SpaceX lunar lader

[JF Mezei]

If I am not mistaken, the big raptor engines would be used only to go
from earth to that weird lunar orbit, and actual lunar operations
between "Gateway" and lunar surface (in both directions) more likely to
be those thrusters placed higher up the stack.


It is wise to carry those 6 raptors as dead weight between Gateway and
lunar surface? Do we kow if the actual lunar engines would draw from
the same tanks as the raptors or need dedicated tanks?

Or is the official plan to use the raptors for much of trip between
Gateway and surface and back ,amd the side thrusters only for operations
within X metres of surface?

Considering what the stack did at its first launch to the concrete base
and OLM, is it wise to fire Raptors with the Starship "safely" above a
lunar outpost? Without atmosphere to disperse thrust, won't thrust from
those 6 raptors reach way down and potentially obliterate a lunar
outpost below?

[Snidely]

Post by JF Mezei
If I am not mistaken, the big raptor engines would be used only to go
from earth to that weird lunar orbit, and actual lunar operations
between "Gateway" and lunar surface (in both directions) more likely to
be those thrusters placed higher up the stack.
It is wise to carry those 6 raptors as dead weight between Gateway and
lunar surface? Do we kow if the actual lunar engines would draw from
the same tanks as the raptors or need dedicated tanks?
Or is the official plan to use the raptors for much of trip between
Gateway and surface and back ,amd the side thrusters only for operations
within X metres of surface?
Considering what the stack did at its first launch to the concrete base
and OLM, is it wise to fire Raptors with the Starship "safely" above a
lunar outpost? Without atmosphere to disperse thrust, won't thrust from
those 6 raptors reach way down and potentially obliterate a lunar
outpost below?

I don't think there's been enough information provided for to be sure,
but you can spend some time working out the delta-v required (as a
shortcut, you can start with the delta-v the LEM used, even though that
was a different orbit, so the altitude delta is probably different),
and the amount of mass involved, and make a better guess. But since
Raptors are deeply throttable, and the Starship dry mass is a little
larger than the LEM's, and since payloads the mass of the LEM may be
involved, I'd expect the Raptors to be used until close to the lunar
surface.

The first landings will probably not involve spraying aluminates in the
exhaust to provide a bit of site preparation, and the dozer to dig the
flame trench might be on a later flight, but careful location of any
permanent presence devices and structures could minimize the danger of
liftoff exhaust.

Note that the National Team's Version 2 lander will also be carrying
the motors used to get from earth orbit to lunar orbit.

/dps

[Snidely]

Post by JF Mezei
Considering what the stack did at its first launch to the concrete base
and OLM, is it wise to fire Raptors with the Starship "safely" above a
lunar outpost? Without atmosphere to disperse thrust, won't thrust from
those 6 raptors reach way down and potentially obliterate a lunar
outpost below?

You might be interested in this interview with Dr Phil Metzger:

(Rover fans might like to start a couple of miunutes earlier)

/dps

[Snidely]

On Sunday or thereabouts, Snidely declared ...

Post by Snidely

Post by JF Mezei
Considering what the stack did at its first launch to the concrete base
and OLM, is it wise to fire Raptors with the Starship "safely" above a
lunar outpost? Without atmosphere to disperse thrust, won't thrust from
those 6 raptors reach way down and potentially obliterate a lunar
outpost below?

http://youtu.be/K6Z1YjROHHA
(Rover fans might like to start a couple of miunutes earlier)

Dr Metzger is also co-author of a paper Gizmodo discusses at
<URL:https://gizmodo.com/future-moon-landings-jeopardize-spacecraft-dust-1850509129>
The paper is at
<URL:https://arxiv.org/abs/2305.12234>

/dps

[JF Mezei]

Post by Snidely
http://youtu.be/K6Z1YjROHHA
(Rover fans might like to start a couple of miunutes earlier)

Thanks. counter intuitive for me. Was thinking that without atmpsphere,
molecules would maintain whatever innertia they had when they leave the
engine.

But thinking a bit more, I assume the gas at the lower edge of engine
bell is still compressed so once leaving engine bell, would be free to
expand both horizontally and vertically. But without atmosphere,
vertical and horizontal speeds would remain constant until it hits the
ground.

I guess the fluid dynamics guys will calculate at what altitude the
raptors could be fired without obliterating the Moon base with people in
it.