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Everything posted by AckSed

  1. https://arstechnica.com/space/2024/06/ars-live-recap-is-spacex-a-launch-company-or-a-satellite-communications-company/ Transcript of talk here: https://cdn.arstechnica.net/wp-content/uploads/2024/06/Starlink-Conversation-Transcript.txt tl;dr With Starlink, SpaceX is the largest satellite operator in the world right now, both in sheer numbers of sats and ground stations, and in revenue: Viasat/Inmarsat and Intelsat/SES ~$4 billion, Starlink $6.6 billion. They have a foot in the door with Indonesia, which is a prime market for satellite internet. If they enter India, despite the recalcitrance India is showing to OneWeb, that's an even bigger market. Estimated launch costs are below $20 million.
  2. A smallsat launcher reaching its 50th launch is very, very good going.
  3. Hannover Institute of Technology has an Einstein Elevator, a micro-gravity drop tower that encloses the vacuum in a small shell and then lifts it: https://www.hitec.uni-hannover.de/en/large-scale-equipment/einstein-elevator/
  4. Always bring your anti-spin running buddy.
  5. This is a chance to mention a recent favourite finding in space medicine involving a bungee cord to simulate Lunar-gravity, and a 10m-wide, 5m-tall Wall of Death, to make a circular vertical track that would allow the runner to experience Earth-normal G-forces when running: https://royalsocietypublishing.org/doi/10.1098/rsos.231906 Essentially, the high dynamic loading of the footstrike when a Lunar wall-runner makes contact reconditions the muscles and bones. They compare volunteers who, when confined to bed for 60 days, underwent 48 sessions of jump training over that time and managed to avoid most of the negative consequences. The preliminary conclusion is that 8-9 laps of the track per day, split into two sessions, should be enough. I like the sound of this for two reasons. One, all it needs is a large circular hab, which you could fill with an exercise bike in the centre, or things of that nature. No rotating components, no power needed. Two, this also suggests that in lunar gravity, you could run up and around the inside of a loop-de-loop. This will definitely be part of my Lunar recreation centre, alongside the Lunar pool and the human-powered flying dome.
  6. A tour around Starliner by the test pilots: https://www.youtube.com/watch?v=RlTsSaj6xEM
  7. In short, yes, and yes. It'd take a lot of mass and expense, so the question becomes "would we?" Opinion: only if reusable/semi-reusable cheap heavy lift becomes a thing. That gets you space stations on the cheap, more and cheaper research opportunities, the beginnings of spin-gravity stations, experiments with lightweight shielding, surrounding the astronauts with a wall of water, and so on.
  8. Robert Truax, designer of the famous Sea Dragon, did the Sea Horse tests as a prelude. Thanks to that, we know that rockets can be fired under water. The normal Raptors would probably survive their dunking. The Vacuum Raptors' bells might break off, as I'd imagine they'd be more fragile.
  9. Where else could I delight in space science and nerd out about rocket propellant mixes? And not suffer blanket pedantry? If it does go, know that I have appreciated you all too.
  10. BO angling for that NSSL money again: https://arstechnica.com/space/2024/06/blue-origin-joins-spacex-and-ula-in-new-round-of-military-launch-contracts/ The focus here seems to be on responsiveness (or perhaps a sniff-check), with the Lane 1 requirement that they have to be available to launch 6.3 tons within a 90-day period.
  11. https://arstechnica.com/science/2024/06/bacteria-use-pieces-of-dead-viruses-to-kill-their-competitors/ Who had, "Bacteria growing self-assembling lances for their enemies" on their biology bingo card?
  12. Perun, who normally follows military-industrial stuff, put out a vid on SpaceX:
  13. I don't know if you've heard of ARPA-E. They are an American skunk-works group, set up by the Department of Energy in 2007, developing high-risk, high-reward energy technologies. Their youtube channel has recordings of their pitch meetings. This one is about industrial processes: https://www.youtube.com/watch?v=GwtucNt6eLc tl;dw drilling for hydrogen, making synthetic coke (most of the carbon is high-quality structured stuff like graphene, graphite, nanotubes. A focus on making rubbish disordered carbon would be less energy-intensive and replace 60-70% of the carbon used in industrial processes today), plasma synthesis and direct reduction to fix nitrogen, sulphur and other things, and reduce the sometimes Byzantine processes to one or two steps. There is so much more in their channel, though. If I ever want some near-future optimism, I will be checking further: https://www.youtube.com/@ARPAEGOV/videos
  14. I'll take this action. There is a wrinkle in that Superheavy is likely flying a lofted trajectory in order to RTLS, so you would need a more powerful second stage like the Starship to circularise the orbits... but I'd like to think we could make a pseudo-Centaur out of an extra-wide F9 second stage and two Merlin Vacuums on the bottom. Hell, even if we don't have a payload, we have an orbital space truck in the Falcon 9, so you could strip the reentry hardware, install a docking port in the payload bay of a naked Starship , fit it out and fly up as a one-shot space station, ready for the Dragon to dock. If it works for Vast, it'd work for Starship Station.
  15. Here's a thing. With that footage of the hot atmospheric gas flaring through the hinges, the odd diagonal extensions of the heatshield on the leeward side made sense. They were expecting this to happen, and assumed that the tiles covering the inside of the flap and hinge were enough.
  16. Side question: What is "the big loop"?
  17. 10-metre hold before finally docking.
  18. Starliner just about to dock.
  19. That was a trip. When the rainbow effect was apparent on the bare steel, like a cooking pot left on the stove, I was concerned. When the sparks started flying and the rear-view camera showed the roots of the rear flap glowing, I was worried. When the steel of the forward flap began melting like it was shoved in the acetylene torch, I though that was it. But it kept. Going. That it made it through re-entry and splashdown makes this a very, very good day.
  20. "Did the primary buffer panel just fall off my gorram ship?"
  21. That still doesn't seem real, but they made the landing in one piece. I really hope they are able to release internal footage from the booster.
  22. I did hear something odd about the specific impulse being 40s less than the 460s of the Centaur upper stage, and I did see a few extra seconds of the Centaur's RCS firing perpendicular to the stage after MECO.
  23. I have a new supposition - supposition, I stress - on what caused the blockage in IFT-3's Booster: oxygen. Specifically slush oxygen, a mixture of liquid and solid O2. SpaceX already uses subcooled propellants in Falcon 9, and slush oxygen and other subcooled propellants were investigated by NASA in the 70s, finding significant mass savings on their then-current dream of SSTO. Near-boiling-point LOX (183.3°C) was 1140 kg/m3, and LOX subcooled to triple point (-218°C) at 1 bar was 1310kg/m3: Cryogenic Propellant Densification Study (1978) Interestingly, triple-point/slush methane is mentioned, though only to say, "We don't have the data, we'll have to make some assumptions and treat it like slush hydrogen or RP-1". Maybe in IFT-3 they were testing out lower temps of oxygen, some transient event like slosh during boostback caused pressure to drop and a clot of oxygen slush developed at just the wrong time. If you've ever tried to wash snow or ice down the drain you'll know that it can cause temporary blockages, and while the impellers inside the rocket engines should chew up any oxygen snowflakes, the tanks being nearly empty combined with the blockage and slosh caused a fatal hiccup.
  24. No-one said our cyborg's power source had to be internal. Perhaps they're plugging into wall current, or lugging a jury-rigged micro-fusion reactor on their back as they trek halfway across the planet to safety.
  25. Images of Io from a ground-based telescope good enough to spot one volcano's outflow covering another's: https://news.arizona.edu/news/glimpses-volcanic-world-new-telescope-images-jupiters-moon-io-rival-those-spacecraft
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