Anyone else watching Starship?

[IanF]

Like when Mir and ISS were built.. building in sections with final assembly in space is more than feasible. Fuel production is being pushed offshore; hence why everyone and their dog is rushing to claim parts of the moon. Station on the moon, especially with caves now found, is achievable with current tech. You’re looking at it as a single endeavour Zed, whilst it’ll be lot more stages, with both success and failures along the way, and then finding people “with the right stuff”, to send on the final mission. Fuel for the return will be manufactured on site (ie Mars) by automated process before the mission even launches to Mars. Like most “impossible “ tasks, they just need breaking down to smaller, manageable parts

[ZedLeg]

Even broken down into small jobs it’s a huge undertaking, if they’re planning of processing fuel on Mars you’ll need to have either a manned plant which pushes the how do you have people live on a dead planet up the list or it’s automated and then you have to figure out how to get a complicated piece of machinery to Mars and to work.

I know I’m sounding really negative but it really is a huge task that I think is beyond us as the world works just now.

I’d love to be proved wrong though.

[Mito Man]

This’ll be cool to see.

[DaveE]

I think getting to Mars, landing, taking off again is relatively simple albeit extremely inefficient. Just park a bunch of fuel resupply tanks in orbit of Mars. Refill starship 1/3 full before landing on Mars as gravity is only 40% of earth and there's much less atmosphere, take off, refill again and come back to earth.
Can probably pack a few years worth of freeze dried food on the resupply vessels too.

You'd think, right?

Until you consider things like boil-off (and other in-space refuelling issues)

Evaporation, or "boil-off", is a significant issue in space refueling because it can cause a loss of fuel and endanger the structural integrity of tanks:
Fuel loss
Evaporation causes a loss of valuable propellant, which can make long-duration missions infeasible. For example, a passive system would cause all the fuel for a three-year Mars mission to be lost to boil-off.
Tank integrity
Evaporation can cause tanks to self-pressurize, which can endanger the tank's structural integrity.
Difficult to measure
In low gravity, it's difficult to accurately measure how much fuel is left in a tank.
Difficult to transfer
In low gravity, fuel can "slosh" around, making it difficult to transfer.

Yeah, people are working to solve these problems, but at the moment, it's still an unsolved problem

[DaveE]

@Mito Man

[directed at that tweet, not you]

"next year" - because we can rely on Musk when he makes statements like that

And "automated fuel production on Mars" - this is based on a proven, reliable, automated fuel production technique that we can do on earth, right?

And of course, we'd need somewhere to store all that fuel too

Related, I saw this graphic a while back, for perspective on what "fuelling" looks like:

[ZedLeg]

It’s why rocket propellant is useless for this type of thing.

Far too inefficient, unless they’re planning on coasting most of the way which is possible but risky.

[DaveE]

The scale of these tasks/things is mindblowing

The main booster stage of Starship burns through 3750 tonnes of fuel in just over 3 minutes - just to get to orbit

I saw a comment re that graphic above that puts another spin on it:

Given you need 278 tankers to fuel the booster, if you could transfer the contents of two tankers per hour, 24 hours per day to the tank/fuel "farm", it would take nearly 6 days to offload enough fuel from those tankers to fill the booster stage

From what I could find with a quick search, it can take a "several hours" to transfer the petrol from a tanker to a petrol station

[DaveE]

It’s why rocket propellant is useless for this type of thing.

Far too inefficient, unless they’re planning on coasting most of the way which is possible but risky.

Except this is exactly what they're planning (i.e. in-orbit tankers that can refuel starship with rocket fuel to power it to Mars)

[ZedLeg]

Yeah, I foresee a massive fuel explosion in space in our future.

[Mito Man]

I think the booster is solely used on earth, once in space only starship is used.
Also would rocket propellant boil off in the near absolute zero of space?

[ZedLeg]

Yes, liquid hydrogen can boil at around 1 Kelvin

[DaveE]

Kennedy made his famous "put a man on the moon speech" in April 1961

Apollo 11 landed on the moon in July 1969

So just over 8 years between the announcement and the event

SpaceX started working on Starship in 2018, and it's yet to launch something into low earth orbit

Just saying

[DaveE]

I think the booster is solely used on earth, once in space only starship is used.
Also would rocket propellant boil off in the near absolute zero of space?

Absolute zero + massive radiation when it's exposed to direct sunlight

[Beany]

A fun breakdown from a couple of years ago on this.

[V8Granite]

I see the space experts are out in force saying what can’t be done

There are amazing things we do right now that were hardly conceivable 10 years ago so I have faith these problems will slowly reduce until the task is doable. Whether that’s a week or 30 years it doesn’t mean we shouldn’t try.

Dave!

[ZedLeg]

Again, no one is saying we shouldn’t try.

All the problems we’ve mentioned are well documented, I read a book that covered the problems of fueling interplanetary travel 20 years ago.

A front runner back then was using nuclear material to make small explosions. The downside was the possibility of our first impact on a new planet being a bigger nuclear explosion

[V8Granite]

Again, no one is saying we shouldn’t try.

All the problems we’ve mentioned are well documented, I read a book that covered the problems of fueling interplanetary travel 20 years ago.

A front runner back then was using nuclear material to make small explosions. The downside was the possibility of our first impact on a new planet being a bigger nuclear explosion

Hey, we risked a black hole in Switzerland and made a rocket crane for Mars, a small nuclear is Childs play

Dave!

[Beany]

Again, no one is saying we shouldn’t try.

All the problems we’ve mentioned are well documented, I read a book that covered the problems of fueling interplanetary travel 20 years ago.

A front runner back then was using nuclear material to make small explosions. The downside was the possibility of our first impact on a new planet being a bigger nuclear explosion

Fuckin' Project Orion!

https://en.wikipedia.org/wiki/Project_O ... ropulsion)

Dropping nukes behind you to impact a pusher plate for acceleration, absolutely potty idea, I love it.

[ZedLeg]

Yeah, I thought they worked on it later. Must be misremembering that book I read two decades ago

[Mito Man]

“ A moderate-sized nuclear device was estimated, at the time, to produce about 5 or 10 billion horsepower.”

Someone fit that to a bus right now!