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Any solar sail that can manage to keep accelerating long enough to get up to an appreciable fraction of the speed of light will have no prayer at stopping, because solar sails only work within star systems and it'll be going so fast it'll pass through the star system in far, far less time than it spent accelerating in ours. You need an equal amount of time in the same energy conditions to decelerate as you had to accelerate.

So either dive into the sun at the target system or do what Robert Forward suggested:

https://arc.aiaa.org/doi/10.25...

Here's a paper on the VOLGA engine:
https://arc.aiaa.org/doi/pdf/1...

Anyway, as usual, opportunities lost in Europe because of lack of political vision.

Supposedly will be a way to maneuver spacecraft, at least those in space, in the future.

http://arc.aiaa.org/doi/10.2514/1.B36120

Why a trip from the lunar surface to LEO? I was referring purely to fuel production on the Moon. Obviously for usage scenarios, you have to do extra calculations, but since no particular one was mentioned, I didn't take that into consideration. In the specific usage scenario for fueling a trip to Mars - assuming you actually meant "Moon as a stepping stone" (otherwise the rest of your text doesn't seem to make sense) -, the logistics for that was studied recently at MIT, with promising results.

(There's a youtube here: www.youtube.com/watch?v=xqQB0WqOahc)

My first reaction was that this was ridiculous, but on second thought the concept itself is not actually all that wrong. It simply relies on a very specific barrier that has not been overcome yet: Gravity. Industrial endeavors of any kind are all very heavy, and current launch methods are all horribly inefficient (the best currently is the Ariane 5 at a little under 39% payload/vehicle weight, but it's still more or less a one-use/disposable vehicle). So for industry of any scale the cost of actually getting the necessary equipment far outweighs, massively outweighs, dare I say it, even ASTRONOMICALLY outweighs any savings you'd have from doing the work in space with a Zero-G environment and 24-hour solar power available (both very real but not immense savings). There is a reason that the International Space Station is the single most expensive object ever created by mankind (at $157 billion it comes in at more than 6 times the cost of the #2 object, the Itaipu Dam).

That being said, if we can manage to get a cheap method of reacting orbit, the primary barrier would be circumvented and it would make all kinds of sense to migrate such things to orbit. As the OP suggested, energy is abundant (both from solar sources and from various theoretical designs of orbital tethers tapping electrostatic energy in the atmosphere or electrodynamic magnetic harvesting. At that point the Zero-G environment would make large scale industrial and manufacturing endeavors much easier, especially if you can accept the idea that by that time the bulk of the raw materials would be harvested from non-terrestrial sources like asteroids, comets, and meteoroids.

Currently the most promising concept on tap seems to be the Orbital Space Elevator. We have basically all the fundamental technologies required with the advent of Carbon Nanotubes (as opposed to more theoretical solutions involving gravity manipulation, for example). It has come down largely to a manufacturing challenge of creating the 22 mile cable required, when currently nothing longer than about one meter has been achieved.

> I have not seen any reasonable theoretical explanation for the anomalous force that is purported to power the EM drive
The only thing that critics have managed to say about emdrive theory over 10 years is " muh momentum "

What else can we reply when there is no actually theory presented that we can reply to or refute? All we have to go on is some micro-wave engineer claims that he has invented a device that violates conservation of momentum without providing any reasonable theory for how it might work. Your attempt to blame the critics for the complete lack of theoretical underpinnings by the inventor is ridiculous. The inventor himself said:

I am just a microwave engineer and all that matters is that it works.

In addition, the Anonymous Coward engineer claims:

Emdrive has been experimentally verified by 5 institutions with results published.

(emphasis added)

Have experimental results been published? Yes. Has the effect been verified? No. Most of the extraordinary experimental results seem to have been either debunked or retracted, claims such as nearly one Newton of thrust by a paper from China which has been shrouded in mystery. The more recent and reliable Tajimar paper explicitly says:

... we successfully identified experimental areas needing additional attention before any firm conclusions concerning the EMDrive claims could be made. Out test campaign therefore can neither confirm or refute the claims of the EMDrive [...]

In one of their experiments their measured thrust was in the wrong direction! Their conclusion that the experiments need to be improved before they can be used to verify the EMDrive claims echoes what I already said (and you mocked) that the current experimental results are buried down with the noise. That is what the fine post linked to by the summary says as well. The experimentalists are working on beating back known sources of noise so they will eventually be in a position to confirm or refute the EMDrive claims. It is not all relevant if totally different experiments with totally different devices had better signal to noise ratios with similar input powers and output thrusts.

Your mocking, your ad hominem attacks, and your appeals to emotion and irrelevancies do nothing to bolster your argument. Your claims far exceed the claims of the very experimentalists whose work you (appear to) cite. You are, of course, free to believe whatever the heck you want but it seems your claims of experimental verification are greatly overblown. For me, the lack of theoretical underpinnings, the violation of the conservation of momentum, and the lack of experimental verification (as I cited above and from the fine post linked to in summary) all make me highly dubious that the effect is real.

It's like you didn't even listen to the parent.

Martian regolith contains perchlorates. It's toxic. We're not talking about nutrient levels. It's up to 2% by mass perchlorate ion. Perchlorates are rocket fuel. Literally, they've actually considered harvesting them to make propellant on Mars. They're also quite toxic, impeding thyroid function at a couple dozen parts per million quantity in water. They're toxic to plants too.

You can't just, like in the book, take some martian regolith, take some manure, sprinkle on some dirt for bacteria (which was BTW a pointless step given the crop choice and the bacteria already present in the manure), mix it all together and call it a growth medium. First you have to bake the regolith to break down the perchlorates. Then you have to rinse it to remove the extra salts. Then if you have a reverse osmosis system you could add the water back in. There's still no guarantees then that it'd be fertile/have all of the needed nutrients in approximately the right ratios, but at least it's not guaranteed to be a health hazard to both you and your plants.

I know this is Slashdot, but the abstracter of the paper is pretty clear:

"Our test campaign can not confirm or refute the claims of the EMDrive"
http://arc.aiaa.org/doi/10.251...

How did we get from that to the summary posted here? Why does the happen every single time an article about this appears on Slashdot?

Because that's what clickbait is all about!

Here is the first page of the actual paper, including the abstract which says:

Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurement methods used so far.

So the /. title says pretty much the exact opposite of what the actual paper says.

I am still extremely skeptical that there is any actual effect. They powered their device with a 700 watt magnatron and measured plus or minus 20 micro-newtons of thrust. To put this in perspective, one Newton is roughly the weight of an apple near the surface of the Earth. If the thrust scales linearally with input power then you would need 50,000 x 700 Watts = 35 Megawatts to levitate a single apple. Of course the inventor claims that the thrust to power ratio is highly non-linear so at these higher power levels you would get a lot more thrust. I have not seen any sensible theoretical model that explains why this would be so.

If you are using hundreds of watts to produce a handful of micro-newtons then it is extremely likely there is no actual effect and what is being measured is just some form of noise. This is especially true when the so-called effect violates a primary law of physics.

> Back when I was working on lasers for power beaming

Short or long haul? Down or up?

We looked at lasers for space-to-Earth power beaming, but it's less practical than you might think-- heat rejection gets to be a serious problem. Most of the practical applications were Earth-to-space or space-to-space power beaming.

http://ieeexplore.ieee.org/xpl...
http://proceedings.spiedigital...
http://www.sciencedirect.com/s...
http://arc.aiaa.org/doi/pdf/10...
http://ntrs.nasa.gov/search.js...

So, Blue Origin just decided one day; "Hey wouldn't it be cool if we could land space ships at sea?" and went ahead and patented the idea without the foggiest notion of how this might realistically be accomplished?

Nah, they most likely just read about how to do it.

The Forward Mass Sensor would disagree with you.

http://arc.aiaa.org/doi/pdf/10...

Only been around for 49 years though.

http://www.regnirps.com/Gravio...

It's probably #2. The paper, as presented at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, is available for purchase. I happened to have a spare $25 and a burning curiosity. The full paper isn't available on the NASA site, only the abstract can be gotten there for free. If you wanna read the details, you have to pay for 'em.

Anyhow, here's the relevant bit from the paper: "Two roughing pumps provide the vacuum required to lower the environment to approximately 10 Torr in less than 30 minutes. Then, two high-speed turbo pumps are used to complete the evacuation to 5x10E-6 Torr, which requires a few additional days. During this final evacuation, a large strip heater (mounted around most of the circumference of the cylindrical chamber) is used to heat the chamber interior sufficiently to emancipate volatile substances that typically coat the chamber interior walls whenever the chamber is at ambient pressure with the chamber door open. During test run data takes at vacuum, the turbo pumps continue to run to maintain the hard vacuum environment."

I'm not a physicist, but the paper is still an absolutely fascinating read, and contains a number of color photos of the test apparatus, the device itself, etc. The amount of detail they went into for the experiment is really impressive; seismically isolating the test chamber, using liquid metal (galinstan) electrical contacts to eliminate any forces due to a mechanical coupling to a wire, compensating for the magnetic field that is created by passing electricity through the device, and so on. This is NASA we're talking about here, the guys that do ROCKET SCIENCE. The idea that they wouldn't test this device in a vacuum is laughable.

Something spooky is going on inside this device, and I hope it doesn't take us too long to figure out what is really happening.

Negative mass is very diferent from antimatter. Antimatter is opposite to normal matter in charge and quantum numbers (such as baryon number, etc.), but still has positive mass.

Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.

This has peculiar consequences. One consequence is that, for objects of negative mass, gravity and electrostatic charge switch. For normal mass objects, gravity is attractive, but like electrical charges repel. For negative matter, gravity is repulsive, but like electrical charges attract.

I wrote about this once, in the AIAA Journal of Propulsion and Power-- not a journal that physicists usually read, I'm afraid. If you have access to AIAA online, it's here: http://arc.aiaa.org/doi/pdf/10...

Or this work:
http://arc.aiaa.org/doi/pdf/10...
Green Aerospace Fuels from Non-Petroleum Sources (2011)

http://arc.aiaa.org/doi/pdf/10...
"Aerospace Fuels from Non-Petroleum Sources" (2013)

Or this work:
http://arc.aiaa.org/doi/pdf/10...
Green Aerospace Fuels from Non-Petroleum Sources (2011)

http://arc.aiaa.org/doi/pdf/10...
"Aerospace Fuels from Non-Petroleum Sources" (2013)

You might be interested in the Eagle lander's great grandfather: Masten are doing a study for Lockheed Martin on the Dual thrust axis moon lander (DTAL). [pdf, 19 pages] Which has led to their Xeus concept.

There was the TAU 1000 AU probe, which was to be sold on parallax measurements (i.e., astronomy). I didn't regard that as compelling.

More interesting are the suggestions of a probe to the solar gravitational lens focus, at 688.81 AU (or greater) (for light - it is less than that for gravitational waves or neutrinos, as they pass through the Sun, while light has to go around the Sun).

At that distance or greater, you could use the Sun as a telescope and greatly magnify any remote object at any frequency (and also for gravitational waves and neutrino's). Trouble is, it would be hard to point it at more than one or two targets (as you would have to move the spacecraft 11 AU / deg to do so). You could (I am sure) arrange a trajectory to get 2 or 3 or maybe even 4 objects over time, but that's not many objects for a multi-decade mission.

Lets be ridiculously generous and assume a scramjet boost phase could lift you to 155 km at mach 18. You have only gained about 5% of the necessary kinetic energy needed for LEO

Pardon my pointing this out, but NASA's got another idea on boosting...

https://info.aiaa.org/tac/PEG/HSABPTC/Public%20Documents/Scramjets%20to%20LEO.pdf

What magic material will they make this net out of?

This PDF slide deck has some additional details. It describes them as "50-g mesh nets", I couldn't tell you how they are supposed to work.

Perhaps I used the wrong link, and yes, it entered a ballistic trajectory after the thrust unit tore off. But prior to that, it was reentering without its heatshield forward. Currently, they do think they have the problem fixed, but they've yet to find the original cause. Interesting article here: http://www.aiaa.org/Aerospace/images/articleimages/pdf/Soyuz_JUN2009.pdf

Actually, the issue with detaching the thrust unit is that one of a number of bolts didn't fire. The unit ended up tearing itself off due to aerodynamic drag, but there's evidence this issue has been around since the first Soyuz missions. There was a pretty good article on it in the June 2009 AIAA magazine. PDF here: http://www.aiaa.org/Aerospace/images/articleimages/pdf/Soyuz_JUN2009.pdf

I'm a just-graduated aerospace engineer from Notre Dame. For our senior design project, we build uav's... well, really RC planes. Everything had to be constructed from scratch, except for the electronics (motor/battery/GPS/receiver/etc). This year's goal was to have a mothership-daughtership configuration where the daughtership would detach mid-flight and maneuver on its own. Believe me, it's loads of fun to build everything from scratch, but it is a lot of work. And I definitely think it is doable by anyone, not just aerospace engineering majors.

Here was my team's plane: http://www.youtube.com/watch?v=eW68B3DnNWA

If you're interested in actually constructing the structure by yourself, I'd definitely suggest picked up a book on model airplane construction. Hobby shop dudes are also a big help, just go in and throw some ideas out and most hobby store owners will be very enthusiastic. And, if you're _really_ interested, I'd suggest Aircraft Design: A Conceptual Approach by Daniel Raymer. Link: http://www.aiaa.org/content.cfm?pageid=360&id=1396

Oh, also, flying a model aircraft requires a hell of a lot of skill- we get the awesome dudes down at the South Bend RC Plane Club to fly ours.

That is almost nutty enough to be interesting, to the extent that I dug up the original paper:

http://pdf.aiaa.org/preview/CDReadyMPDC04_865/PV2004_1419.pdf

Alas only the first page is available; they charge $25 for the full text.

Robert Wood seems to have had an interesting career but to have fetched up in areas that aren't terribly good for his credibility:

(From http://www.majesticdocuments.com/documents/intro.php ):

"Our investigation team, led by Robert and Ryan Woodâ"a father and son team with 50 years of combined UFO studyâ"has applied their skills as both sleuths and scholars. Painstakingly verifying âoedeep throatâ sources, meticulously analyzing old and controversial documents, they arrive finally at conclusions that are as well grounded in fact as they are stunning in their implications. UFO-related secret programs have consumed a significant part of Americaâ(TM)s black budget since the Manhattan Project. [...]"

Oooooh-kay.

This is *not* insightful (and I'm wasting my change to mod it overrated to try and correct it).

1) Nitrogen is one of the most available chemicals on the planet.
2) *Nitrates* are the biologically available form of nitrogen.
3) Farmers dump hundreds of pounds to tons of fertilizer on their fields; depending on crop, soil, etc.
4) As far as I can tell, nitrates are not a major combustion product of nitrocellulose. You can get some
      nitrogen dioxide as a seconday byproduct, but no more so than anything else burned in
      the atmopshere at high temperatures, including perchlorate fireworks. The main effect of which would
      seem to be some minor acidification; NO2 -> N2O4, N2O4 + H2O -> HNO2 + HNO3.

• Wave Drag -- I finally threw away my copy of Zucrow and Hoffman a decade ago, but I remember that dragging a supersonic and really HYPERsonic shock wave was a huge amount of drag. Were that not the case, you could put a bullet into sub-orbit with a sufficent elephant gun. You can't.
• Stagnation Temperature -- You will be in the Mach 7 zone pretty quickly. The stagnation temperature at Mach 7 is... crap. Well, you have Zucrow... look it up. You've seen hypersonic ablation of metals at Mach 7. What are you going to make this thing out of? Carbon Nanotubes? Surplus shuttle tiles?
• Combustion pressure -- Let's assume that this 280s engine is a simple solid motor, like a high-tech Estes rocket. Tube, propellant, nozzle. The combustion pressures you need will require a tube of very high strength to weight ratio. Here's some "back of the envelope" back at ya! If yer using some surplus Ammonium Perchlorate from Thiokol's drip bucket, you know that that's about 2Kg/l. Twice water. 10Kg of propellant is 5 liters. That's a tube 50 sq. cm by 100 cm long. About 8cm diameter. Since you are a rocket engineer, you know that smaller diameter tubes hold pressure better, but that increases the length needed to hold the same amount of propellant. That increases the mass, and increases the size of the fins (we're talking a model rocket on steroids here... no gyroscopes.) needed to stabilize this increaingly long rocket. And the fins will need to handle secondary shockwaves of like Mach 4. DAMN I need Zucrow back! You'll need some nano-tubes in your elmer's glue to hold them on.
• Guidance -- Let's make some assumptions... To orbit 9 times, you'll need to be 100km high... AND going 7.7km/s... PERPENDICULAR to the G-vector. Otherwise, you're not at Apogee, and will dip lower, denser and more drag. You might eke out that 9th orbit, but judging from the debris of US193, I'd say not. So, to get to 100km AND be going 7.7 in a circular orbit, you need to go up, up, up AND east, east, east!!! (West is a waste of delta-V, right?) So, how do you get up AND east? You could do what the Shuttle and the ol' Saturn V did... go up for a while, then arc to the east. How are you going to guide that in this micro-missile? (forget about cost)? Add to that the fact that you run out of air for the spoilerons at about 16km. You have 84km of airless burn. How do you keep the arc flattening out to go only eastward? Tiny little RCS pulses? Someone will come up with something clever, but will it fit into your mass budget?
• Circularization -- I sincerely tip my hat and bow to your rocket design career. But you must design rockets that go BOOM, because you missed something that is REALLY going to be tricky... The Circularization Burn. I'm sure you know that even the Shuttle coasts about 30 minutes from MECO to it's circularization burn. How do you, on this simple rocket, coast for 30 minutes and then burp about 130 m/s? The complexity of that will steal from your mass budget. I know what yer going to say...
• Final Stage! -- The reason I didn't call you on SSTO was a) I was at work at an IT job and didn't have time to go into it. b) it was so OBVIOUS that it wouldn't work, that it went without saying. So, yes, let's stage this fire arrow. And the final stage, which is barely bigger than an

Heh. I read "AIAA" and I thought you were talking about the American Institute of Aeronautics and Astronautics, which is indeed sort of an Air Industry Association of America...

Ethics is an interesting concept - first thing that may come a person's mind :

"good and bad"
"wrong or right"
"black and white"

Personally, when one finds themselves in IT related predicaments, I'm guessing it's not that usual to land in a black or white situation, but one of a million shades of gray.

A few more:

"the way one lives"
"actions that land you on the right (good?) side of the fence"
"oath"
"creed"
etc . . .

What is a creed? One definition in an online dictionary defines it as ( http://dictionary.reference.com/browse/creed ) : " . . .any system or codification of belief or of opinion. . ."

eek . . . the entertainment industry (I'm guessing a person can come up with centuries or more worth of examples there) would have us believe in "good" creeds or "bad" creeds - religions, knights, assassins and more.

One might also ask - will your ethics lead you to copy chunks of the comments to the slashdot article above? Ethics in research and writing papers - that's a fought over issue as well. (people often hate to look in this mirror :)

Several professional groups have published "ethics" . . .

American Chemical Society ( http://pubs.acs.org/meetingpreprints/ethics.html )
American Institute of Aeronautics and Astronautics ( http://www.aiaa.org/content.cfm?pageid=198 )
American Institute of Architects ( http://www.aia.org/about_ethics )
American Institute of Chemical Engineers ( http://www.aiche.org/About/Code.aspx )
American Society of Landscape Architects ( http://www.asla.org/about/codepro.htm )
Instutute of Electronics and Electrical Engineers ( http://www.ieee.org/portal/pages/iportals/aboutus/ethics/code.html )

To pick a few. Look kind of like science/fantasy fans might see as guild rules :)

IT is no different.

People who strive for SANS/GIAC certification agree to their ethics as part of completing the certification process. ( http://www.giac.org/overview/ethics.php )

SAGE, LOPSA & USNIX share the same code of ethics - http://lopsa.org/CodeOfEthics

ACM - http://www.acm.org/about/se-code

CISA, CISM, CGEIT - ( http://www.isaca.org/Template.cfm?Section=Code_of_Professional_Ethics&Template=/ContentManagement/ContentDisplay.cfm&ContentID=20454
)

SSCP, CAP & CISSP (certification) ethics - ( https://www.isc2.org/cgi-bin/content.cgi?category=12 )

I'm sure there are plenty more.

I'm guessing there are very few if any CS or IT related courses that don't include some kind of ethics class or section.

Personally - when I was growing up - with a lot of computer enthusiasts in the neighborhood - some slided one way or the other (ethics wise) and some stood fairly firmly on one side or the other (usually the "old guys").

I've been in the professional IT industry for several years - and doing semi-professional IT stuff on and off years before that. Seeing I'm still there - I hope I'm on the an acceptable side of the fence :)

I've been involved in a few ethics dust-ups over the years . . . never got a horrible

sure.
http://pdf.aiaa.org/preview/CDReadyMJPC2003_775/PV2003_4431.pdf

Yes, getting any object to orbit is the hardest part. You can make anything from nanosatillites (this object would qualify) to geosync communications satellites and send it to orbit if you have the money. Russia, China and several other countries will send your satellite to orbit or any other place in space. Amateurs have launched suborbital rockets in 2004 but getting to orbit is a a lot harder. Here is the /. article about the amateur suborbital rocket: http://science.slashdot.org/article.pl?sid=04/05/18/0133223&mode=thread&tid=134&tid=137&tid=160&tid=193 Here is the industry article about some history and pricing for launching objects into space: http://www.aiaa.org/aerospace/Article.cfm?issuetocid=54&ArchiveIssueID=10

That's why you start with much more than you'll need in the long run ;) But yes, more realistically, I'd think people would use shorter lifespan batteries.

Still, I must strongly disagree with the author's pessimism. Offhand, I can already think of a system that wouldn't suffer degradation, something like a dusty fission fragment reactor. Basically, your "fuel" is a nanoscale powder (say, a tritium polyethylene), which is inherently self-ionizing because of the beta emission. You have them in a core with charged walls, so the particles all distribute themselves roughly equidistant from each other. Since the particles are so small, their individual absorption cross-section is small, so they tend to not thermalize the radiation. You can use magnetic fields to collimate the weak beta into beams and decelerate it in a grid to recover almost all of the energy. Everything except for the magnets is little more than a hollow shell, keeping the weight down.

I haven't done the calculations on what size the device would be, though. That may be a limiting factor in this particular design. Still, I think the article shows a failure of imagination. Just because the current crop isn't up to snuff doesn't mean that all will be.

First, this is a blog troll, to drive traffic to some ".info" site. The actual paper, "Proposed Follow-on Mini-Mag Orion Pulsed Propulsion Concept" presented at an AIAA conference last year, is more useful.

The basic idea is to create a small fission (not fusion) explosion using magnetic compression. Nuclear weapons use chemical explosives to create an implosion, and during the implosion the fissionable material is compressed hard enough to get a 1.5x to (maybe) 2x density increase. With magnetic compression, a small pellet can be compressed hard enough to get a 10x density increase. This allows smaller explosions, around 50 gigajoules instead of the 20 terajoules of a fission bomb. They want to use curium or californium as the fuel, rather than plutonium.

They also want to use magnetic containment, rather than an Orion-style "pusher plate" sprayed with oil. Unclear if that can be made to work.

The experimental work (they compressed an aluminum cylinder with a big magnet at Sandia) was done back in 2002. This isn't really under active development.

It's not a totally unreasonable idea, but it would be a huge job to make it work. For one thing, the plan is to assemble a large spacecraft in orbit, not to take off from Earth. It doesn't help with the problem of putting mass in orbit.

Spectra is a mere 3.5G GPa UTS and *950* kg per cubic meter. You converted g/cm to kg/m^3 wrong. It's not even within an order of magnitude of what is needed. Furthermore, you represented SWNTs wrong. They're SWNTs, not graphite; it's a completely different form that just happens to use the same SP2 bonding structure. Their density is about 1300 kg/m^3.

Furthermore, while it's possible to build a space elevator with a nanotube cable that's only 65 GPa tensile, it's not realistic. It's also possible to build a space elevator out of kevlar. Your taper factor is just preposterous. LiftPort's numbers call for a SWNT fiber with strength 100-120 GPa, yet a total system cost in the tens of billions. You really can't get much lower of a strength and still have a remotely feasible business plan.

Now, the sad truth that Laine refused to address. Early after the discovery of SWNTs, there were all sorts of wild numbers for their strength produced, most around 120 GPa. That's not the reality of the situation. Modern calculations are only for 50-60 GPa, and that matches well what has been tested by using microscopic probes to break nanotubes. But it gets worse! The tubes cluster into ropes by pi bonding and vdw, and these aren't some sort of "reverse-wrap" ropes. Their strengths are only 3.6 += 0.4 GPa. Now, this can probably be improved, but it's obviously never going to surpass, and probably never even approach, the strength of the individual tubes. However, even ropes aren't the end of the story -- then you have to produce an *affordable fabric of an indefinite length* out of them, which puts yet another strength bottleneck into play.

Come on, Laine -- why didn't you address this? It's not like it hasn't been raised.

I think Liftport's development process can best be summed up as:

"In other news, my Teleporation Shoes are performing extremely well in tests. The shoelaces have survived twelve straight tying tests, including one "bunny ears" test conducted by a young child. Sole durability tests are also holding up well. Teleporation will be tested at some time in the future."

Funny, cause AIAA (aerospace engineering journal) takes submissions in Word ... templates are online here (yes, written three journal articles - and thesis - in Word. It really isn't that hard and they all came out great.)

Yes, I'm aware that the steel industry has big dependency chains. That's why you will not find the word "steel" in my original post. I said "cast iron." You know, the stuff humans were working with during the Iron Age, thousands of years ago. Adjusting the chemistry of the product is a level of sophistication that would come a few generations later.

Here is a PDF describing methane production processes that aren't dependent on an oil industry.

For those who are interested, the AIAA covered this [PDF] in the July 2006 issue of Aerospace America.

...and industry is going with civil UAVs. The American Institute of Aeronautics and Astronautics (AIAA) releases an annual poster listing all the world's UAVs. The last one I have is the "2005 Worldwide UAV Roundup." Guess which country has the most UAVs? Yup, the United States. And, the vast majority of them are not military or attack aircraft. Alternatively, you can pick up a Shepard UAV Handbook. That will list them all out as well.

Hey, what did the American Institute of Aeronautics and Astronautics ever do to you? (ducks)

Or maybe they are corporate funded propaganda.

Oh. Sorry. Left my tinfoil hat at home.

You don't know until you check the references and see who has peer reviewed them.

No shit. At least I know when I submit my papers to the AIAA they are peer-reviewed by PhD's and that when I pick up a journal from them, those papers have been too. Same goes for ASME, etc. Wikipedia has no such level of validation, because any asshat can go in and change the math/science/engineering, not just the mathematicians/scientists/engineers. There have been cases of 'vandalism' per see where an expert in her field has posted a perfectly valid page on Wikipedia and then had it changed by someone who doesn't understand the underlying science. It has been posted here before. A system that allows that is not a system that can be relied on for any meaningful data.

It is easy to point out the one or two frauds that exist, and then draw conclusions from your own personal experiance. But the system works (I know ... I live in it)

Its called peer review. You do work. You publish to a credible journal (emphasis on credible). Editors read your submission and assuming you haven't done something stupid (depending on the journal - some excellent journals will deny good papers) your paper will probably get past them. If you f*ed up, you get caught - someone reads your paper and discovers you did it wrong, gravity vector pointing in the wrong direction for instance, the results were too good, etc.

For example the UAH Propulsion Research Center gets over a million a year from NASA and other government/corporate sources for research work. Results get published and reviewed. That research keeps a lot of students in grad school and gets a lot of work done for NASA. (Hint: grad students work cheaper than professional engineers). Not to mention there are few private citizens/small companies that truly want to innovate propulsion. Including the new space startups. They are mostly re-hashing old ideas.

I do research for UAH - same principles apply. I've published two papers (only one citation available online at the moment) and have spoken at two conferences attended by my peers. I also publish reports to the army - since they are the primary customer. People can attend those conferences and pay attention to speakers to review their results, and read papers in journals to critique their analysis. If they have further questions you generally have contact information on the paper (at least in my field).

That's the way the system works. And it works pretty well, except when you fake results in a controversial topic of study. Then you become a hot topic.

-everphilski-

Gamers and people who listen to music are terrorists in the eyes of the ??AA.

You don't mean '??AA'. What you really mean is '[(RI)|(MP)|(GN)]AA'. The NCAA, AIAA, AAAA and NIAA kindly ask that you not lump them in with such filth.

(i was waiting for that response...) Some bullets can, look up a paper by Williams, Hahn, et. al. http://pdf.aiaa.org/preview/CDReadyMJPC2005_1177/P V2005_3847.pdf ... I'm one of the authors and yea, there are bullets that do mid-course corrections :P (many others exist... in existance and conceptual. Just mention this paper cause i knew where it was on the top of my head)

My point is magnitudes of scale. Yes they missed, but if you compare the error - its 3E-7. JAXA was being overabmitious, if you look at their prior projects they just didn't have the experiance to do this kinda thing, they did a damn fine job doing just this.

-everphilski-

Hard to believe this is merely a coincidence, but last month's Aerospace America cover story was on a very similar topic.

PDF of the article: http://www.aiaa.org/aerospace/images/articleimages /pdf/AA_July05_SIE.pdf

Hard to believe this is merely a coincidence, but last month's Aerospace America cover story was on a very similar topic.

PDF of the article: http://www.aiaa.org/aerospace/images/articleimages /pdf/AA_July05_SIE.pdf

That's not how they work

That IS how they work. For god's sake, read before you post. The part of the shuttle that is an insulator is called the "thermal blanket"; it prevents the heat that isn't radiated away from getting to the frame, which being an aluminum alloy, is very temperature sensitive. The entire arrangement, of RCC panels, tiles, and thermal blankets is called the TPS (Thermal Protection System). Read about it some time, will you? I can get you as many references as you want, and can even direct you to an "Ask NASA" page if you still aren't convinced.

By the way, tiles are not nearly as brittle as you pretend. At the speeds that the shuttle flies on liftoff, rain would slice right through your hand as well. At high speeds, the water acts like a solid on impact. With a mass about a quarter of that of buckshot but a velocity about twice as high, it has the same total kinetic energy, focused on a smaller point.

Prior to being at JHU's APL for the second time, Dr. Griffin was also the "president and chief operating officer of In-Q-Tel, a private, non-profit enterprise funded by the Central Intelligence Agency to identify and invest in companies developing cutting-edge technologies that serve national security interests."

Some may be familiar with In-Q-Tel as the CIA's private venture firm.

He had just rejoined APL last April. He was with APL in the 1980s, and left to become the technology chief for the Strategic Defense Initiative.

To expand a bit on what the summary said, "in addition to a doctorate in aerospace engineering, he holds master's degrees in aerospace science, electrical engineering, applied physics, civil engineering and business administration, and a bachelor's degree in physics." He is also the president-elect of the American Institute of Aeronautics and Astronautics (AIAA).

There's no question he is not only a skilled academic with a clear appreciation for space sciences, but a competent administrator and manager as well, and experienced with Washington politics to boot. Let's hope he does well for NASA.

The "few thousand birds" comment is funny, though.

Are you saying that there haven't been more then 2,000 satellites launched?

I was making a rather confident guess but a minutes searching bring up this AIAA article which seems to confirm my supposition.

Indeed looking at the numbers it seems reasonable to assume the US's aerospace industry alone has launched more then 2,000 satellites in it's history. Heck there are even high schools that have assembled and had satellites launched.

speaking as someone who is part of the political wing of a space advocacy group, we are fighting for this legislation to be pushed through.

It provides legitimacy for this budding industry and give legal avenues for people to develop it. Think of it this way: Without any regulation saying where and how a group can launch into space, the government can just shut them down based on noise pollution, safety hazards, possession of dangerous materials, any number of things. By having prescribed rules, groups shooting for space can do so without worrying about operating within a legal vacuum (and later physical one).

There's also the safety stuff that others have commented on but that's been covered.

The Mars Society, AIAA and I think the NSS are all pulling for this so that should tell you something about how spacers view such regulation.

I found these references at AeroSpace Architecture Publications:

Cohen, Marc M. (2003 September). Mobile Lunar and Planetary Base Architectures (AIAA 2003-6280). AIAA Space 2003 Conference & Exposition, Long Beach, California, USA, 23-25 September 2003. Reston, Virginia, USA: American Institute of Aeronautics and Astronautics. Link to on-line order forms

Cohen, Marc M. (2004 February). "Mobile Lunar Base Concepts." In M. S. El-Genk (Ed.), Space Technology and Applications International Forum - STAIF 2004: Conference on Thermophysics in Microgravity; Conference on Commercial/Civil Next Generation Space Transportation; 21st Symposium on Space Nuclear Power and Propulsion; Conference on Human Space Exploration; 2nd Symposium on Space Colonization; 1st Symposium on New Frontiers and Future Concepts (p. 845-853). Albuquerque, New Mexico, USA, 8-11 February 2004. College Park, Maryland, USA: American Institute of Physics. Link to on-line order forms