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Comment by ziffusion | Hacker News Reader

PLEASE PLEASE PLEASE someone post a TLDR. The dude is pleasant to listen to, but he goes ON and ON and ON about his life story and what not. Please just give us the bullet points.

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He’s basically saying the complexity of current Artemis mission design is indicative of lack of communication, mainly due to politics. He points out some of the obvious problems that isn’t being discussed openly (e.g., large number of untested refueling procedure which needs to be done to get one vehicle to the moon). He is trying to persuade the audience to challenge the current way of doing things, and look to the past successful Apollo programs to see why they were so successful.

I did skip some life story part when watching the video - but the talk was not bad at all. You can use the FF button and use 1.25x speed if that helps. I think it was worth my time.

And to communicate truthfully about why things are being done in the way's they're done.

The in-orbit refueling with lots of Starship/SuperHeavy launches is to increase the payload capacity. That's partly needed due to limits imposed by the Gateway architecture (which are largely due to limits of the Orion capsule). But it's also, and IMO more importantly, due to the fact that a manned mission to Mars (which Artemis is supposed to develop technology for) will certainly need in-orbit refueling.

It's a more complex design than Apollo. Some of that is justified due to engineering goals of the eventual manned Mars mission, even though it is detrimental to the moon mission. Some is justified due to political expediency.

The public statements of the agencies involved have often omitted the real reasons for the decisions, and instead invented justifications expected to be more acceptable. They don't want to say "Orion & SLS are used because it's a jobs program" or "we're spending a lot of money & time now on an in-orbit refueling system a moon mission doesn't need because we got the budget for it and haven't gotten the Mars mission we hope to use it on funded yet".

I'm only about half-way through, but if you skip to 30:50 he makes a big point. And frankly the lead up to that point was necessary, which necessity is also part of the message he is delivering.

Q: 'How many Starship launches are needed to execute the Artemis III lunar landing?'

NASA: 'We don't know but at least 15'

Video: 'Oh well that's a huge problem to have a complex project like this and we don't even have an exact answer'

Isn’t this disingenuous? As far as I can tell, Starship can make it to the lunar surface with a significant payload without refueling. The refueling launches are only required if you want to maximize the payload per lunar trip.

The Artemis mission involves landing astronauts on the Moon and bringing them back to Earth. Not landing an empty Starship on the Moon. Maximizing the payload is really important when need to carry humans, and launch a whole large spacecraft off the Moon.

BOTE calculations, approximate numbers:

    - delta-V for LEO-to-the-Moon flight - 3100 m/s
    - delta-V to get to low Moon orbit (a-la Apollo) - 1000 m/s
    - delta-V to land on the Moon from low orbit - 1700 m/s
    - extra delta-V during landing like with Apollo LEM for
      emergencies - 700 m/s
    - delta-V to get back to the Moon orbit - 1700 m/s
    - extra delta-V during lift-off like with Apollo - 500 m/s

Total - 3100 + 1000 + 1700 + 700 + 1700 + 500 = 8700 m/s, that's a pretty large delta-V, almost like an Earth SSTO.

Raptor Isp - 3500 m/s, fueled mass - 1320 tons, empty mass - 120 tons, mass ratio - 1320 / 120 = 11. Tsiolkovsky formula:

    exp(8700 / 3500) = m_fueled / m_empty = 12

that is, we need Starship HLS to be somewhat lighter to get to the Moon surface and back to low Moon orbit from LEO than the current numbers for Starship, and that is without any payload.

It's definitely not the final numbers, so the results will change, but

> Starship can make it to the lunar surface with a significant payload without refueling

is questionable at the moment.

If you mean cargo flights with no return to the Moon orbit - rather than crewed flights as agreed with NASA today for Starship HLS - then of course the numbers are better.

Thanks for this!

I recommend you to watch it, it's really good.

But as I mentioned in another comment, here is a relatively good AI summary:

https://www.summarize.tech/youtu.be/OoJsPvmFixU

Click on see more, to see 5 minute wise summaries.

(Not affiliated with this site, I just use it from time to time)

He is pointing out issues with communication and people not knowing a lot of the required information. Kind of like people only want TLDR instead of actually understanding the point of the information.

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