Personal computing discussed
Moderators: askfranklin, renee, emkubed, Captain Ned
Captain Ned wrote:cphite wrote:Correct. The rocket science aspect is fairly well settled. It's the medical stuff that's the real challenge.
You're still not getting the importance of Earth's gravity well. Yes, we know HOW to lift stuff/people to Earth escape velocity, though we've not sent a human at that speed since December 7, 1972. It's still expensive in fuels and rocket parts, it has an inherent failure rate that will never be zero, and it's damned uncomfortable to boot.
Getting things/people out of Earth's gravity well without using chemical rockets will be the first great step forward. Personally, I've always believed the space elevator to be the best method for this as it greatly reduces the needed mass to be lifted and allows for electrical power to provide the required force. A station above geosync (most elevators are designed with the center of mass at geosync) would greatly reduce the propulsive needs for escape velocity.
Captain Ned wrote:Well, if we're going to throw radiation around let's just go straight to Orion
Lucky Jack Aubrey wrote:With respect to the gravity issue on long space flights, I believe the current thinking is that you have to create an artificial gravity environment for the astronauts to live in. I know that this can be done with centrifugal force as well as other possible means, but I confess I'm poorly read on the subject.
superjawes wrote:The trick to getting into staying in space isn't about getting so far away that the gravity doesn't affect you, but moving fast enough to get into orbit.
Usacomp2k3 wrote:That's what the shuttle was supposed to accomplish by bringing the cost down to a fraction of what it was by going to reusable aircraft versus disposable.
superjawes wrote:Okay, my understanding of gravity wells might be a little rusty/off, but it was my understanding that even if you were on the moon, you were technically still in Earth's gravity well.
The trick to getting into staying in space isn't about getting so far away that the gravity doesn't affect you, but moving fast enough to get into orbit. Anything getting out of Earth's gravity well probably isn't coming back, like the Voyager probes and the Curiosity rover.
Mr. Eco wrote:You do advise others of reading and understanding Russian texts about Buran, yet you posted a link to a page that does not contain anything related to Buran - it is just about the policy of catch up.
Mr. Eco wrote:It is the russian scientits that designed Buran, not the central committee of the Communist party.
clone wrote:Cphite wrote:the fact that we have space tourism is a solid argument against the cost of getting into space as being the primary issue. the costs are being overcome. (even the private corporation SpaceX is sending cargo up to the space station)But the claim was this: "It isn't the lack of artifical gravity in space that's the problem, it's the abundance of natural gravity keeping us of out of it. "
And that simply isn't a true statement. The act of putting people into space is wildly expensive, yes; but it's not the primary thing that's holding us back from establishing a true foothold in space. And with continued innovation, there is every reason to expect that the costs of putting people into space should come down.
It is much less likely that we are going to see advancements that solve the problems of long term stays in micro-gravity.
living in a low to negligible to nonexistent gravity environment for prolonged periods has proven what I believe to be "the" major hurdle with no readily available solution.
clone wrote:while I'm not trying to cause a problem I am trying to figure out how to work my way around this forum which at least on the surface seems to be growing more challenging.
cphite wrote:There are a total of three who have spent a continuous year in space, and a few others who have come close to a year. However, evidence exists that spending much more than that could result in loss of bone and muscle mass, problems with vision, and various other health issues.
cphite wrote:The price has and will continue to come down as space flight becomes more common and the equipment and procedures become more standard. Humans aren't likely to become more capable of withstanding long periods of zero gravity.
cphite wrote:You do understand what science fiction means, right? Heinlein was a visionary, yes; but he was still writing fiction
cphite wrote:Or hell, why not just grab a couple of Star Trek novels... it's only a matter of time before we have teleportation, warp drive, and energy shields...
cphite wrote:Correct. The rocket science aspect is fairly well settled. It's the medical stuff that's the real challenge.
Captain Ned wrote:That, and launching 50+ times per year. How anyone ever believed the projected Shuttle launch rates is a mystery.
clone wrote:the fact that we have space tourism is a solid argument against the cost of getting into space as being the primary issue.
Captain Ned wrote:If you're talking about Branson & Virgin Galactic a recreation of Alan Shepard's suborbital Mercury flight isn't any indicator of the cost issue getting fixed. It's an airplane that happens to be able to reach 100 km altitude and can't come close to the speeds needed for orbit. SpaceShip One barely cracked Mach 3, or roughly 2100 MPH, and SpaceShip Two is designed for 2500 MPH. Orbital speed is 17500 MPH. There's a vast dollar gap between the two. Altitude is not the key rocket problem. Speed is.
ChronoReverse wrote:Multiple engines means better redundancies but it also means greater complexities (the plumbing is difficult).
Glorious wrote:It's settled, and damning. As Captain Ned says, the physics behind chemical rockets is extremely dismal, to the point where without something better they are plainly impractical.
jihadjoe wrote:If we were to start a full Saturn V from LEO, I assure you it would get very far, and very quickly.
Glorious wrote:
Captain Ned wrote:If you're talking about Branson & Virgin Galactic a recreation of Alan Shepard's suborbital Mercury flight isn't any indicator of the cost issue getting fixed. It's an airplane that happens to be able to reach 100 km altitude and can't come close to the speeds needed for orbit. SpaceShip One barely cracked Mach 3, or roughly 2100 MPH, and SpaceShip Two is designed for 2500 MP
Captain Ned wrote:There's a vast dollar gap between the two. Altitude is not the key rocket problem. Speed is.
Captain Ned wrote:OTOH, if you're talking about the $20 million Russia charges tourists to fly to the ISS, just remember that their launcher first flew in 1957 and the development costs have long been amortized. If we'd standardized on the Saturn family back in the '60s and stuck with it we'd see similar economies of scale.
Captain Ned wrote:About the only possible benefit is that you would no longer need to design the first stage F-1s for atmospheric flight, which would increase their Isp by about 40 points [/handwave].
bthylafh wrote:Mainly in that you could fuel them with LOX/LH instead of LOX/RP-1, since you wouldn't need the extra kick the kerosene gives to get started.
Lucky Jack Aubrey wrote:Sidebar: I don't remember it being specifically mentioned in this discussion, so for anybody who is not already aware and who might be interested in reading about NASA's next heavy-lift platform, the Space Launch System, go here: http://www.nasa.gov/exploration/systems/sls/index.html#.UkWeFleiLCQ
The "Read More" link at the bottom of the page links to a PDF.
Lucky Jack Aubrey wrote:Sidebar: I don't remember it being specifically mentioned in this discussion, so for anybody who is not already aware and who might be interested in reading about NASA's next heavy-lift platform, the Space Launch System, go here: http://www.nasa.gov/exploration/systems/sls/index.html#.UkWeFleiLCQ
The "Read More" link at the bottom of the page links to a PDF.
Captain Ned wrote:bthylafh wrote:Mainly in that you could fuel them with LOX/LH instead of LOX/RP-1, since you wouldn't need the extra kick the kerosene gives to get started.
LOX/LH2 - Isp sea level 363 - Isp vacuum 452 (SSME)
LOX/RP1 - Isp sea level 265 - Isp vacuum 304 (F-1)
There's no extra "kick" in RP1. What there is is an acceptable Isp at an acceptable mass fraction. Beside the fact that a 1.5 millon lbf LOX/LH2 engine was far beyond early 1960's rocket tech, the resulting massive increase in the structural size and weight of the S-1C (Saturn V first stage) would have doomed the entire concept. LOX/RP1 is used in first stage boosters because RP1 is far more dense than LH2 and allows for smaller structural designs. Modern boosters do use LOX/LH2 in their first stages but, if you look closely, they all have "stage zero" strap-ons to get the bloody thing off the pad.
superjawes wrote:I just have to say that it is extremely cool to see something that incorporates elements from the Saturn rockets and the shuttle launch in one package
bthylafh wrote:for the purposes of the first stage, RP-1 gives more power and is more desirable.
Captain Ned wrote:jihadjoe wrote:If we were to start a full Saturn V from LEO, I assure you it would get very far, and very quickly.
And absent a space elevator or similar device, the cost of assembling a Saturn V in LEO with all of the concomitant heavy-lifter launches to get parts & consumables to LEO would quickly render the entire idea a farce. About the only possible benefit is that you would no longer need to design the first stage F-1s for atmospheric flight, which would increase their Isp by about 40 points [/handwave].