totm nov 2023 SpaceX Discussion Thread

[KSK]

On 12/22/2021 at 7:44 PM, Beccab said:

Seeing posts about Starship from official NASA accounts always seems so weird

Nice pictures though!

It seems that rockets are like the internet. They're both just a series of tubes, propelled by hot gas and flame, with a non-trivial risk of something exploding.

[RealKerbal3x]

2 hours ago, Jacke said:

NASA didn't commission Starship.

No. But they did award it a major contract. It deserves some recognition given its major role in Artemis.

2 hours ago, Jacke said:

And why shouldn't Starship be rated under the same scheme as Vulcan (and effectively SLS too): two flights without a significant issue before flying a serious payload.  Even that doesn't seem to be enough when a serious payload like the James Webb Telescope is a $10 billion payload.

NASA isn't contracting Starship as a launch vehicle, they're contracting it as a lunar lander. Of course, the contract requires it to act as a launch vehicle, but only because SpaceX bid the entire system - Starship isn't launching the lander, it is the lander. NASA's process for qualifying the vehicle would be the same had they chosen one of the other bidders, despite Starship's architecture being so unconventional.

Even if you ignore the large number of Starship test flights SpaceX intends to conduct on its own dime, the vehicle will be 'rated' in a conventional sense long before it flies for HLS or even other NASA payloads thanks to the qualification milestones for the contract. They'll be flying more than two test flights before any payload gets onboard, never mind NASA.

4 hours ago, Jacke said:

And Starship can't be crew-rated on the pad because there is no abort escape.

This isn't a concern for the HLS contract, because Starship crewed operations will only happen in cislunar space. Crew will not launch or land at Earth with the current arrangement.

If/when Starship ends up flying end-to-end crew missions for NASA, they may require a launch escape system. In that case, SpaceX will have to develop one. NASA may instead choose to trust Starship's launch record and reliability, which it will presumably need to have accrued by the time it's flying crew. The latter is the option SpaceX seems to be going for, but any crewed launch/landing of Starship is several years away at best, so all we can do is wait and see.

[Beccab]

26 minutes ago, mikegarrison said:

Praising SLS is about getting money. There was no money to be gotten for praising Starship, until Starship got selected as the lunar lander. Then there was money to be gotten for praising it, and lo and behold, the praise began.

Absolutely, that's not what I was arguing with my post. As I said, you can certainly argue the reasons behind this, but not that SLS and Starship had the same consideration inside NASA

Hell, it's been almost 9 months and Starship still hasn't replaced the placeholder lander in the Gateway renders, a number of which were released in the last months

Edited December 24, 2021 by Beccab

[tater]

https://www.nasa.gov/artemisprogram

Pic doesn't fit on the page well, but they have a pic on the page. The coloring pages for kids are still all SLS/Orion/Gateway/Spacesuits, but it will get there. As for renderings, it is funny to see notional, generic HLS vehicles in renders made or used after the selection.

[Meecrob]

7 hours ago, Jacke said:

 And Starship can't be crew-rated on the pad because there is no abort escape.

Neither did STS...or Gemini. Craft with pad abort systems were Mercury and Apollo programs. This is just like the debate with regards to Navy fighter jets. Some say they require two engines for redundancy...totally forgetting WWII was fought almost entirely by the Navy with single engine fighters. Not to mention roughly half of the aircraft that have operated from carrier decks since WWII.

Edit: Think about it...go through the entirety of humanity's adventure with spaceflight. Tell me how many people have had their lives spared by a pad abort system?

Edited December 24, 2021 by Meecrob

[GearsNSuch]

35 minutes ago, Meecrob said:

Edit: Think about it...go through the entirety of humanity's adventure with spaceflight. Tell me how many people have had their lives spared by a pad abort system?

https://en.m.wikipedia.org/wiki/Soyuz_7K-ST_No.16L

Two, in this case. 

Edited December 24, 2021 by GearsNSuch

[Meecrob]

40 minutes ago, GearsNSuch said:

https://en.m.wikipedia.org/wiki/Soyuz_7K-ST_No.16L

Two, in this case. 

Exactly. Rockets blowing up on the pad is not the usual method of failure. It boggles my mind that people insist on a Launch Abort System, but no Re-entry Abort System. One is somehow "mandatory" and the other is an extraneous idea that is a waste of weight and engineer's time and resources. Which do you think Columbia would rather have had?

Edit: (from the linked wiki page) "...the launch vehicle was destroyed on the launch pad by fire on 26 September 1983 [...] It is the first case in which a launch escape system has been fired with a crew on board."

I dunno. Gagarin flew in '61. And the rocket equation is notoriously unforgiving about extraneous mass. Am I the only one who sees a disconnect here? Challenger arguably had a launch abort system, but no parachute since the crew were proved to be alive up to point of impact with the water.

I'm not saying LAS's are stupid, just that they have an outsized emphasis based upon their importance.

Edited December 24, 2021 by Meecrob

[tater]

2 hours ago, Meecrob said:

Neither did STS...or Gemini. Craft with pad abort systems were Mercury and Apollo programs. This is just like the debate with regards to Navy fighter jets. Some say they require two engines for redundancy...totally forgetting WWII was fought almost entirely by the Navy with single engine fighters. Not to mention roughly half of the aircraft that have operated from carrier decks since WWII.

WW2 USN aircraft happens to be a particular interest of mine. While the USN aircraft of ww2 were indeed single engine, they were explicitly radial engines for survivability (air cooled). Radials could (and did) fly home with entire cylinders blown off by enemy fire. A single bullet in the cooling system of a liquid cooled engine (say a Merlin), and the pilot is going for a swim inside of 10 minutes. So they got to redundancy a different way.

 

Regarding LES and SS... yeah, that's a tough one for me. I understand their rationale WRT making it reliable, then flying it, but... it's gonna take a lot of launches and landings, and some with edge cases (engine outs, etc) to demonstrate safety for humans even at NASA levels (1:270 LOC).

[CatastrophicFailure]

2 hours ago, Meecrob said:

Edit: Think about it...go through the entirety of humanity's adventure with spaceflight. Tell me how many people have had their lives spared by a pad abort system?

Three more on Soyuz MS-10, which used a backup abort system, and a hair’s breadth of three more on Apollo 12 if not for the steely-eyed missile man. And any kind of abort system at all might have saved the challenger crew. 
 

21 minutes ago, tater said:

Regarding LES and SS... yeah, that's a tough one for me. I understand their rationale WRT making it reliable, then flying it, but... it's gonna take a lot of launches and landings, and some with edge cases (engine outs, etc) to demonstrate safety for humans even at NASA levels (1:270 LOC).

The trouble with the Shuttle (aside from the whole design being inherently dangerous from the get go) is that it could never fly enough to gain and demonstrate the required reliability to be reliable enough. Starship not only has a real possibility of doing so, but it needs to. It won’t work otherwise, since it needs to have that crazy-high launch cadence to get anywhere BLEO.  A dozen flights a year won’t cut it, it needs dozens or even hundreds, and has a far better chance of actually doing so. 

[JoeSchmuckatelli]

Wen Fly?

[Meecrob]

11 hours ago, tater said:

WW2 USN aircraft happens to be a particular interest of mine.

Uh oh, I feel a thread split coming haha! I see your point on redundancy. Rather than argue you on your area of interest, I'll instead refer to the jet age, as you are totally correct on radial engines.

The fact of the matter is that if you have an equal chance of engine failure on a twin vs. single multiplied by the number of engines, all things being equal. Of course, on a twin you can shut the malfunctioning engine own, but on a single you would just not shut it down and ride the reduced power home. Someone can argue me, but please go look up the ratio of single vs twin crashes due to engine failure...I believe it

is similar to a coin toss.

To bring it back to topic, I do not believe that a launch abort system is really that necessary. Seems as fanciful as the zip lines on the pad towers. Like if the rocket blows up, the astronauts are really gonna have enough time to allow gravity to accelerate them out of the blast radius?

 

 

10 hours ago, CatastrophicFailure said:

Three more on Soyuz MS-10, which used a backup abort system, and a hair’s breadth of three more on Apollo 12 if not for the steely-eyed missile man. And any kind of abort system at all might have saved the challenger crew.

I must have not made my point clear. I am not asking for examples of times a launch abort system was useful. I am trying to contrast the amount of deaths in the space industry that have occurred that an LAS could have prevented vs. the amount of deaths that have occurred that an LAS would have had no use.

I also already mentioned challenger. All they needed were parachutes. the crew vehicle separated from the rest of the stack and the crew survived until they impacted the water. No LAS required!

Edited December 25, 2021 by Meecrob

[tater]

Assuming you could drag yourself out of a tumbling crew cabin

[Meecrob]

51 minutes ago, tater said:

Assuming you could drag yourself out of a tumbling crew cabin

Totally fair enough...I'll take my lumps, but my point was more that x amount of people have died on launch whereas x+y people have died in phases after launch. But we only have a launch escape system...no other escape systems.

[Jacke]

10 minutes ago, Meecrob said:

Totally fair enough...I'll take my lumps, but my point was more that x amount of people have died on launch whereas x+y people have died in phases after launch. But we only have a launch escape system...no other escape systems.

That's not true at all.  There are multiple abort modes during a given space mission.  The Launch Escape System covers the initial ones.  Later, usually the space craft main engine is used to pull the spacecraft away from a failing launch vehicle.  There are abort modes throughout a mission, as the propellants are used and portions of the spacecraft discarded.  It's the job of RETRO on the traditional flight team.  Originally just covering the timing of the RETRO burn and where that would put the spacecraft on the ground, it's grown to cover all contingencies when a mission has to abort and save the crew.

[Meecrob]

We are arguing the same point, I think. My point is Launch Abort System is important, yes, but its as important as all other abort plans, yet it seems to have gained a grater emphasis lately. STS had zero launch abort, but we flew it anyways, so the argument that Starship has no LAS is incorrect. Period. NASA has proven they will fly without one for 30 years!

Edited December 24, 2021 by Meecrob

[tater]

3 minutes ago, Meecrob said:

We are arguing the same point, I think. My point is Launch Abort System is important, yes, but its as important as all other abort plans, yet it seems to have gained a grater emphasis lately. STS had zero launch abort, but we flew it anyways, so the argument that Starship has no LAS is incorrect. Period. NASA has proven they will fly without one for 30 years!

NASA pretended they had Shuttle abort modes, like RTLS (which was actually return to the ocean off the east coast and bail out). The possible use of it so constrained as to be not a thing. SS with crew also needs the same safety coming down, though.

[Meecrob]

Again, thanks for correcting me, It makes total sense to use starship as an unmanned cargo/fuel vehicle until it proves a human-rated failure rate.

Edited December 25, 2021 by Meecrob

[Meecrob]

7 hours ago, Jacke said:

That's not true at all.  There are multiple abort modes during a given space mission.  The Launch Escape System covers the initial ones.  Later, usually the space craft main engine is used to pull the spacecraft away from a failing launch vehicle.  There are abort modes throughout a mission, as the propellants are used and portions of the spacecraft discarded.  It's the job of RETRO on the traditional flight team.  Originally just covering the timing of the RETRO burn and where that would put the spacecraft on the ground, it's grown to cover all contingencies when a mission has to abort and save the crew.

And all those modes you speak of do not utilize a launch abort system....which I am talking about.
The point was made that someone thought that Starship could not be human rated due to lack of a launch abort system.  Like obviously starship can do an abort to launch site, Europe, or once around, just like space shuttle.

Edited December 25, 2021 by Meecrob

[CatastrophicFailure]

8 hours ago, Meecrob said:

We are arguing the same point, I think. My point is Launch Abort System is important, yes, but its as important as all other abort plans, yet it seems to have gained a grater emphasis lately. STS had zero launch abort, but we flew it anyways, so the argument that Starship has no LAS is incorrect. Period. NASA has proven they will fly without one for 30 years!

An LAS is, in general, a reasonable thing to include on a rocket. In any kind of capsule—Dragon, Mercury, Soyuz—including one is certainly non-trivial but it’s also not exceedingly difficult, as long as your lifter can manage the mass. Likewise, simply wearing pressure suits, like after Challenger and that Soyuz, is a very reasonable design change. Creating some kind of EDL abort system for a capsule, well… for all intents and purposes, is impossible, the capsule is your abort system.  They actually did study shoving a capsule with abort motors into the shuttle’s payload bay, which would have given it the odd distinction of having a lifeboat during every single phase of flight, including reentry, but since that would have killed pretty much any payload capacity it never went anywhere. 

Anywho, it’s all about managing the risk again, and reducing it to an “acceptable” level. Starship can accomplish this either by demonstrating sufficient reliability with real flights (which the shuttle never could) before launching people, or by including it’s own independent abort system a la that shuttle “capsule in the cargo bay.” Realistically, we might see some kind of hybrid system, since Starship itself is also capable of aborting from a failing Superheavy. I could have sworn that even before upping to nine engines Musk said that Starship would have a TWR greater than 1 on the pad, and could fire its own engines to abort within a fraction of a second. This was one reason the RVac was designed to be able to fire at sea level, too. It certainly can now with those nine. So, question becomes, how many successful launches (and landings) does the system need for that to be reliable enough?

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. 

[Jacke]

2 hours ago, Meecrob said:

And all those modes you speak of do not utilize a launch abort system....which I am talking about.
The point was made that someone thought that Starship could not be human rated due to lack of a launch abort system.  Like obviously starship can do an abort to launch site, Europe, or once around, just like space shuttle.

The nature of many on-pad and early in-flight aborts are explosive.  Without a launch escape system that can quickly pull the crew away from the explosion, the crew will almost certainly die.  Without such a launch escape system, the launch vehicle cannot be crew-rated as those early aborts will be fatal.

The Gemini ejection system, used because the explosion of storeable propellants is much less fast and furious (due to the propellants immediately burning on contact), is now suspected it wouldn't save the crew.  The ejection system of Vostok was likely good.  Voskhod had no launch escape system.  STS flew for years with no launch escape system (the ejection seats on the early flights are now suspect as Gemini's), but as we've seen, that was whistling past the graveyard.  It wasn't the only fault with STS, but it was one that killed at least 1 crew.  If Soyuz didn't have a launch escape system, 1 (maybe 2) crews would have died there.

We're supposed to learn from previous mistakes, not repeat them, either exactly or effectively.

By its nature, Starship will find it hard to add in a launch escape system after the fact.  That means it will never be crew rated.  Because rocketry is still cutting edge technology.  And even with a record like Ariane 5, with 80 consecutive successful launches, when another Ariane 5 launches, likely in a few hours, carrying the James Webb Telescope, it can still fail.

Edited December 25, 2021 by Jacke

[RCgothic]

9 minutes ago, Jacke said:

Without such a launch escape system, the launch vehicle cannot be crew-rated as those early aborts will be fatal.

It wouldn't even be the first to be so.

[Meecrob]

50 minutes ago, Jacke said:

The nature of many on-pad and early in-flight aborts are explosive.  Without a launch escape system that can quickly pull the crew away from the explosion, the crew will almost certainly die.  Without such a launch escape system, the launch vehicle cannot be crew-rated as those early aborts will be fatal.

I'm not trying to be a jerk, but back that up with data. All you did was say what you feel is dangerous about spaceflight. I cannot recall any fatalities on the pad from an actual flight.
Give me one example of a fatality that would have been avoided had there been a launch abort system integrated.
Also, including the ones mentioned upthread, add up all the lives that have been saved from LAS's vs how many lives have been lost in phases of flight where a LAS would not work.

Edited December 25, 2021 by Meecrob

[Beccab]

32 minutes ago, RCgothic said:

It wouldn't even be the first to be so.

You could say it wasn't even the second if you count Buran. Or Gemini

Edited December 25, 2021 by Beccab

[Meecrob]

2 minutes ago, Beccab said:

You could say it wasn't even the second if you count Buran. Or Gemini

Precisely!

[Jacke]

11 hours ago, Meecrob said:

I'm not trying to be a jerk, but back that up with data.

[snip]

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?

Edited December 25, 2021 by Vanamonde