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MP99
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« Reply #60 on: 02/07/2010 09:58 PM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail.
...once you've worked out how to deploy it. If it's reusable, I guess that means repeated furling & unfurling? Also, can you use it to brake into orbit around planets further out than Earth? Martin
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tamarack
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« Reply #61 on: 02/08/2010 02:50 AM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail. NTR - Core, virtually any fuel and a nozzle
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JohnFornaro
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« Reply #62 on: 02/08/2010 02:51 PM » |
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Well, such heat does NOT dissipate quickly. We have a lot of water vapor and that air borne carbon reservoir as well, acting as a blanket. Whatever insulating value the atmosphere has, it will not change upon beaming more heat to the planet surface. The net effect will be to warm the planet on a large scale.
Now it is true that our power usage is more like a straw on the camel's back, and that there are many orders of magnitude of beamed power required before Congress critters fall over in heat prostration while leaving the Capitol. The idea of a tipping point is very real, and certainly poorly understood in our ecological studies so far. Actively ignoring its study, which the "burn baby burn" group would argue, is equivalent to not tracking the NEO's at all, and leaving Nature to run its course.
But the other thing is this idea that we, mankind, have not had an effect on the Earth so far, so therefore, anything we do is fair play. I just hate this attitude in general. We are stewards, not dominatrixes. I can confidently predict that space power generation will not cause any ecological problems whatsoever in the next election cycle.
Anyhow, grumble, we got 16" of global warming the other day... I wonder if the beam could be focused on the driveway? That would be a convenient truth.
That's a pretty interesting observation of the forty year gap wrt Antarctica. The other observation that's good is that the "game changing" technology, the airplane, just came along, and was used for the purpose. The airplane wasn't developed specifically for the purpose. Today, we are hoping to develop a technology for the specific purpose of HSF, which is somewhat different from the past uses of technology. It's more like the Manhatten project, where a specific technology was developed for a specific purpose.
That's the approach needed today. We have everything we need right now, but we need to focus on making it more affordable by making our effort less disposable. It's not that we are NOT developing tech, it's that we are throwing away very expensive items after one use. This is not to open the endless EELV discussion, either, since some things must be expended in order to build other things that are kept.
It is incorrect, tho, to suggest that LEO and the Moon are "static" locations, and with little bearing on Earth's life. First, the South pole doesn't move like the Moon does, and seems more static wrt NYC than the Moon. Second, the Moon certainly does have an effect on Earth and its ecosystem. For example, there is fundamental scientific mystery about the relationship of the menstrual and lunar cycles. Other migratory and reproductive cycles are also quite related to the Moon, although the mechanisms aren't understood.
I want to object to the use of the term "static" once more, because it is a marketing term, not a scientific term. And thanks, Karl, for the reminder of the Hadean Era. Let's also not forget the geological mystery of the Moon's formation.
I want to object also to the "Name one of these", or "Name one of those" arguments as well. Will these arguers admit defeat if you do name "one"? Of course not. It is a rhetorical technique which doesn't explain anything, nor expand our knowledge.
The game changer is not technology, as I pointed out, it is cooperation. It is people. This is another way of saying "mindset of the American people". And if the "monolith" was revealed on the Moon tomorrow, probably within three years, we'd be back up there wiping the dust off. Time is not the problem, either.
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nooneofconsequence
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« Reply #63 on: 02/08/2010 09:33 PM » |
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I want to object also to the "Name one of these", or "Name one of those" arguments as well. Will these arguers admit defeat if you do name "one"? Of course not. It is a rhetorical technique which doesn't explain anything, nor expand our knowledge.
The game changer is not technology, as I pointed out, it is cooperation. It is people. This is another way of saying "mindset of the American people". And if the "monolith" was revealed on the Moon tomorrow, probably within three years, we'd be back up there wiping the dust off. Time is not the problem, either.
There are many ways to establish the 'sincerity' of a game changer. Another way is to describe the "system" or 'plan' of putting it into action. When you do a patent, you describe the surrounding environment and how the new interacts with it to get a benefit. We still have lots of lousy patents, but at least its something to hang you hat on - something that engages critical thought.
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bad_astra
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« Reply #64 on: 02/08/2010 09:40 PM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail.
Marcel F. Williams
electrodynamic tether/magsail, in part because it can also handle breaking chores. I would normally refrain from getting into "Advanced Concepts" material in the General category, but since Bolden is discussing game changing technolgoy, why not. Since we have no working test of either magsail or lightsail, yes I would say a magsail might be more useful, and potentially simpler to operate.
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hydra9
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« Reply #66 on: 02/09/2010 01:39 AM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail. NTR - Core, virtually any fuel and a nozzle
A light sail requires no fuel and last for decades. Marcel F. Williams
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Patchouli
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« Reply #67 on: 02/09/2010 01:45 AM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail. NTR - Core, virtually any fuel and a nozzle
A light sail requires no fuel and last for decades.
Marcel F. Williams
There are several missions where low thrust propulsion cannot be used for the primary source of propulsion. A good example would be a manned mission to Mars. TMI and MOI need a high thrust burn. NTR provides high thrust a solar sail doesn't.
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GasBag
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« Reply #68 on: 02/09/2010 06:26 AM » |
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Game Changing Technology.... Physics is an unbending referee with omniscient eyes on the ball we are trying to advance in order to score a touchdown for our species. As we contemplate a new direction for a national space policy, and look to academia and commercial entities for solutions to engineering challenges that have eluded resolution for half a century we should be willing to embrace the solutions with a basis founded on the rules of the game. New solutions demand that we use the equations we are familiar with in new ways to produce results given the available resources at our disposal. Running the ball will result in forward progress most of the time, but at some point we have to learn to pass the ball in order to win the game.
In the case of space access, the science of logistics (the forward pass) is what we are needing to win the game.
Wars are won or lost by logistical success or failure, and the science of logistics specifies that more now is always better than better later.
The greatest game changing technolgy is more faster for the least cost.
100 Years Ago: Football's First Forward PassBy Robert Roy Britt, LiveScience Managing Editor
Saint Louis University football coach Eddie Cochems called the first forward pass in football 100 years ago, on Sept. 5, 1906. Credit: SLU
Full Size 1 of 1.Saint Louis University football coach Eddie Cochems called the first forward pass in football 100 years ago, on Sept. 5, 1906. Credit: SLUThey called it the "projectile pass" back then.
On Sept. 5, 1906, Saint Louis University's Bradbury Robinson tossed a pigskin to teammate Jack Schneider. It was a remarkably creative play for the era, one that ultimately became known as the forward pass.
The game was scoreless. According to SLU archives, head coach Eddie Cochems was frustrated with the team's inability to move the ball. For weeks, they had been secretly practicing this new art of tossing the ball forward from a starting position behind the ear.
And so football's first air attack began.
And it started as you might expect, with an incompletion. Under the rules then, the ball was turned over to the opponent, Carroll College.
On SLU's next possession, though, Robinson connected with Schneider 20-yards downfield. The defense was so surprised, Schneider waltzed in for the score.
Saint Louis University beat Carroll 22-0.
There's a deadly history to this gridiron breakthrough.
The 1905 season saw several on-field football deaths and serious injuries around the country. President Theodore Roosevelt met with universities officials to find ways to make the game safer. That's when rules were modified to allow passing.
But it took awhile for the technique to take hold. For one thing, nobody knew how to pass, of course. And there were disincentives. A completion within 5 yards of the line of scrimmage was ruled a turnover. Oddly, a catch in end the end zone was ruled a touchback.
What worked in college ball was soon adopted by the pros.
The first authenticated pass completion in a pro game came on Oct. 27, 1906, when George (Peggy) Parratt of Massillon threw a completion to Dan (Bullet) Riley in a victory over a combined Benwood-Moundsville team, according to the NFL.
Some believe that Notre Dame coach Knute Rockne was the first to order a forward pass. But according to SLU officials, Rockne set the record straight in his own biography when he wrote that SLU's Cochems "...enrolled a few boys with hands like steam shovels who could toss a football just as easily and almost as far as they could throw a baseball. "One would have thought that so effective a play would have been instantly copied and become the vogue. The East, however, had not learned much or cared much about Midwest and Western football. Indeed, the East scarcely realized that football existed beyond the Alleghanies."
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hydra9
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« Reply #69 on: 02/09/2010 07:12 AM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail. NTR - Core, virtually any fuel and a nozzle
A light sail requires no fuel and last for decades.
Marcel F. Williams
There are several missions where low thrust propulsion cannot be used for the primary source of propulsion.
A good example would be a manned mission to Mars.
TMI and MOI need a high thrust burn.
NTR provides high thrust a solar sail doesn't.
A light sail could easily transport thousands of tonnes to Mars in less than a year. It depends on the mass and size of the light sail.No chemical or nuclear rocket can match the ultimate speed of a light sail. A chemical rocket with its high thrust levels can accelerate a space craft for only a few minutes. A light sail with its low thrust will continue to accelerate a space craft for weeks, months, and even years as long as the sun continues to shine. And combined with lasers, they could be even faster and could probably be the first interstellar space craft. Marcel F. Williams
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Ben the Space Brit
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« Reply #70 on: 02/09/2010 09:47 AM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail.
Marcel F. Williams
electrodynamic tether/magsail, in part because it can also handle breaking chores.
At a risk of going further OT, I have always liked the idea of using a magsail as the brake for a ramjet-powered starship. Could the sail double as a bussard ramscoop? This is relevant because, if it is, developing magsail is a major step, not just on the road to the planets but also onto the road to the stars - a true game-changer if ever there was.
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MP99
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« Reply #71 on: 02/09/2010 12:31 PM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail.
...once you've worked out how to deploy it. If it's reusable, I guess that means repeated furling & unfurling?
Also, can you use it to brake into orbit around planets further out than Earth?
Martin
Light sails are just titanic ultra lite aluminized kites that continuously reflect sunlight in order to change orbital velocity. The lighter the kite, the faster they are and the more mass they can carry. I believe Eric Drexler estimated that once they were deployed, they could last at least 30 years. Coating nanotube sheets with aluminum film looks like the lightest possible light sail material right now.
How does the "reusable" bit work? Assume we're talking about a reusable Earth/Mars/Earth vehicle. What happens to the sail while the vehicle is waiting in Earth or Mars orbit for the next transit to begin? Do you leave it deployed, or do you have to furl it, then unfurl it to begin the next transit? Martin
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Ben the Space Brit
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« Reply #72 on: 02/09/2010 12:59 PM » |
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Name me a reusable interplanetary technology that you think would be simpler and superior than a light sail.
...once you've worked out how to deploy it. If it's reusable, I guess that means repeated furling & unfurling?
Also, can you use it to brake into orbit around planets further out than Earth?
Martin
Light sails are just titanic ultra lite aluminized kites that continuously reflect sunlight in order to change orbital velocity. The lighter the kite, the faster they are and the more mass they can carry. I believe Eric Drexler estimated that once they were deployed, they could last at least 30 years. Coating nanotube sheets with aluminum film looks like the lightest possible light sail material right now.
How does the "reusable" bit work?
Assume we're talking about a reusable Earth/Mars/Earth vehicle.
What happens to the sail while the vehicle is waiting in Earth or Mars orbit for the next transit to begin? Do you leave it deployed, or do you have to furl it, then unfurl it to begin the next transit?
The light sail isn't in any way fixed. It is equipped with adjustable rigging (much like a wind sail on Earth's oceans) that allows it to be re-angled and the area presented to the sun altered. In parking orbit, it would be partially furled to minimise its area/volume ratio and would also be angled edge-on to the sun so it generates little or no thrust.
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StuffOfInterest
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« Reply #73 on: 02/09/2010 02:08 PM » |
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My feeling is that the biggest game changer has to come in launch vehicles. If you can't get off the ground you can't do anything else. My personal favorite is something based on the DC-X vehicle or its current incarnation with Blue Origin. Give me vertical takeoff, vertical landing with refuel and launch from anywhere. At that point you have a spacecraft which can operate like aircraft do today.
Next thing you know FedEx is offering 12-hour delivery from New York to Sydney with most of the time spent just getting your package to and from the airport. Maybe that is Bezos' plan, order from Amazon and he'll have it in your driveway in Mozambique in two hours.
With cheap, reliable access to orbit all of the other things become easier. You don't need as much redundancy in your communication sats because a repair crew can be there the next day. Your propellant depot can be filled up for cheap and your exploration craft can be bigger (more robust) because it doesn't cost thousands of dollars per kg to get it into orbit.
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clb22
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« Reply #74 on: 02/09/2010 02:37 PM » |
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My feeling is that the biggest game changer has to come in launch vehicles. If you can't get off the ground you can't do anything else. My personal favorite is something based on the DC-X vehicle or its current incarnation with Blue Origin. Give me vertical takeoff, vertical landing with refuel and launch from anywhere. At that point you have a spacecraft which can operate like aircraft do today.
Next thing you know FedEx is offering 12-hour delivery from New York to Sydney with most of the time spent just getting your package to and from the airport. Maybe that is Bezos' plan, order from Amazon and he'll have it in your driveway in Mozambique in two hours.
With cheap, reliable access to orbit all of the other things become easier. You don't need as much redundancy in your communication sats because a repair crew can be there the next day. Your propellant depot can be filled up for cheap and your exploration craft can be bigger (more robust) because it doesn't cost thousands of dollars per kg to get it into orbit.
I disagree. I absolutely believe that the next decades won't get us a revolution in Earth to orbit costs. Maybe, if we are lucky, some technology can get fuel or other non-fragile things up cheaper, but in general the method for humans and most of the hardware for a beyond-LEO mission will be brought up the same way it is done now - by ELVs (parts of which might be reusable). The real game changer comes with the tech we are using in spaceflight itself. Advanced in-space propulsion, advanced power sources, fuel depots, inflatable modules, active radiation shielding, semi-automatic and fully automatic robotics etc. That's where spaceflight can be revolutionised.
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