RCgothic

This feels really impressive:

Excessive fuel consumption by upper stage engine apparently. Currently not stated why, but they've been able to recreate this in ground testing.

The predicted track of Ian currently goes within a whisker of the cape. Rollback definitely the right call.

The person J McD tagged liked the thread now, so it's probably about right.

We got an answer! Edit: although I now note notice this isn't the person J McD tagged, so may not be completely authoritative.

Agree with the numbers up thread. Asteroid density seems reasonable, so only things I can think of are: 1) Impact velocity is incorrect. Seems unlikely. 2) DART enormously over-penetrated Dimorphos. Most of the energy wasn't transferred. 3) Gravity isn't the most significant component of binding energy for small rubble pile asteroids.

Already? Wow, ok. I'll be keeping an eye out, thanks.

I heard someone else say they're trying to avoid interrupting construction at 39A if possible.

Windy.com is currently predicting a direct hit on Kennedy Space Center on Thursday morning. Things can change, and different forecasters have different tracks. Still. Yikes.

You're about the fifth person I've seen make this comment.

They can always change their minds about the roll-back after prep is underway. Shuttle turned back to the pad half way to the VAB one time.

80% weather violation on the 27th. It's clearly not happening. I expect the decision to roll back will be taken tomorrow.

This forcast is way too close for comfort. Plus storm force winds and cloud rules on the 27th guarantee SLS would still be on the pad on the 28th. Certain scrub.

Hurricane now forecast around Florida 27th/28th/29th. Surely they have to roll back to the VAB. It's too big a risk to assume there won't be a scrub that strands SLS on the pad, or to assume the storm will pass by Kennedy. The next viable launch opportunity would probably then be in November.

They also don't especially like being chilled. Ferrous magnets stop being magnets at cryogenic temperature, and Neodymium loses 30% of its strength. Samarium Cobalt are better, losing only 10%. I know this because of a stint as a production engineer where the design engineers gave me some large and awkwardly-shaped steel components to freeze-fit using liquid nitrogen without allowing me to machine any lifting features into them. Had some "fun" designing cryogenic lifting magnets.

It's the combination of being both heinously expensive and therefore also penny-pinching. Any other programme with this budget would have had this sorted.

Interesting that there going closed cycle on the engine. Peter Beck was previously adamant a simple gas gen engine was all the performance needed, in combination with lower structural mass fractions from using carbon fibre construction. The fact the performance seems about the same despite uprated engines makes me think they've had mass creep somewhere.

Lol.

And another thread on some nose cone weirdness: