Everyday Astronaut is going to the moon

[Gargamel]

Good for him. 

[mikegarrison]

... maybe. If a whole lot of things work as hoped.

And then he might survive coming back, if a whole lot of other things work as hoped.

[mikegarrison]

Here's the thing about Starship ... what happens if the engines fail? There really is no possible recovery, right? I mean, not unless they build a crew capsule escape system. Something like the F-111 had, one that separated the entire crew section of the plane from the rest of the structure and had its own parachute.

 

[Beccab]

56 minutes ago, mikegarrison said:

Here's the thing about Starship ... what happens if the engines fail? There really is no possible recovery, right? I mean, not unless they build a crew capsule escape system. Something like the F-111 had, one that separated the entire crew section of the plane from the rest of the structure and had its own parachute.

 

While that's true, that word be a catastrophic failure - you need a total failure in 2 of 3 sea level engines, which have already been fired at the beginning of the mission (thus if there was issues that could risk that, you would have had whole days or weeks to address it and find countermeasures), and much more if the vacuum engines can be used instead both in the 6-engine and 9-engine variant. I'm not saying it's impossible, but it's a very, very low chance in a later starship flight when crew is already launching

That said, this post made me think - it shouldn't be impossible to make a crash survivable, i think? The terminal velocity of 90 m/s seems beyond what could reasonably have survivors , but with 30+ meters of crumple zone available and a properly designed crew module, perhaps?

[mikegarrison]

1 hour ago, Beccab said:

While that's true, that word be a catastrophic failure - you need a total failure in 2 of 3 sea level engines, which have already been fired at the beginning of the mission (thus if there was issues that could risk that, you would have had whole days or weeks to address it and find countermeasures), and much more if the vacuum engines can be used instead both in the 6-engine and 9-engine variant. I'm not saying it's impossible, but it's a very, very low chance in a later starship flight when crew is already launching

That said, this post made me think - it shouldn't be impossible to make a crash survivable, i think? The terminal velocity of 90 m/s seems beyond what could reasonably have survivors , but with 30+ meters of crumple zone available and a properly designed crew module, perhaps?

First off all, they don't have to fail at the end of the mission. If they fail during launch it is just as bad.

Secondly, engines are a system. If something happens that takes out the whole system (no fuel, no ox, an explosion that damages everything back there, whatever) then you lose all the engines at once. Yes, some failures might only affect individual engines, but there are potential failure modes that affect all the engines.

[Beccab]

1 hour ago, mikegarrison said:

First off all, they don't have to fail at the end of the mission. If they fail during launch it is just as bad.

Secondly, engines are a system. If something happens that takes out the whole system (no fuel, no ox, an explosion that damages everything back there, whatever) then you lose all the engines at once. Yes, some failures might only affect individual engines, but there are potential failure modes that affect all the engines.

I mean, not really? The closest examples, even if they're both pretty far, are STS and F9; both of them had a single engine failure during launch, and in neither it took out the rest. Even an SN-something launch lost an engine during ascent, with no damage reaching the rest, and that's with the unshielded engine block that flew during the atmospheric flight tests. Like, the only example of I know of at all in rocket history is the second N1 launch, and even then it wasn't because it actually took out the rest of the engine block but because of terrible programming logic in its avionics. I'm sure that there are some example, but they seem to be extremely rare for sure

As for failing during launch, sure, but again, that's a catastrophic failure your talking about. Both 6-engine and 9-engine variants (and by the time people fly on starship in what, 2027? there's a very high chance that it's a 9-engine variant we're talking about) should easily be able to abort to a lower orbit with a smaller number just like STS did. Either case, even if somehow there was an overlooked unknown failure mode that took out the entire engine block with no chanche of recovery, that's a reason for which there should be a ton of uncrewed flights before Polaris III, both launching normal payload and with straight up the variant capable of transporting people but empty. F9 is at what, a success streak of 140 consecutive successes? Starship should aim at something like that before ever attempting a crewed flight

[mikegarrison]

25 minutes ago, Beccab said:

I mean, not really? The closest examples, even if they're both pretty far, are STS and F9; both of them had a single engine failure during launch, and in neither it took out the rest. Even an SN-something launch lost an engine during ascent, with no damage reaching the rest, and that's with the unshielded engine block that flew during the atmospheric flight tests. Like, the only example of I know of at all in rocket history is the second N1 launch, and even then it wasn't because it actually took out the rest of the engine block but because of terrible programming logic in its avionics. I'm sure that there are some example, but they seem to be extremely rare for sure

As for failing during launch, sure, but again, that's a catastrophic failure your talking about. Both 6-engine and 9-engine variants (and by the time people fly on starship in what, 2027? there's a very high chance that it's a 9-engine variant we're talking about) should easily be able to abort to a lower orbit with a smaller number just like STS did. Either case, even if somehow there was an overlooked unknown failure mode that took out the entire engine block with no chanche of recovery, that's a reason for which there should be a ton of uncrewed flights before Polaris III, both launching normal payload and with straight up the variant capable of transporting people but empty. F9 is at what, a success streak of 140 consecutive successes? Starship should aim at something like that before ever attempting a crewed flight

The two most common complaints about the shuttle were 1) too expensive, but 2) no crew abort mode.

Well, Starship has no crew abort mode for a problem with Starship. Supposedly "it is its own LES" if the problem is with the booster, but if it has a problem itself?

All those engines are fed by common fuel through common pipes from common tanks, so those are all obvious potential single-point failures even without the possibility of fratricide. I mean, a Falcon9 blew up because it had a single failed strut. A shuttle blew up because it launched on a cold day. Apollo 13 had an explosion because of a damaged wire. Things can happen.

I'm just saying, it's a choice to have a manned launcher that has no LES and can only safely land propulsively. A questionable choice. On the moon? Sure. On Mars? Sure. But on the Earth there should be options.

They could avoid some of that risk (at the cost of more complexity and cost, of course) with some kind of crew escape system. The only one I can imagine working would be something like that F-111 design.

Edited December 12, 2022 by mikegarrison

[Nuke]

starship, at present, is in a very preliminary form. all of them seem to be rigged either as disposable test articles or unmanned starlink delivery.  it stands to reason it could get one at some point if the launch is considered too risky without it. i imagine an open nose version that can mount a modified dragon as an escape pod as an optional 3rd stage. crew can transfer into the main body of the ship after launch and before re-entry. an entirely new system could be designed in theory but seems it would work better if you used an established platform as the basis. 

[tater]

3 hours ago, mikegarrison said:

They could avoid some of that risk (at the cost of more complexity and cost, of course) with some kind of crew escape system. The only one I can imagine working would be something like that F-111 design.

Here's a Phil Bono concept for Ithacus (one of his semi-SSTO designs from the 60s):

 

I see humans in Starship—where they enter and leave the vehicle on Earth—as a long, long way away.

[sevenperforce]

18 hours ago, Gargamel said:

Good for him. 

I wish him all the best, even if he annoys me somewhat from time to time. _{(Yes, it's a little sour grapes. I would have preferred to be on that flight. Tim does a lot of research but he lacks some of the fundamental physics and engineering knowledge that you really need to understand what's going on and explain it properly.)}

8 hours ago, Beccab said:

9 hours ago, mikegarrison said:

Here's the thing about Starship ... what happens if the engines fail? There really is no possible recovery, right? I mean, not unless they build a crew capsule escape system. Something like the F-111 had, one that separated the entire crew section of the plane from the rest of the structure and had its own parachute.

While that's true, that word be a catastrophic failure - you need a total failure in 2 of 3 sea level engines, which have already been fired at the beginning of the mission (thus if there was issues that could risk that, you would have had whole days or weeks to address it and find countermeasures), and much more if the vacuum engines can be used instead both in the 6-engine and 9-engine variant. I'm not saying it's impossible, but it's a very, very low chance in a later starship flight when crew is already launching

Assessment of risk is a tricky thing.

Calculating the Loss of Crew ("LOC") risk for a launch requires you to sum the probabilities of every possible failure mode, with all of their interactions and dependencies. Merely summing the probabilities is difficult enough; adding in the interactions and dependencies makes it incredibly hard. The equation looks something like this:

LOC = Σ_1..n(P_Fn * Σ_1..m(1-P_{Cn_m}))

Here, P_F1 is the probability of the first failure mode happening, P_{C1_1} is the probability of the first contingency for the first failure mode working, n is the total number of failure modes, and m is the total number of continencies for each given failure mode. You can add new abort/contingency/escape systems which increase the m for certain failure modes, but each new system also increases the global n, so you have to make sure that the result after the system is added is actually lower than the result before the system is added.

In the spacecraft world, we have had two instances where the abort/escape system itself directly caused a failure, which either resulted in fatalities or would have resulted in fatalities (the Soyuz Dec. 1966 incident and the Dragon April 2019 incident). And of course there are numerous examples from the world of aircraft.

There are certain failure modes which we accept as having no meaningful contingencies. In commercial and general aviation flights, catastrophic losses of structural integrity in the wing (like this or this) or in the tail section (like this or this) are understood to have no contingencies, so you just try to reduce the absolute odds of those failure modes.

The Space Shuttle was particularly bad in terms of LOC because there were MANY significant failure modes, almost none of which had any contingencies. The only significant failure mode that could be survived was a single-engine loss several minutes into flight. An earlier single-engine loss, or the loss of a second engine at any point, and the vehicle was doomed. Any booster failures were also instant LOC.

With Starship, there are at least contingencies for most failure modes, assuming a nine-engine upper stage. With 33 independent engines, Superheavy can survive several engine failures without even having mission loss, and given a reasonably beefy interstage, even a catastrophic structural failure on Superheavy will allow Starship to act as its own abort system and execute a RTLS and nominal landing. That alone makes it much safer than the Shuttle. If the failure is on Starship, however, that's another matter.

5 hours ago, mikegarrison said:

Starship has no crew abort mode for a problem with Starship. Supposedly "it is its own LES" if the problem is with the booster, but if it has a problem itself?

Starship can survive losing up to two of its six total engines on ascent and it can survive losing up to two of its three central engines on landing. All three central engines are ignited at landing, too, so if one or two fail to ignite or shut down immediately after ignition, it's no big deal. The engines have the same frag shields that have been used and tested on Falcon 9, so even a catastrophic engine failure (as in the CRS-1 and the March 2020 Starlink launch) is fine.

All four flaperons have dual-redundant driver mechanisms, and Starship has acceptable control authority even if one of those four flaperons completely locks up. So Starship can lose between 3 and 5 of its 8 flaperon drivers without losing the vehicle. 

5 hours ago, mikegarrison said:

All those engines are fed by common fuel through common pipes from common tanks, so those are all obvious potential single-point failures even without the possibility of fratricide. I mean, a Falcon9 blew up because it had a single failed strut.

Yes, any catastrophic structural failure in the tanks or downcomers will result in LOC. But tanks and downcomers are literally just steel cylinders, really the simplest possible structure in aerospace. "The best part is no part" is helpful here; the failed strut in CRS-7 only existed in the first place because the F9US needs helium COPVs inside the tanks, which Starship doesn't need thanks to autogen press. I'm not saying it's impossible for the main structural components to fail, but the failure of any primary load-bearing metal structure in a commercial aircraft (like an engine pylon, wing spar, or tail) is unsurvivable, too.

5 hours ago, mikegarrison said:

They could avoid some of that risk (at the cost of more complexity and cost, of course) with some kind of crew escape system. The only one I can imagine working would be something like that F-111 design.

As long as the crew escape system didn't further increase possible failure modes, sure.

All the pyros and contingency engines and COPVs and other systems necessary to achieve an independent capsule abort system like F-111 or @tater's Ithacus add to failure modes, though. If we suppose that Starship's risk of a catastrophic structural failure is 1% and the independent abort system's chance of correcting a catastrophic structural failure is 95%, but the independent abort system has 5 separate systems which each have an 0.1% chance of creating their own failure mode for which there is no contingency, then you basically break even.

Ejection seats a la Gemini would be a better solution, even though they introduce their own failure modes too.  

8 hours ago, Beccab said:

That said, this post made me think - it shouldn't be impossible to make a crash survivable, i think? The terminal velocity of 90 m/s seems beyond what could reasonably have survivors , but with 30+ meters of crumple zone available and a properly designed crew module, perhaps?

You need to pull 135 m/s² -- about 14 gees -- to slow down by 90 m/s over a 30-meter distance. So if you could reliably land tail-first and perfectly spread that deceleration out, such that the entire vehicle acted as a crumple zone for a titanium-bathtub crew module, then sure, it could be survivable. The problems are (a) engineering a crew module which can survive the ensuing explosion while also falling at an acceptably-consistent rate through the rest of the vehicle and (b) figuring out a way for the vehicle to enter a tail-down configuration without using the engines to initiate the kick-flip.

2 hours ago, tater said:

I see humans in Starship—where they enter and leave the vehicle on Earth—as a long, long way away.

I agree.

However, the current plan for DearMoon is to expend a Superheavy to allow a direct launch into TLI . . . so they seem gung ho about it.

[magnemoe]

5 hours ago, mikegarrison said:

The two most common complaints about the shuttle were 1) too expensive, but 2) no crew abort mode.

Well, Starship has no crew abort mode for a problem with Starship. Supposedly "it is its own LES" if the problem is with the booster, but if it has a problem itself?

All those engines are fed by common fuel through common pipes from common tanks, so those are all obvious potential single-point failures even without the possibility of fratricide. I mean, a Falcon9 blew up because it had a single failed strut. A shuttle blew up because it launched on a cold day. Apollo 13 had an explosion because of a damaged wire. Things can happen.

I'm just saying, it's a choice to have a manned launcher that has no LES and can only safely land propulsively. A questionable choice. On the moon? Sure. On Mars? Sure. But on the Earth there should be options.

They could avoid some of that risk (at the cost of more complexity and cost, of course) with some kind of crew escape system. The only one I can imagine working would be something like that F-111 design.

The pretty obvious solution to me is to have the top part of the crew compartment be the escape system, it will have the header tanks, this weight the thing down a lot but it give you serious dV. 
Could you make some simple pressure feed rocket engines who could pull the header tanks and say 1-2 decks away? ISP is irrelevant you might want to increase fuel use, just trust and forget 10 g, say 3-4 g. You don't need that g forces as you have the large passenger module, pressurized bulkhead to the cargo bay and its pressurized bulkhead floor. 
I say this has multiple benefits, large capacity even more with two decks, and everybody would be strapped down here in seats on accent and decent. 
Little added weight, the engines and the pressurized bulkhead at the bottom on the escape module, the engines and extra control systems but you might want the main control systems up here anyway. Parachutes even if you technically could land this with propulsive landing. Yes the header tanks could fail but then you are dead anyway. 

And the most dangerous part of a starship mission has to be the flip over and land 
 

6 minutes ago, sevenperforce said:

However, the current plan for DearMoon is to expend a Superheavy to allow a direct launch into TLI . . . so they seem gung ho about it.

Is DearMoon back to using falcon heavy? 

[sevenperforce]

1 minute ago, magnemoe said:

The pretty obvious solution to me is to have the top part of the crew compartment be the escape system, it will have the header tanks, this weight the thing down a lot but it give you serious dV. 
Could you make some simple pressure feed rocket engines who could pull the header tanks and say 1-2 decks away?

SpaceX is already designing pressure-fed landing engines for Lunar Starship HLS, so these could work. This would, of course, require adding dedicated pressurized CH4 tanks to the crew cabin section and dedicated helium COPVs to maintain press.

The main problem is figuring a way to separate the entire nose of the vehicle, including a portion of the heat shield, in a safe and reliable way. What do you do with the forward flaperons? Do they come with, or are they supposed to separate too? It's a huge amount of complexity and new failure modes in an area where you want the maximum structural integrity in the first place.

4 minutes ago, magnemoe said:

Parachutes even if you technically could land this with propulsive landing.

For something this massive, the best you could hope for would probably be drogue-assisted propulsive landing.

5 minutes ago, magnemoe said:

8 minutes ago, sevenperforce said:

However, the current plan for DearMoon is to expend a Superheavy to allow a direct launch into TLI . . . so they seem gung ho about it.

Is DearMoon back to using falcon heavy? 

No, it never was.

Yusaku Maezawa originally contracted to fly around the moon on a modified Crew Dragon (uprated ECLSS, heat shield, etc) on an expended Falcon Heavy, but ever since DearMoon was announced (simultaneous to the announcement of the slimmed-down 9-meter Starship) it has been a Starship project.

The plan to expend the Superheavy (announced at some point within the last 18 months, I can't remember exactly when) means there is no loiter time or need for propellant refill in LEO. 

[mikegarrison]

4 hours ago, sevenperforce said:

Ejection seats a la Gemini would be a better solution, even though they introduce their own failure modes too.

No way. There is terribly little of the flight envelope that would be survivable by an unprotected parachutist. They need some sort of capsule around them. The SR-71 did have at least one person survive a mid-air, high-speed, high altitude event using only his pressure suit (which was specifically designed to be the ejection "capsule" for the SR-71), but an orbital rocket is a different matter. In Gemini they were wearing EVA suits from launch, and it's still not clear how much of the flight envelope would have been survivable if they had ejected.

Also, the main reason they didn't consider using ejection seats on the shuttle (other than the first couple of flights) is that there was no path to eject through if you were in the mid-deck.

[Spacescifi]

6 hours ago, sevenperforce said:

I wish him all the best, even if he annoys me somewhat from time to time. _{(Yes, it's a little sour grapes. I would have preferred to be on that flight. Tim does a lot of research but he lacks some of the fundamental physics and engineering knowledge that you really need to understand what's going on and explain it properly.)}

Assessment of risk is a tricky thing.

Calculating the Loss of Crew ("LOC") risk for a launch requires you to sum the probabilities of every possible failure mode, with all of their interactions and dependencies. Merely summing the probabilities is difficult enough; adding in the interactions and dependencies makes it incredibly hard. The equation looks something like this:

LOC = Σ_1..n(P_Fn * Σ_1..m(1-P_{Cn_m}))

Here, P_F1 is the probability of the first failure mode happening, P_{C1_1} is the probability of the first contingency for the first failure mode working, n is the total number of failure modes, and m is the total number of continencies for each given failure mode. You can add new abort/contingency/escape systems which increase the m for certain failure modes, but each new system also increases the global n, so you have to make sure that the result after the system is added is actually lower than the result before the system is added.

In the spacecraft world, we have had two instances where the abort/escape system itself directly caused a failure, which either resulted in fatalities or would have resulted in fatalities (the Soyuz Dec. 1966 incident and the Dragon April 2019 incident). And of course there are numerous examples from the world of aircraft.

There are certain failure modes which we accept as having no meaningful contingencies. In commercial and general aviation flights, catastrophic losses of structural integrity in the wing (like this or this) or in the tail section (like this or this) are understood to have no contingencies, so you just try to reduce the absolute odds of those failure modes.

The Space Shuttle was particularly bad in terms of LOC because there were MANY significant failure modes, almost none of which had any contingencies. The only significant failure mode that could be survived was a single-engine loss several minutes into flight. An earlier single-engine loss, or the loss of a second engine at any point, and the vehicle was doomed. Any booster failures were also instant LOC.

With Starship, there are at least contingencies for most failure modes, assuming a nine-engine upper stage. With 33 independent engines, Superheavy can survive several engine failures without even having mission loss, and given a reasonably beefy interstage, even a catastrophic structural failure on Superheavy will allow Starship to act as its own abort system and execute a RTLS and nominal landing. That alone makes it much safer than the Shuttle. If the failure is on Starship, however, that's another matter.

Starship can survive losing up to two of its six total engines on ascent and it can survive losing up to two of its three central engines on landing. All three central engines are ignited at landing, too, so if one or two fail to ignite or shut down immediately after ignition, it's no big deal. The engines have the same frag shields that have been used and tested on Falcon 9, so even a catastrophic engine failure (as in the CRS-1 and the March 2020 Starlink launch) is fine.

All four flaperons have dual-redundant driver mechanisms, and Starship has acceptable control authority even if one of those four flaperons completely locks up. So Starship can lose between 3 and 5 of its 8 flaperon drivers without losing the vehicle. 

Yes, any catastrophic structural failure in the tanks or downcomers will result in LOC. But tanks and downcomers are literally just steel cylinders, really the simplest possible structure in aerospace. "The best part is no part" is helpful here; the failed strut in CRS-7 only existed in the first place because the F9US needs helium COPVs inside the tanks, which Starship doesn't need thanks to autogen press. I'm not saying it's impossible for the main structural components to fail, but the failure of any primary load-bearing metal structure in a commercial aircraft (like an engine pylon, wing spar, or tail) is unsurvivable, too.

As long as the crew escape system didn't further increase possible failure modes, sure.

All the pyros and contingency engines and COPVs and other systems necessary to achieve an independent capsule abort system like F-111 or @tater's Ithacus add to failure modes, though. If we suppose that Starship's risk of a catastrophic structural failure is 1% and the independent abort system's chance of correcting a catastrophic structural failure is 95%, but the independent abort system has 5 separate systems which each have an 0.1% chance of creating their own failure mode for which there is no contingency, then you basically break even.

Ejection seats a la Gemini would be a better solution, even though they introduce their own failure modes too.  

You need to pull 135 m/s² -- about 14 gees -- to slow down by 90 m/s over a 30-meter distance. So if you could reliably land tail-first and perfectly spread that deceleration out, such that the entire vehicle acted as a crumple zone for a titanium-bathtub crew module, then sure, it could be survivable. The problems are (a) engineering a crew module which can survive the ensuing explosion while also falling at an acceptably-consistent rate through the rest of the vehicle and (b) figuring out a way for the vehicle to enter a tail-down configuration without using the engines to initiate the kick-flip.

I agree.

However, the current plan for DearMoon is to expend a Superheavy to allow a direct launch into TLI . . . so they seem gung ho about it.

 

I have not read your full message so forgive me if this was answered already but why do they have to worry about rocket engines failing?

 

I do not wonder if my car is going to fail unless I am aware it is already having issues.

 

Are chemical rockets THAT unreliable? Everything is going fine until it is'nt?

I think solid rockets are more reliable but have greater limitations. No one wonders if a solid fueled rocket is going to fail.

 

What is the reason chemical rockets usually fail?

You would think engineers would find a way to eliminate such uncertainty... especially with MANNED space flight.

 

As for your jealousy over Matt going to the moon, it's worth noting that he is youtube famous... so that helps a great deal.

 

To get what he gets then I imagine you would have to get your own youtube channel... with all the time and commitment that takes.

 

Do you really want to go down that rabbit hole?

Edited December 12, 2022 by Spacescifi

[SunlitZelkova]

4 hours ago, Spacescifi said:

You would think engineers would find a way to eliminate such uncertainty... especially with MANNED space flight.

This reminds of me of Neil deGrasse Tyson’s “unhackable systems” comment.

Worrying about the failure of rocket engines is ridiculous! Just build rocket engines that don’t fail!

4 hours ago, Spacescifi said:

As for your jealousy over Matt going to the moon, it's worth noting that he is youtube famous... so that helps a great deal.

 

To get what he gets then I imagine you would have to get your own youtube channel... with all the time and commitment that takes.

 

Do you really want to go down that rabbit hole?

@sevenperforce runs a great science communication TikTok. He is just as qualified as Tim is to be on there. Tim Dodd is going btw, not “Matt” (I assume you are referring to Lowne). Have you heard the Perseverance Sea Shanty?

I don’t know what exact view counts are, but I’d argue catchy 60 second TikTok videos are a better means of reaching a wider audience than 30-40 minute long YouTube videos, if Maezawa’s aim is to bring their experience back to people on Earth.

Edited December 13, 2022 by SunlitZelkova

[AtomicTech]

On 12/11/2022 at 2:54 PM, Gargamel said:

Good for him. 

Still disappointed that @illectro (Scott Manley) didn't get a seat on Starship :\

 

[sevenperforce]

5 hours ago, mikegarrison said:

No way. There is terribly little of the flight envelope that would be survivable by an unprotected parachutist.

True, but there is terribly little of the flight envelope where you need active ejection/escape from a failing Starship.

Starship's failure modes are:

1. Catastrophic structural failure on the pad
2. Failed engine startup during abort from Superheavy failure
3. Catastrophic structural failure during boost
4. Failed engine startup after separation
5. Catastrophic structural failure during the burn to orbit
6. Premature engine shutdown during the burn to orbit
7. Catastrophic structure failure on orbit
8. Failed de-orbit burn
9. Heat shield burn-through on re-entry
10. Loss of multiple flaperon control during re-entry
11. Loss of multiple flaperon control during EDL
12. Failed engine startup during landing
13. Premature engine shutdown during landing

Several of these (7, 9, 8, and 10) are not helped by any ejection/abort/escape system (although 8 could potentially be solved with a rescue mission). Most (1, 2, 3, 12, and 13) can be solved by ejection seats.

Granted, there is a brief portion of boost where the vehicle is too high and too fast for ejection seats, but still low enough in the atmosphere that dynamic forces will rip the vehicle apart. In which case. . . .

5 hours ago, mikegarrison said:

They need some sort of capsule around them. The SR-71 did have at least one person survive a mid-air, high-speed, high altitude event using only his pressure suit (which was specifically designed to be the ejection "capsule" for the SR-71), but an orbital rocket is a different matter. In Gemini they were wearing EVA suits from launch, and it's still not clear how much of the flight envelope would have been survivable if they had ejected.

The failure modes from above that remain (4, 5, 6, 11, and unejectable portions of 2 and 3) are survivable with ejection seats if the cabin area has enough structural integrity to survive vehicle breakup. Even if Starship goes to pieces, an intact cabin area will follow a generally ballistic trajectory until it reaches a low enough altitude that the ejection seats can safely fire. For 4 and 6, the vehicle may even be able to dump its propellant and use a flaperon-assisted glide to perform a controlled descent to ejection altitude.

We know from Challenger that it's perfectly possible to survive a mid-air vehicle breakup shortly after MaxQ. The astronauts on that Shuttle were alive until the cabin hit the water.

5 hours ago, mikegarrison said:

Also, the main reason they didn't consider using ejection seats on the shuttle (other than the first couple of flights) is that there was no path to eject through if you were in the mid-deck.

That was because the Shuttle cabin was horribly designed. They could have built the cabin in such a way that there were ejection seats in the mid-deck, but they chose not to, because they were fools.

Also because ejecting into the exhaust/debris field of the SRBs would have been suicide, but that's beside the point.

4 hours ago, Spacescifi said:

I have not read your full message so forgive me if this was answered already but why do they have to worry about rocket engines failing? I do not wonder if my car is going to fail unless I am aware it is already having issues. Are chemical rockets THAT unreliable? Everything is going fine until it is'nt?

It's standard in crewed spaceflight, no matter how unlikely an engine failure may be.

Think about it. If your car engine fails, you coast to a stop. If your plane engine fails, you glide to a landing. If your helicopter engine fails, you autorotate to a landing. If a rocket engine fails, however, you need a way to get to the ground safely. Starship is the first crewed vehicle which plans propulsive landings on Earth, so it needs a contingency for the highly unlikely event that an engine fails.

4 hours ago, Spacescifi said:

As for your jealousy over Matt Tim going to the moon, it's worth noting that he is youtube famous... so that helps a great deal. To get what he gets then I imagine you would have to get your own youtube channel... with all the time and commitment that takes. Do you really want to go down that rabbit hole?

As @SunlitZelkova points out, I am quite familiar with using social media for science education. I have about seven times as many TikTok followers as Tim. Granted, he has a lot more YouTube followers than me, but still.

Not begrudging it at all, mind you. He's a nice guy and he does a great job, for the job he does. Tim dropped out of college to pursue photography, and that's totally fine . . . but I think it's a real shame that out of eight slots and two backup slots, DearMoon won't have a single person with an actual science background. And it wouldn't have to be me, either. Kirsten Banks, Emily Calandrelli, Lena Vincent, Bill Nye, Scott Manley, Mark Rober, and Hank Green all have real hard science degrees and extensive experience in the intersection of science education, public outreach, and social media. Any of them would do a better job.

Sending Tim along for DearMoon instead of any of the above is kind of like hiring Colonel Sanders to take you on a culinary tour of the world when Gordon Ramsay, Anthony Bourdain (RIP), and Alton Brown are all ready and standing by.

26 minutes ago, AtomicTech said:

Still disappointed that @illectro (Scott Manley) didn't get a seat on Starship :\

LOL, I mentioned him (above) before I saw this post.

Seems obvious that Tim got the spot because he knows Elon.

[mikegarrison]

16 minutes ago, sevenperforce said:

Seems obvious that Tim got the spot because he knows Elon.

Maybe? But he has 1.3M You Tube subscribers.

Scott Manley has 1.5M You Tube subscribers, so sure, it could have been Scott instead. Maybe  Yusaku Maezawa likes Tim's videos better.

Also, I'm pretty sure the whole point for him was to bring a bunch of people who aren't scientists or engineers. To take "regular people" and artists to the Moon. Tim actually fits that better than Scott, although Scott has been a DJ. Tim, on the other hand, is a photographer, so they both have some artistic background.

Edited December 13, 2022 by mikegarrison

[sevenperforce]

6 minutes ago, mikegarrison said:

Maybe? But he has 1.3M You Tube subscribers.

Scott Manley has 1.5M You Tube subscribers, so sure, it could have been Scott instead. Maybe  Yusaku Maezawa likes Tim's videos better.

And Mark Rober has what, 23 million?

Yusaka speaks and understands English, but not super well; I doubt he spends much time on the English-speaking side of YouTube.

6 minutes ago, mikegarrison said:

Also, I'm pretty sure the whole point for him was to bring a bunch of people who aren't scientists or engineers. To take "regular people" and artists to the Moon.

I'm not sure that "regular people" were ever discussed or contemplated; it was about art and outreach and imagination. I certainly get the appeal of going beyond the usual NASA channels and selecting someone who isn't already practically an astronaut, but I think there's a lot of missed utility there. Someone with a hard science background, particularly in physics or chemistry or engineering even at the bachelor level, has a huge advantage in being able to understand what's actually going on without having to learn it all along the way. And while learning it along the way can help you to be a better communicator, that sometimes is just a poor substitute.

[Gargamel]

Since none of us were part of the vetting process, it’s hard to say who got a post for what reason.    I don’t know if any of the other people mentioned even applied, some probably did.    Of those, some might have been ruled out medically right off the bat.   Others might have made it further  along and then ultimately declined due to family and business concerns, cause ya know, there’s a significant chance of death here.  
 

This probably wasn’t their first choice for a team, but it is probably the best team they could make that fit the requirements for the task.    
 

On a side note, as a moderator, let’s keep the starship specific discussion over in the spacex thread, and the EDA discussion over here.   I know, that’s a hard line to find, given the topics,  but we don’t need cross posting.  

[kerbiloid]

So, now NASA needs an extreme upgrade of communication equipment, to dramatically increase the channel capacity.

Otherwise it will simply get drown in the speech flow.

***

It would be also nice to have a famous KSP mod observer in Houston at that time, to synchronize the speech frequencies.

Edited December 13, 2022 by kerbiloid

[sevenperforce]

1 hour ago, Gargamel said:

I don’t know if any of the other people mentioned even applied, some probably did.

Scott, Kirsten, and I did. I don't know about the others.

[Beamer]

On 12/12/2022 at 5:23 PM, sevenperforce said:

I wish him all the best, even if he annoys me somewhat from time to time. _{(Yes, it's a little sour grapes. I would have preferred to be on that flight. Tim does a lot of research but he lacks some of the fundamental physics and engineering knowledge that you really need to understand what's going on and explain it properly.)}

To be fair, that's kind of his shtick isn't it? Hence the 'everyday' part. He's an armchair rocket scientist (as many of us are too I imagine), but he doesn't pretend to be anything more than that. Also, I've seen the rest of the proposed crew, and he's probably the most knowledgeable person on that trip The rest is DJs, actors, singers and fashion giants.

13 hours ago, mikegarrison said:

Scott Manley has 1.5M You Tube subscribers, so sure, it could have been Scott instead. Maybe  Yusaku Maezawa likes Tim's videos better.

According to one of Scott's recent videos he was too late sending in a required presentation, so that's on him. If you can't even follow the rules/schedule of the selection process then it's not so strange you don't get the ticket.

 

[kerbiloid]

47 minutes ago, Beamer said:

He's an armchair rocket scientist

They anyway won't let him untie the duct tape and escape from chair, so this doesn't matter.

48 minutes ago, Beamer said:

The rest is DJs, actors, singers and fashion giants.

OST team.

[Beamer]

1 hour ago, kerbiloid said:

They anyway won't let him untie the duct tape and escape from chair, so this doesn't matter.

OST team.

Honestly, when I saw that crew list my first thought was "If they have a sense of humour they will call it the Golgafrincham Ark Fleet Ship B."

All in all I think it's not that bad. The purpose of the guy who pays for it was to get artists up there. As soon as you put 1 or 2 knowledgeable scientists in the mix, science will be the topic of talk from start to end. If you want the best artsy impressions, you need to keep the science nerds out of the cabin I think. TBH I'm somewhat surprised Mr Everyday wasn't considered too nerdy for this crew, but I sometimes forget he's both a photographer and musician too.