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Nibb31

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  1. Nibb31
    Dragon V1 uses CBM, which isn't a docking port, it's a berthing mechanism. Dragon V2 uses IDS, which is an androgynous docking system.
  2. Nibb31
    The whole point of an androgynous system is that any two parts can dock together. Ports on a spacecraft can switch to active or passive depending on their role: typically the port playing the active role extends, but if it's retracted, then it acts as a passive port. On the ISS, the ports are passive only, because they will always be docked to by active spacecraft, but there should be nothing preventing two Orions or two Dragons from docking together.
  3. Nibb31
    Bad analogy, because a single tanker truck can fill up hundreds of cars. It makes sense to build a gas station to service thousands of cars. In space, you need several tankers to fill up your car for each journey. So you might as well just park your car and use it as a fuel depot.
  4. Nibb31
    Yes, abandon the idea. Which is exactly what NASA did with Skylab.
  5. Nibb31
    Assuming there is a need to store propellant in anything else than whatever it came up in... In most cases, there isn't. You would send up "tankers" as needed and dispose of them when empty. Or you could just deliver disposable tanks with a reusable tug. Or if you have a big large ship that needs multiple tankers, then it would simply be its own propellant depot. It will be a long time before there is a need for a multi-purpose propellant depot.
  6. Nibb31
    You wouldn't outfit the tank. You would need to design a whole new stage. As mentioned, it would need internal insulation, or several tons of coating on the outside to prevent shedding foam. On the inside, you would need airlocks between the tanks, and some sort of docking device. It would need station-keeping if you want to dock to it, which means power (solar panels), avionics, RCS, navigation, comms... You probably wouldn't want live directly inside a tank that has been filled with H2, LOX and helium, and the coatings on the inside of the tank wouldn't be very pleasant, so you would probably need some sort of inflatable bladder to fill the tank with a breathable atmosphere and serve as liner/padding. Then you would need to install the wiring, fluid loops, air ducts, assemble walls and floors and install the equipment... The whole outfitting job would probably take months or years of EVA and IVA assembly, and many delivery flights to bring up the equipment. Having a large empty volume isn't nearly as valuable as some people think. It's what you put inside that volume that matters. In the end, it's much cheaper to build your habitat on the ground and have it operational immediately for orbital work.
  7. Nibb31
    I love the introductory sentence. "95% of statistics are pulled out of thin air". Then it goes on to "many of the engineers" that worked on the space shuttle, who now work at Space Island Group... as if it was actually more than 2 guys in a shed (and I'm not even sure they have a shed).
  8. Nibb31
    SpaceX's conclusions were based on sample testing. There were no forensics on actual debris. So, yes, it's likely that some struts had QA issues. But the investigation couldn't confirm that the struts on the CRS-7 were actually defective, nor could it confirm whether a failed strut was the root cause of the failure, a contributing factor, or something totally unrelated. That's why NASA wasn't 100% satisfied with SpaceX's results. In this case, they will be able to recover debris and perform some forensic analysis on the materials, so the investigation has more material to work with and identifying the root cause should be somewhat more affirmative.
  9. Nibb31
    But that would be a totally different rocket. Have you got a source for their intentions of having their own shuttles ?
  10. Nibb31
    There is no "grounding" by the FAA, but business sense dictates that there will be no more flights until they have identified and fixed the problem. After CRS-7, Falcon 9 flights resumed after 6 months, and the root cause was never identified with 100% certainty. In the best case they will find rapidly that this failure was due to a ground equipment problem that isn't present at LC-39A or Vandenberg, and they're good to go. In the worse case, they identify a design flaw on the launcher which requires a redesign of the tanks and a requalification of the second stage. In that case, we're looking at least at a year, maybe more.
  11. Nibb31
    It can't.
  12. Nibb31
    I don't the SLS core can actually reach orbit. The upper stage does the job of finalizing the orbit. The Shuttle was different, because keeping the ET attached wouldn't prevent the OMS circularization burn. It would just cause a payload penalty. I don't think Space Islands ever planned to operate their own Shuttle fleet. They simply wanted to reuse the ETs and NASA was actually open to the idea as long as they would get assurance that the ET wouldn't become a hazard. The whole "wet lab" concept is another one of those false good ideas. It seems attractive at first, but when you start looking at the actual engineering details, it quickly gets impractical. Outfitting a spent tank requires more than just an airlock on it. For example the insulation foam on the ET (or the SLS core) isn't meant to withstand vacuum. You would rapidly end up floating in a cloud of orange foam debris. And there are hundreds of other details that would need to be thought out.
  13. Nibb31
    Actually, the AN225 is used quite a lot for oversized cargo, including satellites, rocket parts, aircraft parts, locomotives, nuclear plant equipment, oil drilling equipment, generators, military equipment (including for NATO), wind turbines, disaster relief, etc... It's flown to Afghanistan, Iraq, Alaska, KSC, Kourou, Haiti, Australia... It's really a rather busy aircraft, and I can understand why a second one would be useful. This is Mriya #2: Not quite flight ready.
  14. Nibb31
    It's not a copy, it's going to be built under license, probably with available spare parts. This is a unique aircraft with unique capabilities that are totally different from a 747. If the Chinese have a need for those capabilities, it makes sense to use an existing design. Airbus went through the exact same process with the Super Guppy. They had a unique requirements, and there was only one existing design that met those requirements. So they bought two of the three existing aircraft from NASA, then they purchased the plans and built two more under license in the 1980's, 20 years after the first batch.
  15. Nibb31
    So you are claiming malicious intent, because SpaceX is so awesome it can't screw up ? That's the most ridiculous thing I've heard today. Every design has its flaws. All procedures have loopholes. Everybody makes mistakes. Accidents happen. SpaceX is under a lot of pressure, and employees take the brunt of that pressure. They are notoriously overworked and underpaid. Their procedures and paperwork are leaner than the rest of the industry. It wouldn't be surprising if corners got cut somewhere down the line. There are all sorts of things that could have caused the explosion, inside and outside the rocket. We simply don't have enough evidence yet, and unless there is some evidence found, malicious intent is way down on the list of probably causes.
  16. Nibb31
    No, it's called statistics. That's what risk assessment involves. "Attitude" is irrelevant.
  17. Nibb31
    The pad is toast. a minute or two after the first stage explosion, you could see the ground tanks go. The strongback tower is scrap too. Rebuilding the pad will take at least 6 months to a year. LC-39A is supposed to be "nearly ready" for F9 and FH, so they will probably accelerate that while they repair LC-40. You are still looking at several months of delay, a growing backlog, FH being postponed, the 2018 Mars mission being pushed to 2020 and the MCT reveal being pushed back until after F9 has a successful flight or two. This is definitely a bad day for SpaceX.
  18. Nibb31
    I'm not. SpaceX did. http://www.spacex.com/news/2015/07/20/crs-7-investigation-update The result of SpaceX's root cause analysis after the CRS-7 failure was that one of the struts that support the COPV (the composite helium tanks) failed under G load, which caused the COPV to go lose and puncture the LOX tank. SpaceX put the blame on the manufacturer of the struts as the investigation revealed that some of them did not meet the requirements. NASA wasn't too impressed with the investigation report provided by SpaceX and because of the lack of evidence, some doubts remain that the root cause was actually found. If evidence points to today's incident being linked to the COPVs themselves (the explosion seems to originate in the same general area), then SpaceX might have some explaining to do regarding the CRS-7 report... But this is all just speculation, and I'll stop commenting on the causes of today's accident here. We simply don't have enough evidence.
  19. Nibb31
    Of course it is, which could be a good reason to cut corners.
  20. Nibb31
    Supplier are selected by their customers based on audits and tests. So obviously, something was wrong with SpaceX's certification process that allowed this to happen. This is what SpaceX does: They go to one of the big aerospace suppliers, those who provide stuff for Boeing, Airbus, etc... and they ask for a quote. They usually decide that it's too expensive, so they go to Joe's Strut Factory, who happens to be cheaper, and they pay them to bring themselves up to aerospace-grade standards, and certify them. So yeah, maybe they have the paper trail, but in this case, they were still providing junk that didn't meet the standards, which means that their certification was bogus.
  21. Nibb31
    The difference is in the "certification". One part is off the shelf and designed to resist a certain load. The other is designed to resist the same load, but has a paper trail that goes all the way back to the source materials, test results in various environments and temperatures, calibration of the test equipment, certification of the tooling, manufacturing procedures, personnel qualifications, etc... Yeah, it's mostly just paperwork, and you might strike lucky with the cheaper part for some applications, but there are very good reasons to use aerospace-grade components on multi-million dollar aerospace projects.
  22. Nibb31
    Imagine the guys on the site of the "emergency" scratching their heads... "Ok, so how do we get this thing off the plane and in the water now?"
  23. Nibb31
    An Airbus A320 fuselage has a diameter of 4 meters. The An225 cargo hold is 4.4m tall. It would be a tight fit, but you could fit it. It also has external attachment points for larger cargo.
  24. Nibb31
    Which would make SpaceX look even worse if it turns out that they put the blame on the provider of the strut when it was something else, maybe internally designed.
  25. Nibb31
    It can also be used to transport rocket stages or aircraft fuselages. MAKS is off the table.
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