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I don't think we are in a strong position to lecture NASA on technical matters, given what has just occurred off the Isle of Wight
** The Official Space Flight Thread - The Space Station and Beyond **
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I don't think we are in a strong position to lecture NASA on technical matters, given what has just occurred off the Isle of Wight
They're designed to keep the water out, and they're able to do that. Not able to move, but still keeping the water out.I don't think we are in a strong position to lecture NASA on technical matters, given what has just occurred off the Isle of Wight
What is "the range" that they are talking about in the press conference to do with whether the rocket can stay on the pad or have to go back to the Vehicle Assembly Building?
EDIT: https://www.nasa.gov/centers/kennedy/home/eastern_range.html
EDIT: https://www.nasa.gov/centers/kennedy/home/eastern_range.html
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Hydrogen is the smallest molecule around and has a habit of finding the smallest possible gaps, especially under high pressure and low temperature. The old Saturn 5 used kerosene (pretty much jet fuel) and liquid oxygen so wasn't as prone to leakage.
Which would be fine, except they've had decades of experience fueling the space shuttle with hydrogen.
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What's the betting that rather than having the whole valve assembly built by just the one company, the valve in question has parts made by company A in Oregon, company B in rural Louisiana and company C in up state New York, none of the companies liaise with each other during the process and the first time the valve is put together is when all the parts are shipped to the VAB?
I believe the main engines are reused off the Space Shuttle so don't think this is that relevant. Building components across the country is usually what they do to win support for the programme though.
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I agree, but the SLS is on a different scale, and the hydrogen tank itself is almost as big as the complete shuttle external tank. I coldn't find any figures for it, but I'm sure I read it's operating at much higher pressures and the meterials used are also different.
One story also claimed (not sure how true it is yet) that apparently a wrong command was sent to the system which opened the filing line to max pressure by accident causing the initial leak, instead of it being slowly opened up. Considering it's an umbilibal point there's always going to be a higher chance of that being the weakness in the system.
It's frustrating, especially when you read the news reports from years ago stating the initial launch in 2016, and then as you go on it slips and slips for so many reasons. As much as I support everything space-wse, this is the downside to government funded efforts and where private coporations can have an advantage as they operate completely differently. I would expect anything of this scale, Starship and New Glenn included, to be having issues in the same way any rocket does. They made a winner in Falcon 9 reliability-wise so hopefully they can make something out of Starship too.
This is how everything is made. Cars, planes, spaceships, washing machines - no single company for any modern equipment makes all the indiviual parts.
Watching the NASA livestream press conference post-scrub the lead engineer said that some of the commands were manually sent (i.e. typed in by hand) and not part of an automated script, and that is where the mistake was made and it's something they're going to change before the next attempt.
Not to beat this point to death - simulations are "perfect", there's no way to simulate human's buggering something up, which is why doing real testing is still the best, alongside the initial simulations.
Don Lind, shuttle astronaut whose moon mission was cancelled, dies at 92
https://www.space.com/nasa-astronaut-don-lind-obituary
If it was the ramp up of the pressure that caused the issue - recently watched a video on fuelling process for hydrogen cars - which itself after user makes the physical couple pressure tests the junction and then slowly ramps up to 900Bar I thought ... (volume aside) are rocket engines much different in pressure.
e: 10,000 psi Here’s How Long It Takes To Fully Fill A Hydrogen Car!
It was an incorrect valve fully opened (via the incorrect command) which allowed full pressure Hydrogen to flow into an area that it wasn't supposed to be in and that caused a valve to seize - from my limited understanding via the press conference. The rocket pressure was far lower, NASA mentioned 3-5 BAR in the tank when full but what the pressure in the external pipework is (where the pipes connect to the rocket) I've no idea.
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Ariane 5 launch, currently at T- 3 minutes
Liquid (and gaseous) Hydrogen have a higher requirement for joint integrity than water. because of this, Water is not a good enough test medium to ensure that there are no leaks because it’s molecules are too big. a hole may not let water get through but hydrogen will happily slip by.
Edit: video on superfluids
Admittedly I haven't seen the footage so I don't know what you saw but just a heads up, liquid hydrogen is cold enough to liquify the oxygen and nitrogen in the air. So what you could be seeing is oxygen/nitrogen in the air condensing on the surface of the pipe work and then draining/dripping off at a point on the structure. The volume of liquid from condensation can be quite high.
Regarding simulation testing vs physical testing. It's annoying but I get why they do it. Due to the low volumes and high manufacturing cost the budget would need to ballon for them to do adequate physical testing. Consider all the major components you would want to test. You would need money to buy one for testing and one for the final product. You would need at least enough money to buy 2 comeplete rockets and you rarely want just one part for doing tests. Such a large budget would be very difficult to get past congress, or for the general public to stomach.
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You'd think so, but...
Pressurised with nitrogen and using hydraulics to simulate the loads, it lasted at 260% of the expected flight load conditions for 5 hours before bursting. Liquid hydrogen is just difficult stuff to work with.
One of the explanations of TLP (Transient Lunar Phenomenon) has been electrostatic conditions along with various other theories, given what the video above explains in a reallye asy to digest way, it's more clear than ever that the influx of positive vs negatively charged solar particles rushing over craters and then merging to build up hundreds of thousands of volts of electricity is going to be the reason why TLPs are observed on the moon. It is the most logical explanation and a completely sound one given our understanding of how charged particles behave in this way.
Also the video highlights the reason why Moon landings have not been a thing since the early 70s, it's just too risky, not because of alien moon bases, but because the environment is just too hostile without further R&D which takes decades.