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The reporters do not really care if the war is successful or not (remember how they prodded America into starting the war in the first place). They just want a sensational story to report that will get people's attention. What makes for a more exciting story, peace and boredom or people getting killed?
Seven more American soldiers were KILLED yesterday in Iraq.
Seven more lives thrown away for absolutely nothing. If you focused on that you would see the logic in my "argument."
There are over 25 MILLION people living in Iraq. If we nuked Iraq, we would have 25 million people killed for absolutely nothing. Plus, the diplomatic consequences of doing something like that would hurt America much worse than anything that terrorists could do.
In order to give a thorough argument on the merit of saving Hubble I decided to do further research into adaptive optics (to increase my knowledge on the subject as its been a while since I looked at them). I wish people would give up to date information on science related web sites - one says that the biggest adaptive optics telescope is just under 5 meters in diameter, another states that one is 8 meters... the list goes on and on.
Maybe my google search phrase "adaptive optics ain't worth sh...." does not help
Does anyone have any uptodate info on adaptive optics or links to sites that does.
http://en.wikipedia.org/wiki/List_of_la … copes]list of large refracting telescopes
All major research telescopes have started using adaptive optics, beginning with Keck I in 1993. The 2 Keck telescopes and the 4 VLT telescopes can act as interferometers. That gives the Keck interferometer an 85 meter baseline and 150m^2 of light gathering power, while the VLT interferometer has a 200m baseline and 210m^2 of light gathering power. VLTI has an optical resolution of .001 arcseconds. http://www.eso.org/outreach/ut1fl/]VLT official site
Hubble has 2.4 meter mirror for 4.3 m^2 of light gathering power and a resolution of .1 arcseconds.
1^2+2^2=1+4=5
3^2=9
5 does not equal 9.
You also can't have a 1,2,3 triangle at all since the 3 side is as long as both the other sides combined.
A 3,4,5 triangle is the smallest pythagorean triangle.
If it is too heavy to nudge by some big kenetic impactor, the choices are to either send several propulsion devices, probobly a nuclear reactor hooked up to a high thrust electric drive like a Hall thruster or a flotilla of LOX/Methane or Hypergolic rockets... or to use a series of intermediate sized nuclear warheads, and push the thing like an Orion pusher plate. Luckily, we happen to have quite a few medium warheads sitting around, and we could easily spare hundreds of them if it came to it.
This asteroid is much smaller than you seem to think it is. If we pessimistically assume a density of 3000 kg/m^3, then it will weigh about 10^11 kg. That sounds big, but it is about 16,000 times smaller than the asteroid that killed the dinosaurs. If it hit Earth, it would release about the same amount of energy as the maga-earthquake that just killed 12,000 people in the Indian Ocean. Due to the differing ways that asteroids and earthquakes release their energy, it would probably cause more devastation than a giant earthquake but it would still be a regional, rather than global, catastrophe.
Given the long lead time available, one delta IV-launched ion engine probe might be able to deflect it enough to avoid an impact with Earth. However, that would be fairly marginal, so it would be better to send several or use an HLLV.
It really should be easier to destroy the asteroid rather than deflect it. The gravitational binding energy of the asteroid should be on the order of 2*10^9 J, or equivalent to the energy released by 500 kg of TNT (this is 10,000,000 times smaller than the gravitational binding energy of the dinosaur killer). As MarsDog pointed out in the other thread, the accretion process should not have released enough energy to melt the asteroid, so it should be composed of chunks that are only loosely bound together. A 10 ton impactor traveling at 50 km/s would have 1.25*10^13 J of kinetic energy, or the equivalent of 3 kilotons of TNT. Nuclear warheads run up to 100 Megatons. Either should be more than enough to destroy the asteroid and ensure that most of the pieces easily miss Earth.
2004 MN4 is small enough that it could be destroyed or nudged out of the way by simply slamming a probe into it. That would be easier than trying any sort of ISPP on the asteroid and would be politically more acceptable than using a nuke.
http://en.wikipedia.org/wiki/Gravitatio … vitational binding energy
Interestingly, the asteroid would have to be very large to melt from accretion.
Smaller asteroids would not be destroyed, but just split into smaller parts.
In that case, it should work well. The probe would have sufficient kinetic energy that each piece of the asteroid would fly away from the center at a speed higher than the escape velocity.
Using an impactor might be a good option for 2004 MN4. Using very rough calculations, it looks like an ion engine probe lifted by a Delta IV heavy should be able to nudge the asteroid by about the radius of the Earth if it impacted 10 years before the asteroid's possible collision with Earth. Of coarse, this is a very rough estimate, given that we don't know the mass of the asteroid or how much of it will be ejected by the impact.
Edit: you would also have consider the possibility that the probe might punch through the asteroid or destroy the asteroid completely. The gravitational binding of the asteroid can't be very high, so if it is made of rubble the probe should have enough kinetic energy to destroy it.
You know whats really ironic?
The shuttle disaster that Michael Collins and numerous others have feared for decades, a main engine explosion, is the one that hasn't even happened yet!
An engine explosion that takes out the other two engines and probably causes the entire aft end of the orbiter to disintergrate...might never happen.
Or it could happen the very first return to flight mission.
They had good reason to fear such an accident in the early period of shuttle flights. The SSMEs originally emphasized performance above safety, and so they were very risky. However, improving safety has been the driving force behind nearly every SSME upgrade that has happened, sometimes even at the cost of performance. The current Block III engines with Advance Health Management are orders of magnitude safer than the original engines.
http://quality.nasa.gov/qlf/6sigma.pdf]Here is a something on the safety upgrades that the Shuttle has had and the estimated mission risk.
How much head pressure would it take to pump the water down hill to the pole?
It is not down hill at all. The centrifugal affect of the Earth's rotation exactly balances the difference in the distance to the Earth's center. If it were down hill, then the Ocean itself would flow towards the pole and correct the imbalance.
If you pump the water NET down hill, then it stands to reason if you try and pump it back, it would be NET UP hill. This ain't rocket science! 13mi - 16,000ft = ~53,000ft that you would be taking advantage of to get DOWN to the poles, but you would have to fight to get UP to the equator!
There is no net down hill at all. Water at sea level at the poles has the same amount of potential energy as water at sea level at the equator.
I think that the budget deficit will continue to grow anyway. Even if non-Defense discretionary spending only grows by 1%, that is a small portion of the total budget. If the tax cuts are extended and social security is privatized, we will continue to have record deficits despite the President's goal of cutting the deficit in half by 2008.
Germany for instance only has 60% of its population employed full time, and theirs is supposed to be the strongest of the continant?
The US only has 47% of it's population employed. The US also has massive current account deficits while the EU does not. I think that Europe definately can afford a Mars mission, the problem is convincing them to actually do it.
Weather is not really a huge issue for ground based telescopes. Most large scientific telescopes are based in areas that are both extremely dry and very high altitude. These are places that often go for months at a time without seeing any clouds.
One question what do ground telescope cost to build, this includes land purchase and fighting the public perception of we do not want it here additudes.
The land is generally cheap, and there is not usually much trouble with people who don't want a telescope nearby. In fact, there often aren't any people nearby at all.
IIRC, the VLT array cost about $400 million to build. It is a n array of 4 8.2 meter telescopes and several smaller 'scopes(all with adaptive optics and an assortment of the most advanced astronomical instruments ever built) that can operate as an interferometer when necessary. It's capabilities are far beyond Hubble's in both resolution and light gathering power.
$1.7 billion is about as much as the cost estimates for OWL. OWL(overwhelmingly large telescope) would be a single aperture 100m diameter telescope. Needless to say, for most purposes OWL>>Hubble.
So what would you invest in for a telescope, in earlier threads you say we can replace Hubble with a better space telescope cheaper than repairing it, then you say you can do just as well with ground based scopes with adaptive optics.
For a space telescope, I think I would go for a planet-finding infrared interferometer. Ideally, it would be able to image planets down to Earth's size or smaller.
Spin-offs can't be the primary reason for a Mars mission. They can be an important secondary reason since we can leverage the spin-offs to reduce the "cost" of the mission, but they have to compete with so many other programs that produce spin-offs that spin-offs are not viable as the only justification. The NSF, Department of Energy, HHS, other NASA programs, etc. can produce spin-offs more efficiently than a manned Mars mission.
Just going for “science” is also hard to justify because you are competing with robotic missions, and people will wonder why we should spend so much to learn about Mars if we never want to live there.
Going out of pride and nationalism seems a bit petty, and while it can generate a lot of funding, this funding would also be very unstable and would probably not include money for working towards building a colony.
Colonization is really the only good justification for Mars, and it is also the reason why most Mars advocates want to go to Mars in the first place. We don’t need NASA to actually come up with a plan for starting a colony right now and we don’t need to ask congress for money to build a colony right now. What we do need to do is admit that this is the real reason why we want to go to Mars since using the other reasons to try and trick people into supporting a Mars mission using the other reasons just isn’t very effective.
NASA has tried to gain funding by not mentioning any plans for colonization; all that has resulted is a progressively shrinking portion of the federal budget and the cancellation of any programs that would make colonization easier. If we can't convince congress to support a goal of eventually having a permanent base on Mars, then it is unlikely that any subterfuge will get us anywhere.
The best option for us right now is to openly state that the main reason for going to Mars is to eventually colonize it, and to try and increase public support for that goal. If we want to go to Mars we need a good reason why we should go to Mars.
No no, the shuttle engineers aren't idle and playing cards, they are infact kept busy trying to make the most complex machine in the world which must suffer the most brutal mechanical and thermal conditions and engineering constraints operate. The simple problem is that Shuttle requires too many of them to operate safely and cheaply. Shuttle requires an absolutely rediculous number of skilled man hours between flights, its just CRAZY. If you would get the labor costs free and build a new shuttle every launch, it would probobly be cheaper.
The number of man-hours needed to operate the shuttle has decreased substantially since it first began operating. However, I think that much of the money in the shuttle budget wedge goes to things besides making the shuttle operate. For instance, it pays for all of the R&D used for shuttle upgrades, and for all of the shuttle-related infrastructure that NASA uses. I suspect that it also pays for all of the astronaut training programs that NASA has, and for most of the science projects that are carried out by shuttle crews. While the shuttle is expensive, I think that we would still be left with many of these expenses even we stopped using shuttle.
But since the H-F reaction is more exothermic than H-O you do get improved ISP (~550), flourine is the best oxidizer you could possibly find. It might also be possible to easily covert existing engines and tanks over to a H-F system, the oxidizer-fuel ratio should be the same, and the tanks might not require any modification. Also, the concurns about toxicity aren't such a big deal at high altitudes and in space.
Actually, the oxidizer/fuel ratio for F2/H2 is double the ratio for O2/H2. F2 is also a bit denser than O2, which ends up giving the F2/H2 combination an overall density that is about 65% higher than the density of the O2/H2 combination.
If you want to get fancy, you could also ad some Li and have a tripropellant reaction. That would give you an even higher Isp, but it would also introduce some extra difficulties.
Alternativly, you could mix some Flourine in with your oxygen for improved efficency as well.
There have been some studies using Flox (F2/O2 mixture) and various hydrocarbon fuels. It turns out that Flox can actually achieve a higher isp than either F2 of O2. A 70% F2+30% O2 mixture has the highest Isp for use with Kerosene (it seems that the O reacts better with the C, and the F reacts better with the H).
I have also seen an idea for mixing Li metal powder into a hydrocarbon base and then reacting it with Flox. That should be capable of some pretty good performance if it works properly.
Can you explain this. I think a spin of the built might create some lift in air although I am not necessarily sure of the physics but for a small gun wouldn’t the velocity of the payload leaving the gun be greater then the velocity of they payload leaving a mass driver of the same size or am I missing something.
One of the main problems with mass drivers in the atmosphere is that the projectile creates a shockwave that damages the inside of the mass driver. That is why mass drivers would be more effective in a vacuum. The reason why a gun would be less effective in a vacuum is that normal gunpowder burns rather than detonates. If there is no atmospheric oxygen, then it can't burn. This problem can be overcome, but there is another concern with a gun on the moon: where will you get your gunpowder? It would not be economical to import it from Earth, and I suspect that it would be difficult to produce large quantities of an acceptable propellant on the Moon.
I think that it would be easier to use asteroid material than it would be to use lunar regolith.
I am concerned about flying dirt damaging an L1 space elevator but the space elevator could be put at L2 instead.
If you have a space elevator, then I don't think that the mass drivers would be necessary.
Perhaps they could be fired out of a large gun kind of like the Missouri. I suggest a large gun because they are smaller and lighter then electromagnetic propulsion and perhaps even more accurate.
You also have to consider that there is no air on the moon. That would make it easier to build a mass driver, but harder to build a gun.
How about offering to sell the ISS at a bargin basement price to Richard Branson, Virgin Galactic Real Estate!
What could he do with it? He does not have any vehicles that can even come close to getting to it.
I think that Lockheed is currently working on starting a RD-180 line in America, to make the USAF happy.
That date for when the production in America will begin keeps getting pushed back. The last I heard is that it would not happen until 2012.
What does the future hold for the Atlas V?
The administration has been thinking about downselecting one of the EELVs. If I were Lockheed, I would be worried as it would seem more logical to keep the Delta IV.
The VSE plan was to pass the FY2005 budget with a $900 mil increase over FY2004 to $16.2B, followed by yearly increases only to match inflation. So it's doubtful we will see another increase this big betwwen now and 2020.
I agree with this. Thus, how can we expect a new clean sheet booster?
You could try to convince the Air Force to build the HLLV. They spend more money on space than NASA anyway, and their budget generally increases much faster than inflation.
How about just making the array lighter. Maybe even make the array lighter then air.
If the power supply by itself has a higher weight than the thrust that the crafts generates, then you will not be able to make it fly by simply reducing the mass of the array. I suppose you could use it to propel an airship, but this technology would have to improve a lot before it could become competitive with propellers.
The ERV's life support system has to run for six months only; the Hab's for 24+ months (6 months to Mars, 18 months on Mars).
That should not make such a huge difference. You might need some extra spare parts for the Hab's system, but you should not get a 3 fold reduction in weight just by shortening the mission duration to 6 months. Based on experience designing Transhab's LSS, The DRM assumes a LSS mass of 4661 kg in each vehicle(to support 6 people).