When is the NASA SLS launch date?

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Something about that sounds like it’d be incredibly dangerous in a crewed flight. Like they’d skip off the atmosphere and go careening off into space.
Apparently this will be done actively, not passively. In other words the thrusters on Orion will orient the craft to lift during the first dip and climb, then re-enter a second time.
The briefer had a chart showing all the numbers and the re-entry curve, so this has all been planned out,
Now to see if results follow the theory.
😄
 

Funkworks

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Something about that sounds like it’d be incredibly dangerous in a crewed flight. Like they’d skip off the atmosphere and go careening off into space.

Apparently this will be done actively, not passively. In other words the thrusters on Orion will orient the craft to lift during the first dip and climb, then re-enter a second time.
The briefer had a chart showing all the numbers and the re-entry curve, so this has all been planned out,
Now to see if results follow the theory.
😄
It can surely be done in simulations (the "theory"), and as long as they have real-time data, they can keep tuning thrusters to match the simulation. All automated of course. Supervised automation that can be overuled at any moment (although at this point, I actually doubt a human can be do better). After enough testing, I would assume it's now safer to let the robots run this. I don't want to go off-topis, but programming a robot to safely drive a rocket sounds much easier than programming a robot to safely drive a car. Space is much more predictable than road traffic.
 
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It can surely be done in simulations (the "theory"), and as long as they have real-time data, they can keep tuning thrusters to match the simulation. All automated of course. Supervised automation that can be overuled at any moment (although at this point, I actually doubt a human can be do better).
Simulation: It should work.
Doing it live: It does work.
 

Funkworks

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Simulation: It should work.
Doing it live: It does work.
Same as OpenRocket and RockSim, except the equations in the code are bigger, and they take into account lots of real-time input from sensors.
 

boatgeek

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In theory, there's no difference between theory and practice.

Hopefully, the test plan works and there isn't a need for a massive rethink.
 
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This brings to mind something that was discussed at today's briefing. There are some electrical components that are going into standby mode without a command being issued. They are connected to a controller that is supposed to issue commands. When they checked the log of the controller, the components were going into standby without any command being issued. They don't know why at this point. But because of the redundancy built into the system no hardware was affected.
The best laid plans (sims) of mice and men.
 

cls

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Hmmm, I'm pretty sure Apollo capsules did a 1 skip reentry. Can't find a reference right now, sorry.
 
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Speaking of anomalies, one briefer on more than one occasion referred to the anomalies/glitches as "funnies".
At least that's what it sounded like to me.
That's a highly technical term, I guess.
 

Jeff Lassahn

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This has a bunch of graphs showing Apollo doing a little skip where it dips comes a bit up and then down again:

The idea that skipping off the atmosphere is more dangerous than anything else that happens in a moon mission is something that people say occasionally but it's not really true. In particular you can't skip off into deep space never to be seen again, because that would violate conservation of energy. After the skip you're in a lower orbit than you were before the skip no matter how badly it goes.

coming in too steep and getting too much heat and too strong of deceleration forces is actually a much scarier prospect.
 
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coming in too steep and getting too much heat and too strong of deceleration forces is actually a much scarier prospect.
Orion is supposedly coming in faster and hotter than any previous man rated craft.
In fact it was mentioned during the briefing that Orion on its' second dip will be travelling just as fast as Apollos' reentry velocity.
So one of the test objectives is evaluating the performance of the heat shield.
This has a bunch of graphs showing Apollo doing a little skip where it dips comes a bit up and then down again:
They showed a similar curve at the briefing.
 

Lord Rory Gin

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Most everything on the actual flight has gone smoothly EXCEPT for 4 of the 10 cube sats have not worked successfully. They aren't really part of the Artemis mission, in fact some of them aren't even NASA projects. There was a 47 min communications blackout with Orion that has yet to be explained. It's on its way back to earth with a splash down on Sunday. They they will download all the data and analyze for a while before they can incorporate any changes into the Artemis 2 build. I believe they also have had problems with the portable launch tower too - parts of it will have to be rebuilt for Artemis 2 and 3 launches. Artemis 4 (Block 1B) and beyond will have a brand new launch tower.


 
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There is a briefing scheduled today at 5 PM EST to discuss Orion's re-entry to earth and recovery.
Test objectives for today include a propellant slosh test.
I wonder if flexible fuel bladders could be used inside the tanks.
As the fuel draws down the bladder shrinks. Less sloshing.
:questions:
 

boatgeek

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There is a briefing scheduled today at 5 PM EST to discuss Orion's re-entry to earth and recovery.
Test objectives for today include a propellant slosh test.
I wonder if flexible fuel bladders could be used inside the tanks.
As the fuel draws down the bladder shrinks. Less sloshing.
:questions:
Yes, but ... then you have a bladder sloshing around as well as the fluid. I'm guessing that dealing with a moving bladder is worse than dealing with sloshing loads. Unless there's some kind of mechanism to hold the bladder in place and keep ratcheting it down as fuel is used. That sounds really hard to implement though.
 

Tyeeking

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Yes, but ... then you have a bladder sloshing around as well as the fluid. I'm guessing that dealing with a moving bladder is worse than dealing with sloshing loads. Unless there's some kind of mechanism to hold the bladder in place and keep ratcheting it down as fuel is used. That sounds really hard to implement though.
Sort of the spacecraft equivalent of a “slack tank”.
 

Peartree

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There is a briefing scheduled today at 5 PM EST to discuss Orion's re-entry to earth and recovery.
Test objectives for today include a propellant slosh test.
I wonder if flexible fuel bladders could be used inside the tanks.
As the fuel draws down the bladder shrinks. Less sloshing.
:questions:
But now you also have to worry about designs and materials that can contain the fuel and oxidizers, and also remain flexible in a vacuum, at zero g, and at cryogenic temperatures.
 
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Briefing summary:
The splashdown site was moved 300 miles further south due to a cold front that was forecast to be in the initial splashdown area.
They showed the trajectory curve of the skip entry again.
The heat shield evaluation is a primary objective.
It was mentioned that the re-entry speed of Orion will be Mach 37 32.
:eek:
They still don't know why the latching current limiters are tripping on their own.
(Twilight Zone music plays).
Mr. Mike used "funnies" again.
 
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Blast it Tom!

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You know, it still flat amazes me that they can basically  almost miss the earth from a quarter of a million miles away, and almost miss it at just the right tangent (more or less) to catch the atmosphere and bring them back successfully.

I, too, don't understand the "hotter and faster than Apollo" bit. Apart from the fact that that's a  horrible way to talk about Apollo's sister, the speed number I've heard is the same... 25,000 mph more or less. Of course with the extra mass and diameter there will be more energy to dissipate, so that aspect I could see, but if it's faster, it isn't by much.
 
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Watching the live stream, splashdown in about 1 hr 15 min.
Learned some new things.
The drogue chutes don't have a solid canopy. It is a bunch of ribbons.
So more like streamers than a parachute.
The shroud lines of the mains are made of kevlar.
Shot of Orion approaching the earth.
2022-12-11.png
 

Adrian A

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Watching the live stream, splashdown in about 1 hr 15 min.
Learned some new things.
The drogue chutes don't have a solid canopy. It is a bunch of ribbons.
So more like streamers than a parachute.
The shroud lines of the mains are made of kevlar.
Shot of Orion approaching the earth.
View attachment 550381
It's been fun watching Earth get bigger and bigger in the field of view.
 
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