Is SLS outdated or just right

[Nuke]

2 hours ago, darthgently said:

I still think Lunarized Crew Dragon as  lunar lander, LEM,  is compelling when paired with a service module.  So no separate LEM.   Lugging a heat shield to the lunar surface and back to orbit annoys, but what if the heat shield stayed with the service module in lunar orbit, but coupled to Dragon and detached from SM upon return?   I'm just trying to get mileage out of what exists.  If that is a crime, then SLS is a war crime, ha

i think the retrofits would be such that you are better off with a purpose built lander. you would need extended life support consumables. i suppose you could install tankage in the trunk and use the super dracos as your main propulsion. strip out the heat shield for extra tankage so you can leave the trunk on the moon, this worked out well for the lm, except in this case you would use the same engines. because you would need fittings for the hypergolic propellants the craft would technically be refuelable, though with the trunk on the moon you wouldnt have the land and return capability (landing on the moon might be possible but without return capability, i dont see that being useful unless you have a moon base).

two problems remain, if the changes are significant you will need to have the thing go through the man rating process a second time, and if you are going to do that you are better off making a more optimized design. spacex has a knack for being able to develop hardware fast. the other problem is this is just apollo redux, mostly done for political brownie points with science being a distant second. continuing to develop starship gives you a lot more capabilities and can help bootstrap rapid development of a moon base. its entirely possible that spacex could do this without sls at all, but i suspect spacex is relying on the contracts to pay for it, so it doesn't go to the moon without sls. 

[RCgothic]

Whether it not we have SLS, a lander would have to be developed. The questions are if, without SLS:

1) Could we design a lander as effective as the Artemis landers?

A resounding yes. SLS is not sending the lander in Artemis, so we can expect no substantial difference in lander capability here. In fact we can expect an improvement, because for fast transits the round trip DV of LOI, landing and ascent is less than the round-trip DV of NRHOI, landing and ascent, so for the same delivered mass a greater proportion could be devoted to the mission instead of propulsion.

2) Could we get crew to and from rendezvous with the lander?

Again, a resounding yes. With a 16t hypergolic propulsion module met in LEO and a docking target in the trunk, Dragon can get in and out of LLO from TLI with reasonable modification. The Falcon upper stage can send over 32t through TLI if falcon heavy puts it into LEO with 63.5t of residuals and it meets the mission there. And this has none of SLS's cost or cadence issues. Such a mission mode could easily support permanent inhabitation.

[DDE]

On 2/13/2024 at 11:18 AM, RCgothic said:

SLS is not sending the lander in Artemis

...which is, frankly, absolute idiocy that I still fail to understand.

[tater]

1 hour ago, DDE said:

...which is, frankly, absolute idiocy that I still fail to understand.

Meaning it should sent the lander, not the capsule?

[RCgothic]

2 hours ago, DDE said:

...which is, frankly, absolute idiocy that I still fail to understand.

If SLS were to send the lander as well, if it had twice the payload capacity it still wouldn't be as good as either lander in the current Artemis plans. The co-manifest volume isn't big enough.

Alternatively SLS would need both the ability to launch twice as many times per calendar year and to launch twice within a very short interval to supply both the lander and crew. For which, lol, Boeing. And even then, relying on SLS would set back the development of reusability and orbital refilling which are IMO necessary techs which are already long overdue.

[DDE]

12 hours ago, RCgothic said:

And even then, relying on SLS would set back the development of reusability and orbital refilling which are IMO necessary techs which are already long overdue.

Boeing may disagree that those are good things.

[RCgothic]

Well Boeing isn't exactly renowned for its judgement.

Edited February 17 by RCgothic

[magnemoe]

On 2/3/2024 at 7:52 PM, Nuke said:

as far as space goes the dragon capsule has plenty of leg room, but it has endurance limits, iirc, as with any other orbital station wagon. it was designed for leo, not lunar operations after all.  it could probibly be retrofit for the job though.

you could probibly launch with a service module (replacing the trunk) in the heavy config just fine.  and a second heavy can bring up the lander.  possibly all without expending a stage. whats the maximum cadence for the heavy, can two be launched at a short enough interval? does spacex even need nasa to go to the moon?

i still dont think the sls is useless though, it still can launch a lot of payload and thus has a place. even if it is more of a governmental flex than a launch platform.

You could probably launch Orion on FH and even an 3rd launch for a transfer stage cheaper if needed. SpaceX don't bother they want to use Starship. 
"Hate that name, I demand they launch one to Alpha Centauri or rename it" Yes its the far most impressive rocket in development but. 
But its also overkill for moon landings, but if you have an big rig and wife has the other car using the big rig to buy something small is than ordering an taxi or other solutions. 

Now then the SLS plans started it could make some sense but not in the current environment then they even rely on Starship or New Glenn for the landings and both making SLS outdated.

[darthgently]

1 hour ago, magnemoe said:

You could probably launch Orion on FH and even an 3rd launch for a transfer stage cheaper if needed. SpaceX don't bother they want to use Starship. 
"Hate that name, I demand they launch one to Alpha Centauri or rename it" Yes its the far most impressive rocket in development but. 
But its also overkill for moon landings, but if you have an big rig and wife has the other car using the big rig to buy something small is than ordering an taxi or other solutions. 

Now then the SLS plans started it could make some sense but not in the current environment then they even rely on Starship or New Glenn for the landings and both making SLS outdated.

And..if you are going to take the big rig, you might as well move a lot of stuff.  When you come home from Costco with a 53' full of toilet paper when she only asked for a few rolls she may be perplexed.  Until you explain that you will be delivering it to another location for a fee that will cover the house payment and a small supply of toilet paper.   The point being that it will be great to get past thinking of space missions as small errands and start moving massive amounts of cargo.  I like the idea of starting with an Earth-Moon major cargo hauler and not a "lander".

Edited February 18 by darthgently

[AckSed]

As a postscript to the thread, here is Ivan Bekey in 2000, champion of reusability and SSTO inside NASA, wondering why Shuttle-derived launch vehicles are being considered as "affordable" competitors to the 2nd gen. RLV: https://spaceref.com/press-release/testimony-of-ivan-bekey-before-the-house-science-committees-subcommittee-on-space-and-aeronautics/

Quote

One of the main findings was that even though billions of dollars were spent on improving the Shuttle, the flight costs would not become significantly lower.
[...]
I am not aware of any study that has come to significantly different conclusions, and thus I fail to see why a Shuttle Derived Vehicle would be baselined as one of the competitors to the 2nd generation RLV. It is, of course, appropriate to continue Shuttle upgrades that increase its safety, as NASA cannot afford another catastrophe. That does not mean, however, that we should designate a new Shuttle Derived vehicle to become one of only two competitors for the 2nd generation RLV, as it sends the message that NASA really intends to fly the Shuttle forever in one form or another.

The other competitor was the Venturestar. We know how that turned out. :-(

[SunlitZelkova]

Shuttle derived is more about using existing components for political reasons (keeping contractors in key states busy) than actual performance reasons, IMO.

[kerbiloid]

I would expect that they will produce as many Shuttle components for SLS, as they would if the shuttles were continuing flying until retiring.