like that the weight to begin testing it is minuscule since you would begin by navigating a single sail into a retrograde orbit.
Reminds me a bit of my 'solar butterflies' idea...
Im still sort of in love with that orbital ring, but for a distant future where there is so much urban sprawl in LEO that the ring also serves as their subway. Its certainly not happening anytime soon.
Solar butterflies was just various speculations about the sorts of megascale engineering you could do with a flock of solar sails that do nothing but control their own angle, especially if self reproducing. I imagined a single element looking sort of like a butterfly with a tiny body.
Paste form is quite a disadvantage
The orbital ring can accelerate you as gently as you like, take a suborbital craft up to at least twice orbital velocity, and also reverse this, taking an incoming craft back to earth velocity.
Why is matching transverse velocity hard? That means sideways right? I see it as essentially landing on a runway except there is no weather up there.
There would probably be a tram with a cable that latches on when you get to within a few meters or hundred meters so the suborbital craft does not need to carry heavy magnets. Docking with that I guess would be a bit like inflight refueling.
The ring would not need to be a solid piece. An accident would only wipe out the tram, a few segments and possibly not even the craft given it is on a cable.
What other ideas do you see as becoming practical with a large infrastructure? Beamed power would be a complementary addition. I never liked space elevators, rotovators only a little better.
Quote from: aero on 06/06/2011 05:26 amI've always liked the Scifi idea of force fields. Have no idea how to start the construction of one but a force field having the strength of a steel cylinder with no or very little mass would sure improve the mass ratio of solid rockets. Of course Vasimr already uses a magnetic field for its rocket nozzle so that is a kind of force field. Not sure if its strength is at that level, but there is such a tech restricted to inch-scales due to power requirements.
Unfortunately, an accident would cause an explosion of debris, and half of the nearby ring is screaming toward the debris at 8km/s. The initial cloud of debris is mostly only a threat for a some seconds, as gravity pulls it down to Earth. But in the meantime, many kilometers of orbital ring will be shredded by it--and THIS will result in a stupendous amount of space junk in orbit. This secondary debris will repeatedly return to the path of the orbital ring. Each bit of debris will pass near the ring twice every 90 minutes until it hits.
Quote from: IsaacKuo on 06/10/2011 03:37 pmUnfortunately, an accident would cause an explosion of debris, and half of the nearby ring is screaming toward the debris at 8km/s. The initial cloud of debris is mostly only a threat for a some seconds, as gravity pulls it down to Earth. But in the meantime, many kilometers of orbital ring will be shredded by it--and THIS will result in a stupendous amount of space junk in orbit. This secondary debris will repeatedly return to the path of the orbital ring. Each bit of debris will pass near the ring twice every 90 minutes until it hits.I don't see it happening that way. As you say any elements moving at 8km/s relative to the ring would remove themselves immediately.
The arc of any fragment travelling from a point on the ring has to travel halfway around the world before it possibly intersects the ring again.
Therefore any fragment with less than orbital velocity should be removed by that point. Since the ring is in as low an orbit as possible (and having no forward surface this can be lower than for any usual satellite), any trajectory which is not extremely exact will intersect deep into earths atmosphere and be removed.
Most of the extremely exact trajectories that do survive would be essentially inline with the ring and have low relative velocities.