Will Mars-bound Starships actually be reused?

[TheRadicalModerate]

It's purely a question of the timeline.  Early on, Starship will be changing so quickly that returning anything that's unnecessary, just to scrap it, doesn't make sense.  In contrast, Starships that stay on Mars make excellent pressure vessels, or can be scrapped for a wide variety of purposes.

But there are some good reasons to return at least a few Starships:

1) You'll need to return crews as needed.  (FWIW, I expect 90% of early passengers to return.  Later, when the colony isn't quite so Wild West, that number may come down.)

2) You'll need to return a few Starships for engineering purposes.

3) There may be a need to do some sample return.

All three of these reasons can probably be satisfied by the same Starship.

Later on, when the Starship design is mature and colonization is ramping up, it probably makes sense to deadhead many Starships back to Earth.  But I'd guess that's at least 10-15 years after the first successful crewed mission.

Bear in mind that something has to happen to Category V planetary protection before anything returns.  It's an almost certain bet that the reforms that allow crews to land on Mars will be accompanied by reforms that let them come home, but how they come home is still up in the air.

[TheRadicalModerate]

It seems that the majority of people posting in this thread think that SpaceX have, or will have, changed their minds on reuse of Mars-bound Starships.  I'm not sure I agree with that consensus myself.

It will be interesting to find out whether this is another case of Elon having a plan that is too revolutionary for people to get their heads around until they see it actually happening, or SpaceX just coming up against the cold realities of the engineering and economics of the situation.

It's not a question of changing their minds.  It's merely a difference between their end goals and what makes sense as they progress toward those goals.

Insisting that the first Starships be returned from Mars is like planning for the first Starship orbital test flight to land both the SuperHeavy and the Starship perfectly on the chopsticks.  You return 'em when it makes sense.  Until then, you use 'em for stuff on Mars--or just throw them on a martian scrap pile.

[oiorionsbelt]

It seems that the majority of people posting in this thread think that SpaceX have, or will have, changed their minds on reuse of Mars-bound Starships. 

The manner in which Starships will be reused rather than whether they will be reused is the take away I get from posters on this thread. The majority Starships returning to Earth is the change expressed.

[MDMoery]

It seems that the majority of people posting in this thread think that SpaceX have, or will have, changed their minds on reuse of Mars-bound Starships. 

The manner in which Starships will be reused rather than whether they will be reused is the take away I get from posters on this thread. The majority Starships returning to Earth is the change expressed.

With the overall long-term goal of Starship being Mars colonization, it would be my speculation that whether or not a Mars-bound Starship is reused will depend largely on that particular trip's objectives, along with the design version and flight history of the particular ship.  Early trips will be aiming to return crew/cargo to Earth.  Later one, more and more trips will be one-way the percentages will shift.  I agree, they will not bother to return them if there is a better reason to keep it on Mars.

I am sure that a certain percentage of the Starships that land on Mars will be damaged and unable to return, even if returning was the plan.  So spare parts and spare ships will be a something they will need to have on hand.  Beyond that, once the spares logistical requirements are met, I am sure there are a lot of potential uses for bulk scrap stainless steel along with various components (eg. high capacity pumps from the engines.)  They will make use every single item they have I am quite sure.

Even beyond spares and salvage, I am sure ships will be re-purposed as needed.  Tanks for the Sabatier process.  Or tip it over for habitats or workshops.

If a ship does return, then the question becomes will it be re-launched?  And of course that answer will almost certainly change over time as well.  I would speculate that older designs might be used for lower-priority cargo on their subsequent Mars-bound trips. And of course, once an older design ship lands for a 2nd or more time on Mars, it would be more likely to be utilized there for spares or raw material.

I would speculate that if they go to the trouble of sending a ship back from Mars, it might be more likely to be utilized than scrapped on Earth even if it has an older design or multiple flights.  It would seem to be of less value to scrap it rather than to utilize it for either another Mar trip with lower priority cargo, or utilize them for LEO missions.

[InterestedEngineer]

Multi-year time frame voyages may need to be something we think about again, as in the early days of intercontinental sailing.

For example the Niņa went one quite a few voyages.  One of her sisters crashed into sand bars and everything they could grab was used for colony building.

https://en.wikipedia.org/wiki/Ni%C3%B1a
https://en.wikipedia.org/wiki/Santa_Mar%C3%ADa_(ship)

[AmigaClone]

Personally, I would guess that the reuse of Mars-bound Starships likely will depend in part of how easy it might be to implement ISRU on Mars, specifically in terms of propellant production. Initially most Starships would become fixed parts of the base - either mostly intact or cut up and used as the source of materials for more advanced structures on Mars.

[steveleach]

It seems that the majority of people posting in this thread think that SpaceX have, or will have, changed their minds on reuse of Mars-bound Starships.  I'm not sure I agree with that consensus myself.

It will be interesting to find out whether this is another case of Elon having a plan that is too revolutionary for people to get their heads around until they see it actually happening, or SpaceX just coming up against the cold realities of the engineering and economics of the situation.

It's not a question of changing their minds.  It's merely a difference between their end goals and what makes sense as they progress toward those goals.

Insisting that the first Starships be returned from Mars is like planning for the first Starship orbital test flight to land both the SuperHeavy and the Starship perfectly on the chopsticks.  You return 'em when it makes sense.  Until then, you use 'em for stuff on Mars--or just throw them on a martian scrap pile.

I don't think anyone is insisting that the first Starships be returned; my OP specifically states that we're talking about the majority, not all or none.

Musk has always talked about the Mars transport infrastructure requiring reusable vehicles, which to me implies that the majority of ships will be reused. If, with hindsight, that turns out not to have been the case then he/SpaceX will at some point have changed his mind.

[notthebobo]

Most responses seem to focus on SpaceX as the sole customer for Mars transport. Once Starship proves itself to be a reliable vehicle, all types of new customers will appear which will encourage the reuse market.  If other countries or industries can buy room on a second-hand Starship at a fraction of the cost of developing their own, they're going to take it, even if this costs SpaceX more than building a new one. If cheap enough, the millionaire/billionaire-expeditionist groups may start planning trips.

Consider the Falcon story for comparison.

[DanClemmensen]

[...]
Consider the Falcon story for comparison.

Sorry, but the economics are very different. The value of a used Starship on the Martian surface will be very high, because resources will be very expensive. A competent worker using fairly lightweight tools can fabricate an amazing variety of items from stainless steel scrap. The cost of returning the Starship to Earth will be high, probably higher than the cost of building a new one. SpaceX is working very hard to keep the cost of a new Starhip as low as possible.  And the time cost of money will be high due to the long transit delays.

By contrast, a reused F9 booster on Earth compares to a new-build F9 booster on Earth, and recovery and shipping back to the refurbishment site is less than a week instead of more than two years.

[Robotbeat]

NOT reusing the starships puts a floor on the price that SpaceX can reasonably afford to charge passengers to Mars, and that floor is like $500,000-$1,000,000. If you reuse them, you could make reduce that cost to a third. That's not a small thing.

[meekGee]

NOT reusing the starships puts a floor on the price that SpaceX can reasonably afford to charge passengers to Mars, and that floor is like $500,000-$1,000,000. If you reuse them, you could make reduce that cost to a third. That's not a small thing.

I'd be surprised if it saves even 50%, and then you need to add back the cost of shipping the ISRU storage tanks and other parts, also per colonist, from Earth.   This is also part of the floor.

But here's a fun fact.  Common learning curve discount is 20% per doubling in production volume.
When you go from two ships to two-thousand (10 doublings), the cost per ship goes down to 0.8 ^ 10 = 0.1 of the original cost.
This is what they should focus on.

[steveleach]

NOT reusing the starships puts a floor on the price that SpaceX can reasonably afford to charge passengers to Mars, and that floor is like $500,000-$1,000,000. If you reuse them, you could make reduce that cost to a third. That's not a small thing.

I'd be surprised if it saves even 50%, and then you need to add back the cost of shipping the ISRU storage tanks and other parts, also per colonist, from Earth.   This is also part of the floor.

But here's a fun fact.  Common learning curve discount is 20% per doubling in production volume.
When you go from two ships to two-thousand (10 doublings), the cost per ship goes down to 0.8 ^ 10 = 0.1 of the original cost.
This is what they should focus on.

You could use that argument to justify only using cars for one trip though: think about how many we would need to build, and how many doublings that is, so how cheap the cars would be using that formula.

[Twark_Main]

...Simpler than removing pieces habitats from a cargo starship and assembling them on the ground is to use 2 starships to lower a 3rd human rated starship to the ground flat.

How about a mobile crane?

Human rated starships will already have 1-2m of plastic radiation protection

Try working out the mass on that. It is... not small. 

You only really need 20-30 cm of plastic for radiation. The remaining 0.7-1.8 meters would achieve very little incremental dose rate reduction.

[Twark_Main]

I have been wondering if they will send raptors back to be reused.  They could, but will it be worth it?

Raptors and Raptor spare parts should be far more valuable on Mars. There will be a glut on Earth.

Just cover and store them outside,Tatooine style. 

[waveney]

Well I have actually modelled a likely starting of a colony.

Synod 0: 4 or 5 cargo ships.   1 deploys Marslink satellites and MPS (Mars GPS). and 4 land (or attempt to) - 2 with ISRU plants, 2 with supplies. (2026?)

Synod 1: 2 Passenger ships, 7 cargo ships.  Gain a toe hold, live in a ship, start local exploration, start to establish a permanent base.  (1 passenger ship will return)  (2028?)

Synod 2: 2 Passenger ships, 15 cargo ships.  Complete the first dome and 1 building within it.  (1 passenger ship returns) (2031?)

Synod 3: 2 Passenger ships, 24 cargo ships.  Start real exploration of the planet (2 passenger ships - 1 empty and 4 cargo ships (mainly Raptors) return.  (2033?)

Plotting numbers beyond is difficult, but expect at least a doubling of the passenger ships each synod from this point, but less than a doubling of cargo ships.  All (most?) passenger ships will return, some cargo ships.  Most cargo will be retained for the resources they contain.  Also the ISRU refuelling will be limited.

[Twark_Main]

Even beyond spares and salvage, I am sure ships will be re-purposed as needed.  Tanks for the Sabatier process.  Or tip it over for habitats or workshops.

Why even bother tipping it over? Just separate Starship above the upper dome, and lower the payload bay to the ground.

Voila! You now have a compartmentalized gas storage tank and a multi-story hab. The hab has the unpressurized cargo bay on the ground floor (complete with conveniently located dual redundant airlocks), meaning you don't even need to cut through the pressure hull. 

It should be a relatively easy to make sure the plumbing etc allow for easy separation on Mars. Mainly you just need to ensure that all the tank-related systems are located on one side of your intended "cut surface," and all hab-related systems on the other side.

[AmigaClone]

Well I have actually modelled a likely starting of a colony.

Synod 0: 4 or 5 cargo ships.   1 deploys Marslink satellites and MPS (Mars GPS). and 4 land (or attempt to) - 2 with ISRU plants, 2 with supplies. (2026?)

Synod 1: 2 Passenger ships, 7 cargo ships.  Gain a toe hold, live in a ship, start local exploration, start to establish a permanent base.  (1 passenger ship will return)  (2028?)

Synod 2: 2 Passenger ships, 15 cargo ships.  Complete the first dome and 1 building within it.  (1 passenger ship returns) (2031?)

Synod 3: 2 Passenger ships, 24 cargo ships.  Start real exploration of the planet (2 passenger ships - 1 empty and 4 cargo ships (mainly Raptors) return.  (2033?)

Plotting numbers beyond is difficult, but expect at least a doubling of the passenger ships each synod from this point, but less than a doubling of cargo ships.  All (most?) passenger ships will return, some cargo ships.  Most cargo will be retained for the resources they contain.  Also the ISRU refuelling will be limited.

My timing would have two synods prior to starting with the crewed ships. One of the ships that landed in the first synod would be launched mostly empty back to Earth in the second of these synods. It's cargo would consist of certain components of one of the Starships that is staying - provided it can be disassembled remotely - and a variety of samples.

[lykos]

Mars-Starships will only fly back to Earth ("be reused") if there is enough propellant and something valuable to transport (people or cargo)!
Otherwise it is much better to let them on Mars!!
Have some arrived on Earth it depends for sure on their condition and the demand for ships if they can and will be repaired/reused again.

This "reuse-thing" for costsaving is especially necessary for LEO (Tanker!!, crew to space stations, cargo) and Moon, and the possibility to fly back from other planets if desired.
If somewhere in a distant future there will go thousands of ships to mars, things might change, but then Starships will have changed too!

[BitterJim]

NOT reusing the starships puts a floor on the price that SpaceX can reasonably afford to charge passengers to Mars, and that floor is like $500,000-$1,000,000. If you reuse them, you could make reduce that cost to a third. That's not a small thing.

I'd be surprised if it saves even 50%, and then you need to add back the cost of shipping the ISRU storage tanks and other parts, also per colonist, from Earth.   This is also part of the floor.

But here's a fun fact.  Common learning curve discount is 20% per doubling in production volume.
When you go from two ships to two-thousand (10 doublings), the cost per ship goes down to 0.8 ^ 10 = 0.1 of the original cost.
This is what they should focus on.

You could use that argument to justify only using cars for one trip though: think about how many we would need to build, and how many doublings that is, so how cheap the cars would be using that formula.

No, it wouldn't. For one thing, the cost to reuse a car for a second trip is a negligible part of the cost to build a new one (as opposed to the 1/2 assumed by MeekGee), which changes the math significantly. For another, that formula doesn't approach zero when factoring in all the trips you'd be taking. Then you're looking at 2^n*0.8^n*C=C*1.6^n (where 2^n is the number of trips and C is the current cost of a car). There are savings to be had from reusing ships, but with the long time between trips and relatively high cost to reuse, the economics are a lot different than your car or an LEO starship.

[waveney]

Another factor on reuse is how the ships land.

The early ones landing on Mars will have to use legs.  These are likely to be one use.

A returning ship can be caught by chopsticks.   But they are going to need repairs before they are reused.   They may not be worth it.

Later (quite a bit later) they will have chopsticks on Mars to catch ships there as well as earth.  This will save mass on the ships going and may then allow reuse.

Chopsticks may appear on Mars from Synod 4 (on my timeline above)