The issue isn't necessarily protecting the bulk of the spacecraft, it's protecting those parts that have openings to the outside world. It's easy to design an ablative thermal protection system, or a ceramic-based one, but the tough part is sealing the air inlets, docking ports, etc, etc, etc, such that superheated gasses can't melt the turbine blades or fuel nozzles within the engines. Yeah, you can have moveable doors that would swing open to block the ports, but you've got to make sure they're SEALED, and you've got to make sure that they can open again, reliably, after re-entry, so that you're able to start up your engines on the air cycle and make a safe landing.
Personally, I think SLS is only a stop-gap measure because NASA is too deeply engrained with...ahem...an older generation that won't move outside of a certain comfort zone, so I'm really happy to see something like this. I'm also hoping that they've got enough financial backing to make it a reality. Who knows? Maybe Peter Diamandis, James Cameron, Larry Page, and Eric Schmidt can use this technology to launch the second phase of Planetary Resources' mining operations!
I do know several people that have geothermal systems attached to their newer homes in Southern New Jersey, but like I said, it's just for heating and cooling. Because the ground is always at a stable temperature, regardless of season or air temp, heat pumps are used to cool or heat the house. Combined with his 100' x 10' array of solar panels, my buddy barely pays for energy, and his loans on the solar panels were very favorable, due to energy company and government incentives. Given that he's pumping electricity back into the grid, after three years, the panels are almost paid off ($60k original cost).
I'm as pro-nuclear as they come, and am in NO way in favor of 'green energy,' but if I could get paid to make electricity for the energy company, I would. The cost of entry, though, is still WAAAAAAAYYYY too high.
The problem with hydrogen, specifically, splitting hydrogen atoms from oxygen atoms, is that current processes require more energy to be input than you get out. The conversion process is a net energy sink, and until someone figures out a way to split them without an energy input, hydrogen is NOT going to be a viable option.
I'm not a geothermal expert, but I don't think it's been scaled to the point where it can support an entire city block, let alone an entire city. Sure, there are homes that use geothermal for heating and cooling, and there are likely some factories or industrial buildings that use it to augment their existing energy capacity, but I just don't think it's a viable option.
I couldn't find your source on that, but it likely means that there are hundreds of older B-52 models that have been retired, while the newest, -H models, are the only ones left in service.
Exactly. The only reason the US 'lost' in Vietnam was that the length of the war, and the number of young men coming home in body bags broke the spirit of the nation, and its tolerance for more dead soldiers. To date, roughly 4400 Americans lost their lives in the Iraq War, with about 31,000 injuries. More than 58,000 Americans lost their lives in Vietnam. Big difference.
That's about the most asinine comment I've ever read on Slashdot, and I've been reading here for same time.
The USAF, USN, and USMC all used aircraft (F-16, F-15, F/A-18) as a first strike aircraft in Iraq and Afghanistan within the last decade. Yes, they also sent in many cruise missiles from Naval platforms (DDG, CG, SSGN) and air platforms, but for the most part, it was the F-15 and F-14 taking care of air superiority, and the F-16 and F/A-18 dropping guided munitions and taking out enemy air defenses, where necessary. After the initial suppression of enemy air defenses, the B-1, B-2, B-52, AC-130, and A-10 were used for high yield bombing and close air support. At the same time, the fighter aircraft were still bombing the bejesus out of hardened points on the ground.
As for the visible range of an enemy, the only thing that's really good for is small arms fire, maybe a shoulder launched missile. In most cases, a fighter aircraft is going to be too fast for a guy to hit with an AK-47, though it has been known to happen. A low flying, fast platform would be out of range very quickly, and even if the enemy were able to snapshot a ground to air missile at the aircraft, flying low would help confuse the missile, due to the effect that ground clutter has on radar.
Moving on to fourth gen fighters, you're greatly overestimating their worth in the hands of poorly trained pilots from any air forces the US might encounter, and the point of a B-2 is that it's invisible to radar. You can't hit what you can't see, and even if an enemy pilot caught one visually (they're used primarily at night), the same principles of radar evasion apply. If his aircraft's radar can't see the B-2, how do you think his missile's radar will be able to?
Why? Fighters cost more, carry the same guided precision ordinance as the B-1, B-2, and B-52, but carry a fraction of what they can carry. Also, fighters need to carry air to air missiles for self defense, eliminating more hardpoints.
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The issue isn't necessarily protecting the bulk of the spacecraft, it's protecting those parts that have openings to the outside world. It's easy to design an ablative thermal protection system, or a ceramic-based one, but the tough part is sealing the air inlets, docking ports, etc, etc, etc, such that superheated gasses can't melt the turbine blades or fuel nozzles within the engines. Yeah, you can have moveable doors that would swing open to block the ports, but you've got to make sure they're SEALED, and you've got to make sure that they can open again, reliably, after re-entry, so that you're able to start up your engines on the air cycle and make a safe landing.
Personally, I think SLS is only a stop-gap measure because NASA is too deeply engrained with...ahem...an older generation that won't move outside of a certain comfort zone, so I'm really happy to see something like this. I'm also hoping that they've got enough financial backing to make it a reality. Who knows? Maybe Peter Diamandis, James Cameron, Larry Page, and Eric Schmidt can use this technology to launch the second phase of Planetary Resources' mining operations!
Don't piss us off, or we'll come after your country next! :)
I do know several people that have geothermal systems attached to their newer homes in Southern New Jersey, but like I said, it's just for heating and cooling. Because the ground is always at a stable temperature, regardless of season or air temp, heat pumps are used to cool or heat the house. Combined with his 100' x 10' array of solar panels, my buddy barely pays for energy, and his loans on the solar panels were very favorable, due to energy company and government incentives. Given that he's pumping electricity back into the grid, after three years, the panels are almost paid off ($60k original cost). I'm as pro-nuclear as they come, and am in NO way in favor of 'green energy,' but if I could get paid to make electricity for the energy company, I would. The cost of entry, though, is still WAAAAAAAYYYY too high.
The problem with hydrogen, specifically, splitting hydrogen atoms from oxygen atoms, is that current processes require more energy to be input than you get out. The conversion process is a net energy sink, and until someone figures out a way to split them without an energy input, hydrogen is NOT going to be a viable option.
I'm not a geothermal expert, but I don't think it's been scaled to the point where it can support an entire city block, let alone an entire city. Sure, there are homes that use geothermal for heating and cooling, and there are likely some factories or industrial buildings that use it to augment their existing energy capacity, but I just don't think it's a viable option.
I couldn't find your source on that, but it likely means that there are hundreds of older B-52 models that have been retired, while the newest, -H models, are the only ones left in service.
Sounds like bullshit to me.
Exactly. The only reason the US 'lost' in Vietnam was that the length of the war, and the number of young men coming home in body bags broke the spirit of the nation, and its tolerance for more dead soldiers. To date, roughly 4400 Americans lost their lives in the Iraq War, with about 31,000 injuries. More than 58,000 Americans lost their lives in Vietnam. Big difference.
That's about the most asinine comment I've ever read on Slashdot, and I've been reading here for same time. The USAF, USN, and USMC all used aircraft (F-16, F-15, F/A-18) as a first strike aircraft in Iraq and Afghanistan within the last decade. Yes, they also sent in many cruise missiles from Naval platforms (DDG, CG, SSGN) and air platforms, but for the most part, it was the F-15 and F-14 taking care of air superiority, and the F-16 and F/A-18 dropping guided munitions and taking out enemy air defenses, where necessary. After the initial suppression of enemy air defenses, the B-1, B-2, B-52, AC-130, and A-10 were used for high yield bombing and close air support. At the same time, the fighter aircraft were still bombing the bejesus out of hardened points on the ground. As for the visible range of an enemy, the only thing that's really good for is small arms fire, maybe a shoulder launched missile. In most cases, a fighter aircraft is going to be too fast for a guy to hit with an AK-47, though it has been known to happen. A low flying, fast platform would be out of range very quickly, and even if the enemy were able to snapshot a ground to air missile at the aircraft, flying low would help confuse the missile, due to the effect that ground clutter has on radar. Moving on to fourth gen fighters, you're greatly overestimating their worth in the hands of poorly trained pilots from any air forces the US might encounter, and the point of a B-2 is that it's invisible to radar. You can't hit what you can't see, and even if an enemy pilot caught one visually (they're used primarily at night), the same principles of radar evasion apply. If his aircraft's radar can't see the B-2, how do you think his missile's radar will be able to?
Why? Fighters cost more, carry the same guided precision ordinance as the B-1, B-2, and B-52, but carry a fraction of what they can carry. Also, fighters need to carry air to air missiles for self defense, eliminating more hardpoints.