berthing is *harder* than docking. they are doing it this way because it is a cargo transport, and the berthing ports are much larger than the docking ports.
if/when Dragon starts carrying people, it will dock.
the problem is you can't just 'fix' TCP. even if you make it work with both IPv4 TCP and IPv6 TCP, you're still missing the other protocols out there (SCTP, UDP, etc, etc), and more importantly, can NEVER fix protocols that are being encrypted (ie TCP inside VPN packets). the protocols that you aren't 'fixing' will just continue barging their way through.
the only workable solution is to drop packets and assume the protocols themselves will adjust (which they will, if they are working correctly, and if they're not working correctly.. they'll be penalized with a lot of dropped packets).
dropping packets is unpleasant, because it is wasting bandwidth, and causing TCP stalls.. but ECN barely works because half the routers out there drop or mangle it, so it's the only solution.
no, it's specifically aimed at conventional weapons, not nuclear. the point is NOT to send an ICBM, because doing so tends to make our Russian or Chinese friends get all retaliatory (even if it's not nuclear tipped.. how do they know?) - instead this thing would fly through the atmosphere and deliver a conventional payload.
it's intended to be a very, very fast cruise missile, with the objective of being able to hit any point on the planet in an hour or less.
that video is over three years old, and quite a lot has changed since then.
for example: they show an escape tower being jettisoned - there isn't going to be one now, SpaceX are working through NASA sponsored milestones to design and build a 'built in' launch abort system, which they also plan on using for landing at a later date (ie: no dunking in the sea).
they are also working on designs for crew cabin (again, part sponsored by NASA). that's what the original posting is talking about - a step in that process.
I definitely wouldn't take that video as gospel for how the piloting systems will look.
the major reason none of the web servers support multiplexed fastcgi is that none of the fastcgi servers support it (ie PHP etc).
that said, there is a third party module for nginx to provide multiplexed fastcgi.. ie comes with demo fastcgi servers to test with.
that site seems to be getting hammered... try this cached copy:
http://www.free-photos.biz/photographs/science/astronomy/67895_c_venera09_processed.php
I have a counterpoint:
http://blogs.nasa.gov/cm/blog/J2X/posts/post_1297869180794.html
this is a duct for the J2-X rocket engine, produced using Direct Metal Laser Sintering (3D printed metal, in other words). it has to operate at insane temperatures and pressures... and it does, perfectly.
Most (if not all, Taurus II is yet to fly) of the engines in question are and will be brand new; sold profitably. Redesigned quite a few times. Put into production (or prepared for one) in "high labour cost" place.
they are cleaned, polished, given a new coat of paint and some new gaskets. a new wiring harness and modern electronics.. fired on a test stand to make sure they don't explode (and apparently a third of the NK-33s WILL explode when used.. without some fixes. that's why Taurus is delayed). but they are definitely not 'brand new'. none of those engines has been built new in decades.
But at least you, suddenly, insist that economy of rockets does matter after all...
the whole topic of discussion was about the price of *fuel*. which is insignificant compared to the rocket, engines, electronics, and payload. of course the cost of the engines makes a difference. a single engine costs ten or more times the fuel and oxidizer..
this would be the (one of) the reasons SpaceX designed a relatively simple, cheap to make, engine. it's not as efficient as the Soviet-era engines, but it's just as cheap, and can be mass produced now. that means you need to use more fuel. but guess what? the cost of the extra fuel is basically a rounding error.
for the upper stage, I absolutely agree with you - efficiency is king. but Soviet-era engines are not the best choice for that... a super high ISP kerolox engine is still 30% worse than an average hydrolox engine.
Why is that, why do ~half of US launch systems might end up with ex-Soviet / Russian engines? The staged combustion cycle, which only the Russians successfully implemented, is extremely efficient.
because they are cheap? they were built with Soviet labor, then left in warehouses to rot. found and sold to the US in the 90s for pennies on the dollar. they are VERY good engines.. but that's NOT why they're being used.
efficiency is only terribly useful for a rocket in a vacuum. that's why they're rebuilding the J2 for upper stage work (and even it's not particularly good).for first stages you need thrust. that's why the shuttle and the proposed Aries-V (cough) SLS needs expensive, dangerous solid rocket boosters strapped to it, because it's using hydrogen fueled engines which are good at ISP but not as good at thrust. Saturn-V used kerolox for the first stage for a very good reason. high thrust, not so good ISP.
When you have cheap Fuel and no Concerns about global warming. Making Bigger and Faster means transportation is easy. Fuel isn't cheap anymore. So we are trying to keep the same old stuff from the 60s but make them use less fuel a much harder engineering challenge. I want to make my car faster and fuel isn't a concern make the engine with more cylinders and grater gear ratios. But to make my car 10% more fuel efficient while keeping the existing power is much harder to do.
fuel (and oxidizer) is a TINY percentage of the cost of a rocket launch - usually less than 1% of the cost of the launch. launch vehicles are never optimized for fuel economy - they are optimized for performance above all else.
they are reusing components from the shuttle because they are still (just) available. components from Saturn V (engines, mostly) would do a far better job, but they haven't been built in decades and couldn't be reproduced for a sensible amount of money. NASA is half way through a project to reproduce a J-2 engine for the new vehicle's upper stage (the same engine was used for Saturn V upper stages 50 years ago), and it's cost a VERY large amount of money to get as far as they have.
there is also a huge dollop of politics and pork involved. re-using shuttle components keeps existing contractors (and jobs), rather than causing uncomfortable restructuring and job losses right before an election year.
that's just one. there are dozens of NASA 'human rating' standards documents that are expected to be followed, plus (possibly) some standards that are unofficial or just in the heads of certain managers.
SpaceX say they have adhered to every *published* NASA human rating requirement. they keep asking if there's anything else that's not published..
BTW the space shuttle did not follow several of those standards, but was 'waived'.
sigh. forgot to log in. parent article was me, if anyone cares.
took a while to find... it was from an interview with Aviation Week:
he says they're leaning towards a 1.7 million lbf engine, but they've also been looking at a 3.5 million lbf engine with a throttle setting for use in smaller rockets (back to 1.7, presumably).
the F-1 engine from the Saturn-V (Apollo), for reference, was only 1.5 million lbf, and still holds the title for 'largest rocket engine'.
that was their evolution plan - build a 'Merlin 2' sized to replace the 9 x Merlin 1s required for Falcon 9, then start building bigger rockets with multiple Merlin 2s.
BUT Elon has talked about building a Merlin 2 engine sized all the way up to 3 million lb/f (about three times bigger than the 'Falcon 9 replacement' size), which might be the route they took if there was suddenly a lot of money available to skip a step (and it would probably be sensible, if there was a tight deadline).
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