The Next Generation of Human Spaceflight

[chrismb]

errr.... . I have written 'Field', as put in inverted commas, because in the Standard Model any 'field' has a related mediating particle. I am not aware that Einstein ever indicated the existence of a mediating particle for gravity.

The mathematical notion of a field is quite different. I'm happy to have gravity described as a field, but it is not a physical field as per SM. General relativity 'merely' describes electrodynamic motion as 4 simultaneuous equations which solve for time-variant solutions in a 4-field.

What kind of physicist are you?

[GIThruster]

I'm not a physicist, but I'm not pretending I know gravity better than Einstein either. . .sheesh.

[chrismb]

OK. That seems settled as I have not made any claims about Einstein's knoweldge of gravity. Back to the question at hand; where can I see evidence of light-pressure on objects in space?

[GIThruster]

Both the Mariner 10 mission, which flew by the planets Mercury and Venus, and the MESSENGER mission to Mercury demonstrated the use of solar pressure as a method of attitude control in order to conserve attitude-control propellant. Hayabusa also used solar pressure as a method of attitude control to compensate for broken reaction wheels and chemical thruster.

from:

http://en.wikipedia.org/wiki/Solar_sail ... de_control

[chrismb]

The information you provide looks fine. Roll on a practical demonstration of primary propulsion by light-pressure, independent of the effects of gravity and solar wind....

[GIThruster]

Not my thing. I think solar sailing is a dopey idea for anything other than robotic missions to the outer planets, when it doesn't much matter how long a mission takes. I'm much more interested in human spaceflight and especially fast missions.

[rjaypeters]

I think you misunderstood the report. 2 things: first is this is not an accounting report. This is a NIAC report. It doesn't do any hard number crunching. They made a guess.

Second thing is the $1 billion figure is not for a laser projector. It's what they guessed would be necessary to develop a 100 MW laser. That's development only, it does not include the cost of building them and as stated previously, you need a lot of them. As something circles the globe it will be continually going out of direct line of sight.

Yeah, I had to read fast, but I can tell the difference between an accounting for a built project and a speculative report. Everything gets taken with large grains of salt. Still...

$US 1Billion for development + $US 2Billion for construction (near the end of the report). Still much less than $US 1Trillion.

Oh, I don't know, infrastructure isn't always evil. This infrastructure is largely on the ground, with all the attendant good (it's accessible) and bad (it's accessible) points. I actually have another potential objection to the heat exchanger concept:

In a previous life, I worked for a heat exchanger company and we had to be careful not to run the working fluid too fast through the heat exchanger or the material would erode. Something to watch as one balances mass and performance.

This is an infrastructure rich architecture. It's not the right way to lower launch costs. Remember, fuel is the smallest portion of launch cost. Infrastructure costs much more and the laser solution is going to require much larger infrastructure and a larger standing army of engineers. The cost would be astronomical.

Yes, the infrastructure doesn't get accelerated to orbit each time we want payload to go someplace. We end up accelerating much less mass each time. And that's the advantage. Laser launch arrays let us continue to send up consumables and commodities while we save the TRITON VentureStar for the bigger/awkward payloads.

Standing army of engineers? No, we get fired as soon as the executives and accountants figure they don't need us anymore.

Conversely, once you have a TRITON, you have what's needed for both launch and exploration, and you have flexibility you do not have with stationary laser stations that have severe limitations as to the orbits they can contribute to.

Pick a location on earth, it will be better suited for some launch azimuths than others. The equatorial locations have the array extend to the east. Higher latitude locations extend the array in more polar directions. What, you thought we'd build only one launch location?

About your later posts.

About the X-33, nobody knew how to build that tank, then. Aerospike and linear aerospikes are pretty cool, but I try not to love anything that can't love me back...so I'd be happy to use good old de Laval nozzles if they work better.

Yeah, I keep an eye on that Burt Rutan... always thinking and not telling us what he's thinking. Sounds like another group of people who frustrate us.

[GIThruster]

$US 1Billion for development + $US 2Billion for construction (near the end of the report). Still much less than $US 1Trillion. . .

Oh, I don't know, infrastructure isn't always evil.. . .

Standing army of engineers? No, we get fired as soon as the executives and accountants figure they don't need us anymore. . .

Pick a location on earth, it will be better suited for some launch azimuths than others. The equatorial locations have the array extend to the east. Higher latitude locations extend the array in more polar directions. What, you thought we'd build only one launch location?

I hope this above composite doesn't misrepresent your thoughts here. My essential point is that this is indeed much more expensive than one would guess for several reasons. Shuttle is the most expensive launch system per pound there is because of its needed infrastructure. The maintenance is just outrageous. Thousands of tiles that need to be checked after every flight, refurbing the SSME's, etc. The Shuttle operation requires a standing army of tens of thousands of engineers. That's why it costs more to use a reusable spacecraft than it does to launch an Atlas, Titan or soon a Falcon.

Second thing, guess I wasn't clear: a single, 100 MW laser cannot loft a spacecraft into orbit. As the spacecraft displaces horizontally, in order to pick up orbital velocity, it will move out of range of a laser. There are ways to mitigate this some. The laser vehical trajectory is mostly vertical to start and then turns horizontal later, which enables a ground based system to track the spacecraft longer, but it cannot track it long enough to loft it to LEO. You have to build many of these 100 MW lasers, each manned by it's own company of engineers, each needing to avoid cloud cover, storms, etc for a launch. What you end up with is an enormously complex and expensive infrastructure that makes no use of existing infrastructure at all. A trillion dollars is probably not far off.

Now if you have to have a TRITON or something like it for exploration (according to the scenario I was painting), you don't actually need the lasers or their infrastructure at all! Using the lasers might save some fuel, but the fuel is the cheapest part of launch. If we have a scenario that costs several tens of billions just to start, we have a scenario no one will ever pay for.

I once had lunch with a top shelf DoD contractor who wanted to pursue the laser method, but when I asked about the cost he just shrugged. Fact is, if it's ever going to be built, there can be no shrugging. We can't afford another Shuttle type boondoggle.

This is why I'm saying, something like TRITON holds out the possibility of a game changer. Remember, if you can't loft significantly cheaper than Falcon, at just $40 million/launch, then there is no raison d'etre for a launch system, especially one that can't launch whenever there's cloud cover over many different laser sites. They all have to be clear at once!

[GIThruster]

About the X-33, nobody knew how to build that tank, then.

Yes, but they chose a tank team with no experience at all. Rutan could have glanced at the tank design and told them off the top of his head that it would require so many seams that it would weigh much more than what they wanted. The problem was in the systems engineering--everyone put the troubles in their section off on someone else.

And then there's the fact the tank delaminated. Rutan would never have let that happen. Fact is, they needed a wet filament wound tank, which means NO CONCAVE SURFACES; and they pursued one that was laid up by hand because of its concave surfaces. Anyone with Rutan's knowledge of composites would have avoided this trouble from the outset. The tank that delaminated weighed near twice what it should have--more than the lithium aluminum tank they knew was too expensive before they built!

[rjaypeters]

...then there is no raison d'etre for a launch system, especially one that can't launch whenever there's cloud cover over many different laser sites. They all have to be clear at once!

GIThruster:

One of the advantages of the laser launch array is modularity and geographical distribution (I know, you see these things as disadvantages under the heading 'infrastructure'). If a laser site is obscured by weather from human eye visibility, are there not other wavelengths that travel through clouds? The heat exchanger doesn't care too much about the color of light it receives.

If the chosen wavelength is sensitive to weather, geographically distribute laser sites so one doesn't need all of them for a launch. Yes, I know this increases costs, but also available performance when the weather is clear.

This is why I'm saying, something like TRITON holds out the possibility of a game changer. Remember, if you can't loft significantly cheaper than Falcon, at just $40 million/launch...

I suspect the Falcon $40 million/launch will not cover heavier payloads, but that's a nit as they are trying to reduce the cost/Kg to orbit and $40 million probably covers a certain payload+orbit combination.

And here we agree completely. It's all about the money. Reduce costs, in whatever way makes the most sense.

One thing we must handle is the TRITON's use of fissile materials. Aside from the other aspects, we must find a way to solve the political problem of flying fissile material. And it's going to be a lot worse than out-of-sight-out-of-mind nuclear weapons or deep-space probes which launch and might make one or two close-approach delta-v maneuvers on the way.

No, GIThruster, you want to fly those lovely fissile materials over the heads of every man, woman and child on the planet, routinely and visibly.

I welcome ideas on how to get passed the anti-nukular-at-any-cost Luddites.


I read this in a cartoon once: "Look, maybe you're right. But just for the sake of argument, let's assume you're wrong and drop it."

I certainly don't expect anyone on this forum to just drop it!

[GIThruster]

One thing we must handle is the TRITON's use of fissile materials. Aside from the other aspects, we must find a way to solve the political problem of flying fissile material. And it's going to be a lot worse than out-of-sight-out-of-mind nuclear weapons or deep-space probes which launch and might make one or two close-approach delta-v maneuvers on the way.

No, GIThruster, you want to fly those lovely fissile materials over the heads of every man, woman and child on the planet, routinely and visibly.

I welcome ideas on how to get passed the anti-nukular-at-any-cost Luddites.

Honestly, this is a serious issue. I doubt people would have much an issue with using a TRITON thruster to poke around the solar system so the exploration role is fairly secure. If you never come closer than LEO, anyone asking will immediately have access to enough facts that they'd feel safe, even in ignorance. Launch is another story. If you really think you can use the existing TRITON or some such for launching much cheaper than SpaceX, then you have to make the case to the public.

Certainly OBama could do this if he so wished. He could sell an Arab a bag of sand. Also, it's noteworthy that after so many decades the pendulum is now swinging back on the nuke power issue. Coal is the source being vilified and we will be building new nukes over the next decade or two. That change in attitude is widespread and it's very unlikely to change, given the popularity of the AGW myth.

[rjaypeters]

GIThruster: I saved the anti-nuclear feeling argument for last because I knew it would be the toughtest.

If you really think you can use the existing TRITON or some such for launching much cheaper than SpaceX, then you have to make the case to the public.

Certainly OBama could do this if he so wished.

Despite President Obama's intellectual (he probably could see the merits of the case) and oratorical gifts, I strongly doubt he will ever make the case for TRITON VentureStar (TVS for short). First, there are too many things on his plate he actually wants to do and second, there will be too many things which will end up on his plate which he must do. TVS, unfortunately, I expect will not be in either category.

Finally, the President's advisors including NASA and the DOD are not thinking in these directions, so he will probably never hear about TVS.

...we will be building new nukes over the next decade or two. That change in attitude is widespread and it's very unlikely to change, given the popularity of the AGW myth.

First, I agree we should be building fission power plants regardless of AGW reality or fantasy. However, if AGW proves to be false, will our currently increased leniency toward fission power plants go away? You bet it will. The final stake in the heart for new fission power plants would be another nuclear accident even smaller than Three Mile Island. Remember, the public is fickle.

I fear TVS will need a "Captain Nemo" strategy which can only be applied by a wealthy individual. IIRC, Capt. Nemo built the Nautilus by using independent and unaware contractors to supply the pieces of the submarine which he integrated. The sticking point for TVS is the fissile material.

Whose best supplier would probably be Russia. Heck, they sell material to the Iranians, so they'd probably roll out the red carpet to sell TVS fuel to Capt. Nemo. I'm not sure the Russians could fool the IAEA about the magnitude of sales necessary, but I don't discount Russian ingenuity. The remainder of the components for TVS should be reasonably easy to come by, e.g. Scaled Composites does have a good reputation for keeping secrets.

I don't know of any sufficiently motivated Capt. Nemo out there taking on this project. But lil' ol' me in sleepy South Carolina wouldn't, hmmm. Absence of evidence is not evidence of absence?

I'd been hoping to avoid this, but I'm afraid the next generation of human spaceflight should be a secret project to design and build Project Orion as conceived in the middle of the Twentieth Century (eject and detonate small fission bombs behind a pusher plate and shock absorbers). The aims of this secret project would be two: a last-ditch defence of the planet (or human life) from a Large Object(s) or should the defence of the planet seem likely to fail, transplantation of a feasible colonies to someplace else.

[ladajo]

And other than political, what was the physical catastrophy at TMI-2? Why do people view it as a horrific nuclear accident?

China Syndrome it was not. It makes a really good case for US design guidelines and redundant safety features. Even better than the Prompt Criticality Facility in Idaho. TMI-2 was real life, not a test.
Boy, did the power industry lose the publicity war. Now we can thank our efforts of group stupidity with the recognition that France has the cheapest electrical power, courtesy of a successful accident free national nuclear program. Plus, they get to make money selling cheap surplus power to thier Euro Neighbours.
We are dumb.

[rjaypeters]

ladajo: As usual you have hit the nail on the head. "We are dumb." But it's worse than we think. We are also cowards. TMI-2 should be seen as a triumph, but see my signature line.

[GIThruster]

::GROAN::

I could spew a 30 page rant here, but instead; let me remain optimistic.

The technology exists today to clean up the fission waste mess we've created the last few decades. Originally, the method of dealing with nuke waste was "out of sight is out of mind" meaning, bury it. Trouble is, the stuff is dangerous for far longer than the very best containers we might put it in. So what we have is 38,000 sites storing dangerous goop, and places like Hanford where we don't even know how dangerous the goop really is.

We could reprocess/burn it all.

If the next gen nuke industry were committed to coping with the mistakes of the past, we could sell next gen nukes as the SOLUTION to the troubles we've already caused. We could in fact unite the Luddites, the environmentalists, the nay-sayers, the on-lookers all--to build a better, cleaner, safer future; that embraces fission.

Just takes vision. I for one would be thrilled to see reactor designs built not just to eliminate wastes of the past, but provide energy for the future. In an environment like this, it's easy to see that fission thrusters would be happily accepted as the next step toward human exploration.

::end rant:: I need some tequila.