100 tons of payload. Rockets are typically about 2% payload so 5000 tons fully fuelled. Fuel and oxidizer combine to H2O, OH, CO and CO2. So, not all the exhaust product is CO2. But some of the CO released is combined with atmospheric oxygen to CO2, so that increases the mass of CO2 besides direct propellant mass.

We could as first guess say that it's about 5000 tons of CO2 per launch. So 1000 launches would be 5 million tons.

US CO2 emissions per capita are about 16 tons per year, so it would be equivalent to the yearly emissions of 300,000 Americans or one thousandth of the country's yearly emissions.

10,000 launches would be 1% of US total emissions.

Except it's not 10,000 launches, it's 170,000 (see other comments here).

So that's 850M tons, about a 10% increase (on top of the 2nd most polluting country in the world), so yeah, not happening.

I would personally rally against the govt. (and everything that allowed that to happen) if Elon gets a free pass on that.

Ok, I'm not that familiar with the plans with starship.

I think the premise of the article is wrong anyway.

I think no matter what the system is like, it still makes sense to optimize for mass in a reasonable way. That means, not sending dead weight to high delta vee. Leave big tanks or engines behind.

It's a bit like you don't transport your car with the airplane. It would be madness.

Exponentials are unintuitive. The total mass of all fuel in all stages is directly proportional to the mass that needs to be sent to the highest delta vee. So for example (to take a few shortcuts) if your moon ascent stage is 1% heavier, everything has to be 1% heavier, including the first stage of the launcher. So 1 kg in the ascent stage might not look like much but it grows the first stage at something like 1000 kg.

That's why I'm really skeptical of the architecture of landing atmospheric stages to the surface. They are just unnecessarily heavy. You have maybe quadrupled your total launch amount from the surface (haven't done an analysis).

Early Apollo planning had direct landing because docking in orbit had not been demonstrated. Gemini validated that. Orbital docking works fine and Apollo could continue with muchh more efficient architectures. Actually, docking has gotten a lot better, we did have Apollo, yes, and we have robotic tugs routinely flying to ISS.

Engines haven't made significant progress since the sixties, not enough to warrant really big architectural changes towards less mass efficiency.

If anything, the improved docking and automation that has already been demonstrated would swing the architectural plans for moon or Mars to have even more docking, berthing, refueling and staging!

Direct landing might only make sense with something like nuclear propulsion...

> That's why I'm really skeptical of the architecture of landing atmospheric stages to the surface. They are just unnecessarily heavy. You have maybe quadrupled your total launch amount from the surface (haven't done an analysis).

Lunar starship is not an atmospheric stage.

In the fine article, in Casey Handmer's plan, Starship is landed to the surface and returns directly to LEO or even to Earth surface.

So yes the heat shield goes all the way down to the lunar surface and back.

https://caseyhandmer.files.wordpress.com/2021/03/artemisspac...

The Starship actually being built by SpaceX under the HLS contract for NASA has no heat shield or atmospheric engines. It is meant to be expendable, or for reuse only in space without servicing.

Yes, which the fine article was criticizing.

The plan is to use atmospheric processing to produce methane and LOX on-site using renewable power. So it’d be net-zero carbon emissions.

This hand wringing about CO2 Emissions by rockets is the weirdest ongoing trend I've seen. If you want to complain about environmental issues, at least complain about something interesting like how sound at the launch pad disrupts the breeding patterns of an animal or something.

At least that can cause interesting discussion other than , BUT CO2 and WARMING.

It doesn't matter whether it's interesting or not, it only matters whether it's happening and who and what it's affecting.

A Starship's gonna generate about the same emissions as a similarly sized passenger aircraft generates from a full fuel load.

We fly ~40M flights a year. It'd be a drop in the bucket.

A 737-800 has a max take off weight of 175,000lbs

Super Heavy Dry Mass: 350,000-440,000lbs Super Heavy Fuel Weight: 7,500,000lbs Starship Dry Mass: ~200,000lbs Starship Fuel Weight: 2,600,000lbs

Starship+Booster total: 10,695,000lbs

175,000lbs vs 10,965,000lbs!

There is no such thing as a similarly sized aircraft!

A 747-8's MTOW is about a million pounds. Ten-ish 747s for a Starship, as a roughly worst case estimate. Only so much carbon you can stuff into a ton of fuel.

A single-digit percentage global increase in aviation emissions.

(I'm also very skeptical of that level of Starship launches. By the time you're getting anywhere near that, you're likely to have captured some comets and are processing fuel for interplanetary missions in an orbital refinery. Net zero emissions except for getting the people and Earth-only parts up to LEO.)

> By the time you're getting anywhere near that, you're likely to have captured some comets and are processing fuel for interplanetary missions in an orbital refinery.

I think you’re underestimating both the mass of a comet and that the geopolitical implications of a private company being one industrial accident away from replicating something several orders of magnitude closer to Chicxulub than to Tsar Bomba would prevent them being allowed to even try it.

I did a napkin estimate a while back, and even optimistically 10,000 Starship launches is just where you start going “hmm, perhaps we should think about starting to seriously plan the basics of an orbital ring or a launch loop” — a 40Mm circumference steel loop with a cross section of 1m^2 is still about 30 times less massive than 67P/Churyumov–Gerasimenko.

> I think you’re underestimating both the mass of a comet and that the geopolitical implications of a private company being one industrial accident away from replicating something several orders of magnitude closer to Chicxulub than to Tsar Bomba would prevent them being allowed to even try it.

Meh, you could regulate it fairly effectively. Changing the path of a comet is something that's gonna have to be done years out. Deviating from the planned course would be obvious long before it'd hit anything.

Bet your life?

If it was a naïve straight-line path with no funky orbital mechanics to make things even harder to get right, the difference between hitting the Earth at 90° and missing by the orbit of the moon is a sideways delta-v of 13 m/s one year in advance. The sideways Δv between a 45° impact and LEO, 7 days in advance, is 3.5 m/s.

I’m curious: Even ignoring engine errors, given near-Earth solar orbital velocities, what’s the mass of the smallest asteroid which, if it impacted that comet 7 days before the comet reached Earth, could cause it to hit Earth? For whatever orbit you want to put it in, and whatever mass of comet you want to suggest using.

> The sideways Δv between a 45° impact and LEO, 7 days in advance, is 3.5 m/s.

In other words, the larger the comet, the better.

You'd need a fairly obvious number of rockets to impart that sort of velocity change on a large one, right? And if you're doing it to a pebble, it doesn't matter too much?

> In other words, the larger the comet, the better.

I don’t think so? If you’re bringing in a big one you need more engines to push it into the right orbit to start with, so I think the risk is always things that scale up directly with the comet’s mass, e.g. “the engines are misaligned by $foo degrees”.

Also, a pebble in space terms is still a potential city-killer, and no nation in their right mind is going to want to let a private company — not one of their own, let alone a private company in another nation if they have even the slightest say in the matter — wield that kind of potential: https://en.wikipedia.org/wiki/Meteor_Crater

In the "whoops" scenario (i.e. non-malicious), an engine misalignment would be apparent with enough time to correct. You're a year out.

We watch asteroids zing by regularly. The ones we know about have their chances of hitting calculated years or decades out.

Sideways motion is harder to determine than motion towards us; the former needs angular resolution, the latter doppler radar.

And the sort of rock that could shift 67P from a safe to a dangerous path (LEO to 45 degrees one year ahead) would be about 13 metres radius. The Wikipedia citation is 5 years old, so I don’t know what we know today, but in 2016 the estimate was we only knew somewhere around 1.3% of asteroids between 40m and 3.5m diameter (and 0.003% of smaller than that, because things get harder to spot as you get smaller).

Wiki: https://en.wikipedia.org/wiki/Near-Earth_object#Size_distrib...

ArXiv link because the citation in Wikipedia was giving me a server error: https://arxiv.org/pdf/1604.06328.pdf

You are passive aggressively attacking the guy who is basically doing the only really inspiring thing in the world today, while at the same time basically single handedly forcing the auto industry into electrifying like 30 years early.

So, honestly, please, stop.

The beliefs that Elon Musk

A) Was attacked by the parent comment B) Needs defending here of all places C) Is the only person doing something inspiring in the world

Indicate that you might want to broaden your worldview.

Electric cars will not save us from climate change, nor will rockets send us into climate oblivion.

Starship contains a total of 3,400 + 1,200 = 4,600 tons of propellant [1]. The propellant being methane and oxygen.

So, someone can do the math to work out how much CO2 is generated by burning that much of that mix. In any case, that is very small compared to the overall emissions of human society.

That being said, methane can be produced a number of ways, for instance digestion of food waste. Therefore, they could source methane in a way that would allow to claim (quite reasonably) that they are carbon-neutral.

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

Musk has promised that eventually they will use synthetic methane to launch Starship, so net emissions will be zero.

He also promised fully self driving cars were six months away. And sweared Vernon Unsworth was a pedophile.

Not sure why PR statements matter.

I am more concerned about the Ozone damage.

https://www.tandfonline.com/doi/full/10.1080/147776209027688...

Everyone keeps pointing to the CO2 of the rocket itself but forget the enormous infrastructure requirements to launch a rocket the CO2 that creates. Even if starship bursn clean, it's infrastructure does not.