What are the chances that SLS fails its first launch?

[woods170]

Comparing Starship failure rates to SLS is like comparing two completely different systems. 

Starship may turn out to have the highest failure rate of any launch vehicle of all time.  Chances Starship fails on the next flight are very very high.  In fact, makes you wonder if Starship is just designed to fail - as if to say, if we couldn’t make our stuff work, then the other stuff surely wouldn’t work.  Seen this play out as a marketing trick in the industry during the 90s.

But SLS has tremendous heritage.  It will be highly successful.

Poe's Law strikes again!

Ha.  No serious.

Take a look at the wiki for Starship development.  This isn't sustainable....

https://en.wikipedia.org/wiki/SpaceX_Starship_development

Comparing apples to oranges. All of the destroyed/scrapped vehicles were development vehicles, unlike the current SLS vehicle. And none of them were intended to go orbital, unlike the current SLS vehicle.

You can start comparing SLS to Starship once both have done their first orbital attempt.

[CorvusCorax]

Comparing Starship failure rates to SLS is like comparing two completely different systems. 

Starship may turn out to have the highest failure rate of any launch vehicle of all time.  Chances Starship fails on the next flight are very very high.  In fact, makes you wonder if Starship is just designed to fail - as if to say, if we couldn’t make our stuff work, then the other stuff surely wouldn’t work.  Seen this play out as a marketing trick in the industry during the 90s.

But SLS has tremendous heritage.  It will be highly successful.

Poe's Law strikes again!

Ha.  No serious.

Take a look at the wiki for Starship development.  This isn't sustainable....

https://en.wikipedia.org/wiki/SpaceX_Starship_development

Totally off topic. Also wrong. Starship is a hardware rich development program. As such, yes , there have been a lot of destroyed test articles, but actually so far Starship had more successful flights than SLS at a fraction of the cost. (Which is mind boggling on its own) Still apples to oranges and off topic for this thread.

[kevinof]

Don’t feed the troll boys and girls. This guy belongs on Reddit, not NSF.

Comparing Starship failure rates to SLS is like comparing two completely different systems. 

Starship may turn out to have the highest failure rate of any launch vehicle of all time.  Chances Starship fails on the next flight are very very high.  In fact, makes you wonder if Starship is just designed to fail - as if to say, if we couldn’t make our stuff work, then the other stuff surely wouldn’t work.  Seen this play out as a marketing trick in the industry during the 90s.

But SLS has tremendous heritage.  It will be highly successful.

Poe's Law strikes again!

Ha.  No serious.

Take a look at the wiki for Starship development.  This isn't sustainable....

https://en.wikipedia.org/wiki/SpaceX_Starship_development

Comparing apples to oranges. All of the destroyed/scrapped vehicles were development vehicles, unlike the current SLS vehicle. And none of them were intended to go orbital, unlike the current SLS vehicle.

You can start comparing SLS to Starship once both have done their first orbital attempt.

[dglow]

Comparing Starship failure rates to SLS is like comparing two completely different systems. 

Starship may turn out to have the highest failure rate of any launch vehicle of all time.  Chances Starship fails on the next flight are very very high.  In fact, makes you wonder if Starship is just designed to fail - as if to say, if we couldn’t make our stuff work, then the other stuff surely wouldn’t work.  Seen this play out as a marketing trick in the industry during the 90s.

But SLS has tremendous heritage.  It will be highly successful.

Poe's Law strikes again!

Ha.  No serious.

Take a look at the wiki for Starship development.  This isn't sustainable....

https://en.wikipedia.org/wiki/SpaceX_Starship_development

Comparing apples to oranges. All of the destroyed/scrapped vehicles were development vehicles, unlike the current SLS vehicle. And none of them were intended to go orbital, unlike the current SLS vehicle.

You can start comparing SLS to Starship once both have done their first orbital attempt.

Don’t feed the troll boys and girls. This guy belongs on Reddit, not NSF.

No worries. Just get him to say his name backwards and we'll be safe for a while.

[deltaV]

Recent NASA programs (both human spaceflight and science) seem to be reliable and expensive. I therefore guess that SLS has somewhat better odds of failure in its first flight than typical for new launch vehicles. My estimate is 15% chance of failure to reach the target orbit.

[jstrotha0975]

I'm not an expert but I put the chances of a first successful launch at 50/50 imho.

[Jimmy_C]

Shouldn’t this thread be in the SLS or Artemis section?

[LaunchedIn68]

Probably not as good as Starship failing on that first launch.  With SLS the only thing really new is having 4 already flight proven engines on the bottom of what was the ET.

[space_cat]

The key thing people are missing here regarding shuttle re-use hardware is the loads environment. The structural loads are different on SLS than on shuttle. A different set of loads introduces risk into the existing hardware's capabilities and may be one of the primary reasons why there are planned changes to re-used shuttle hardware for future Artemis missions. Of course the hardware has been analyzed & tested to be best of everyone's abilities but the fact remains that there is life already taken out of some of the hardware due to the shuttle launches and the hardware is seeing a different loads environment all together. The shuttle hardware was not designed or optimized for the current mission.

[bd1223]

I think the most likely failure cause for Artemis I is flight software. It is brand new and as I understand it Boeing was responsible for its definition, creation, and verification. Several years ago the development of SLS core stage flight software was reportedly in disarray and behind schedule. Of course Boeing's failings with CST-100 software is well known.

1) Boeing did not do the flight software for SLS.
2) Flight software for SLS was never the cause of schedule delays, and has never been in serious disarray.  Previous reports to the contrary have been attributed to disgruntled former workers.

[TheRadicalModerate]

I'd think that the chance of an SLS failure is pretty low, but it's certainly lower than the chance of an Orion failure.  This is the first time that a real ESM, with real fairings, real solar array wings, and a real Orion stage adapter, have flown.

As for things that could go wrong on SLS proper, there are new interstages and adapters on both sides of the ICPS.  There's a small but non-trivial chance of a separation oopsie.

[DanClemmensen]

I'd think that the chance of an SLS failure is pretty low, but it's certainly lower than the chance of an Orion failure.  This is the first time that a real ESM, with real fairings, real solar array wings, and a real Orion stage adapter, have flown.

As for things that could go wrong on SLS proper, there are new interstages and adapters on both sides of the ICPS.  There's a small but non-trivial chance of a separation oopsie.

I don't understand why you consider Orion to be more likely to fail. As seen from the outside, The SLS portion of SLS/Orion is a complex system with many complex subsystems, none of which has ever actually flown except for some pieces from the Shuttle that have been in storage for a decade. The SRBs are past their (admittedly arbitrary) pull date, and SLS will have a higher takeoff thrust than anything that has ever flown (unless Starship launches first). I hope Artemis I is successful, but it's not guaranteed.

[jkumpire]

 From a quick look at the internet no betting sites have posted odds on failure, so success must be a sure thing! 

[Toast]

And what chances would this group have given the first shuttle launch?

A high portability of more launch delays and a very low probability of a major failure. Whether you like NASA or not, you have to give them some credit for knowing what they are doing.

The first shuttle launch had multiple anomalies, some of which came very close to causing a full loss of vehicle. If anything, looking at the first shuttle launch should make people more nervous about SLS.

For what it's worth, my estimate is:
~80% chance of anomalies that delay Artemis II
~50% chance of at least partial failure (failure to achieve flight goals)
~10% chance of catastrophic/LoV mission failure

[aperh1988]

flight computer software that has been tested less than it should have (remember Boeing, the software specialists)

SLS FSW is designed, implemented, and tested in-house by NASA. Boeing provides the FC hardware, not the software nor testing/V&V.

I think the most likely failure cause for Artemis I is flight software. It is brand new and as I understand it Boeing was responsible for its definition, creation, and verification.

Again not sure where these misconceptions are coming from. NSF has articles about FSW development that clearly identify that FSW development and testing is in-house.

[TheRadicalModerate]

Again not sure where these misconceptions are coming from. NSF has articles about FSW development that clearly identify that FSW development and testing is in-house.

I trust NASA to have been more thorough than Boeing, but AFAIK the system is still being developed with a waterfall methodology, isn't it?

In addition to waterfall being simply inferior to the iterative development models in use on more modern systems, it's not how software engineers have been trained for the last 10-15 years.  Everybody learns to adapt to the development environment imposed upon them, but development and testing in a waterfall environment is kind of like doing engineering in a foreign language to anybody under the age of 40.  It's a lot easier to have a failure of imagination--the source of almost all systemic testing mistakes--when you're doing that.

This is not an SLS-specific problem.  Requirements, acquisition, and acceptance cycles of software throughout the government--and consequently big chunks of the aerospace industry--are predicated on a waterfall architecture.  Getting off this treadmill is going to be a big deal, requiring major government reforms.

All of that said, a launcher is a pretty dumb piece of equipment compared to a lot of aerospace systems.  I'm a little nervous about the engine controllers, but I doubt that the software for SLS has major risks baked into it.

[Jim]

I think the most likely failure cause for Artemis I is flight software. It is brand new and as I understand it Boeing was responsible for its definition, creation, and verification. Several years ago the development of SLS core stage flight software was reportedly in disarray and behind schedule. Of course Boeing's failings with CST-100 software is well known. I think the odds of LOV is about 10% and LOM is about 20%.

Another post made without knowledge of the facts.

[Khadgars]

I'll enjoy coming back to this thread after Artemis I 

[TheRadicalModerate]

I'd think that the chance of an SLS failure is pretty low, but it's certainly lower than the chance of an Orion failure.  This is the first time that a real ESM, with real fairings, real solar array wings, and a real Orion stage adapter, have flown.

As for things that could go wrong on SLS proper, there are new interstages and adapters on both sides of the ICPS.  There's a small but non-trivial chance of a separation oopsie.

I don't understand why you consider Orion to be more likely to fail. As seen from the outside, The SLS portion of SLS/Orion is a complex system with many complex subsystems, none of which has ever actually flown except for some pieces from the Shuttle that have been in storage for a decade. The SRBs are past their (admittedly arbitrary) pull date, and SLS will have a higher takeoff thrust than anything that has ever flown (unless Starship launches first). I hope Artemis I is successful, but it's not guaranteed.

Other than the RS-25s, which are pretty much known quantities, I'd say that Orion is considerably more complex than SLS.

Orion has navigation and communications systems much more sophisticated than SLS.  It also has thermal and ECLSS systems, which don't exist on SLS at all.

Beyond that, let's look at the number of separation and significant deployment events.  SLS has:

1) Launch
2-3) SRB SEP
4) ICPS staging.

Orion has:

1) LAS jettison (a powered separation)
2-4) ESM fairing jettison
5-6) Solar array wing deployment
7) ICPS separation
8) SAW repositioning.
9) Command module / ESM separation.

One could argue that a successful SLS launch followed by a loss of Orion would constitute a partially successful flight.  However, I suspect that this would result in a lot of hard questions.

[aperh1988]

Again not sure where these misconceptions are coming from. NSF has articles about FSW development that clearly identify that FSW development and testing is in-house.

I trust NASA to have been more thorough than Boeing, but AFAIK the system is still being developed with a waterfall methodology, isn't it?

In addition to waterfall being simply inferior to the iterative development models in use on more modern systems, it's not how software engineers have been trained for the last 10-15 years.  Everybody learns to adapt to the development environment imposed upon them, but development and testing in a waterfall environment is kind of like doing engineering in a foreign language to anybody under the age of 40.  It's a lot easier to have a failure of imagination--the source of almost all systemic testing mistakes--when you're doing that.

This is not an SLS-specific problem.  Requirements, acquisition, and acceptance cycles of software throughout the government--and consequently big chunks of the aerospace industry--are predicated on a waterfall architecture.  Getting off this treadmill is going to be a big deal, requiring major government reforms.

All of that said, a launcher is a pretty dumb piece of equipment compared to a lot of aerospace systems.  I'm a little nervous about the engine controllers, but I doubt that the software for SLS has major risks baked into it.

I guess that’s fair in a general waterfall vs something more agile type of way. But even in classic waterfall development cycles you still have iterations. It’s not like the FSW requirements are the same ones they started with 10 years ago. The cycles are slowerand they don’t go through as many as other more modern dev methodologies, but they still iterate.

As for the new CSECs they’ve been hotfired a lot more often than the core stage has so if anything you should feel less nervous about them.