NASA says they have found the root cause of the Orion heat shield
issues. But they're not telling us what it was. Maybe by the end of the
year.
The pitting experienced by Artemis 1 during reentry. According to the OIG report, NASA found more than 100 locations on the heat shield where material “chipped away unexpectedly”.
The End.
I'll take a stab at it.
ReplyDeleteThe secrecy is because the root problem is exactly that of the problems in the early days of the Shuttle tiles.
To admit that is itself fraught with problems; chiefly that they have forgotten that which was learned thirty years ago.
There are others, but that's the biggee.
Oops, forty years ago.
DeleteOh, how time flies.
I think it's different than shuttle tiles and more like Apollo-era ablative coating. The Ars article says, “The heat shield, made of a material called Avcoat, was supposed to gradually and evenly burn away when the Orion spacecraft plunged into the atmosphere at a velocity of more than 24,500 mph (nearly 40,000 km/h), significantly faster than a capsule returning from low-Earth orbit....
DeleteInstead, the Avcoat material cracked unexpectedly, causing charred chunks to fall off the heat shield, and leaving cavities resembling potholes. The Orion spacecraft safely splashed down, and if astronauts had been inside, they would have been fine.”
Maybe they don't want us to know how bad it really is. Another 30 seconds of heating during reentry might have caused a total failure, with the loss of the craft.
ReplyDeleteAs long as this subject has been talked about, they always say the same part about if it had been crewed "...they would have been fine." Pardon my skepticism but I'd like to see some data on that.
DeleteWhy did it fail? Three reasons a heat shield fails.
ReplyDelete1. Bad material design. If the material is borked or put on incorrectly, it will exhibit these problems.
2. Bad implementation. Like a bubble in the matrix will cause the blowouts. Or incorrect mixing of the shield matrix will cause weak spots and thus blowouts.
3. Bad geometry of the shield itself. The geometry of the parabolic curve on the bottom is very critical. It affects all sorts of things, like the amount of resistance the capsule meets during reentry, the amount of heat that builds up and where it builds up. Even as to the maneuverability and entry profile of the capsule.
Or a combination of bad material, bad implementation and bad design.
The bullscat line, is, as you pointed out, is "The astronauts would have been okay." Maybe, maybe not. Maybe the additional weight of the astronauts and their gear would have been enough to totally bork the reentry.
Yeah, don't trust it. And I'd be skeptical of any 'fixes' that aren't pr
And, jeez, when is 'just barely good enough' good enough? Where's the vaunted 'over-engineered' that used to be industry standard. Seriously, 'over-engineered' stuff breaks all the time in the harsh reality of spaceflight or even airspace flight or even on the friggin highway. 'Just barely good enough' isn't good enough on a critical part like a heat shield.
Hmmm... I wonder if they could mock up a heat shield and then use a rocket motor to provide the velocity and heat of a reentry?