RCgothic

Even if Artemis I launches this year, it's only as a test vehicle. The next launch is likely late 2024 or early 2025. The falcon family is on track to launch 60+ times this year, likely more next year, likely more the next. If Artemis I launches this window I wouldn't bet against 100-200 falcon flights before the next one. There's a good chance Starship will fly 20 times by the next SLS launch, and a good chance Vulcan will have 10 flights by then. Credible lunar programmes can be built around these vehicles. Why should the programme be limited by SLS/Orion's meagre cadence?

It's also alarming the tail mast leak is still present. Come on, there's been 2 months to fix that.

How am I not surprised that something that should have been WDR tested but wasn't tripped up the first launch attempt.

Note that transferring fluid out to a rotating ring will decelerate the ring due to conservation of angular momentum.

You'd most likely have a flooded/pressurised annulus on one part and a radial tap-off on the other. The annulus would need dynamic seals on each side.

Wow. That's a fair envelope expansion. Any idea how they managed that? Did these Starlinks just deploy to a trajectory closer to the ideal reference orbit?

Leaks actually wouldn't cause the fuel to go critical. Water is a moderator, and removing the water makes the fuel less reactive. A leak is less dangerous from a criticality perspective than dilution. For thermal management the soonest fuel might get loaded into a dry cask is 6 years best case, but 10 years is more typical and the pools are sized appropriately for that. Secondary pools do get considered for capacity increases sometimes, but usually they're considered undesirable. It's unnecessary handling operations, which should be minimised, and another pool facility, which has additional costs. Pools are built to survive anticipated earthquakes, and have no possible method of siphoning out the water. No pipework is permitted below the level of the fuel for this reason. They're reinforced concrete, with a liner and leak detection channels. A catastrophic leak is extremely unlikely. The most likely scenario for uncovering of the fuel is failure of the cooling plant and top-up supply, in which case the water simply evaporates over a period of weeks. But that's a pretty long-lead fault with plenty of opportunity for recovery. In terms of placement, the pools need to be positioned so that the free surface is the same as that in the refuelling cavity above the reactor when the reactor head is unbolted for refuelling. If the pools are within reactor containment they'll just fill a canal between the two. If the pools are outside of the reactor containment then the fuel gets posted in and out through a fuel transfer port and excessive water flow through there needs to be minimised.

It's 10 years in my experience.

The two choices were: 1) Protect the criticality defense against flooding. 2) Allow that in the event of a leak (and concrete structures both tend not to leak catastrophically and also have leak detectors), and also the loss of all other top-up methods such as mains water and road-tankers, a vulnerability to flooding might be useful if there is also flooding at the same time. The first is by far the more sensible choice. We *do not* want our nuclear fuel storage facilities to be vulnerable to flooding. We *do not* design around disaster scenarios covering for other faults. Yes, the auxiliary generators should have been higher.

I have professional expertise in this area. Fuel storage must comply with the "double contingency principle", which means that two or more unlikely independent things need to go wrong simultaneously before you end up with criticality incident. One defence is spacing, but big pools are expensive so fuel is stored close enough together that absent any other mitigations it would go critical, so in most cases this doesn't count. Another defense could be neutron absorbers in the racks themselves, but if there's a problem with the absorbers, that's only one contingency, so we add another - soluble boron in the pool water. Soluble boron is gains its effect from its concentration. If it gets diluted, it loses its effect. What could cause it to get diluted? Flooding. What causes flooding? Big Tsunamis, for one. So for me as a nuclear professional I'd say Fukushima's designers got this one right. The pools didn't get diluted by the enormous tsunami and the critically contingency was preserved.

Liked by Zack. Alterations to all engines most likely needed plus all QD panels on the OLM.

Goes here as well I guess

Yup, but it's still the most powerful rocket stage ever fired, even if only firing one engine. It's a little bit into semantics, but it'd be hard to tell if a minimum throttle 20-engine fire had exceeded N1 anyway. Today's test was a single engine for 21 seconds. Caught the NSF guys by surprise with how long it was!

Now technically the most powerful rocket stage ever fired (even if at minimum thrust).

I think David Weber's stories are a good example. As I recall he goes into great detail about the *implications* of the technologies and how they can be used tactically. Does it matter how efficient the Bomb-pumped X-ray laser is? No. What matters to the reader is they're proximity weapons that don't need a contact hit to cause damage. Reader: Ok, cool, understood. Another example, Jump Gates. How do they work? Doesn't really matter. The plot relevant details are that they're faster than regular FTL, and get destabilised by the amount of mass they transit. So you can send light cruisers through basically continuously, but if you send a battleship it will destabilise the jump point for several minutes and if you send an entire fleet you'd better hope it doesn't need reenforcements or to retreat any time soon. This creates a PROBLEM, and it is the solution to the problem that is interesting, not the minutae of how the gate actually functions.

A reminder that Superheavy only needs to fire 17 raptor 2 engines to beat SLS or 19.7 R2s to beat N1 as the most powerful rocket stage ever fired, and the current Superheavy config has 20.

Interesting that there aren't any aerocovers on those. I strongly suspect B8 has been promoted to orbital launch attempt.

Symbols don't follow the same rules as units.

It's a capital letter if the unit is named after a person. James Watt. Baron Kelvin. Anders Celcius. Rolf Sievert. James Joule. Andre-Marie Ampere. Joseph Henry. All capitalised units. gram, second, metre, mole, candela, not so much.