[avmich]

When Korolyov worked on N-1 rocket in 1960-s, some plans included building a hydrogen upper stage. http://astronautix.com/n/n1blocksr.html Hydrogen is rather hard to keep cold, but that stage was designed to work for over 11 days.

Falcon-9 flies almost every other day, about 3 times per week. Methane is way more storable than hydrogen. Of course we'd like to compare numbers, but, given that Starship is way bigger than than N-1 stage - about 15 times, and there is the law of squares-cubes, which for our case says the bigger the tank the less percent of boiloff per unit of time, and it's methane, and we can afford to lose a little and top off with another tanker...

Now, how many tanker flights we'll need? That's a favorite riddle in Musk's plans :) . Korolyov, again, had some early ideas for 5 tankers - https://graphicsnickstevens.substack.com/p/sever-the-bridge-... ... For Starship - if you have 1500 tons of fuel in the Starship, and 150 tons of payload in a tanker, you need 10 flights. You can probably optimize, or be disadvantaged by some obstacles - so, 8-12 flights? That many can fly in less than a month. We can also use additional measures to reduce boiloff - better protection from the Sun, active cooling, maybe more permanent orbital refueling depot - but still, with our today's Falcon-9 flight rate we may consider one Starship per month refueled on LEO. Even if some refueling flights won't be successful, the replacements could be sent.

I personally suspect Starship will fly much more often than Falcon-9. We're so much better in rendezvous and docking these day than we were during Apollo flights, the reliability is so much higher - just take a look how many Falcon-9 flights in a row are successful - so I don't think operationally LEO refuelling will present a significant problem. And I'm sure we need maybe a couple of years to see first examples of that.

Space is hard, yes. But we're getting better, for sure.

[TheOtherHobbes]

Theres a huge difference between sending up a stage full of H2 and transferring H2 from one stage to another with acceptable losses at cryo temperatures.

NASA is actually further ahead with space refuelling tech than SpaceX. But either way the tech is unlikely to work at scale this decade.

[grepfru_it]

Allow me to reply with an anecdotal story.

In 1992 I watched a car parallel park itself in NYC on Today, on nbc before I went to school. My mind was reeling, automated car technology is right around the corner! That technology did not ship for 20 years.

It is easy to say we are getting better, that doesn’t mean we will see, in this case, starship fly in the near future. And while I have the utmost confidence in Gwynne Shotwell, I am not holding my breath that we see starship launch with any meaningful payload in this decade.

[NetMageSCW]

They are already past the point that they could have expended Starship and just reused Super Heavy and launched payloads successfully. It is only their own goals to have a fully reusable system that is preventing it.