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  1. Nibb31

    SpaceX Discussion Thread

    What a dumb idea.
  2. Nibb31

    what is geo orbit

    GEO stands for Geostationary Earth Orbit. It's a specific orbit, at ~36000 km, over the equator, where your orbital speed matches the Earth's rotation, and therefore the satellite remains over the same spot. This orbit is very popular with telecom and TV satellite operators who want permanent coverage of a particular country. The drawback of reaching this orbit is that it is very high, and therefore requires a lot of dV to get there, and it needs to be equatorial, which means that you need to launch from near the equator.
  3. Nibb31

    Russian Launch and Mission Thread

    I'm not sure that the problem with Russian space is due to funding. I think it's mostly a problem with workforce qualifications. Russia is suffering from a brain-drain, where skilled engineers and technicians tend to either flee Russia or go work in more lucrative businesses (gas and petrol for example). I suspect that a large part of the Russian space program is made of poorly qualified technicians, with a high turnover rate. Also, the fact that many of the materials and processes used are obsolete doesn't help.
  4. Nibb31

    Russian Launch and Mission Thread

    I know you're joking, but I don't see BFR ever docking to the ISS. It is large and would put a lot of stress on the structure. It's probably too "dirty" too (thruster gas pollution). We also don't even know if there is a docking adapter in any of the recent designs. At any rate, it would have to go through years of certification with NASA before it would be certified for operating in vicinity of the ISS, at which point the ISS will be near its end-of-life.
  5. Nibb31

    Russian Launch and Mission Thread

    Dragon 1 cannot unberth without someone on the station closing the hatch and controlling the arm, so any options involving Dragon 1 are a no go - Any option involving leaving the crew without an evacuation vehicle (Soyuz) are a no go. Any option involving a vehicle that is not yet ready to transport crew (Dragon 2, Starliner or Orion) or to operate in vicinity of the ISS (Shenzhou) is a no go. The shelf life problem with MS-09 is not just about fuel, so #10 is a no go. In your list, only #1 and #2 are options at this point. There are other opportunities that involve shuffling around the Progress launch that was scheduled for November. However, resuming Soyuz launcher operations assumes that the investigation determines that the problem was a one off and is not systemic. Given the reliability issues that Russia has been having over the past years, I wouldn't be very confident with that sort of conclusion, and neither would NASA. And don't forget the concerns about hole in the MS-09 for which there still hasn't been a satisfactory explanation. Who knows if Soyuz is still safe at this point? What if there is another hole (or other manufacturing problem) on the next Soyuz ? There seems to be a deep-rooted systemic problem with Russian quality control that has to be addressed, and that can take a lot of time.
  6. Nibb31

    Space shuttle and iss

    The docking modules were not originally part of the Shuttle design. They were built by Russia and retro-fitted as part of the Shuttle-Mir program. This is why the US segment of the ISS was fitted with Russian APAS docking ports. Also, Columbia was never fitted with the docking equipment.
  7. Nibb31

    Buoyancy rockets!?

    Submarine-launched rockets don't use bouyancy to get out of the water. They use solid rockets. Those things are pretty heavy solid boosters. Adding the structural reinforcements to make your rocket withstand underwater pressure, plus the complexity of the thing and all the additional failure modes would take away any benefit of extra delta-v if there was any (but there isn't).
  8. Nibb31

    SpaceX Discussion Thread

    They are not wings, they are fins. Unlike something like DreamChaser, they do not generate lift, and since they are symmetric, they should be pretty much neutral. The canards are also symmetrical and can be trimmed to be neutral. If anything, they should help stability. After all, fins on the front of a rocket are nothing new. Now, vertically launching with a spaceplane on top (X-20 DynaSoar, DreamChaser, or Hermes) is much more problematic, because those vehicles are designed to generate lift on re-entry. You are going to need strong control authority to keep it flying straight. That's why the Space Shuttle flew to orbit "upside down". It could use some of the lift generated by the wings to rotate the flight curve rather than fight the lift with the engine gimballing. You just have to keep in mind that although it looks like it has wings, the BFS is not a spaceplane.
  9. Nibb31

    SpaceX Discussion Thread

    Or it implies that there might be a version of the rendering where some other number of engines is firing.
  10. Nibb31

    SpaceX Discussion Thread

    It's not the length that bothers me, it's the surface area in contact with the ground. 100 tons per leg, on a surface of a few square centimeters, is bound to sink into the ground, even on a prepared surface. It needs feet or pads with a wider surface area.
  11. Nibb31

    SpaceX Discussion Thread

    The petals look like they could be some sort of inflatable device. A ballute maybe ? Or a landing device ? I'm having problems imagining telescopic landing stilts that extend out of the fins. Without feet or pads, the weight/surface area ratio is going to cause problems on unprepared terrain, and even prepared terrain. The whole ship could weigh several hundred tons and that entire weight will press on a total surface area of about 1 square meter.
  12. Nibb31

    SpaceX Discussion Thread

    A meta-nozzle might not work as well as a proper vacuum nozzle, but it might be a good enough compromise to make the reduction of engines worthwhile. Those petals might also be for protecting the engines from debris during landing.
  13. Nibb31

    SpaceX Discussion Thread

    Speculation at this point, but that explains the lack of vacuum Raptors. Not with the petal things in the way. I still think D2-like nose-to-nose docking is more flexible and provides more contingency options (evacuation, rescue, tug operation, access to ISS and other vehicles)
  14. Nibb31

    SpaceX Discussion Thread

    This design makes much more sense than the 2016 and 2017 designs. I really couldn't see those doing any realistic re-entry and flip-over maneuvers, nor could I see fitting a landing gear wide enough for unprepared terrain, high enough to keep the engines safe, and strong enough to support the ship and cargo in 1G. This version solves most of those problems. I'm pretty sure the lower fins fold upwards on re-entry, giving it a DreamChaser-like profile. The petals could be for vacuum propulsion, but they could also be some sort of device to protect the engines during re-entry and landing. One thing that this design breaks is the back to back refueling method. I suppose they could still have nose-to-nose docking, which actually provides more flexibility (ability to transfer crew, ability to fire the engines while docked...)
  15. Nibb31

    Amateur rocket to orbit

    ITAR has nothing to do with hitting planes. It's about exporting technology, and it's a US-only thing.