Comments by "H. de Jong" (@h.dejong2531) on "Why NASA's Next Space Suits are not Pressurized to 14.7psi - Smarter Every Day 296" video.

  1. Let's be real , all of the evidence says 12 people have walked on the moon. You have no evidence for your claims.
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  2. There was a TV camera on the lunar rover. This could be remotely controlled from Mission Control, AND it could send its video signal directly to Earth.
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  3. Oxygen toxicity happens when the partial pressure of oxygen is about 2 bar. In orbit, the partial pressure never gets above 0.3 bar.
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  4. Coarse sand tends to settle out more quickly than small grains, so using coarse sand helps reduce clouding.
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  5. This is a documentary, not propaganda.
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  6. That footage was captured by a camera on the lunar rover. That camera could be controlled remotely from Mission Control. The LRV also carried a transmitter that could send the video signal straight to Earth.
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  7. Well, that's what NASA did, within the confines of what they can do. SLS has been mandated so they can't get rid of that, but one of the landers will be a Starship supplied by SpaceX.
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  8. Outer space has one thing in common with being underwater: you can float (i.e. be neutrally buoyant) in both environments. That makes this pool hugely useful for training complex tasks like spacewalks. By acclimating the astronauts to how weightlessness feels, and how they can do tasks in weightlessness BEFORE the mission, they make those spacewalks during the mission a lot more efficient as the astronaut isn't wasting time doing these tasks for the first time. Training in a vacuum is mostly pointless, as that's very similar to just being in our atmosphere.
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  9. Nope. Space videos are shot in space, not under water. This is immediately obvious: no space video shows the huge drag that is obvious when filming underwater.
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  10. What time stamp are you referring to? I just reviewed that section of the video and all I found was glint off of the PLSS radio antenna.
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  11. The Apollo suits could not be used for the long missions planned for Artemis: they were wearing out after 3 days. Also, for Artemis they want to be able to have more-or-less universal suits, instead of having to custom-fit each suit for one person. And that's just one of the major differences between Apollo and Artemis.
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  12. We don't believe, we know we actually went to the moon. There's so much evidence that proves this that there's no room for doubt.
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  13. The pool had to be large enough to fit the ISS mockup and be able to work around the outside of the ISS.
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  14. The evidence says otherwise, grow up.
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  15. A quote that has been misinterpreted by moon landing deniers. They falsely assume it means "we no longer know how to get to the moon", which is nonsense. It means "we dismantled the production line and if we want to go back to the moon, we'd have to start by building new rockets and spacecraft".
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  16. They did look at Apollo. The Apollo solution has drawbacks, as does the solution now used at the ISS, so they're experimenting to find a solution that's better than both.
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  17. That's a dumb conclusion, and the wrong one.
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  18.  @evidece4divine  Because all of the evidence on this shows that the Apollo missions are real. There is no evidence any of those missions were faked. This video shows they're doing experiments to optimize spacewalks (reducing the time it takes to prepare for a spacewalk). There's nothing in it to indicate the solution they used in the Apollo program was unworkable.
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  19. The nice thing about science is that it's verifiable, which makes NASA's claims not propaganda, but reality.
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  20. Running oxygen rich allows them to go to a really low pressure. 5 psi at 80/20 would kill you. 5 psi at 100% oxygen is fine.
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  21. It doesn't. I measured the dirt getting kicked up in one of the Apollo videos. 1. it doesn't slow down as it travels, which means they must be in a vacuum. 2. The dirt takes 2.5 times longer to get to the ground than it would on Earth, which means they are in 1/6 g instead of 1 g.
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  22. For Apollo, this is how they handled that: once the astronauts were in the cabin, a few hours before launch, they were on 100% oxygen at slightly over 1 bar pressure, while the cabin was at 1 bar pressure of normal air. So they had several hours of prebreathing pure oxygen, which meant they no longer could get the bends in the event of rapid decompression. During launch, the cabin atmosphere was vented to ~0.3 bar, and supplied with 100% oxygen. The suit pressure was lowered at the same rate (it took only a few minutes to get to the target pressure).
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  23. Sky "scholar" is a crackpot. His experiments do not prove what he thinks they prove.
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  24. We don't need shielding for humans to travel safely through the van Allen belts. All we need to do is use radiation-hardened electronics. Those are available off the shelf, because we have built hundreds of satellites that operate in or above the van Allen belts already.
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  25. That is incorrect. There 's no proof that the landings were faked. There's not even evidence that suggests they were faked. All you have is low-quality arguments that have all been debunked.
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  26. 1:39 the takeoff of the LM was filmed on 3 missions: Apollo 15-17. The LRV carried a TV camera that could be controlled remotely from Houston, and a TV transmitter. The astronauts parked the LRV in a position where it had a view of the LM. During takeoff, Ed Fendell controlled the camera (having to account for the delay in sending the signal to the moon, so he started tilting the camera up 3 seconds before liftoff).
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  27. Apollo space suits: assembled by women. Software for the guidance computer: made by a group of programmers led by a woman. Hardware for the guidance computers: made by women. Calculations for navigation: made by women.
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  28. To give you an idea, let's do a Fermi estimate. The moon weighs 1E20 kg. To change its orbit by 1%, we need to change its mass by 1%. Every year, Earth is hit by 5000 tons of meteorites, that's 5E7 kg. Assuming the moon is hit by the same amount, changing its mass by 1% takes 18-7 is 1E11 years.
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  29. In space, they're probably going to use 100% oxygen. They can't do that in the pool: in the pool the suit pressure is above 2 bar, and 100% oxygen at more than 2 bar is toxic. In space, the suit is at 0.3 bar, and 100% oxygen at that pressure is safe.
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  30. In all those hours of footage, not a single cable can be seen. What we can see is that everything in those videos, from the astronauts to the smallest grains of dust, falls with an acceleration of 1.6 m/s2, instead of the 9.8 m/s2 we get on Earth. This is impossible to reproduce on Earth. Which means those videos are proof (one of many) that the Apollo landings are real.
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  31. Oxygen toxicity depends on pressure. Anything over 2 bar at 100% oxygen gets toxic. Apollo ran at 0.3 bar, 0.25 for the space suits.
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  32. Look up tonight, you can see the ISS pass overhead, proving that NASA runs real projects. The computer you're shitposting on was made possible by the huge advance in computer technology that started with NASA's investment in ICs for Apollo.
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  33. Because then it'd be really stiff: the higher the pressure, the more force you have to exert to e.g. bend your elbow or close your hand. This is fatiguing enough at 4.7 psi, at 13.7 psi you'd be exhausted after 3 hours.
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  34. The moon landings are real. There's a ton of evidence that proves this beyond doubt.
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  35. False. The radiation level in the belts is low enough that humans can pass through the belts safely.
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  36. Anyone can prove that space is real by looking up at night. You can see satellites pass overhead.
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  37. More and more people are being deceived by charlatans, you mean. I've looked at the "evidence" they present, and it's all worthless. There is no viable evidence that shows the landings were faked, while we have a mountain of evidence that shows the landings are real. I've discussed this with moon landing deniers, and they have their head firmly in the sand. They're not interested in evidence.
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  38.  @wynand988  No, it doesn't. For example, all of the Apollo photos and videos have been analyzed extensively, and we found it's impossible to replicate them on Earth. The Apollo videos show they were in 1/6 g gravity, not the 1 g you get here on Earth. The Apollo photos and videos show lighting that is impossible to recreate in a studio.
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  39. Nobody does that. When an astronAut leaves their spaceship, they'll always wear a space suit which is designed to handle the temperature and the vacuum. Only INSIDE the spaceship, where the temperature is maintained at 20ºC and there's plenty of air, do they wear normal clothes. So, you are making baseless claims.
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  40. NASA does put humans in space suits into vacuum chambers, so your claim is without merit.
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  41. They were filmed by a guy in Mission Control, who controlled the camera on the LRV remotely.
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  42. The weights all over the body are used to adjust the CG with better resolution than just putting on boots would provide.
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  43.  @4windz803  Read again. The important part of this test is that they need to figure out how to work in 0 g or in this case, 1/6 g. The suit is also tested in a vacuum chamber: that's done to see how the suit behaves in a vacuum. But in the vacuum chamber, the astronaut is at 1 g, so that test is useless for preparing the astronaut to walk on the moon.
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  44. The astronauts use rovers because moving in the suit takes a lot of energy. A pedal-powered rover would negate that advantage.
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  45. To have the hands at a lower pressure, you'd need a collar around the wrist that seals that area of the suit, and then you'd have the pressure difference pressing against your wrist. I think that would be uncomfortable.
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  46.  @stanleyhampton7185  NASA is studying radiation as part of Artemis because the goal is to have humans spend months on the moon or orbiting the moon, and at those time scales radiation becomes an issue. None of the Apollo missions were longer than 2 weeks. James van Allen concluded that if you put a human in the center of the inner belt (where the radiation level is highest), he'd get a lethal dose of radiation after one week. None of the Apollo crews spent more than 3 hours traversing the belts.
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  47. When the pressure in the suit is at 1 bar, that's 1 kgf of force on every cm2. At that pressure, it becomes very difficult to e.g. close your hand to grip an object. You can try this with a bicycle tire: at 0.3 bar, it's easy to pinch the tire with your fingers. At 1 bar, it's almost impossible.
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  48. It's a two-stage process: heat is removed from the equipment using a liquid cooling circuit. The hot liquid goes to a radiator panel on the outside of the spacecraft, and runs through the panel. The panel radiates the heat away.
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  49. That is incorrect. We have millions of non-photoshopped photos of Earth, including hundreds made by every Apollo mission. When a ship goes over the horizon, zooming in does not bring it back into view. Flerfs like to claim this, but when you look at those videos, you will see that the ship they zoom in on is in front of the horizon. There is one method that will bring the ship back into view: go to a higher elevation. This demonstrates that the horizon is a physical obstacle, just like a hill can hide objects on its far side.
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  50. 1. by training on Earth. If you've done it a few times, it gets easier. 2. by taking their time. 3. by assisting each other.
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  51. The Apollo missions did not defy the laws of thermodynamics, they took advantage of them. In a vacuum, heat transfer is done only through radiation, which means making the suit white already reflects away most of the sunlight and reduced the thermal load to manageable levels. The cooling system in the suit only had to deal with the body heat of the astronauts. They used sublimation cooling. Simply looking things up defeats every single one of your objections.
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  52. They use thermal vacuum chambers for that, where both the vacuum and the temperature can be tested.
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  53.  @artistart55  Here on Earth, there are 3 mechanisms for heat transfer: conduction, convection and radiation. In space, two of those mechanisms don't work: conduction and convection don't work in a vacuum. So you only have to deal with radiation, and we have developed multilayer foil insulation that is very effective at reducing heat transfer through radiation.
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  54. Well, they're saved by bringing them back into the pressurized spacecraft. That's similar for the treatment divers get when they get the bends: those are put in a hyperbaric chamber. The higher pressure forces the nitrogen back into solution, removing the bubbles which usually solves the problem.
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  55. Vacuum testing is not necessary for the experiment they did in this video.
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  56.  @bbt305  You're wrong. Destin presents science, not propaganda.
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  57.  @bbt305  He has access to those because he has a history of making documentaries that are both informative and entertaining, and he's built a large audience. That makes it attractive for these organizations to work with him.
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  58. The evidence says otherwise.
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  59. Under water, you can train for weightlessness. Being in a vacuum requires no special training. During underwater training, they have the suit pressure at ambient pressure plus 4 psi, which makes the suit feel exactly the same as when they're in space with the suit at 4 psi. Vacuum testing is done for every space suit: someone wears the suit in a vacuum chamber, and the leak rate of the suit is measured. Occasionally they'll do tests where the astronaut has to run on a treadmill, to test the thermal performance of the suit (has to be done in a vacuum, or your result will be skewed by the suit exchanging heat with the ambient air).
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  60. In orbit, they're using100% oxygen at 0.3 bar pressure. In the pool, the pressure has to be a lot higher because they're in 1 bar atmosphere, plus 1.3 bar from the water pressure, so the pressure in the suit has to be at least 2.3 bar, and at that pressure 100% oxygen is toxic.
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  61. We don't need to beg. Every aspect of Apollo is documented in public archives.
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  62. Nope. We've been to the moon 6 times with manned missions, and over 30 successful unmanned landings.
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  63. The actual space suit weighs around 90 kg. When the astronaut weighs 80 kg, the suit is trimmed for 1/6 kg by adding weights until the net weight (measured under water) is (80+90)/6 is 28.3 kg.
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  64.  @duarteconchinhas  The process is shown at the start of the video. The weighing system is put in the pool, and the astronaut is weighed with his suit. The weights are distributed to put the center of gravity in the same place as the center of buoyancy. So the weight of one arm may not exactly correspond to the buoyancy of that arm, but the sum total is made to match.
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  65. There is no CGI in NASA space videos, obviously. You fell for a con.
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  66. To make it comfortable for the divers.
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  67. 14.7 psi/1 bar.
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  68. Yes, we can prove it wasn't faked.
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  69. The SpaceX suits were not made for use on the moon. Even for EVAs they're very limited at the moment. They rely on an umbilical connection instead of having a backpack, for instance.
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  70. Oxygen toxicity depends on pressure. Anything over 2 bar at 100% oxygen gets toxic. When you're in the NBL, the pressure of the air you breathe has to be at least equal to the water pressure. At 10 meters, you have 1 bar of water pressure plus the 1 bar of the atmosphere overhead, so you'd be at 2 bar minimum for your air supply.
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  71. You do a lot with your legs on the ISS. Workstations on the ISS have a rail on the floor that the astronauts hook their toes under, so they can 'stand' at the workstation instead of floating.
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  72. 100% oxygen is toxic at pressures above 2 bar (which you get when diving to 10 meters depth), in the space suit the pressure is only 0.3 bar.
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  73. The suits ARE tested in a vacuum chamber. Every new suit goes through extensive testing. What they're doing under water is find out how the suit behaves in 1/6 G or 0 G, both of which you can't do in a vacuum chamber. The suit does not expand like a balloon because the pressure suit is wrapped in a tight mesh that keeps it from expanding.
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  74. Oxygen is toxic if you inhale far more of it than your body's designed for. In those suits at the bottom of the pool, they're at 2.3 bar. That would be toxic. In space, the suit is at a pressure of 0.3 bar.
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  75. You can't really negate the effect of gravity in the body, that's why they talk about these sessions only simulating part of the experience.
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  76. A space suit does all that, yes. It provides oxygen for 8 hours at 0.3 bar. In the pool, they're at 2.3 bar. They use a nitrox mix instead of pure oxygen, which adds another 50%, so the tanks have to be 12 times larger than in space. There's not enough room in the suit for all that. Having tanks that large would also make the backpack a lot heavier, making the simulation less realistic. The backpack contains a cooling system that only works in a vacuum, so that has to be replaced. Radio doesn't work well under water, a cable gives more reliable comms.
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  77. Not so strange when you consider the cost of Apollo versus NASA's budget after Apollo. NASA could never afford manned lunar missions once the goal of beating the Russians to the moon was achieved. And no, NASA does not claim 'they cnat figure out certain pieces amd how to replicate the process'. Even the 'some of that technology was destroyed' is not accurate. We have enough information on Apollo that we could replicate it entirely.
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  78. Flexibility depends on the pressure difference. The bigger the difference, the more effort it takes to bend e.g. the fingers of the glove. The large joints (elbow, shoulder) use rigid, rotating rings to reduce the effort needed to reposition them. At 4.5 psi, the suit is flexible enough that you can work in the suit for 8 hours.
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  79. Yes. Pure oxygen at a pressure of 1 bar is toxic: the chemical processes in your body would speed up because there's so much oxygen available to react with. At 0.3 bar, the amount of available oxygen is similar to what we have in our atmosphere at sea level.
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  80.  @Joe-mobilegaming  The problem with 0 G training in an airplane is that 1. you only get 30 seconds at a time, followed by 20 seconds at 2 G. and 2. 0 G in an aircraft is 'bumpy'. It's very difficult to stay suspended in the same place. Airplane training is still done. It tests the astronaut's reaction to 0 G, so every astronaut goes through it. And occasionally they use the aircraft to study specific operations. e.g. during Apollo they installed a lunar rover mockup and tested how the astronauts could get in and out of the LRV.
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  81.  @Deadwindshadow  Look at your finger as it bends. You'd need a series of elements that can slide over each other to follow that movement. Now build a mechanism that does that smoothly when there's 1 kg/cm2 of force pushing those sliding elements against each other, without having massive leakage. It's a difficult problem.
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  82. During Apollo, we found that the Apollo suits had some serious limitations. They were getting noticeable wear and tear after only 3 days on the lunar surface, from the very abrasive lunar dust. You're basically walking around on sandpaper grains and glass shards. So for Artemis, a much better, more resilient suit is needed. The Apollo suits were tailored for each astronaut. This meant they fit well, but could not be shared. For Artemis, instead of making new suits for each astronaut, we want standardized suits that can be adapted to the body size and profile of the wearer. That's another major change. This video shows another major change: Apollo just picked the lowest suit pressure they could get away with. This has advantages (lighter construction, less resistance to movement) but also disdvantages. Apollo lived with those disadvantages. Now they're trying to eliminate those disadvantages by experimenting with other pressure settings.
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  83. Eh, no. You'll find that as you go faster, it starts to take more and more energy to accelerate. Einstein predicts there is no way for a macroscopic object to reach the speed of light. 'travel at 1 G for one year' is not achievable. The equation does mean you cannot go faster than c.
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  84. That's easy: by not spending sp much time in the belts that the radiation dose builds to a dangerous level. They only spent 3 hours crossing the belts, and a dangerous dose does not build up until you spend a week in the belts.
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  85. Sibrel has long been exposed as a liar.
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  86. he mentions this in the video. 86ºF or 30ºC.
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  87. 1. the suits used in the NBL have similarities, but also differences to the suits used in space. They are mechanically similar (so movement will feel similar). But the life support system is completely different, using an umbilical instead of having all of the equipment in the backpack. A suit designed for a vacuum is airtight, which means it is also watertight. The temperature management under water is different to that in a vacuum. 2. Space suits are tested regularly in vacuum chambers. Astronaut training is done in the pool, because the important thing they have to train for is how to operate in zero gravity, which can be approximated through neutral buoyancy. If you put the astronaut in a vacuum chamber, he still weighs 200 kg with the full suit and backpack. 3. NASA publishes just about everything they do. Tons of technology developed for space has made its way into commercial products.
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  88. Starship is not a failed project. It's in the middle of being developed, with good progress being shown recently. SpaceX has a history of doing what they claim to do (remember the early skepticism toward reuse of the Falcon 9 first stage? They've successfully landed 200 stages and have been reusing them up to 15 times per stage. They also have a history of being overly optimistic with their timelines, but getting there in the end, on a timeline that would be fast for anyone else but slower than their own initial estimates.
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  89. That's one of the options they are considering (the Russians already do this with their suits).
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  90. The radiation level in the belts is low enough that humans can travel through the belts safely, as long as you don't spend too long in the belts. In the center of the belts, the level is high enough that you accumulate a lethal dose in one week. The Apollo missions took 3 hours to cross the belts.
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  91. These astronauts were not part of Apollo, so they have to learn how to operate in this environment.
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  92.  @spartanpatriot3163  Neither was I: I was talking about procedures: these astronauts are learning how to move in 1/6 g gravity.
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  93.  @StariDido  I can measure the speed and altitude of a satellite from the ground, using nothing more than two cameras and some math. When I do that, I find that every satellite I see is at an altitude of 400 km or more, and a speed of 8 km/s. That's 10 times higher than any balloon has ever been, and a hundred times faster than any balloon has ever been. I can also aim a telescope at the satellite, and easily see there's no balloon attached to it.
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  94. The radiation level in the belts is high enough that long exposure is lethal. Spending 3 hours in the belts gives you a radiation dose that's equivalent to a few chest Xrays.
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  95. You need a telescope with a mirror diameter of about 100 meters to see the flag from Earth. However, we have several telescopes orbiting the Moon, that have photographed the Apollo landing sites with enough resolution we can see the foot tracks left by the astronauts. LRO and Chandrayaan-2. Look them up. NASA lost one copy of one broadcast, of one mission. We have other copies of that same broadcast. We have complete footage for every Apollo mission.
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  96. Take a closer look. Those are pressure gauges.
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  97. Fuel transfers are inevitable if we ever want to get farther than putting 2 men on the moon for 3 days (which is about the limit of what's possible with a single launch from Earth). Any trip to Mars or Venus will require fuel transfer, so we might as well get started testing it now. I'll also note that the alternative lander (from Blue Origin) will also require fuel transfers for its mission.
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  98.  @peterprice2048  We're in the middle of working out the details, converting a concept into actual flying hardware. And we'll get plenty of experience flying Starship in Earth orbit before the first HLS is sent on its way.
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  99. Ample evidence proves that they did. You, on the other hand have nothing. No evidence at all for your claims.
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  100. It would have to be pretty sharp. The Apollo A7L suit consisted of 15 layers, and the pressure bladder (the one you care most about) is the second layer from the inside. i.e. there's 13 layers outside of that, including a pretty thick woven outer layer that's designed to protect the inside of the suit in a fall.
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  101. Oh, and the contingency if you do spring a leak is that the PLSS can supply more air, so if the leak is not too large it can keep the pressure in the suit near normal despite the leak.
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  102. They left a camera on the LRV, which was controlled remotely from Mission Control in Houston. The LRV had its own transmitter that could send the TV signal directly to Earth.
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  103. They are doing these tests to simulate being weightless. You can't do that in a vacuum chamber. Vacuum chamber tests are done to test every new space suit (not just every new design, but every item that is produced).
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  104.  @foopah  Youtube won't allow me to put links in a comment, but you can find videos of space suit testing in a vacuum chamber.
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  105. The Apollo Flight Journal and Apollo Lunar Surface Journal are good places to start.
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  106. At 1 bar, a space suit would be so stiff you'd be exhausted after 2 hours. At 0.25 bar, moving in the suit becomes a lot easier and you can do an 8-hour spacewalk.
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  107. The pressure in the spacecraft is 1 bar. That's far too high for a space suit: the higher the pressure, the stiffer the suit and the more effort it takes to move in the suit. So they currently use a pressure of 0.3 bar in the space suits. This test is exploring other pressure settings.
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  108. Yes, that's Neil Armstrong.
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  109. No. In the Apollo videos, we see that the astronauts can easily get back up from some positions, less so from others, depending on how much leverage they can apply, and in which direction they have to apply it (the suit can't move in all directions). One big difference between the NBL and being on the moon is the drag you experience. An astronaut who falls forward on the moon, can push himself back up and gain enough momentum to get upright again. In the NBL, you're fighting a whole lot more drag so you end up building far less momentum and you can't get back up.
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  110. At 14.7 psi, it would take a lot of force to do anything in the suit: the higher the pressure, the more force you need to bend e.g. your elbow or grasp something in your hand. You'd be exhausted after 2 hours.
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  111. Why would they go boom?
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  112. We did not lose that information. We can look up exactly how Apollo did it. And when we do that, we find that the Apollo lunar module used an atmosphere with 100% oxygen at 5 psi, so there was no prebreathe time: they did not have this problem.   The ISS is an oxygen/nitrogen atmosphere at 14.7 psi, and the Artemis lunar lander will use this too. So they have the experience of the ISS to draw on, and that experience shows a lot of time is lost with prebreathing/decompression. So they are doing experiments with the goal of finding ways to reduce that time.
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  113. We solved that problem in 1962: we measured the radiation levels in the belts, and realized those levels are low enough that humans can safely travel through the belts, as long as you don't stay in the belts too long. When you stay in the center of the inner belt for one week, you accumulate a lethal dose of radiation.
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  114. They use imperial units in communication to the public.
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  115. No. The pressure is so low that even the lightest possible envelope is too heavy for a balloon to generate any lift. When the Apollo LM took off from the moon, it doubled the atmospheric pressure on the moon, that's how little atmosphere there is.
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  116. Because at high pressure, pure oxygen becomes toxic.
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  117. People who believe humans walked on the moon, do so based on a mountain of evidence that has been examined extensively and found to be valid. People who believe the moon landings were faked do this based on no evidence at all. This is what we call a conspiracy theory.
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  118. We don't "believe" NASA went to the moon, we know NASA went to the moon. The evidence is conclusive.
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  119. Yes. Many factors influence GC/CB.
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  120. Yes. The Apollo missions had the astronauts live for up to 2 weeks at 5 psi. Skylab had an atmosphere of 70% ox/30% nitrogen at 5 psi, and the longest Skylab mission was 84 days.
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  121. The Apollo suits carried enough oxygen for 8 hours plus a reserve. The suits used on the ISS can carry a bit more than that. Using pure oxygen at only 0.3 bar reduced how much you need, and the backpack includes CO2 scrubbers (like a rebreather for divers). The backpack contains tanks with liquid oxygen, which means they can carry more in the same volume. Divers carry a tank with pressurized gaseous air or another gas mixture. Diving time is limited by several factors:  1. the air has to be delivered at a higher pressure than the surrounding water. 2. they have to use air: pure oxygen at high pressure is toxic. This means part of the tank contents is not breathable. 3. most divers don't use a rebreather, so exhaled air is lost.
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  122. The question is 'what pressure should we run the spacecraft and spacesuits at'.
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  123.  @PramochanYaan  it's caused by the pressure difference. So when you're on Earth and have the suit pressure at 1.3 bar, it feels the same as being in space with the suit at 0.3 bar.
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  124. People thinking we faked the moon landings when we have a ton of evidence that proves the Apollo missions are real, is nothing short of laughable!
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  125. The Apollo A7L suit consists of many layers. The critical one (the pressure layer) has a pretty substantial layer around it that keeps the rubber bladder from expanding. This is covered by thirteen layers of material which were (from inside to outside): rubber coated nylon, 5 layers of aluminized Mylar, 4 layers of nonwoven Dacron, 2 layers of aluminized Kapton film/Beta marquisette laminate, and Teflon coated Beta filament cloth. The Mylar and Kapton don't give much protection, but the Dacron and Beta cloth are strong, resilient materials. In addition, they had Teflon knee and elbow patches. It's pretty good, but they found tears in the outer layers on several of the suits after the missions.
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  126. They used a TV camera on the lunar rover, which could be operated remotely from Mission Control.
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  127.  @pytlakowski77  Pressure tests can be done in any environment. As long as the pressure difference between inside the suit and outside of it is the same as would be seen in space, the suit behaves exactly the same. In the NBL, the suit is inflated to the pressure of the surrounding water, plus 5 psi.
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  128.  @pytlakowski77  Every space suit is vacuum-tested. These are very boring tests to look at, so not much video is published on them.
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  129. They're not acting as if it's the first time they are on the moon, they are trying out procedures and systems that are not identical to Apollo so they have to be tested before being used in practice.
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  130. 101 kPa is not a problem for the suit, but a problem for the astronaut. At 101 kPa, the suit is much stiffer than at the ~30 kPa they use now. At 30 kPa, you're exhausted after moving in the suit for 8 hours. At 101 kPa, it would take only 3 hours to be exhausted.
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  131.  @Guapter  Yes, and the dive shown in this video is part of a program for testing some of those options.
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  132. The current SpaceX suits are for use inside the vehicle, not for spacewalks or walking on the moon. That means the suit can be lighter and more compact, but it provides less protection to the astronaut.
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  133. They spin out of control when they haven't perfectly adapted to the combination of being in 1/6 g and wearing a 90 kg backpack in a stiff spacesuit yet. Practicing in the NBL is valuable, but it's not a perfect analog of being on the moon so mistakes are still made on occasion.
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  134. They start at 1.3 bar, as they go underwater, the suit pressure rises with the pressure of the ambient water. At the bottom of the pool they are at 2.6 bar.
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  135.  @artistart55  In a desert on Earth, not long, because the presence of an atmosphere enables heat transfer through conduction and convection. The air is hot, and that heat is conducted into the spaceship. On the Moon, those mechanisms are absent, so all you have to do is reflect the sunlight, and your spaceship will stay cool. The Apollo space suits had a white outer layer that reflected 90% of the incoming sunlight. The LM was mostly covered in very reflective materials too. The ascent stage had MLI under the outer skin, which is still very effective. The LM, CM and the space suit were all designed to have a comfortable interior temperature without active cooling.
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  136.  @artistart55  That picture was not expected to survive the heat. No measures were taken to help it survive the heat. The LM and the space suit WERE designed to survive the heat, as I described above.
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  137. IFT-3 did the first fuel transfer test in orbit, between two tanks in the same vehicle. IFT-4 will continue those experiments, and with 6 Starship flights planned this year it would not surprise me to see a fuel transfer between two starships soon.
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  138. None of those are valid claims. 1. No, the suit is not compressed. The pressure bladder is on the inside of the suit. Directly around that there's a mesh that prevents the pressure bladder from expanding when it's inflated. 2. There's rust on the space station because a. air leaks out, and b. you get atomic oxygen from the atmosphere even at 400 km. Atomic oxygen is very reactive. You'll notice that the rust is mostly around the airlocks. 3. The only bubbles you see in space are WATER bubbles that are used by the astronauts to demonstrate weightlessness. Then there are charlatans that take footage from the NBL, and falsely claim "NASA says this footage is from the space station". 4. The outer airlock cover is thermal insulation. There's no need for this to be rigid. 5. Having the hatch open inward means that when it's closed, the air pressure against the hatch presses it against its seals. This makes the hatch safer (there's no way for a failing hinge to result in depressurization) and reduces the leak rate.
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  139. Having a vacuum is not useful for learning how to operate in space. The big difference is not the vacuum, it's the weightlessness. So most of the training is focused on dealing with that. The vacuum has two consequences: 1. the suit is stiff because the pressure inside is higher than outside. When the astronauts train in the NBL, their suit is kept at ambient pressure plus 5 psi, ie the same as they get in space, so that aspect is already covered. Vacuum training is done: just like air force pilots, astronauts learn what it's like to go through a depressurization, how to recognize a lack of oxygen etc.
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  140. He mentioned this early in the video. 100% O2 is toxic at high pressures. At 40 ft you get close to the pressure where that happens.
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  141. They weren't lying. We have a mountain of evidence that proves the Apollo landings are real.
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  142. It is archived, much of it on the NASA Technical Report Server, which is open to anyone. Those reports showed that the Apollo suits had some drawbacks. One example: they were showing noticeable wear after only 3 days on the surface. For Artemis, the suits have to last much longer than that. For Apollo, they also didn't to the research that was shown in this video: the pressure for the Apollo CM was only 5 psi, so there was no need to test suit pressures higher than that.
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  143. We have hours of video from Apollo that are impossible to replicate on Earth. Kubrick's best efforts can be seen in 2001, and the moon footage in that is immediately obvious it's not recorded on the mon but on Earth.
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  144.  @mikeprice4079  One person said that, and he was wrong. The technology is not lost. We can still look up how everything worked on Apollo: that's all in public archives.
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  145. Nope. The ISS is in the sky. You can see it pass overhead with the naked eye.
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  146. Yes. At 14.7 psi/1 bar, moving your limbs would be exhausting.
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  147. Adding nitrogen would mean the suit has to be run at a higher pressure, which makes it stiffer and harder to move in.
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  148.  @samarbid13  Dave McKeegan did a video (How were Moon take offs FILMED?) that answers this.
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  149. It's easy to prove the Apollo videos were not recorded in a studio: Everything in those videos moves in perfect 1/6 g gravity, not the 1 g you'd get when you recorded it here on Earth.
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  150. False. All you have to do is build your suit strong enough to withstand the force that comes from the pressure difference between inside and outside. For a space suit in a vacuum, that's 0.3 bar, or 0.3 kg/cm2. Every day, airliners are subjected to a larger pressure difference than that when they fly at 10 km altitude.
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  151. the Apollo 1 astronauts, you mean. That happened because for the test, they were sitting in 100% oxygen at 1.3 bar pressure. That is a huge fire risk, so that was never done again. In space suits, we continue to use 100% oxygen, but at a pressure of 0.3 bar, which is no more a fire risk than our normal 80% N2/20% O2 atmosphere.
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  152. 1. only what's incidentally provided by the suit layers. 2. Yes, NASA and others have been experimenting with such systems for decades now. IDK why this never made it to the production stage.
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  153. that's pretty easy: the important thing is that the difference between the pressures inside and outside the suit are the same. So they take the pressure at the bottom of the pool and add 0.3 bar to get the suit pressure.
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  154. Nope. It's immediately obvious from the Apollo videos that they were not underwater. For example, the dust kicked up by the astronauts flies away as if it's in a vacuum instead of in a water tank.
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  155.  @weirdshit  The lunar surface consists of grains of all sizes from microscopic to gravel to boulders. I've measured falling objects in Apollo videos, and they all accelerate at 1.6 m/s2, which is consistent with lunar gravity, and inconsistent with how objects fall in water.
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  156.  @weirdshit  No, that was not suspicious. When I go to the beach and jump, some of the sand is launched upwards at the same speed as my feet, so that sand lands at the same time as my feet. Other particles are launched at lower speeds so they follow a shorter arc and land earlier.
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  157. No. The center of buoyancy depends on the distribution of the *volume*.
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  158. Look up at night. You can see the ISS pass overhead, proving you wrong.
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  159. We have abundant evidence that proves the Apolllo landings were not filmed here on Earth, but on the moon.
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  160. They talked about that in the video. There's a piece of foam in the helmet. The astronaut can push his nose against that to close his nose for clearing the ears.
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  161. The center of buoyany would only shift if the volume of the spacesuit changes.
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  162. Yes, that's what's done for missions: the astronauts practice a lot before the mission, and have autonomy during the mission. This test, however, is something different. The test has to be controlled, for it to give useful data.
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  163. the environment in the suit is pure oxygen. That makes the backback less complicated (no nitrogen circuit needed) and allows them to use a lower pressure. Apollo used 100% oxygen in the cabin as well. For the Shuttle and later projects they switched to having a normal 80/20 atmosphere at 1 bar/14.7 psi.
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  164. The US does something similar. Space suits are never fully sealed. Instead, they measure the leak rate and as long as it's below a preset threshold, the spacewalk goes ahead. The PLSS contains enough oxygen to keep the pressure in the suit at nominal level with that leak rate.
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  165. The body uses oxygen for various processes. Feed far more oxygen into a human than they're used to, and those processes speed up to where they endanger your health.
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  166. Scuba gear can't provide the same duration for two reasons: 1. The PLSS includes a rebreather. SCUBA systems are open-circuit. You can get rebreathers for under water. 2. under water, you have to provide air at a pressure above the water pressure. This means an open system goes through a lot more gas than necessary. In the space suit, you can provide air at 0.3 bar.
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  167. The cooling tubes that circulate water around the body lead to a heat exchanger with the vacuum. This is a radiator; water is sprayed onto the radiator. This freezes, then sublimates, carrying away the heat.
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  168. They test by filling the suit to the pressure of the ambient water, plus 4 or 6 or 8 psi, ie the pressure difference is made the same as it would be in space.
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  169. you mean a low viscosity fluid. Well, try to find a benign one that's cheap enough to use a whole pool of. Alcohol: you have to deal with the fumes when you have this much of it. White spirit is even worse (toxic). etc.
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  170. air pressure would be the same for everyone.
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  171. They touch on this early in the video. They realize that large-scale movement is unrealistic because of the drag component, so for instance they won't have astronauts simulate an 8 hour lunar EVA where the astronaut has to walk a lot, they'd simulate just the bits in between the long walks (gathering rock samples, other science/engineering tasks).
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  172. That would require a pressure seal over the wrist, I can't imagine that will be comfortable.
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  173.  @whitemiasma5288  You severely underestimate how hard it is to do anything in a space suit, even with tons of practice.
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  174. After a brief adjustment period, the Apollo astronauts were able to move easily on the moon. The first thing Armstrong and Aldrin did was find out what the easiest method of locomotion was, and they arrived at the bunny hop, in which the astronauts jump instead of walking.
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  175. Why would you advertise such junk?
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  176. such thermal vacuum tests are done without the ISS mockup. They use a vacuum chamber with a treadmill, so they can measure the performance of the insulation and cooling system at different exertion levels.
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  177. All you have is empty claims. The actual evidence proves beyond doubt that the Apollo landings are real.
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  178. nope. This research and testing has to be done because we're not blindly reusing the stuff Apollo had. In this case, the space suits. The A7L suit was good enough for Apollo, but on the longer missions (i.e. 3 days on the moon instead of one) they noticed the suits were starting to get damaged from the very sharp abrasive moon dust. Those suits are not going to continue functioning well if you use them daily for a month (which is the goal of the Artemis missions). So we need better suits than we had for Apollo.
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  179. On top of Mt Everest, air pressure is 33 kPa, close to the pressure in the suit when it's used in space. The pressure of the water remains the same (depends only on the depth of the water), so you still end up with a suit pressure under water of more than 1 bar so the bends are still a concern.
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  180. We know deep down that we did go. We have a mountain of evidence that proves this, and no evidence that the Apollo missions were faked.
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  181.  @spartanpatriot3163  Have you ever learned anything new, that required motor skills you haven't used before? Juggling, or ice skating, for example? Was it enough to watch someone else do this, or did you have to practice yourself? Similarly, these astronauts don't magically get skilled at working in 1/6 just because 12 men did that 50 years ago. They have to practice this themselves.
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  182.  @spartanpatriot3163  This particular lab is from the 1990s. But the first use of a pool to simulate neutral buoyancy is from 1964. When those tests proved successful, NASA built the Water Immersion Facility at the Manned Spacecraft Center and the Neutral Buoyancy Simulator at Marshall Space Flight Center.
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  183. Yes, we have devices that can simulate gravity of more than 1 G. They're called centrifuges. They're commonly used for fighter pilot training, those go up to 9 G but are pretty small. There are a few labs that have much larger structures that can be spun. These are used for research into space stations that can spin to simulate gravity.
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  184. This video doesn't explain that. The airtight layer of the suit is on the inside, it goes over the cooling garment Destin wears when he tries on the suit. Over the airtight layer there's a strong mesh that keeps the flexible airtight layer from expanding. Hoses used for liquids under pressure do something similar. Brake lines for instance: there's a rubber hose, and then a metal mesh around it. Cut that mesh away, and the hose will swell up if you pressurize it.
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  185. Yes, they still feel those effects, so working inverted for long periods is avoided in the NBL.
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  186. The whole lecture is on YT (Ottinger LLRV Lecture). Yes, there's a proportional relationship between acceleration and tilt angle. We're using thrust from the main engine to accelerate horizontally, by tilting the spacecraft: that gives the thrust a horizontal component, which moves the spacecraft horizontally. On the moon, you're in 1/6 G, so your engine is providing 1/6 the thrust it needed on Earth, so to get the same horizontal acceleration you had on Earth, you need 6 times the tilt angle.
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  187.  @carlosschagun6922  The leak rate that was considered acceptable (i.e. the threshold above which the EVA will be cancelled if they find this rate during the pre-EVA test) is 180 standard cm3/minute. The Apollo PLSS carried oxygen for 8 hours, plus a 30-minute emergency supply, plus the option to link up to a partner to share air and cooling systems.
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  188. For Apollo, yes the pressure in the spacecraft is about 0.3 bar. They solved this by having the astronauts breathe pure oxygen for the several hours before launch, to remove the nitrogen from their bodies.
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  189. This takes tome for the same reason divers don't swim to the surface immediately after a deep dive. If you do that, you get decompression sickness.
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  190. Investment in NASA alsways grows the US economy by more than we put into the project. So instead of a burden, Artemis is a boon to the US economy.
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  191. Wrong, they are done in space. You can see the ISS pass overhead in the night sky.
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  192.  @cannabearr  Of course we can see it. The ISS is visible to the naked eye at the beginning and the end of night, when the ground is in darkness but the ISS (400 km above us) is still in sunlight. It's one of the brightest objects in the night sky. With a telescope, we can confirm we're looking at the ISS: we can see enough detail to recognize it.
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  193.  @cannabearr  Boats do go over the horizon. Anyone who claims they can zoom in on a ship that has gone over the horizon and bring it back into view, is lying to you: they are zooming in on small boats that have not gone over the horizon yet.
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  194. Skylab was used for 3 manned missions, then its orbit decayed and Skylab reentered our atmosphere, burning up.
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  195. A tank is a device for storing liquids or gases. You have a fuel tank on your car.
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  196. The little flares that appear are reflections off of the radio antenna that sits on top of the PLSS. This antenna is easily visible in many photos. It's generally less visible in the TV shots, due to the very low resolution, unless the camera catches a specular reflection.
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  197. What do you mean by negative pressure? Pressure can't get lower than 0.
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  198.  @MisterDishWash  Yes, I see what you mean. I'm afraid that would make the suit a lot more complicated for no benefit. At the start of the video you see Destin putting on the cooling garment. The next layer that goes over that is the pressure bladder: this is the airtight layer. Over that goes a fabric mesh that keeps the pressure bladder from ballooning when it's pressurized. Everything outside the pressure bladder is at vacuum already, when you're in space.
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  199.  @OzDeaDMeaT  That's part of it, yes.
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  200. The ISS is at 1 bar (14.7 psi) with a normal air composition. The suit has to be at a much lower pressure because the higher the suit pressure, the more resistance it has to bending. So they tend to go as low as possible, which means using close to 100% oxygen. Using pure oxygen also makes the backpack much simpler and lighter: you con't have to carry nitrogen tanks and a mixing system.
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  201. Watch the first 30 minutes today, and the rest tomorrow. You'll be glad you did.
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  202.  @stanleyhampton7185  Again, you misunderstand. from 1958 to 1962 we measured the van Allen belts and the space above it with a series of satellite missions. This gave us a radiation map. These are the results: 1. the radiation levels in the belts are higher than above them. 2. the level in the belts gradually increases as you get closer to the center of the belts. At the center of the inner belt, the radiation level is 4 orders of magnitude higher than outside. 3. At the center of the inner belt, the radiation level is high enough that a human gets a lethal dose in 7 days. 4. Above the belts, the radiation level is high enough that a human gets a lethal dose in 2 years. But the radiation level varies: in a solar flare or CME, the radiation level gets a lot higher. The Apollo missions were not built to protect the crew against the levels seen in a CME. The Apollo CM, with its pressure hull and heat shield, provided incidental radiation shielding. The Apollo missions spent no more than 3 hours in the belts. The radiation exposure of the astronauts during an Apollo mission was on the order of 1 Rad, and most of that was from the time they spent above the belts. For Artemis, the radiation levels in the belts still are not a problem. But the radiation levels above the belts will be a problem for long missions, and so will CMEs. THIS is what they are looking into.
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  203.  @stanleyhampton7185  There are no contradictions. 1. You misunderstand the basics. Radiation dose = radiation intensity multiplied by exposure time. A 3-day mission has 1/10 the exposure time of a 30-day mission, so the crew gets 1/10 the dose. 2. The problems they are solving now are problems they didn't have in the 1960s. a. Modern integrated circuits are a million times smaller than the transistors used in the 1960s, so they are a million times more susceptible to radiation damage. As ICs got smaller, we learned how to design ICs that can survive for a long time in high-radiation environments. These days, you can buy radiation-hardened electronics off the shelf. For Orion, these electronics were going to be used for a manned spacecraft for the first time, so they did their due diligence and tested this specific configuration. b. For Artemis, we're looking beyond the Moon. We want to go to Mars. And those missions are long enough that you want to have radiation shielding in place. So it's time to start developing that.
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  204. The temperature of the moon is ignored in this video because it's irrelevant to the discussion of this underwater training. Your talk of an "air conditioner" reveals your lack of knowledge. Clearly you have not spent even the least time studying how they did this. Temperature management on the moon begins with the color of the suit: it's white, which means about 90% of the incoming sunlight is reflected. Underneath the outer layer there are insulation layers which reduce heat transfer into the suit even further. The PLSS contains a cooling system. This is not terrestrial air conditioning with a compressor and a fluid that changes phase. Instead, the water that's circulated in the suit is fed through a radiator in a closed loop. The outside of the radiator is exposed to vacuum. Water is sprayed onto the radiator. This freezes first, then sublimates. This removes thermal energy from the radiator. The gaseous water is vented to outside. So, when we dig deeper, we find no lies, we find a thorough explanation of how they handled this, and we can calculate from first principles that the approach they took was valid.
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  205. When Youtube's automatic anti-spam system sees you are posting a link, or are posting the same text more than once, it deletes your post and bans you from posting for a day, usually without informing you. It happens to everyone. The only thing you can do is wait a day and try again.
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  206. Nope, no lines are visible in ANY of the Apollo footage. The Apollo videos show perfect 1/6 g gravity. Even individual grains of dust behave exactly as they should in 1/6 g and a vacuum. If the astronauts were on lines, the dust would be falling at 1 g instead of 1/6 g.
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  207.  @Dziaji  Wrong again. The footage is not slowed down, as is obvious from looking at how the astronauts move.
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  208. Apollo used 100% oxygen at 1.3 bar during the Apollo 1 test. So ppO2 was a lot higher, which led to the fire.
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  209.  @bdennyw1  That would have required adding a nitrogen system to the SM, making it more complex and heavier, or running extra plumbing to supply that from the ground. The whole point of going with a 100% oxygen system is to simplify the SM and make it lighter.
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  210. There is no deception. Spaceflight is real. It's easy to verify this through many different means. We have multiple independent confirmations of the reality of the Apollo lunar landings as well.
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  211. The only way to make a gas that heavy is by putting it under huge pressure. That pressure creates all kinds of problems.
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  212. Why not? There's a ton of evidence that shows the Apollo landings are real, and no evidence that shows they were faked.
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  213. That's a binary clock.
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  214.  @sylvainbriere7039  Yes, your'e right. It's not binary. That's a TIX clock. Count the number of illuminated squares in each block to find the time. At 0:40 in the video it's 04:51. The pattern changes every second, but the number of illuminated squares stays the same.
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  215. The question is: what should the air pressure in the spacecraft and in the space suits be?
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  216. No.
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  217. Musk is an optimist. His timelines cannot be trusted. But he generally achieves what he sets out to do.
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  218. Pure oxygen at a pressure of 2 bar or more is toxic. Not at 0.3 bar which is used in orbit.
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  219.  @maplifiers  The human body is built to deal with a certain amount of oxygen coming in per second. That oxygen is used in various processes in the body. If you get more oxygen coming in than you need, those processes speed up, with bad results if they speed up too much.
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  220. 5 psi for the CM and LM, 3.7 psi for the A7L suit, and 100% oxygen for both.
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  221. That's rich, coming from someone who swallowed the words of a charlatan instead of checking his claims.
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  222.  @mikew8914  Yes, you have been lied to. There is no footage of people on spacewalks being filmed by people who wear scuba tanks. All footage where people wear scuba tanks is recorded at the NBL. Reality deniers take NBL footage and claim "NASA says this was recorded in space". You'll notice who's doing the lying here.
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  223.  @mikew8914  Every single instance of "people on wires" is footage where no wires are visible. The only footage where astronauts "fade out" is from the Apollo missions. On Apollo, they used a custom TV camera that recorded at only 10 frames per second, to reduce the bandwidth of the signal. On Earth, that signal had to be converted to a normal TV signal. This was done by displaying it on a monitor and recording it with an NTSC camera. This process causes the fading.
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  224.  @mikew8914  There is NO footage where people on a spacewalk are "filmed by people with scuba tanks". All you have is footage shot at the NBL, where a dishonest space denier claims "NASA says this footage was shot in space" when NASA said no such thing.
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