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A rocket a day keeps the high costs away (1993)

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Re: A rocket a day keeps the high costs away (1993)

#31

Post by lacksconfidence »

flashback2199 wrote: post #24
wolfram74 wrote: post #21

Earlier quoted context omitted.

one upside is many modern rockets use methane, synthesizing methane with pv/wind power would be much lower impact, depending on how much of the exhaust is actually at escape velocity it could be very slightly carbon negative, like new forged steel with ore prepped with clean hydrogen.

Correct me if I'm wrong but I am under the impression that Starship does not use that, the least expensive fuels for rockets are highly CO2 emitting, and the least expensive fuels are what will get rolled out in mass numbers if SpaceX, Blue Origin, and others succeed in building a rocket transportation industry.

starship uses methalox, a combination of methane and oxygen. I'm far from an expert, but my understanding is the methane comes from refining LNG.

Re: A rocket a day keeps the high costs away (1993)

#32

Post by [deleted] »

cma wrote: post #22
lkbm wrote: post #17

Earlier quoted context omitted.

There are thousands of long-haul flights—and something like 100k flights overall—per day. If we're doing 10k+ rocket launches per day, then that's a huge problem. If we're doing 1 per day, it's a rounding error. This is premature optimization. (Either way, the solution, of course, is a carbon tax to price in the emissions.)

Elon said by 2028 they will be in active passenger service replacing long haul aviation for cheaper than a business class ticket.

[deleted]

Re: A rocket a day keeps the high costs away (1993)

#34

Post by avhon1 »

flashback2199 wrote: post #27
actinium226 wrote: post #25

Earlier quoted context omitted.

These are not great comparison numbers. When rockets fly passengers it's ~4 people as compared to ~200 for a plane. A modern 737 has a max fuel load of almost 30000L of jet fuel [1]. The density of jet fuel is 775-840 g/L [2]. Let's take 800g/L so that we can just multiply the lead numbers - that gives 24,000 kg of fuel. According to spaceflight101 [3], the Falcon 9 uses 123,570 kg of RP-1 (similar to jet fuel) in th…

Right, I think people are misunderstanding a key point here, which is that SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes, in which case we are talking about a dramatically increased number of launches.

> SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes

Why? Rockets are intrinsically less efficient and less safe than airplanes. Why would they try to compete for use cases where they are at such a disadvantage, and where they have to-date shown no interest in competing with fixed-wing aircraft?

The closest those companies have done to showing interest in pitching rockets against aircraft is Elon Musk saying that his company will offer ultra-high-speed flights via rocket, which is more like a Concorde-killer 25 years after the Concorde got killed by its own costs.

Re: A rocket a day keeps the high costs away (1993)

#35

Post by looofooo »

actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

What would another James Webb Telescope would have cost? Far far less then the first. Sure it is costly to destroy a prototype, but not as much as you think.

Re: A rocket a day keeps the high costs away (1993)

#36

Post by foobarian »

twic wrote: post #13
mlsu wrote: post #12

Earlier quoted context omitted.

Starlink wasn't really considered for years until SpaceX already was well underway. It was fortuitous but unplanned, not a factor in the original vision of the company when it was founded.

Before Starlink, SpaceX assumed/hoped that a mass of new customers would come out of the woodwork when cheap launches became available (the easyJet strategy!). When they didn't, they came up with Starlink to be that customer.

Although, aren't they launching something pretty much daily or weekly, even without accounting for Starlink? It just isn't in the news much.

Re: A rocket a day keeps the high costs away (1993)

#37

Post by joebig »

wolfram74 wrote: post #23
joebig wrote: post #18

Earlier quoted context omitted.

Oxides are incredibly stable chemically. Any further conversion or sequestration process is guaranteed by thermodynamics to be very energy-intensive.

we know transitioning to pv/wind is going to lead to some months where we've got megawatt-hours coming out of our ears. If the only problem is energy cost, that won't be a problem long.

If it takes a day worth of solar/wind to offset a minute of rocket emission, then the equivalence is not really sustainable.

Re: A rocket a day keeps the high costs away (1993)

#38

Post by flashback2199 »

avhon1 wrote: post #34
flashback2199 wrote: post #27

Earlier quoted context omitted.

Right, I think people are misunderstanding a key point here, which is that SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes, in which case we are talking about a dramatically increased number of launches.

> SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes Why? Rockets are intrinsically less efficient and less safe than airplanes. Why would they try to compete for use cases where they are at such a disadvantage, and where they have to-date shown no interest in competing with fixed-wing aircraft? The closest those companies have done to showing interest in pitching rockets against…

You have answered your own question.

Re: A rocket a day keeps the high costs away (1993)

#39

Post by appplication »

looofooo wrote: post #35
actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

What would another James Webb Telescope would have cost? Far far less then the first. Sure it is costly to destroy a prototype, but not as much as you think.

It would have cost less sure, but it would have delayed the program years. And such a delay could easily shutter the program if political support faltered.

Re: A rocket a day keeps the high costs away (1993)

#40

Post by promiseofbeans »

actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

Isn't Astra developing a reusable launch system now?
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