Right, some nice inventions are due to space race but just after two giant boosters worth of propergol were burnt. And making those things that go to space are not completely carbon neutral either.
Random googling gives following two figures to compare:
"A jumbo jet (Boeing 747-400) flying from London to New York burns approximately 70,000 kilograms of fuel"[0]
Falcon 9 Full Thrust - Takeoff mass (tonnes) 549, Payload to LEO (kg) (from Cape Canaveral) 22,800 (expendable)[1]
So, roughly 70 metric tons of fuel for a London->New York flight, vs. 500 metric tons for a LEO launch. It's quite comparable. Now consider that there's five orders of magnitude more flights than there's rocket launches[2]. Even if you take an order of magnitude off that to account for most flights being shorter than LHR->JFK, you still end up with space launches barely registering. And then some rocket fuels are non-carbon-emitting.
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[0] - https://www.flightdeckfriend.com/ask-a-captain/how-much-fuel...
[1] - https://en.wikipedia.org/wiki/Falcon_9#Performance
[2] - https://garfors.com/2014/06/100000-flights-day-html/ says > 100k flights per day, and there's less than 1 space launch per day.
Space industry definitely isn't emissions-free, but right now it doesn't even register. We might have a problem in the future, but there's hope in switching to cleaner fuels planetside and eventually sourcing fuel for space operations from space. As it is today, in my opinion space industry has very good value proposition in terms of utility/carbon emitted.
The 747’s net cargo of passengers plus luggage probability amounts to around 300-400 lb per passenger. 22,800 / 400 ~= 57 passanger equivalent to 22,800 / 300 ~= 76 passanger equivalents.
Further people take much longer trips than your benchmark getting them even closer.
Maybe less if you're not talking about Americans. Even counting 40lb of luggage those are pretty porky passengers. :)
Clearly no :P Also I realized that, unless I have a specific problem I need to solve, I don't remember or like reading about things. I have been taught things in school/uni that I thought were terribly boring and was bad at, until I needed to solve a problem with that information and then I had to re-learn everything. Kind of a waste of time, but I can't change my brain!
That said, they usually have an even larger CO2 footprint because processes used to make them take natural gas an an input, or use lots of electricity mostly coming from fossil fuels. The main reasons they're chosen are for their specific impulse (hydrogen) or long-term stability and readiness (solid fuel in ICBMs), rather than their CO2 emissions.
If numbers like this were regularly given to laypeople, the climate change discussion situation would be much better. That number for a single flight is ENORMOUS!
Per passenger you are getting something like 50mpg.
Perhaps it's better to restrict oneself to flying OR driving that kind of distance. And it adds up - if you drive: do you ever look at your total mileage, then calculate your carbon emissions?
https://www.nytimes.com/2013/01/27/sunday-review/the-biggest...
"For many people reading this, air travel is their most serious environmental sin. One round-trip flight from New York to Europe or to San Francisco creates a warming effect equivalent to 2 or 3 tons of carbon dioxide per person. The average American generates about 19 tons of carbon dioxide a year; the average European, 10."
Seems like there's some tricky math going on, notice: "equivalent" in the above quote:
http://www.carbonindependent.org/sources_aviation.html
This calculates 180 kg CO2/hour per passenger. So 8 hours or so between NYC and Paris? 1,440 kg. 1.6 tons. Not quite a few orders of magnitude.
Once through all the calculations, the above then states, "The CO2 emissions are therefore rounded up and the Carbon Independent calculator takes a values of 250 kg i.e. ¼ tonne CO2 equivalent per hour flying."
So that's more like 4 tons to Paris. (on Basis 1)
Look at the correction at the bottom of the NYT piece:
> "A news analysis article last Sunday about the impact of air travel on global warming referred imprecisely to the environmental impact of one round-trip flight from New York to Europe or to San Francisco. It has a warming effect equivalent to 2 or 3 tons of carbon dioxide per person, but does not generate that much carbon dioxide per person. (The estimate also includes warming from other greenhouses gases.)"
So actual carbon output per person was correctly calculated, but there is some "carbon equivalent" multiplier slapped on other gasses that brings their totals up from 170kg/px to 2-3T/px.
I personally would not consider that a "enormous" amount of fuel to move 400+ people 5,500km.
If anyone is really serious about global warming, shutting down coal plants should be priority 1, natural gas plants priority 2 and transportation emissions priority 3.
In the US using the average electricity mix, an EV like the Model 3 emits a factor of 2.5x less GHG than an equivalent diesel vehicle. Because 40% of electricity is from clean sources (nuclear, wind, hydro, solar, geothermal), and coal is just 27% now.
As for moving transportation to electrical propulsion, the real effect has to be judged by the marginal effect it has on emissions. If the marginal change is covered by coal, the benefit is much smaller than if the marginal change is covered by clean sources.
Citation needed. Hydrolox has the highest Isp, but for a boost stage, that alone at all costs is not the most important quality. Hydrolox engines, tanks and piping all needs to be much larger and heavier than other fuels, and in practice, this eats the gains that the higher Isp buys you and more.
It's not an accident that basically all the new engine designs, by multiple different companies, have tested hydrolox and then switched to methalox.
Additionally: operating oxygen-rich causes the bulk density of hydrolox to improve dramatically. This is relevant for first stages, and if reusable launch vehicles become so cheap that propellant cost becomes a major constraint, then I should point out that liquid oxygen is practically free: less than $100 per ton.
For first stages, you're right (unless you get clever and are able to solve the engineering challenges of running oxygen-rich). For upper stages, hydrolox again looks very attractive (because a first-order optimization shows that it's energetically favorable to use higher Isp on the upper stage than the lower stage if you need to make a choice... of course, commonality of stages is also desirable at lower flight rates).
The opposite is true. The relevant problem of hydrogen is that it readily leaks through thin walls. This means that as methalox rockets move to ever thinner composite tanks made of better materials, hydrolox really cannot do better than the current state of the art.
> operating oxygen-rich causes the bulk density of hydrolox to improve dramatically.
True. But it also makes your exhaust into a hot, oxidizing torch, meaning you need much more durable (and heavier!) engine bells.
> For upper stages, hydrolox again looks very attractive
The other problem is that it must be cooled much deeper, and takes much less energy to boil off, making long term storage a hard problem. This makes hydrolox less interesting for any upper stages/manouvering engines that do anything more complex than deliver cargo to earth orbit. Once you add long coast times, it gets really bad -- to the point that the SLS moon missions actually get lower efficiency from their upper stages than they would get from kerolox, once you account for the extra hydrogen they have to ferry up just to let it boil away.
> commonality of stages is also desirable at lower flight rates
Commonality of stages is desirable at all flight rates. Paying for the highest possible efficiency gadget for every task is one of the reasons old space has such huge problems competing in cost with the new entries. Just having a little more thrust and burning a little more fuel is more cost-efficient than having another engine manufacturing line.
Methalox engines will probably power almost everything newly designed going forward. Not because they are the best solution for anything, but because they are 90% there at everything, while lacking the worst problems of everything. Their fuel is easy to contain and stable for long-term storage, they have no carbon build up in the exhaust, their exhaust is reasonably cool and not heavily corroding, and they have enough thrust and enough of Isp that these advantages will outweigh a minor efficiency loss in almost all situations.
The winds of the industry have shifted, and now that methane has been proven, no new hydrolox engines are being developed, with basically everyone choosing methalox for new designs instead. JSC Kuznetsov, SpaceX, BO, ESA and Landspace all independently made the same choice. Others have chosen to use engines developed by some of them. The end result is that the only major rocket operators still developing a future rocket with non-methalox engines are:
- Roscosmos (The Angara rocket family development was started before methalox was seen as viable. There are future plans for switching propellants, but afaik no funding for them currently.) - Arianespace (The Ariane 6 development was started before methalox was proven. Ariane NEXT is going to run on methane.) - NASA (SLS was mandated to use existing engine designs by the senate, because the senators' home states needed the money.)
Your points about hydrogen leaking are not actually accurate. This doesn't negate the advantages at all, and as vehicles get larger, the advantages become even more pronounced. Oxygen-rich is used on Russian engines, which are some of the best engines ever made (although they haven't improved on them much in the last couple decades).
Commonality of stages is more important at lower flight rates since you have to pay for amortization of the greater development costs.
I like methane/oxygen. It is a very good choice. But I also don't buy into the hydrolox phobia that has become popular. Hydrolox is still a very good choice.
(I think that SpaceX and Blue Origin are completely right for picking methane/oxygen for BFR and New Glenn; I'm speaking even more long-term...)