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Correct on the subduction, et al. What happens is that the Earth's mantle is convecting like water on the stove and the crust gets carried along. At points where the mantle dives back down, some of the crust is carried down with it. Since the crust material is much lighter, when it melts, it bubbles back up and burns through the crust in the form of volcanos. The Pacific rim activity is a result of this.
As for pressure causing heating, that's a no go. The pressure at the center of the Earth caused a lot of heating originally but that heat would have dissapated quickly. Someone (lord Kelvin, IIRC) used that as proof that the Earth was less than 10,000 years old.
Instead, the decay of radionucleotides such as uranium and its decay products keep the furnace burning as it were. Being dense, most of the uranium is in the mantle and core and releases tremendous amounts of energy as it decays, constantly heating the core of the Earth.
Broken tubes aren't going to be a problem, the whole thing is going to be one of those MEMS lab-on-a-chip deals. Basically, analyte is pulled into a capillary and electrophoresed. The different animo acids are labelled with a fluorescent probe (probably the CBD stain from Molecular Probes) and the difference in speed of their movement through the capillary will distinguish the various amino acids. The chirality is determined by lining the capillary with a chiral compund that slectively retards one handedness over the other.
Yes, kind of. Nanotech for computing will make computers in general moer powerful. However, raw power isn't really that critical for space travel. Remember that we got to the moon using computers that are less powerful than today's wristwatches.
Technically speaking, nanotech has traditionally been associated with building structures under 100 nm in size. (this is a poor definition, nanotech is now generally associated with structures that show quantum confinement effects which occurs under 10 nm, generally and the 10-100nm size scale is now often referred to as mesoscopic) By the old definition, current semiconductor tech is now nanotech since it has feature sizes of 90 nm. Both Intel and AMD are already gearing up for the next jump to 65 mn. In the next 5 years, both companies are expected to get to 35 nm processes where the laws of physics finally wreck the party.
Personally, I'm partial to the old 'will the last person leaving please turn off the lights' sign we had in Seattle back in the late 70's.
I assume that you're talking about the X-15 specifically, the X-plane program is still very much alive. The scramjet program that NASA ran a few weeks ago was the X-43 or something like that.
The X-15 was interesting but really pushed the limits of technology at the time. Interestingly, a lot of the X-prize stuff is closer to the X-15 than standard rockets. Things like the NASP are descendants of the X-15 but none have worked successfully. The challenges of trying to get orbital speed through the atmosphere a re not something that are lightly approached.
I stumbled across a webpage for acompany called electron power systems that discovered small, stable plasma toruses that can survive at atmospheric pressure. For a while, they were claiming that you could store energy in the magnetic fields of the thing to stupid energy densities - claims going higher than the rest mass energy of the plasma were made.
However, NASA did a study and found that one of their numbers was off by many orders of magnitude. To the company's credit, they accepted NASA's criticism and have since scaled down their claims.
Ah, good 'ol D. radiodurans. IIRC, it's still one of the record holders for radiation tolerance. It can shrug off loads of over 1000 rad as if nothing had happened. One of the big D. radiodurans researchers, Mary Lidstrom, works on the floor above me. The mechanism it uses to survive radiation is not well understood but seems to be an adaptation to be able to survive drying out. (which damages DNA in ways similar to radiation)
From what I've read about Fusor technology, the biggest hurdle is having particles hit the accelerating electrodes. Because of the design, the electrode is within the particle field and the vast majority of the particles quickly impact the electrodes and don't get a chance to fuse. If someone clever were able to design an electrode that could deflect particles around it, there's no reason that a fusor couldn't get well over break-even.
Buildinga rusor on high school is quite impressive. I woudn't even try to build one of those on my own with all of the high voltage circuits. However, on the scale f fusion devices, the fusor is pretty trivial compared to, say, a tokomak.
Cool, the view you posted looks like a view of one of the quartz gyroscopes. (two of the gyroscopes are quartz, the other two are silicon to make sure that any peculiarities inherent to one material don't cause problems. Either Scientific American or SCience had a nice cutaway diagram this month of the whole probe. Imagine a big, pear-shaped balloon with a fat stick running most of the length down the center from the skinny end and that's what gravity probe B looks like.
The big pear is the lead jacket that contains all of the liquid helium. At those temperatures, lead superconducts and therefore blocks out almost all of the Earth's magneic fields and stray electromagnetic signals. The 'stick' is the actual workings of the probe.
There's a long tube that lets light in and supports the rest of the assembly in the middle of the liquid helium reservoir. After the spacer tube, there's the star scope. This was made of big blocks of solid, ultra pure quartz. No glue was used, the pieces were machined to super close tolerance and cleaned so well that they just atomically fused together when they were assembled so the entire star scope is one big piece of solid quartz. This eliminates differential movements due to heating or cooling. The star tracker zeros in on that guide star and tracks it with incredible precision. There's some sort of trick with wobbling the probe back and forth to get the star to move so that the accuracy is high enough. The guide star is also being tracked from the ground since any movement it makes will actually throw off the probe!
Finally, at the end of the 'stick', there's the 4 gyroscopes which are electrostatically suspended and spun up with gasseous helium to peroper speed. A coating of chromium on the gyroscopes generates a tiny magnetic field which can be read by a superconducting quantum interference junction, allowing tracking of the motion of the spheres.
Now you've got me wanting to pick these DVD's up! I think you should be getting a kickback from the publisher. :;):
Re: the digital artifacts. How old is your DVD player? I've noticed that older players tend to have a lot of problems with some of the newer disks as the player gets older. I think the player gets out of alignment or something and the newer DVDs for some reason have tighter tolerances than the old ones. With good players under $100, it might be time to upgrade.
The widening exhaust os probably caused by the atmospheric pressure. One of the big problems with designing rocket engines is that you have to compromise between designing the engine bell width for the differing amounts of exhaust expansion you get with different air pressures.
ecrasez - the gravity 'tornado' effect was predicted by general relativity and figured out by a couple of researchers about 2 years after Einstein published his theory. We're expecting to see the effect. If it's not there, it'll be very big news. However, that's not expected.
The whole 'missing space' thing is just a poor interpretation of what's going on. My understanding is basically that as the satellite orbits the Earth, the Earth is slowly dragging the fabric of spacetime around it. As a result, the satellite's actual path ends up being slightly skewed. The gyroscopes can detect this deviation which is VERY small.
Really, in some ways gravity probe B is very boring - it's expected to find what's already been predicted and nothing else. The operation of the probe and the precision it had to be made to, however, is anything but boring. It's by far and away the most impressive piece of engineering I've every seen. It's 4 nearly perfectly smooth spheres spinning inside a solid quartz starfinder scope bathed in liquid helium in a superconducting lead balloon.
CM - If you're going for absolute evidence, I agree. OTOH, there's very good evidence that gravity waves exist. Relativity gives predictions for what the energy in gravity waves should be (with error bars, of course). The rotational slowdown of those neutron stars is right smack dab where it should be if gravity waves are the cause. If LIGO were detecting gravity waves, something would be wrong - it's too noisy to be able to detect them. In theory, LIGO should pick something up but potential signals are just getting lost in the seismic noise of the Earth. However, LIGO's shortcomings don't in any way invalidate the exitence of gravity waves. The true test is a space-based interferometer which should be able to detect the waves.
Further - if gravity waves don't exist, relativity has to be wrong. If you posit that (which is a valid point, relativity could have flaws in it), there's no reason to think that gravitational frame shifting is any more likely to be observed than gravity waves.
Gamma rays are simply the most energetic form of Electromagnetic radiation (carried by photons). EM radiation goes radio, infrared, visible, UV, X-rays and gamma in order of increasing energy. Other forms of radiation like alpha, beta and cosmic rays are other sorts of subatomic particles that have rest mass. (helium nuclei, electrons and a various mix of particles make up those three previously mentioned) Gamma rays are very high energy, penetrate along way through matter (several feet of concrete are often not enough to stop them) and are moderately dangerous to get hit by.
As for what happens when two black holes merge, I'm pretty clueless. I vaguely remember reading that it would release a tremendous amount of energy but to be honest, I'm not certain how that would occur. The problem with black holes is that a lot of the stuff associated with them is very counterintuitive. (eg: hawking radiation, etc) You'd have to talk to a high energy physicist to get the lowdown here.
The costs of a large manned space effort are just too large for private industry, IMO. However, there's a lot of room for innovation for private industry in space. For example, the Planetary society is launching a test solar sail later this year. Electropropulsive tether and M2P2 drive technology are two other potential systems that are lightweight and have a great deal of potential. Assuming that you can get LEO masses down to <200 kg, there are sub-$million launchers (old Soviet ballistic missiles) that can get you to orbit.
NASA is the only game in town for things like large space nuclear reactors but they tend to prioritize the little experiments like M2P2 too far down the list, IMO. There's little return on the investment but if an angel investor were willing to put up a few million, a small expermental space probe is perfectly feasible. It's too small to do much of anything useful but the experience gained would be potentially very useful for NASA or other agencies in the future.
CM Edwards - I've got to respectfully disagree regarding LIGO. The fact that the instrument hasn't seen anything yet is not suprising, the noise level they can get is just not low enough to spot gravity waves unless they happen to catch the gravity waves from something like a pair of black holes merging. In order for LIGO to work, it's really got to be in space. We know that the gravity wave phenomenon exists from observation of binary neutron stars where the slow decreasing their orbital rotation rate around each other is nicely explained by energy lst by the generation of gravity waves.
The bit about 'lost space' is pretty bogus though. It's not really being lost, it's being dragged around the Earth and therefore the spacetime path travelled by the probe deviates from what one would expect.
Here is a link to the Gravity Probe B website [http://einstein.stanford.edu/]here! Take a gander at the 'what is gp-b'/'story of gp-b' link for an excellent description of how the instrument works, what it's measuring and how it was built.
For example, those 4 gyroscopes have a maximum devation from being a perfect sphere by less than 20 nm - that's equivalent to the Earth having a maximum height feature of 16 feet.
I stumbled across the gp-b website about 5-6 years ago and have been following it off and on since. It's nice to finally see it up in orbit.
Yeah, you could probaly get away with hitting it with Ceres - Mercury would probably just result in Mars turning into debris.
The only problem is that most of the surface of MArs would be gone and turned into magma. You'd have to wait thousands or millions of years for it to cool off and settle down. Kinda obviates the whole point of terraforming, IMO.
The biggest obstacle to using inland seawater to irrigate the Sahara is the size of the holes you'd have to dig. Nothing short of a lake the size of one of the great lakes would suffice. Of course, it wouldn't have to be deep but still, you'd have to use nukes or something to excavate the lakebeds. The current occupants of those areas might have some issues with that plan. :;):
Particle beams have three big problems. One - as GCNR mentioned, particle beams are even more inefficient to produce than lasers. Two - particle beams tend to be heavily scattered by air. Three - high energy particle beams are highly destructive, if they hit the target, you'll get all sorts of radiation damage.
Microwaves are the only real variant of this technology that looks practical with the technology we have available.
The low gravity would help the insects get larger but you'd need a very high O2 content for that to happen. Insects are limited in size by both their weak musculature and lousy repiratory system.
It's a common misconception that insects are strong. Actually, their muscle content is tiny. They only carry large proportional loads becasue they're so small. If an ant were made human sized, it couldn't even lift itself off the ground. Conversely, a human shrunk to insect size would be an insect Hercules, able to fend of arthropod enemies by simply rending them limb from limb.
Fed Man - phytoplankton account for most if not all of the CO2 sequesteration on the planet. most terrestiral forests are pretty much a net zero for getting rid of CO2 - it gets put back into the atmosphere from burning or rotting. Phytoplankton, however, make CaCO3 skeletons that sink and end up becoming limestone. (the cliffs of Dover are basically giant phytoplankton graveyards)
While the conditions for phytoplankton survival on Mars are a long ways off, they would represent a good tool to pull that CO2 out of the air.
kippy - it could be done alright, just not cheaply as you seemed to be hoping. If the optics nad pointing mechanisms are going to be pricy, you might as well start making giant mirrors to get the most mileage out of 'em. If you're going to make cheapo, small mirrors, just put then in a polar orbit around Mars - as long as they're relecting light in the general direction of the planet, you're OK.
I always did that with short articles in the newspaper. It first occurred to me when reading the local section and there was a story about a local man who stabbed his brother to death over an argument over toilet paper.
The sort of life events that would have lead up to killing one's own brother over ass paper is something that still crosses my mind every once in a while. There's something about the reduction of a person's life to a few lines of newsprint that falls somewhere between being bleakly depressing and having a wierd sort of haiku-like beauty.
Why do we necessarily need to have a man rated launcher right now? The Russians have a perfectly good one and are already doing the work to upgrade it up to a 6 person capacity. It's a lot cheaper to just buy space on the Soyuz/derivatives. Used the money saved and put it into the HLV program, Shuttle/EELV derived or de novo design.
Of course, we'll want to eventually wean outselves off of the dependence upon outside launchers but in the timeframe for plan Bush, I can't see a huge change in US - Russia relations and from a financial standpoint, it makes sense.
It's always hard to figure out what stuff is from an orbital prcitre but I've seen similar looking things at the beach where wind is blowing on the sand. You tend to get those big V's behind things like rocks and stuff.
I wouldn't be too suprised if there were some occasional geysers somewhere on Mars. It's just the idea that the big mountains like Olympus Mons were made by geyser activity that we're objecting to.
verifying that pants can survive in Martian conditions.
I dunno, while embarassing, I would hardly characterize a chronic lack of pants as fatal. :;):
Although I'd argue that the reasons for the Hermes cancellation were more complex than that, I largely agree. However, the simple fact that NASA could run the Shuttle for so long is a sign of the sheer amount of manpower and material it can field. Now that the Shuttle is being phased out, those resources can be directed towards more productive endeavors.