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Scrubbed due to engine bleed temperature issue. Sounds like this was a point of concern, but also something that was specifically tested during the dress rehear

by addaon 4y ago

Scrubbed due to engine bleed temperature issue. Sounds like this was a point of concern, but also something that was specifically tested during the dress rehearsal. More debugging being done on the pad (not defueling yet), but no going to space today.

zardo 4y ago
> More debugging being done on the pad (not defueling yet), but no going to space today. Does that mean they sent people out to the pad while it was still fueled?
xeromal 4y ago
FYI, I believe the solid rocket boosters are due to expire this summer so if they delay any more, they may really bone themselves.
- IshKebab 4y ago
  They'll just say "we re-evaluated and they're fine for a bit longer". I'm pretty sure they've already done that for something.
nordsieck 4y ago
For those who don't know, SLS gets 3 launch attempts per launch window (essentially per month). This is due to a number of constraints, but 2 big ones are the length of time the Flight Termination System batteries are certified to last and how much hydrogen they keep on hand in local storage.
- tppiotrowski 4y ago
  Do they pump the hydrogen back into storage or bleed it all into the atmosphere if they need to empty the fuel tanks?
  - nordsieck 4y ago
    > Do they pump the hydrogen back into storage or bleed it all into the atmosphere if they need to empty the fuel tanks? They pump it back. But some of it warms and turns to gas while it's being "used", so that part bleeds off. > While the vehicle is filled with liquid propellant, some of the LH2 is consumed for engine conditioning and some boils off inside the tanks. If a launch attempt was to be scrubbed after waiting through a whole two-hour launch window, and the propellants in the tanks were drained back into the spheres, they would end up being over 280,000 gallons short of the LH2 needed for another attempt. https://www.nasaspaceflight.com/2021/11/artemis-1-launch-periods/ https://www.nasaspaceflight.com/2021/11/artemis-1-launch-per...
cratermoon 4y ago
> something that was specifically tested during the dress rehearsal Something that should have been tested during the wet dress rehearsal, but because of a hydrogen leak issue, they never completed the wet dress and this was not tested. Hmm, skipping tests. SHIP IT.

by addaon 4y ago

zardo 4y ago

> More debugging being done on the pad (not defueling yet), but no going to space today. Does that mean they sent people out to the pad while it was still fueled?

xeromal 4y ago

FYI, I believe the solid rocket boosters are due to expire this summer so if they delay any more, they may really bone themselves.

IshKebab 4y ago
They'll just say "we re-evaluated and they're fine for a bit longer". I'm pretty sure they've already done that for something.

nordsieck 4y ago

For those who don't know, SLS gets 3 launch attempts per launch window (essentially per month). This is due to a number of constraints, but 2 big ones are the length of time the Flight Termination System batteries are certified to last and how much hydrogen they keep on hand in local storage.

tppiotrowski 4y ago
Do they pump the hydrogen back into storage or bleed it all into the atmosphere if they need to empty the fuel tanks?
- nordsieck 4y ago
  > Do they pump the hydrogen back into storage or bleed it all into the atmosphere if they need to empty the fuel tanks? They pump it back. But some of it warms and turns to gas while it's being "used", so that part bleeds off. > While the vehicle is filled with liquid propellant, some of the LH2 is consumed for engine conditioning and some boils off inside the tanks. If a launch attempt was to be scrubbed after waiting through a whole two-hour launch window, and the propellants in the tanks were drained back into the spheres, they would end up being over 280,000 gallons short of the LH2 needed for another attempt. https://www.nasaspaceflight.com/2021/11/artemis-1-launch-periods/ https://www.nasaspaceflight.com/2021/11/artemis-1-launch-per...

cratermoon 4y ago

> something that was specifically tested during the dress rehearsal Something that should have been tested during the wet dress rehearsal, but because of a hydrogen leak issue, they never completed the wet dress and this was not tested. Hmm, skipping tests. SHIP IT.