totm nov 2023 SpaceX Discussion Thread

[Meecrob]

11 hours ago, Jacke said:

Look up any launch pad or early flight detonation of rockets.  Explain how the crew will survive that completely.  Then there's the data from the airpacks on the Challenger; some of the crew seemed to have survived the initial failure of the launch vehicle, but that didn't matter as they died when the crew cabin impacted the sea.

EDIT: Here's two examples of the crew being saved by the launch abort system, Soyuz T-10-1 and Soyuz MS-10:
https://en.wikipedia.org/wiki/Soyuz_abort_modes#Soyuz_abort_history
https://en.wikipedia.org/wiki/Soyuz_7K-ST_No.16L
https://en.wikipedia.org/wiki/Soyuz_MS-10

You say a launch escape system isn't needed.  Roscosmos has one on Soyuz.  NASA insisted on one for Dragon 2, for Starliner, and for Orion.  Roscosmos and NASA have a whole lot of experience and actual engineers and scientists who are used to calculating risk.  And learning the proper lessons from history.

Just because Gemini, Voskhod, and STS (Buran never had a crewed flight) had substandard or no launch escape system doesn't justify making the same mistakes now.  We're supposed to learn from the faults of the past, not repeat them.

People talk about aircraft not having a launch escape system.  They don't need it.  The structure of the aircraft is designed to survive the failures that happen.  Short of massive catastrophe, the wings and control surfaces and systems will survive and the aircraft will operate in a degraded capacity, at worst as a glider.

And aircraft don't push the technology as close to the bleeding edge as rockets do, not even military aircraft.  That's why no launch vehicle family with any significant launch count has a perfect record.  Because on the pad, a launch vehicle is mostly propellant and when things go wrong enough, that explodes.

You want to fly 1000 crews to space.  Without a launch escape system, some of them will die.  Are you satisfied with that?

I get what you are trying to say, but just because something feels "right" does not mean it is correct.

It is logical to think that launch is a dangerous phase of flight. After all, we have the maximum amount of fuel and oxidizer, maximum weight and the minimum of performance. But that does not mean that historically people have had a lower survival rate during launch than other phases of spaceflight. I am asking you to look back in history. I ask this with the best of intentions. I'm not trying to antagonize you. Please show me an example where a rocket blew up on the pad and the launch escape system saved the crew's life? Upthread it has been mentioned that 5 lives have been saved. Compare that to the amount of lives that have been lost in spaceflight to reasons that could not have been solved with an LAS, such as Columbia, etc.

Edit: Also I do not understand what is so difficult about the concept that Challenger saved its crew. They were alive until they hit the water. The stack literally exploded! The crew was within what? 150 feet of the explosion and they survived! If they had a method to decelerate, they possibly would still be with us.

Edited December 25, 2021 by Vanamonde

[Jacke]

11 minutes ago, Meecrob said:

It is logical to think that launch is a dangerous phase of flight. After all, we have the maximum amount of fuel and oxidizer, maximum weight and the minimum of performance. But that does not mean that historically people have had a lower survival rate during launch than other phases of spaceflight. I am asking you to look back in history. I ask this with the best of intentions. I'm not trying to antagonize you. Please show me an example where a rocket blew up on the pad and the launch escape system saved the crew's life? Upthread it has been mentioned that 5 lives have been saved. Compare that to the amount of lives that have been lost in spaceflight to reasons that could not have been solved with an LAS, such as Columbia, etc.

The military trains for many phases of war.  In the defence, in the offense, etc.  There are many activities that all have to be done at the appropriate times.  A sufficient failing in one of them means near total failure of that operation.

Launch is a dangerous time of a spacecraft's flight, as takeoff is the most dangerous time of an aircraft's flight: maximum mass, including the most propellant.  It needs appropriate design.  That includes--for crewed spacecraft--a launch escape system.  Just because in the record more people have died in other regimes of space flight doesn't reduce the risk during launch.

Do you think the Gemini and early STS crew like the fact that if they actually had to use their ejection seats, they likely wouldn't have survived?  Do you want to put crews on a launch vehicle without a launch escape system?  When the current best standard for any launch vehicle family is around a 1% LV failure rate.

That's like having a car without an emergency brake.  Doesn't get used a lot, but when needed, it's there and it works.

I just don't understand you wanting to denigrate the need for proper launch abort modes and the equipment, like LES, needed to carry them out.  It just seems I can't crack this state of mind.  Why?  Because acknowledging the need of an LES for crewed flight means Starship will almost certainly not be crew rated?  I can see no other reason to mindlessly denigrate this significant risk and the ways to ameliorate it.

[Meecrob]

Look man, I've read every word of your replies to me, you can do me the same courtesy, rather than literally paraphrase what I said in your reply to me.  Full disclosure: I am a pilot. We don't have any sort of escape systems because they are heavy, and 999,999 times out of a million, you are better off flying the plane to the site of the crash in the event of a failure, as opposed to jumping out. Its pretty simple - pilots are trained to be pilots, not skydivers.

As far as military aviation goes, I feel I'm pretty safe to say that ejection seats qualify as not only "launch", but "all phases of flight" abort system. And this is entirely my point. What is the point of having a system that protects you from something that is statistically not of concern? At least military aircraft are toting around all that weight for a useful purpose. Rockets take a performance hit for their entire flight for something that only has a purpose for like 90 seconds. Bottom line is it is reduced TWR off the pad.

Upthread, I explicitly stated that I do not think launch abort systems are stupid or useless, I merely am trying to say that I think they have been given an outsized importance.

To be honest, I really don't care if Starship ever launches with humans aboard because whatever happens, they can rendezvious crew in orbit. That also allows for crew to not be aboard for the bellyflop at landing, because I'm sure even the most sycophantic SpaceX fan will admit that is a cool maneuver, but its not the smartest to have humans at risk during it.

You say you do not understand my point of view. I feel you, brother! I cannot understand why you think that rockets blowing up on the pad is something that happens with frequency. I know you do not believe me, so I say look up the statistics. You are correct in that there is the greatest potential for "destruction" at launch, but that does not give any indication of the likelyhood of failure.

Edited December 25, 2021 by Meecrob

[Jacke]

4 minutes ago, Meecrob said:

Look man, I've read every word of your replies to me, you can do me the same courtesy, rather than literally paraphrase what I said in your reply to me. Full disclosure: I am a pilot.

Spaceflight is similar to but is not exactly similar to airflight.

Of all takeoffs, what percentage include a mishap that leads to the total loss (even after a crash landing that has some survivors) of the aircraft?  For spacecraft, that number doesn't go much below 1% because of the factor of launch vehicle failure.

 

4 minutes ago, Meecrob said:

We don't have any sort of escape systems because they are heavy, and 999,999 times out of a million, you are better off flying the plane to the site of the crash in the event of a failure, as opposed to jumping out. Its pretty simple - pilots are trained to be pilots, not skydivers.

That's the factor that aircraft are now designed that they very rarely have the main structure and flight control surfaces and system all fail.  The aircraft itself is the abort system.  Even in mishaps, things mostly degrade gracefully and the highly trained aircrew can respond to the initial incident and minimize further failure as they work the problems to maximize survival.  That's dealing with 1 in 100,000 or rarer events.

 

4 minutes ago, Meecrob said:

As far as military aviation goes, I feel I'm pretty safe to say that ejection seats qualify as not only "launch", but "all phases of flight" abort system.

With the most modern ejection seats, the most common limitation now is overspeed, which in most serious failures can be waited out before punching out.

 

4 minutes ago, Meecrob said:

And this is entirely my point. What is the point of having a system that protects you from something that is statistically not of concern? At least military aircraft are toting around all that weight for a useful purpose. Rockets take a performance hit for their entire flight for something that only has a purpose for like 90 seconds. Bottom line is it is reduced TWR off the pad.

Would you fly an aircraft that had a 1% chance to kill you before you left the confines of the aerodrome?

With most rocket designs, the LES is jettisoned early in flight, so equivalent in mass exchange with the first or second stage, AKA mass cheap.  Or just carried along anyhoo as its impact on overall performance is low, as with Dragon 2.

Starship to me is a design that carries a lot of stuff because it's both a launch stage and a landing stage.  It should not be used beyond LEO because it is hauling a lot of mission dead weight, much more than any LES.  And I'd leave it uncrewed as its hard to retrofit abort systems to an established design.  If someone dreams up a way to make a Starship version with LES and more abort modes, then that can be considered.  But again, only for LEO, because it's hauling a lot of mission dead weight.

[Meecrob]

9 minutes ago, Jacke said:

 

 

I think we are derailing the thread. 

So I'm guessing not, but anyone have any word on B4 static fire?

Edited December 25, 2021 by Meecrob

[RCgothic]

The sort of launch abort system being talked about won't work on The Moon or Mars. There isn't enough atmosphere for the parachutes. Starship has to just work.

Similarly, the landing burn is *far* scarier than the launch. There's no reasonable system that can mitigate that. Starship has to just work.

Starship has to just work.

Traditionally that's been difficult, but SpaceX is the only company who routinely gets their rocket stage and engines back for inspection post flight, so they know what sort of failures to look out for and how to mitigate them.

Also, this whole discussion is very counting bridges before we come to them. Starship doesn't need to have crew on it for launch and landing. It doesn't need to launch or land with crew on earth at all until the safety has been demonstrated, likely through a combination of rapid launch cadence and analysis.

NASA fully expects to crew-rate the system for launch from the moon, which has no survivable abort.

There are plenty of moments in aviation where a failure probably wouldn't be survivable. Not every moment is practical to cover with an abort mode, and the mitigations aren't usually escape systems, but safety factors and redundancies.

Let's all just relax about crew-rating for launch and landing from Earth for now. There's a lot of other hurdles to clear first 

Edited December 25, 2021 by RCgothic

[Beccab]

4 minutes ago, Jacke said:

It should not be used beyond LEO because it is hauling a lot of mission dead weight, much more than any LES

That's a false comparison. You're saying that it is less efficient than a multistage, single use and precisely designed system for that specific purpose, which is correct, but ultimately irrelevant: if it is capable of doing so, why should it not? It's made to be fully reusable and inexpensive, and if it ends up actually being so, then why not. You can have efficiency, or you can save a few billion dollars and years of development. Red Dragon would have been less efficient than a purpose designed lander for example, but also projected to cost an order of magnitude less; Shuttle remained in LEO not because it would be inefficient to sent it beyond it, but because it didn't have the deltaV to do so (hell, NASA even made studies to verify to what degree it couldn't go to Lunar Orbit just in case). And the reasoning for no LES goes well beyond the mass cost, as it can require heavy structural changes and can fail itself independently from the rest of the spacecraft. You said that everyone learned that LES are necessary going forward, but that's incorrect. Buran is the most recent Soviet or Russian spacecraft which came one step from carrying crew, the others being just technological upgrades of the much older Soyuz (and it only didn't carry it because of the disappearance of the nation building it, nothing to do with the LES); even some proposed Russian ones (MAKS for example iirc) didn't carry a proper LES either. Once you go past a certain size a LES just isn't practical (there were some conceptual designs for Shuttle II, but the fact that it required splitting the heat shield in half mid flight, firing some huge SRB and somehow flying back to the landing zone makes them as unlikely as Shuttle RTLS), and the arguments debating at which point it can be removed both have merits. It's not "I want the crew to live" vs "I fanboy Starship"

[Meecrob]

10 hours ago, CatastrophicFailure said:

Also, a note on those zip lines: remember, the shuttle and Apollo were boarded after being fully fueled, so you’d have an entire ground crew up there, too. Those zip lines to APCs or Apollo’s bunker are exactly what you’d need for evacuating that ground crew, even if the flight crew were already buttoned up inside, if a fire broke out on the pad, very much like that Soyuz incident. If memory serves, the fire was going on for several minutes between the “oh, crap!” moment and the Big Boom. 

I forgot to mention: thanks for that interesting tidbit!

[CatastrophicFailure]

4 hours ago, Beccab said:

It's not "I want the crew to live" vs "I fanboy Starship"

This. 

NASA’s “acceptable” risk for crew is something like chance of LOCV of less than 1 in 250. Starship can achieve this by simply flying 250 times in regular operation (not counting special experimental versions along the way), heck, the requirement could even be 250 safe flights in a row and Starship could realistically do this in a reasonable time frame. The shuttle could have demonstrated reliability like this too, at least in theory, but it never had a realistic chance of the needed flight cadence (requirement for people on board notwithstanding). Starship could theoretically make enough flights in a single year. And still come in cheaper than developing an independent LAS the old way. 
 

@Jacke You asked if I’d get on a rocket with a 1% chance of failure? HECK. YES. For the chance of getting that experience that so few have that is an extremely low risk. And there’s plenty of others who would accept that risk, too, even if you are not among them. The more Starship flies, the lower that risk becomes. When SpaceX is truly serious about putting a hundred or a thousand people at a time on board, as in rocket’s on the pad ready to go, that risk will have been retired down to a much, much smaller number. It’s not black/white either/or, even the most ardent SpaceX fanbois acknowledge it’s gonna be some time before anyone rides this thing uphill. That does not, however, mean never. 
 

[Vanamonde]

Some comments have been removed. Back off of the tempers, please. Also, if you want to get in-depth with abort systems, please make a thread for it. 

[magnemoe]

8 hours ago, Meecrob said:

Look man, I've read every word of your replies to me, you can do me the same courtesy, rather than literally paraphrase what I said in your reply to me.  Full disclosure: I am a pilot. We don't have any sort of escape systems because they are heavy, and 999,999 times out of a million, you are better off flying the plane to the site of the crash in the event of a failure, as opposed to jumping out. Its pretty simple - pilots are trained to be pilots, not skydivers.

As far as military aviation goes, I feel I'm pretty safe to say that ejection seats qualify as not only "launch", but "all phases of flight" abort system. And this is entirely my point. What is the point of having a system that protects you from something that is statistically not of concern? At least military aircraft are toting around all that weight for a useful purpose. Rockets take a performance hit for their entire flight for something that only has a purpose for like 90 seconds. Bottom line is it is reduced TWR off the pad.

Upthread, I explicitly stated that I do not think launch abort systems are stupid or useless, I merely am trying to say that I think they have been given an outsized importance.

To be honest, I really don't care if Starship ever launches with humans aboard because whatever happens, they can rendezvious crew in orbit. That also allows for crew to not be aboard for the bellyflop at landing, because I'm sure even the most sycophantic SpaceX fan will admit that is a cool maneuver, but its not the smartest to have humans at risk during it.

You say you do not understand my point of view. I feel you, brother! I cannot understand why you think that rockets blowing up on the pad is something that happens with frequency. I know you do not believe me, so I say look up the statistics. You are correct in that there is the greatest potential for "destruction" at launch, but that does not give any indication of the likelyhood of failure.

Ejection seats are used on combat planes not transports as the combat planes live much more dangerous also out of combat as they are pushed much harder.
You also need to design the cockpit for this, but yes they are very good, you don't want to eject going supersonic as in this is very dangerous but you can usually just ride the plane until subsonic. 

Now for SS, I say landing is an fail source. The belly flop and powered landing is an dangerous operation there lots can go wrong. But I don't think its much more dangerous than an carrier landing. Still if I was SpaceX I would plan for an escape module if they wanted to fly manned missions early. If they are happy doing starlink and mars demonstration flights for some years they might not need it. 
 

[RCgothic]

I didn't know until today that the James Webb has a design life of 5 years, maybe up to a little over 10 depending on the accuracy of the L2 injection burn that just took place and the size of any required mid-course corrections. Unlike Hubble it needs to use fuel to maintain its position in L2 and this is a hard limit on life.

The follow up to JWST, LUVOIR/HabEX is not due until the 2040s. This leaves the prospect that we could be left with a gap in major flagship space observatories.

This article from earlier this year suggests that Hubble may well last until 2026 or later. https://www.technologyreview.com/2021/03/09/1020563/how-long-hubble-space-telescope-safe-mode-nasa/

Therefore, is there any prospect at all for another Hubble servicing mission, HST-SM5, to extend the life of the aging observatory? It appears the observatory has enough life left in it in order to prepare a servicing mission.

And it's conceivable that this is a mission a crewed Starship with a robotic arm might be ideally suited to accomplish at a reasonable price. The payload wouldn't be big, so high LEO should be reachable in a single launch.

How long might Hubble's life be further extended? Surely it would be worth it?

[tater]

JWST likely too fragile to get anything close (RCS, etc). Not designed for service, since that was not thought possible.

Hubble might be possible with Dragon, but it would need a servicing module in trunk that it could release, then dock to. Module would need an airlock and arm, not sure it would fit. I suppose it could be done with 2 launches (Hubble is in KSC inclination which helps).

Normal Crew Dragon launch to Hubble orbit, and a normal F9 launch with a servicing module. That allows a much larger orbital module. Dragon only needs to do phasing burns and burns to head home, not much dv.

[RCgothic]

1 hour ago, tater said:

JWST likely too fragile to get anything close (RCS, etc). Not designed for service, since that was not thought possible.

Hubble might be possible with Dragon, but it would need a servicing module in trunk that it could release, then dock to. Module would need an airlock and arm, not sure it would fit. I suppose it could be done with 2 launches (Hubble is in KSC inclination which helps).

Normal Crew Dragon launch to Hubble orbit, and a normal F9 launch with a servicing module. That allows a much larger orbital module. Dragon only needs to do phasing burns and burns to head home, not much dv.

I suspect it would take a starship launch. Or at least, Dragon to rendezvous with a Starship.

Starship has the capacity and space for airlocks, robotic arms and payload bay simultaneously, as well as plenty of margin to reach Hubble altitude and potentially re-boost it.

[magnemoe]

56 minutes ago, tater said:

JWST likely too fragile to get anything close (RCS, etc). Not designed for service, since that was not thought possible.

Hubble might be possible with Dragon, but it would need a servicing module in trunk that it could release, then dock to. Module would need an airlock and arm, not sure it would fit. I suppose it could be done with 2 launches (Hubble is in KSC inclination which helps).

Normal Crew Dragon launch to Hubble orbit, and a normal F9 launch with a servicing module. That allows a much larger orbital module. Dragon only needs to do phasing burns and burns to head home, not much dv.

Easiest way to do an life extension on jwst is probably to clamp an control satellite on to it, using the payload adapter or at worst the engine. This would then take over doing the station keeping burns and perhaps take some pressure of the reaction wheels. A couple of missions like this is planned for some geo communication satellites. 

and yes an dual launch with an orbital module and a dragon might work, nice that SpaceX has two falcon 9 pads. 

but as launch  Seriously they will be 1-2 orbits between. 

[Cloakedwand72]

When will the FAA release the environmental assessment review before the launch attempt in a month or two? Or is SN20/BN4 launch permanently scrubbed for the next version? 

[Gargamel]

Overlapping threads have been merged

[JoeSchmuckatelli]

1 hour ago, Cloakedwand72 said:

When will the FAA release the environmental assessment review before the launch attempt in a month or two? Or is SN20/BN4 launch permanently scrubbed for the next version? 

SOON^TM

[magnemoe]

2 hours ago, Cloakedwand72 said:

When will the FAA release the environmental assessment review before the launch attempt in a month or two? Or is SN20/BN4 launch permanently scrubbed for the next version? 

They need to finish the static fire testing and get the chopsticks ready to put SS on top of SH, now they need to test the top quick disconnect and probably do some load testing with ship on top of SH, might even do an static fire with the full stack to get the vibrations SS face. 
Now its an good chance SpaceX has some ready date and is working towards that. 

Last was that SN20/ BN4 is launching according to an Musk tweet. They are moving to raptor 2 and as first superheavy will splash down it makes sense to use SN4 for this. 
I say if they has an second raptor 1 booster I would splash that to for more data point before trying to catch the raptor 2 kitted one.

[Beccab]

"Mission Architecture Using the SpaceX Starship Vehicle to Enable a Sustained Human Presence on Mars", paper authored by Jennifer L. Heldmann, Division of Space Sciences and Astrobiology, Planetary Systems Branch, NASA Ames Research Center

https://www.liebertpub.com/doi/full/10.1089/space.2020.0058

For info on RESOURCE itself which partially funded the paper: https://www.nasa.gov/resource-home

Edited December 27, 2021 by Beccab

[tater]

 

 

[tater]

Cool can crusher animation.

 

[Beccab]

The GSE has yet to receive methane and the crane moved near B4 yesterday, so this notice is possibly for an S20 static fire

[Beccab]

Meanwhile, the pad around S20 is clear and the overpressure notice still not cancelled, so at least that seems to be going forward for now. B4 static fire NET January

Edited December 28, 2021 by Beccab

[JoeSchmuckatelli]

February 28... 

;/