totm nov 2023 SpaceX Discussion Thread

[mikegarrison]

How much methane was released to the atmosphere from this aborted test, I wonder? Granted, one test is not a huge deal in the big picture of things, but methane is an extremely potent greenhouse gas. I am somewhat concerned about how many of the new rockets are using it (and likely releasing some of it unburned).

[cubinator]

Clock's ticking again! Only another 6:55 to go! 

Sorry, that's 6 hours 55 minutes.

[tater]

Stream says second attempt possible today!

The clock reset is likely generic, they'll set it to a proper countdown at some point, the window is not 7 hours today.

[tater]

Tomorrow. Boo.

 

[cubinator]

3 minutes ago, tater said:

Tomorrow. Boo.

Technically 1AM is still tomorrow so...

[mikegarrison]

17 minutes ago, cubinator said:

Technically 1AM is still tomorrow so...

Where I live, that's still today.

[CatastrophicFailure]

So, they are using spark igniters (I’m assuming that’s what that meant).  Thought I’d heard somewhere these early production Raptors still used TEA/TEB. 

Edited August 27, 2019 by CatastrophicFailure

[mikegarrison]

Ah. My guess is that they pressed the "ignite" button and nothing happened.

(Not to say I think there is literally an "ignite button". I'm sure the computers do this. But ... it would be hilarious if the launch command were given by hitting the spacebar.)

[tater]

50 minutes ago, CatastrophicFailure said:

So, they are using spark igniters (I’m assuming that’s what that meant).  Thought I’d heard somewhere these early production Raptors still used TEA/TEB. 

Nope. All have been spark ignition.

[StrandedonEarth]

*Sigh* Just like trying to launch a model rocket, and the ignitor pulled out a bit and just goes *phffft*. Or worse, the battery was too weak (as happened last time I tried to launch a rocket with my son)

Are they checking Starhopper's batteries along with the ignitors? Maybe they should try one of these...

[CatastrophicFailure]

1 hour ago, mikegarrison said:

Ah. My guess is that they pressed the "ignite" button and nothing happened.

(Not to say I think there is literally an "ignite button". I'm sure the computers do this. But ... it would be hilarious if the launch command were given by hitting the spacebar.)

Well, the Russians still use an actual physical launch key, so I suppose it’s not outside the realm of possibility. Some keystroke must be the last interaction that starts the launch sequence...

[kerbiloid]

0.8 s is a whole lot of time in Texas.

Spoiler

[sevenperforce]

14 hours ago, tater said:

Nope. All have been spark ignition.

The first firing of a dev raptor used TEA-TEB but all the fullscale raptors were spark torch igniters.

[tater]

 

[tater]

 

[KSK]

16 hours ago, mikegarrison said:

How much methane was released to the atmosphere from this aborted test, I wonder? Granted, one test is not a huge deal in the big picture of things, but methane is an extremely potent greenhouse gas. I am somewhat concerned about how many of the new rockets are using it (and likely releasing some of it unburned).

I got curious about this, so here are some rough numbers from cattle farming for comparison. This site reckons a cow will release about half a pound of methane a day, less if it’s fed on corn. That’s about 180 pounds or just over 80kg a year. There are various ifs and buts attached to that (soil bacteria can get rid of some methane for example), so I’m going to go with 50kg  per year per cow to take some account of different cow ages, different diets etc.

Also 50 is a nice round number for further guesstimates.  

Hopefully that site is an acceptable source - I did steer clear of the global warming type sites which I thought might be a bit biased.

US cattle population is about 94.4 million as of 2018. So approximate methane release from those cattle was 4700 million kilos or 4.7 million metric tons, assuming my arithmetic checks out.

Methane release from launch vehicles is a legitimate concern in my opinion (no sense piling a small problem on top of a larger problem if you can avoid it) but I think the above figures put that release into context. All the more so because enteric fermentation in cattle is far from the largest source of methane globally.

Edited August 27, 2019 by KSK

[tater]

Don't they burn off the released methane, anyway? They did last time (remember the huge vent flame from the top side of Hopper).

15 hours ago, mikegarrison said:

Ah. My guess is that they pressed the "ignite" button and nothing happened.

(Not to say I think there is literally an "ignite button". I'm sure the computers do this. But ... it would be hilarious if the launch command were given by hitting the spacebar.)

Wetlands apparently release 167,000,000 metric tons of methane into the atmosphere annually. I'm not concerned .

[mikegarrison]

As I said, I'm not concerned with one test. But routine rocket operations -- for more than just SpaceX -- have the potential to add up. Leaks, boiloff, failed launches, leaks during production and delivery, etc. etc.

I use methane for my home heat and hot water, so I'm not saying we can't use it. But the answer that "there are other, bigger sources" is handwavy nonsense. There are always "other sources". We are still responsible for ourselves.

I would at least like to see SpaceX address the subject of their greenhouse gas emissions rather than just constantly comparing themselves to national and international totals (which is what they seem to do in their EISs).

Edited August 27, 2019 by mikegarrison

[kerbiloid]

"How many cows does it take to fuel Starship?"

[Guest]

3 minutes ago, mikegarrison said:

But the answer that "there are other, bigger sources" is handwavy nonsense.

It's not "handwavy nonsense". It doesn't matter if rockets emit methane or not. Simple as that. Their contribution is less than statistical variation in methane emissions from cattle. 

You're falling to the same fallacy that most environmentalists do. "Let's save the planet by turning off the light to conserve energy!" Yeah, it's not going to make one bit of difference if the aluminium plant keeps chugging along, cheerfully burning through several orders of magnitude more energy. The only reason to transition to "ecological" lighting and other such things is to save money on power bills. If you want to reduce emissions, you need to target the largest sources, ones which actually contribute a statistically significant amount. Otherwise, you're just deluding yourself that you're doing something.

[mikegarrison]

Just now, Dragon01 said:

It's not "handwavy nonsense". It doesn't matter if rockets emit methane or not. Simple as that. Their contribution is less than statistical variation in methane emissions from cattle. 

You're falling to the same fallacy that most environmentalists do. "Let's save the planet by turning off the light to conserve energy!" Yeah, it's not going to make one bit of difference if the aluminium plant keeps chugging along, cheerfully burning through several orders of magnitude more energy. The only reason to transition to "ecological" lighting and other such things is to save money on power bills. If you want to reduce emissions, you need to target the largest sources, ones which actually contribute a statistically significant amount. Otherwise, you're just deluding yourself that you're doing something.

You're falling to the same fallacy a lot of non-environmentalists do: the ocean is so big, it doesn't matter if I pollute it. Except EVERYONE does the same thing, so....

SpaceX has an opportunity to get in front and lead here. Instead they are very vulnerable to being attacked for caring more about Mars than about Earth.

[Guest]

6 minutes ago, mikegarrison said:

You're falling to the same fallacy a lot of non-environmentalists do: the ocean is so big, it doesn't matter if I pollute it. Except EVERYONE does the same thing, so....

Wrong. What I was saying is "it doesn't matter I pour used bathwater into the ocean if the nearby factory keeps pumping raw sewage into it". What matters here is scale. You're trying to clean up the ocean by telling people to do invest in septic tanks, while completely ignoring the steam of industrial sewage, presumably because the plant executives would laugh in your face and toss you in the sewage steam if you tried talking to them. That's how it works in real world (well, except some executives will feed you lies and laugh after you're out of the door). "Private" contribution is, in most areas, insignificant compared to industrial sources, even if added up.

Edited August 27, 2019 by Guest

[mikegarrison]

Just now, Dragon01 said:

Wrong. What I was saying is "it doesn't matter I liquid into the ocean if the nearby factory keeps pumping raw sewage into it". What matters here is scale. You're trying to clean up the ocean by telling people to do their business on land, while completely ignoring the steam of industrial sewage, presumably because the plant executives would laugh in your face and toss you in the sewage steam if you tried talking to them. That's how it works in real world. "Private" contribution is, in most areas, insignificant compared to industrial sources, even if added up.

Actually, I'm not ignoring other sources. But this is a SpaceX thread, so I'm not talking about them here. Regardless of other sources, SpaceX is still responsible for their own actions. They can at least address the subject, if they care about it at all.

[Guest]

You are. SpaceX isn't making any more of a difference here than somebody throwing bathwater into the ocean. It doesn't matter if they care or not, and it would be stupid of them to be concerned about something so meaningless. They are entirely correct to say that their contribution is insignificant. Unless there is a way to address emissions from cattle (there isn't), this discussion is perfectly meaningless.

[tater]

35 minutes ago, mikegarrison said:

As I said, I'm not concerned with one test. But routine rocket operations -- for more than just SpaceX -- have the potential to add up. Leaks, boiloff, failed launches, leaks during production and delivery, etc. etc.

I use methane for my home heat and hot water, so I'm not saying we can't use it. But the answer that "there are other, bigger sources" is handwavy nonsense. There are always "other sources". We are still responsible for ourselves.

I would at least like to see SpaceX address the subject of their greenhouse gas emissions rather than just constantly comparing themselves to national and international totals (which is what they seem to do in their EISs).

The majority of SpaceX methane release without burning would be leaks, etc. The entire SS/SH stack is 3-4000 tons of propellants.There's more LOX than CH₄, and LOX is denser. Even if all the methane were to leak out ever launch, unburned, we're talking about 0.0006% of the methane released just from swamps (livestock is apparently ~90Tg/yr). If in fact only a fraction of the methane used in a launch is leaked---1%? then add 2 zeros, and the contribution is just 0.000006% of what is released from only one natural source.

The bottom line is that methane leaks from rockets is not even noise. Ie: it looks like the swamp figure I used might be low by a factor of almost 2, BTW, depending on the year: I see other sources saying 140-280 Tg/yr. So the total likely release from leaks is maybe (assuming 1% leak loss) 0.000006% of the difference between any given year's natural variation from one source alone (wetlands).

24 minutes ago, mikegarrison said:

Actually, I'm not ignoring other sources. But this is a SpaceX thread, so I'm not talking about them here. Regardless of other sources, SpaceX is still responsible for their own actions. They can at least address the subject, if they care about it at all.

What is the impact of other rocket propellants? Kerlox?