A list of things SpaceX will unlikely be doing

[Lar]

Surface power on the other hand makes a lot of sense... at some point a solar infrastructure will be bootstrapped, it doesn't make sense not to... but for initial power a small reactor might mass less and be more plug and go...

Initial reactor needs to be like 1 Megawatt, though. Kilopower is only up to 10kW, you'd need 100 of them... & they're expensive. And nothing else is really under development.

I remember a rumor going round that SpaceX had talked to some marine reactor company, and add that to Gwynne saying they were seeking nuclear material and you get something bigger than 10kW I think.

[rakaydos]

Surface power on the other hand makes a lot of sense... at some point a solar infrastructure will be bootstrapped, it doesn't make sense not to... but for initial power a small reactor might mass less and be more plug and go...

Initial reactor needs to be like 1 Megawatt, though. Kilopower is only up to 10kW, you'd need 100 of them... & they're expensive. And nothing else is really under development.

I remember a rumor going round that SpaceX had talked to some marine reactor company, and add that to Gwynne saying they were seeking nuclear material and you get something bigger than 10kW I think.

The 10 kw Kilopower is 2 tons. (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160012354.pdf page 4)
How strong is the BFS's crane? how much bigger can a reactor get, before it has to stay on the spaceship?

[JamesH65]

Surface power on the other hand makes a lot of sense... at some point a solar infrastructure will be bootstrapped, it doesn't make sense not to... but for initial power a small reactor might mass less and be more plug and go...

Initial reactor needs to be like 1 Megawatt, though. Kilopower is only up to 10kW, you'd need 100 of them... & they're expensive. And nothing else is really under development.

I remember a rumor going round that SpaceX had talked to some marine reactor company, and add that to Gwynne saying they were seeking nuclear material and you get something bigger than 10kW I think.

The 10 kw Kilopower is 2 tons. (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160012354.pdf page 4)
How strong is the BFS's crane? how much bigger can a reactor get, before it has to stay on the spaceship?

I think we can guarantee that the crane in the BFS will be big enough to handle all possible/known requirements.

[CuddlyRocket]

How strong is the BFS's crane? how much bigger can a reactor get, before it has to stay on the spaceship?

Depends where that spaceship is: a crane's capacity is determined by the weight its load-bearing structures can sustain - and that weight includes the weight of its cable etc., all of which depends on gravitational strength.

I think we can guarantee that the crane in the BFS will be big enough to handle all possible/known requirements.

Certainly. Although you could have two cranes (at each end of the loading hatch) to allow for faster loading/unloading and some redundancy, which can work together for really heavy objects.

[docmordrid]

Alternative unloading plan: the early ships unload the parts for  mobile elevators which then have the capability to unload much heavier items, de-crew more elegantly etc. Crop of the Moon Base Alpha image,

[Dalhousie]

Surface power on the other hand makes a lot of sense... at some point a solar infrastructure will be bootstrapped, it doesn't make sense not to... but for initial power a small reactor might mass less and be more plug and go...

Initial reactor needs to be like 1 Megawatt, though. Kilopower is only up to 10kW, you'd need 100 of them... & they're expensive. And nothing else is really under development.

I remember a rumor going round that SpaceX had talked to some marine reactor company, and add that to Gwynne saying they were seeking nuclear material and you get something bigger than 10kW I think.

Ship reactors are cooled by seawater.  You would need a new cooling system.  Rule of thumb for thermal output of marine reactors is, I think, 5 X 10 electrical capacity. So 5-10 MW radiators.

[Lar]

Alternative unloading plan: the early ships unload the parts for  mobile elevators which then have the capability to unload much heavier items, de-crew more elegantly etc. Crop of the Moon Base Alpha image,

Agree.  A mass optimization would be to (eventually) remove the crane (just leave the mounts so it can be put back) from ships that are on the Earth-Luna run as they don't need it... but leave it in for ships that venture elsewhere, especially new places.... But I bet SpaceX doesn't bother with that mass optimization.

[envy887]

Surface power on the other hand makes a lot of sense... at some point a solar infrastructure will be bootstrapped, it doesn't make sense not to... but for initial power a small reactor might mass less and be more plug and go...

Initial reactor needs to be like 1 Megawatt, though. Kilopower is only up to 10kW, you'd need 100 of them... & they're expensive. And nothing else is really under development.

I remember a rumor going round that SpaceX had talked to some marine reactor company, and add that to Gwynne saying they were seeking nuclear material and you get something bigger than 10kW I think.

Ship reactors are cooled by seawater.  You would need a new cooling system.  Rule of thumb for thermal output of marine reactors is, I think, 5 X 10 electrical capacity. So 5-10 MW radiators.

How about a ground-coupled heat exchanger? Does the temperature, thermal capacity, and conductivity of the near subsurface at Mars support dumping that kind of heat with a small-ish HX?

[ValmirGP]

* No use of metallic tanks, carbon fibre all the way

Falcon family has metallic tanks. BFR will have CF tanks so no more metallic tanks after Falcon family production stops.

Highly speculative question. Could it be that from these assertions it would be also feasible/desirable to convert F9/FH tanks to CF too?

[Jim]

Highly speculative question. Could it be that from these assertions it would be also feasible/desirable to convert F9/FH tanks to CF too?

No, since they are going to be retired
 

[Lar]

How about a ground-coupled heat exchanger? Does the temperature, thermal capacity, and conductivity of the near subsurface at Mars support dumping that kind of heat with a small-ish HX?

There is a whole Power on Mars[1] thread that went through a lot of this. One important thing to rememeber is that on Mars, heat is not a thing to be shed. Rather it is a useful byproduct that can be used for many things.. process heat for the Sabatier, greenhouse heating, liquefaction of ice mined and a scad of other things. Might take several heat exchanger loops before you have water that is highly unlikely to have radioactive traces in it high enough to be worrisome. But you also don't really care if the heat exchangers are leaking heat to the atmosphere....

1 - https://forum.nasaspaceflight.com/index.php?topic=39785

[hkultala]

Added few more.. also edited these to the first message

8 ) They will not drop FH now when it's ready and delay all FH missions ~5 years to move them to BFR/BFS.


9) They will not switch back to 12m BFR/BFS , at least until their Mars colony already exists.

Their facilities can handle 9m but not 12m, their engines are sized for 9m, not 12m. 9m is much better for general purpose usag.

[JasonAW3]

Highly speculative question. Could it be that from these assertions it would be also feasible/desirable to convert F9/FH tanks to CF too?

No, since they are going to be retired

Eh, you never know, the F9's could still be pretty useful as strap-ons for a BFR Super Heavy design.  (Yes, I realize that the BFR booster would need to be beefed up for something like that, but it would be possible).

[envy887]

Highly speculative question. Could it be that from these assertions it would be also feasible/desirable to convert F9/FH tanks to CF too?

No, since they are going to be retired

Eh, you never know, the F9's could still be pretty useful as strap-ons for a BFR Super Heavy design.  (Yes, I realize that the BFR booster would need to be beefed up for something like that, but it would be possible).

And that would be inefficient and expensive. If the 9m BFR works great and there is demand for an even heavier LV, building a 12m or 15m version would be far more effective.

Falcon will be done once DoD switches to BFR.

[philw1776]

Highly speculative question. Could it be that from these assertions it would be also feasible/desirable to convert F9/FH tanks to CF too?

No, since they are going to be retired

Eh, you never know, the F9's could still be pretty useful as strap-ons for a BFR Super Heavy design.  (Yes, I realize that the BFR booster would need to be beefed up for something like that, but it would be possible).

Not only bad design but totally against SpaceX's cost philosophy.  Now you have 2 completely different propellant families, adding cost, and the F9 is NOT designed clean sheet, ground up to be rapid, inexpensive launch & re-launch servicable.  A Kerbal lego rocket fantasy out of whack with engineering reality.

[hektor]

At some point there were discussion the Falcon 9 would lift off from ASDS and land back on launch site to save on trips by the ASDS. Can we consider now that this is something Space-X will not do ?

[nacnud]

Depends where that spaceship is: a crane's capacity is determined by the weight its load-bearing structures can sustain - and that weight includes the weight of its cable etc., all of which depends on gravitational strength.

The crane could be very light, a dyneema rope strong enough to lift 2 tonnes in lunar gravity masses less than half kilo per 100m

http://www.samsonrope.com/Pages/Product.aspx?ProductID=872

[envy887]

At some point there were discussion the Falcon 9 would lift off from ASDS and land back on launch site to save on trips by the ASDS. Can we consider now that this is something Space-X will not do ?

They are probably saving that for BFR and even then it's well down the road.