kerbiloid Posted May 5, 2021 Share Posted May 5, 2021 Don't the upper stages fall down since 1957? Quote Link to comment Share on other sites More sharing options...
Kerwood Floyd Posted May 5, 2021 Share Posted May 5, 2021 56 minutes ago, kerbiloid said: Don't the upper stages fall down since 1957? I think the point is that most of the time since 1957 the upper stages have fallen down in such a way that we knew they were falling in the ocean far from inhabited areas, and indeed, far from busy shipping lanes. This time we have only a vague idea where it's coming down. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 5, 2021 Share Posted May 5, 2021 13 minutes ago, Kerwood Floyd said: I think the point is that most of the time since 1957 the upper stages have fallen down in such a way that we knew they were falling in the ocean far from inhabited areas, and indeed, far from busy shipping lanes. This time we have only a vague idea where it's coming down. He knows this. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 5, 2021 Share Posted May 5, 2021 4 minutes ago, sevenperforce said: He knows this. Several posts ago it was stated that random atmospheric effects vary so much, that we can't predict the upper stage trajectory. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 5, 2021 Share Posted May 5, 2021 Unless I miss my guess, the Long March 5B configuration is the first launch vehicle designed to orbit its entire first-stage core since Sputnik 3 in 1958. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 5, 2021 Share Posted May 5, 2021 18 minutes ago, sevenperforce said: Unless I miss my guess, the Long March 5B configuration is the first launch vehicle designed to orbit its entire first-stage core since Sputnik 3 in 1958. R-7 lateral boosters are the 1st stage. They get jettisonned. Quote Link to comment Share on other sites More sharing options...
Spaceman.Spiff Posted May 5, 2021 Share Posted May 5, 2021 (edited) 49 minutes ago, sevenperforce said: orbit its entire first-stage core I mean.... Didn't the External Tank go to orbit? Edited May 5, 2021 by Spaceman.Spiff i am dumb the OMS finished orbit insertion Quote Link to comment Share on other sites More sharing options...
Beccab Posted May 5, 2021 Share Posted May 5, 2021 (edited) 29 minutes ago, kerbiloid said: R-7 lateral boosters are the 1st stage. They get jettisonned. True, but they aren't orbital as far as I know. That's the important part Edited May 5, 2021 by Beccab Quote Link to comment Share on other sites More sharing options...
tater Posted May 5, 2021 Author Share Posted May 5, 2021 19 minutes ago, Spaceman.Spiff said: I mean.... Didn't the External Tank go to orbit? No. It could have, but perigee was intentionally left low. Circularization burn was done by the OMS engines. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 5, 2021 Share Posted May 5, 2021 41 minutes ago, Beccab said: True, but they aren't orbital as far as I know. That's the important part Russians count the stages in the order they fall off: one, two, three. Americans count the stages in order of how close they are to the ground: boosters, one, two. So we say that the SLS and the Delta IV Heavy and the Falcon Heavy and the Soyuz-FG are two-stage rockets with parallel boosters on the first stage. Russians say all those are three-stage rockets. What I mean above is that the Long March 5B configuration (what Americans call a single-stage rocket with parallel boosters and what the Russians would call a two-stage rocket) is the first rocket since 1958 to have its central core fire all the way from the ground and end up in orbit. The R-7 Semyorka, which launched Sputnik, Laika, and Sputnik 3, had the same configuration as the Long March 5B with the central core reaching orbit. This is generally regarded as a bad idea. The R-7 launched several times after that in its ICBM configuration but never went to orbit. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 5, 2021 Share Posted May 5, 2021 26 minutes ago, sevenperforce said: Russians count the stages in the order they fall off: one, two, three. Americans count the stages in order of how close they are to the ground: boosters, one, two. Reminds me of the house storey enumeration: "1st floor, 2nd floor, etc." vs "ground floor, 1st floor, 2nd floor, etc." Quote Link to comment Share on other sites More sharing options...
YNM Posted May 5, 2021 Share Posted May 5, 2021 1 hour ago, kerbiloid said: "1st floor, 2nd floor, etc." vs "ground floor, 1st floor, 2nd floor, etc." If anything in this case the American version is the one without distinction for the ground-level floor. 2 hours ago, sevenperforce said: What I mean above is that the Long March 5B configuration (what Americans call a single-stage rocket with parallel boosters and what the Russians would call a two-stage rocket) is the first rocket since 1958 to have its central core fire all the way from the ground and end up in orbit. The R-7 Semyorka, which launched Sputnik, Laika, and Sputnik 3, had the same configuration as the Long March 5B with the central core reaching orbit. This is generally regarded as a bad idea. The R-7 launched several times after that in its ICBM configuration but never went to orbit. Will say that the size probably contributes to the extra danger this time as well... Didn't Atlas also have it's only stage end up in orbit for the Mercury missions ? Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 5, 2021 Share Posted May 5, 2021 Just now, YNM said: If anything in this case the American version is the one without distinction for the ground-level floor. Yes, I've always lived in America and it makes no sense to me for the "first floor" to be anything other than the first floor you can enter, the "second floor" being the second floor you can reach, and so forth. Just now, YNM said: Will say that the size probably contributes to the extra danger this time as well... Didn't Atlas also have it's only stage end up in orbit for the Mercury missions ? The Mercury capsule had posigrade separation motors but I don't think they provided much total impulse relative to the booster. That booster did end up in orbit, but it only would have hung out in space for a few orbits because they deliberately targeted a low enough perigee to ensure that John Glenn made it back to earth promptly if the retrograde deorbit motors failed. In contrast, the payloads for Sputnik 1-3 were not intended to be recovered and burned up on re-entry, so they didn't care where they came down. Thus they put them quite high, and the boosters stayed in orbit for a while. Most people who reported seeing Sputnik 1 were actually seeing the R-7 core (which was actually about the same length as the Long March 5B core but had a mass less than 8 tonnes and an engine cluster 83% lighter). Sputnik 1's R-7 core stayed in orbit for two months but re-entered without incident. Quote Link to comment Share on other sites More sharing options...
tater Posted May 6, 2021 Author Share Posted May 6, 2021 Yeah, good "hygiene" is to leave the perigee low on a large core stage so it immediately is disposed of, then raise orbital vehicle perigee with the upper stage as such a burn is not very costly. This is so ingrained in me I do it without thinking in KSP. Quote Link to comment Share on other sites More sharing options...
YNM Posted May 6, 2021 Share Posted May 6, 2021 (edited) Edited May 6, 2021 by YNM Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 6, 2021 Share Posted May 6, 2021 Narrowed to a 42 hour window. It also looks like they have narrowed to 29 total possible ground tracks. Quote Link to comment Share on other sites More sharing options...
RCgothic Posted May 6, 2021 Share Posted May 6, 2021 It'd actually be quite funny if bits fell on the US. In a "haha, now we get to analyse the bits, maybe control your re-entry next time" kind of way. Europe looks mostly safe at least. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 6, 2021 Share Posted May 6, 2021 17 minutes ago, RCgothic said: It'd actually be quite funny if bits fell on the US. In a "haha, now we get to analyse the bits, maybe control your re-entry next time" kind of way. Europe looks mostly safe at least. Yeah, with the exception of like one pass over Spain, Europe is in the clear. Actually I may have misspoken in that tweet. The tightest cluster would be apogee, not perigee, since it is moving fastest at apogee (the dots on the lines are five-minute increments). Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 6, 2021 Share Posted May 6, 2021 Does anyone know what the probability curve for this sort of re-entry prediction is? Like, is it "basically anywhere in this window with equal probability"? Or is it a bell curve? Quote Link to comment Share on other sites More sharing options...
tater Posted May 6, 2021 Author Share Posted May 6, 2021 1 minute ago, sevenperforce said: Does anyone know what the probability curve for this sort of re-entry prediction is? Like, is it "basically anywhere in this window with equal probability"? Or is it a bell curve? I think this far out it's probably pretty random as the stage is tumbling (I assume). Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 6, 2021 Share Posted May 6, 2021 Okay, this is about as good as it gets for now. Quote Link to comment Share on other sites More sharing options...
Codraroll Posted May 6, 2021 Share Posted May 6, 2021 (edited) I see one of the paths crosses over northeast China. There would be some cruel irony if it were to fall down in Beijing. Edited May 6, 2021 by Codraroll Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted May 7, 2021 Share Posted May 7, 2021 3 hours ago, Codraroll said: I see one of the paths crosses over northeast China. There would be some cruel irony if it were to fall down in Beijing. The paths shift constantly as the stage decays so any path could change. Last update for the night. Quote Link to comment Share on other sites More sharing options...
SOXBLOX Posted May 7, 2021 Share Posted May 7, 2021 (edited) So, how much of the engines can we expect to survive, based on past events? If it comes down on a non-PRC landmass, and is (sort-of) intact, then I expect it would be analyzed... Edited May 7, 2021 by SOXBLOX Me dumb. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted May 7, 2021 Share Posted May 7, 2021 3 hours ago, sevenperforce said: The paths shift constantly as the stage decays so any path could change. Last update for the night. Last bets. 6 hours ago, Codraroll said: I see one of the paths crosses over northeast China. There would be some cruel irony if it were to fall down Sector "Zero". P.S. Now the local roulette got world-wide. Quote Link to comment Share on other sites More sharing options...
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