sevenperforce

Yeah, I am surprised that they didn't do a cryo proof FTS test, especially given how cheap the tanks are. Then again, perhaps there's some difference with blowing the tanks at altitude vs at sea level. I actually have a reasonably significant amount of experience with brittle vs ductile fractures in steel, although typically with much higher pressures and much thicker vessels. I wonder if they were expecting a ductile fracture propagation from the FTS point but ended up with a brittle fracture surface that didn't propagate.

IMO the pacing item for a human mission to Mars is not currently the transportation system. Life support, ISRU, surface power, and countless other small but complicated systems are required. Agreed. Also, the most important parts of the Mars Starship program -- Superheavy and the rapidly reusable tanker -- are also the most important part of the HLS program.

Not from orbit but if you was strapped to an fairing on the inside that suborbital flight is probably survivable with an spacesuit. Landing might be rough however. There's probably a decent amount of thermal radiation coming off of that plasma in the wake but yeah, as long as you have a reflective spacesuit of some kind you should be find. Probably want a good dark visor too. Landing should be easy. You've seen how smoothly the fairing floats down to the water, right? How so? Two-stage reusable is the sweet spot. The lower stage can boostback to the launch site and the upper stage can loiter on orbit until it's time to initiate a re-entry that will bring it back to the launch site. A three-stage reusable architecture, on the other hand, is extremely challenging. The second stage won't make it all the way to orbit but will be entering at such high speeds that it needs essentially a full heat shield, and it's going to come down halfway around the world, so how does it get back to the launch site? The only thing I can think of that might work for a rapidly reusable three-stage architecture would be a RTLS booster with a second stage that brings the third stage to just shy of orbit, then re-enters about 3/4 of the way around and enjoys a hypersonic glide the rest of the way to the launch site. But then there's no real reason to make the third stage reusable. I wonder if they tried to get away with punch-out FTS instead of the detcord that ordinarily unzips the tanks, thinking that popping the tanks alone would be sufficient to destroy them.

One of the cool things about the FH launch last night -- if you watch SES-3, it actually shows the velocity decreasing as the burn begins. That's because speed was being measured relative to the ground station in a geocentric coordinate system.

The next Great Alignment is in the 2400s, I believe. But again, this is merely "all on one side" of the sun, more or less; it's not anywhere close to a true alignment. Although perhaps it would get to a point that all of the planets WOULD end up in a line, in correct order, if viewed from the side. One possibility would be to make it an outlined line, with the infill taking a particular shade. So the first time around would be a high-contrast outlined line, while the second time around and subsequent loops would start to fill in the line with contrast. Of course Mercury would always just be solid black, you know? Yep, very similar! That's super cool. I was thinking of something broadly simpler, though. More like the plain top-down view with all the planets at equally-spaced orbits. More abstract and thus more approachable.

Yes, exactly, that's how I was conceptualizing it. A planetary fingerprint. I like that.

I have a good friend whose dad passed away yesterday at just under 89 years old, so I put together this graphic as a sort of tribute. Green marks where the planets were when he was born; yellow marks where the planets were yesterday. The dark grey lines show how much the planets changed positions during the lifetime, while the light grey indicates that the planet completed at least one full orbit. As you can see, he made it just slightly over one full orbit of Uranus and just over half a full orbit of Neptune.

Sobering but somehow sweet idea: a graphic showing how far the planets moved during someone's life.

Yes, they do (I think they are called natal charts), but while I’ve seen these charts depicting the arrangement of the planets relative to the zodiac, I don’t think I’ve seen a depiction of the planets themselves relative to the sun. It’s always a mishmash of planets and constellations aligning, never the physical locations of the planets. I felt like there might be an appeal to this because (a) it’s more grounded and approachable than “your conflict resolution strategy is Mars in Leo Rising with Jupiter Ascendant” and (b) it’s actually a truly unique identifier.

Someone saw an image depicting all of the planets lined up in a row on one side of the Sun, and asked me how frequently such an alignment occurs. I wasn’t quite sure so I did a little digging. Turns out that although the planets will end up clustered within a 90° arc every few thousand years, actually getting them into anything approaching a perfectly straight line would take trillions of years. This sparked a realization. If getting all the planets into a perfectly straight line (ignoring inclination) is vanishingly unlikely, then so is the repetition of any particular arbitrary alignment. That means that the alignment of the planets on any date in history is unique. Pick any date you like; the planets never arranged themselves in quite that way before and never will arrange themselves in that way ever again. If you imagine a top down view of the solar system, the planets are like the hands on a clock, with each planet making a full revolution in connection with its orbital period. Of course, this clock runs counterclockwise, but that is beside the point. With eight separate “hands“, however, it is a clock that never repeats itself. I did the math, and as long as mercury is at least 15 pixels away from the “sun”, you can uniquely depict any date in history, from the start of the universe until the universe’s end. How cool would it be if I set up a website where you could punch in your date of birth or any other date of significance and it would rotate the hands backward or forward on the clock from today’s date to show you the precise alignment of the planets on the date you chose? And then you could print it out and give it to someone as a gift or put it on a coffee mug or whatever else. Is this as cool as it sounds in my head or am I nuts?

It's done with work and so it's cosplaying Delta IV.

Correct -- concrete floats when you least expect it.

Interesting reversal of my idea.

I feel like something along these lines could work well. Big steel "dance floor" hung from the legs, so that they can still service the booster from underneath. Three giant steel triangles on hydraulics that translate inward and outward and fold up and down.

I will note that those are also nontrivial. If you put them on Superheavy, they impinge on Starship, which you may not want. If you put them on Starship, the impingement on Superheavy is less of a big deal, but that's also a lot of mass to push. Quick calculation -- at separation, Superheavy probably masses on the order of 650 tonnes, almost five times more than the S-IC first stage of the Saturn V. The eight retrorockets on the S-IC produced 394 kN for a period of just under a second. To get the same amount of pull-away acceleration on Starship, you'd need retrorockets producing a collective 1.9 MN of thrust...more than a Raptor 1 engine. If SpaceX used the same booster separation motors that Northrup Grumman uses for the SLS SRBs, they would need a cluster of 14 of them, which is pretty extreme. If the fuel and oxidizer are allowed to mix without igniting, and are then ignited, you absolutely end up with a detonation. Old strategy: use Starship to go to Mars New strategy: use Starship to make Earth into Mars

Agreed. Not waiting to put in a diverter was obviously a mistake, in hindsight. I'm guessing that they looked at the damage to the pad after the 50% static fire, did some modeling, and accepted the model's predictions about a full-up launch. The model most likely failed to account for the failure cascade discussed upthread, and so here we are. But if they were going to fire without a diverter, I completely agree with the decision to do it in an all-up test. Getting 5 million kg of propellant away from the pad as fast as possible is FAR better than firing and letting it sit there and go kablooey.

They are for both; there is no refuel on the lunar surface. True. However, the first few star ships to Mars will be one way. The upper section could incorporate blow-off panels in the heat shield to allow for those canted landing engines.

Any mention of steam or water tables is entirely off-base. While it is true that the water table in Boca Chica is quite close to the surface, that is not relevant to this discussion. At these temperatures, iron boils; whether or not water boils is entirely insignificant. The soil is probably somewhat saturated but that was not part of the failure cascade. In other news, it looks like my bad animation has already been picked up and people are running with it wildly. https://www.reddit.com/r/SpaceXMasterrace/comments/12uoqnv/starship_stage_separation_animation/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1 It does have a nice sort of beauty to it, though.

I will push back on this slightly. It's true that the stack was moving much slower than intended when it attempted the separation maneuver, but it was also MUCH lower in the atmosphere than intended. I mean, we can do the math fairly easily. At 40 km, the density of the atmosphere is 0.003996 kg/m3. At twice that altitude (but still below where the separation was planned), the density of the atmosphere is 0.00001846 kg/m3. That's a factor of 216.5 or thereabouts. You would have to be going 14.7 times faster at 80 km to experience the same amount of drag you experience at 40 km. Assuming that the separation maneuver was intended to take place at Mach 5 and 80 km but actually took place at Mach 1.5 and 40 kilometers, the drag and moments of torque on the stack were roughly 1949% of what was anticipated. That's a pretty good safety margin if you ask me. And that's before you factor in the number of rotations, the type of tumbling, and everything else going on.

You don't need fire for an explosion. FTS may have been what triggered it, but it still exploded from the fact that it was pressurized. This is why it breaks up into an incomprehensible number of pieces, not like... 3. True, but I do get the sentiment. A "Rocket exploded during launch" headline gives a very different vibe from a "Test launch terminated 24 miles over Gulf of Mexico after successful liftoff". The former gives the sense of something like Antares or Challenger or Ariane 5's maiden flight.

Wait, did SpaceX buy Spinlaunch?

An exoatmospheric Crazy Ivan should have very little structural strain -- aerospace members are usually stronger in tension than they are in compression. Here's a crude gif: Remember that this is a top-down view, not a side view.

I... Excuse me? The flip was planned? They were going to do a supersonic hammer-throw with a building-sized rocket to avoid fitting a normal separation mechanism. The HELL? This is Philip Bono levels of far-out. SpaceX, you have flabbered my gast most thoroughly, and I salute you. I've since received updated information and I've updated the graphic accordingly. It's more like this: Note that all of this is in the yaw axis. So less Pugachev's Cobra, more Crazy Ivan. Except the stack yaws 90° to port before commiting to the Ivan, and the booster then does a 270° Crazy Ivan but releases the Starship a third of the way through.

I don't think so. There's no confirmation that the booster actually fully lost hydraulic power at any point, and latches seem like the sort of thing that would get redundant loops. If I recall, one Falcon 9 was lost because of a hydraulic loss on the grid fin drivers, so they put in a backup hydraulic to make the grid fins dual redundant. The latches probably operate off the same hydraulic system as the grid fins, which makes them independent of the engine hydraulic unit.

The description from those on the inside is that the separation WAS commanded but didn't happen for some reason. The Starship is already supposed to have an abort mode for Superheavy failures. Granted, it might not have been programmed in yet, but trajectory issues alone wouldn't have been a reason not to attempt separation. That's a huge assumption. FTFY. It's not an assumption; it's just one possible theory. Do you really think this would have been the case on all latches on all sides ? Visually there was no seperation happing at all. It may have been that the set of aerodynamic forces and torques and the type of latches involved caused only one of the latches to seize, but it was in a position where it acted like a hinge and thus kept the stack connected: The gray arrow is the direction of travel, and the blue arrows are wind. At the moment of commanded separation (when Starship is pointed straight down in my graphic) the separation latches on the leeward side of the interstage are under slight compression (somewhat balanced by centrifugal force), while the latches on the windward side are under tension only. If they're under too much tension (because of higher than expected drag) then perhaps they wouldn't be able to retract, and so they would remain seized. This could explain the split-second image of Starship after Superheavy FTS but before Starship FTS, when the remains of the Superheavy interstage appear to be dangling from the aft of Starship by a single latch: If this wasn't SpaceX, I would think anyone bringing up this manoveur as being completely nuts I showed the (secondhand) source this image, and he's said it's the right idea but without a complete flip -- going back to the drawing board.