[lukealization]

Tell me why I shouldn't be concerned about thousands of starships launching from Earth and emitting multiple megatons of Carbon Dioxide in the fragile upper atmosphere? Some studies indicate emissions here are significantly more impactful, and can also damage the Ozone layer as well.

Any answers shouldn't consist of "well it's a fraction of what the aviation industry emits" because _the entire point_ of Starship is to scale-up to aviation-like operations.

[MVissers]

If needed and wanted methane can be created sustainably. But not sure about upper atmosphere issue.

[_2d30]

Tell me why we should be. Your answer can’t just be a vague reference to “some studies”.

[lukealization]

Yes, because the "charge forward and worry about the consequences later" mantra has proven so historically successful over the past 100 years when it comes to environmental stewardship. CFC's, HFC's, PFAS, leaded fuel, and abundant plastic waste are proof we definitely know what we're doing when it comes to ensuring we don't pollute our planet or ourselves, right? The science on this remains novel precisely because the idea of launching hundreds of rockets a day was inconceivable even 10 years ago.

You want more specifics, I take it?

* It's been well known for decades that high-altitude supersonic flight damages the ozone layer significantly faster than conventional aircraft. New Scientist, 1997 [1]

* More recently, concerning reentries of spacecraft: Atmospheric impacts of the space industry require oversight, Nature, 2022 [2]

Our upper atmosphere is fragile and contains the bulk of the ozone layer that protects us all from skin cancer and being bathed in brutal ultraviolet radiation. You willing to risk it because "space is cool"?

[1]: https://www.newscientist.com/article/mg15320692-500-science-...

[2]: https://www.nature.com/articles/s41561-022-01001-5

[_2d30]

So pretty much just vague references to some studies? Your second reference link is literally just the title of a study and you cite nothing directly from it.

For the first study, you have conveniently focused on "supersonic flight" as the issue which is not the fundamental issue cited in the article (link isn't working for me, btw, I had to google it find it myself). The fundamental issue is in aircraft fuel and the sulphur based impurities it carries. Starship burns Methane and LOX. In general, these fuels (fuel and oxidizer) are typically kept as pure as possible and are unlikely to contain much more than trace sulphur impurities as there removal is a standard and well followed practice.

So for full clarity, your argument as presented here is completely without merit and it looks like your first study was intentionally presented in a way to obfuscate its extremely tenuous link to the issue at hand.

As an aside, you're also quite focused on your mood affiliation with the topic, doing things like asserting the motivation of those you reply to without any evidence (eg 'You willing to risk it because "space is cool"?'). This won't help you think clearly about a topic.

[fallingknife]

If we listened to naysayers like you we wouldn't have ever moved out of caves

[lukealization]

A wholly reductionist comment that misstates my opinions. Believe it or not I think there’s an optimal space between the environmental conservatism I’m espousing and charging forward into an unregulated and environmentally destructive bliss that doesn’t result in being opposed to any form of new development ever.

[davidguetta]

That is still a lot of word for no substance beside vaguely quoting two articles you probably found with a 1min google search

If you are an engineer or even have half a brain nothing prevents you from doing a more in depth analysis, make a blog and post it here.

Right now not only are you a naysayer but you are even putting on hacker news commenter the burden of defending your point.

[golol]

Because you should consider the upside when you mention the downsides. 1000 Starships launching a year can mean exoplanet imaging, drilling on Europa, interstellar probes, an actual Mars colony, asteroid mining, brilliant pebbles, O'Neil cylinders, L1 solar shields, space junk removal and so on. Not all at the same but each of these is a project that is potentially feasible with enough mass in orbit. I'm not saying you have to like or care about any of them but you should consider what you actually gain for all that emitted CO2.

[lukealization]

I agree space is cool. But why do you think the "space is cool" mantra is more important than ensuring that for the 8 billion humans that call this planet home—we have somewhere sustainable and safe to live?

Your asteroid mining for profit is arguably meaningless if we have no ozone layer.

[golol]

So Starship+Superheavy have about 4.6kt of propellant which should mean about 1kt of methane. That's about 2.5kt CO2 per flight which yields 2.5mt CO2 annually for 1000 launches. The US releases around 4.4Gt CO2 annually so you end up with around 0.05% of US emissions. I actually thought it would be more so I hope I didn't miss an order of magnitude somewhere. Quick search says US airliners release less than about 200mt annually so you're looking at less than 2.5% of that. Annually about 850 million people fly in the US so if you imagine a Starship flight having 100 passengers then in some weird way flying with Starship is maNe about 200 times more CO2 intensive than flying with a plane.

Now high-altidude effects would increase the greenhouse effect of these emissions by some factor I don't know. At the same time a large amount of fuel is actually burned by the booster at below airliner altitudes. Another mitigating effect is that some of this methane could be produced renewably.

I haven't heard about Ozone depletion from spaceflight except for the case of reentering Aluminum burning up. Well this wouldn't be an issue with Starship flights.

So you know overall, let's just give it a lot of conservative margin and imagine we are looking at about 10% of the US airline or 0.2% of total US greenhouse impact. That is on the scale of a whole new industry, yes, but if you can imagine a world which has attained a sustainable rquilibirum surely you can also imagine one which has a bit of margin left? And this is only for the US!

What do you gain? Three of the points I mentioned have potential direct benefit for people.on earth: asteroid mining, L1 solar shield and brilliant pebbles.

Asteroid mining "for profit" also means that the economy profits, unless you believe that capitalism doesn't work. I read that less than 200t platinum are produced annually. Say your asteroid mining crashes that economy. I found some figure of 20kt of CO2 for each ton, so 4mt in total. That is more than your 1000 launches emit! Now my calculations are of course wrong but it seems plausible that the orders of magnitude could match. So you should definetly consider that your asteroid mining operations might stop other mining operations from happening which reduces your greenhouse impact.

Then you have the solar shield. It is certainly possible, although of course difficult and has some risk. But it's good to have a backup plan, no?

[la64710]

And turn planet earth to barren mars in the process..

[golol]

I replied with some guesstimations to the other comment, I would be curious to hear what you think.

[la64710]

Thank you. I don’t know how right or wrong your calculations are but thanks for putting the numbers together. It would be greatly reassuring to see that something similar or a proper environmental impact study has been done for a massive project like starship and shared with the public. It will also be cool to see if more efficient way of propulsion fuel could be discovered for these launches. Progress can be mindful and sustainable.

[IndubitableCoil]

Because we can convert all produced carbon dioxide from a Starship back into methane using the Sabatier process [1].

[1]: https://en.wikipedia.org/wiki/Sabatier_reaction

[lukealization]

Why isn't SpaceX doing that then? Why isn't any airline doing that then? Oh look, it's cheaper to use refined natural gas from a well. That's why. In the absence of either properly priced externalities, the market will always choose the cheapest option—Sabatier-generated Methane is not remotely comparable in price to fossil nat gas.

Mentioning theoretical solutions doesn't help if they will never be used practically.

[rstupek]

I don’t think airliners use Methane?

[lukealization]

Aircraft use hydrocarbons which require similarly intensive chemical processes to create the fuels from the same constituent ingredients as the Sabatier reaction.