Jump to content

[New] Space Launch System / Orion Discussion Thread


Recommended Posts

11 minutes ago, RealKerbal3x said:

SLS is a rocket designed with no specific mission in mind - overpowered for LEO operations, underpowered for beyond LEO. It's not powerful enough to get Orion to low lunar orbit, leaving landers to spend extra dV flying between a distant elliptical orbit and the surface. The entire program has been addled by delays and cost overruns (it was legally required to fly in 2016).

And it's not really the only option. Seeing as SpaceX is already designing a variant of Starship to land crew on the Moon, why not just cut SLS out entirely and send crew to and from LEO aboard Dragon/Starliner? With orbital refuelling and maybe some light aerobraking it could probably be done.

I can agree with what I put your comment in italics. But I don't agree with the  bold. That's a new design that would take months or years to test and try. Why not do both? have something that's been proven and tested AND something innovative at the same time. 

11 minutes ago, cubinator said:

The rocket isn't what I dislike about SLS. It's the convoluted management that prioritizes politics over missions. NASA hasn't been allowed to go through with actual lunar plans for a long time. By the time SLS is operational, multiple alternatives will be available for a tenth or a hundredth of the cost.

That sounds untrue. I'm pretty sure SLS is more expensive than Saturn V.

In the bold that's an interesting thing I haven't heard before. Its true that the SLS has some political management problems, but is that a big issue? I would say no. Politics has always been a key factor in NASA. Since politics isn't allowed on forums, i'll stop there.

59 minutes ago, tater said:

This is untrue.

I have said SLS sucks since the beginning because it has always been a "rocket to nowhere."

Saddled with Orion—as it has been from the start—it is completely incapable of useful BLEO missions, and it can never be made capable as long as Orion is the payload. Something has to go. Make a smaller spacecraft, and an updated SLS (Block 2) could do useful missions.

While most arguments I see online are because of starship, the forums is an exception. The OG post has been edited.

While I see SLS a good idea, I don't fully agree with the Orion concept. Seems obsolete when we already have Starliner or Dragon that can be put on top with a few modifications. 

25 minutes ago, RCgothic said:

It's basically optimized to send a specific spacecraft to a specific orbit where that spacecraft can't do anything useful without help and SLS is not flexible enough to be used for other missions.

Most of its LEO mass is fuel, but it could put up about 40-50 tons... But there aren't any monolithic payloads that size. If the payload is fuel, then it's a very expensive and infrequent way to refuel something in LEO.

For BLEO, other than crew flights its lack of availability has seen it stripped of its one assigned cargo mission.

There is nothing really wrong with that. SLS doesn't have to be a rocket of many purposes, it's like the Saturn V, it only had one purpose but then found other purposes later onto the program.

Link to post
Share on other sites

Now there's the politics, the cost, the ineffectiveness, all that.

Honestly I would feel much better about SLS if they weren't wasting RS-25s.

I don't understand why they aren't even going to attempt something like the Vulcan's SMART reuse concept.

That would make me feel a lot better about the program. 

Link to post
Share on other sites
1 minute ago, The Doodling Astronaut said:

I can agree with what I put your comment in italics. But I don't agree with the  bold. That's a new design that would take months or years to test and try. Why not do both? have something that's been proven and tested AND something innovative at the same time. 

And it's going to be four years at minimum until SLS is actually flying humans to land on the moon, and a similar length of time until that lunar variant of Starship is in service. SpaceX could be in a position to make an orbital Starship flight by the end of the year, and therefore testing aerobraking from orbit. Orbital refuelling is required for the lunar Starship to work, so, should Starship be selected as an Artemis lunar lander, they need to test that and get it working before SLS flies a lunar landing crew on Artemis III. 

6 minutes ago, Spaceman.Spiff said:

I don't understand why they aren't even going to attempt something like the Vulcan's SMART reuse concept.

I could see that adding five years to the program. Better to just wait for the commercial superheavy lift vehicles to come online.

Link to post
Share on other sites
9 minutes ago, The Doodling Astronaut said:

There is nothing really wrong with that. SLS doesn't have to be a rocket of many purposes, it's like the Saturn V, it only had one purpose but then found other purposes later onto the program.

Saturn was big enough to complete a lunar mission by itself, and flexible and available enough to be used for other missions such as lofting space stations in a single launch. 

SLS is not big enough to complete a lunar mission (with Orion) by itself, and neither flexible enough nor available enough to be used for other purposes.

SLS requires other heavy lift rockets to complete a distributed mission, which begs the question why not distribute the crew portion of the mission.

I reckon 2 medium lift rockets could put up a slightly modified Dragon/Starliner, a propulsion module based on an existing spacecraft bus, and the combined assembly could then be boosted to the moon by a heavy rocket that meets them in LEO with just fuel. It is already planned to send the lander separately.

Link to post
Share on other sites
5 minutes ago, The Doodling Astronaut said:

While I see SLS a good idea, I don't fully agree with the Orion concept. Seems obsolete when we already have Starliner or Dragon that can be put on top with a few modifications. 

They are not at all capable of a useful BLEO mission at this time. They cannot get back (lack of dv). They have SMs designed explicitly for LEO operations, and indeed ISS as the target, not long flight LEO missions. Yes, they could be fixed, but that was never in the scope of SLS, as they did not yet exist. So they'd need new TPS (or at least testing in the case of Dragon if it is capable already), and they would need a SM capable of doing what is needed.

The Orion CEV (Constellation) was supposed to serve both ISS, AND be used for lunar missions.The Orion MPCV (bizarre label given it doesn't even have ONE purpose, much less multi-purpose) is functionally the same vehicle, though heavier now, I think.

Looks like Block 1 B does ~38t to TLI (crew, says 42t cargo, so trajectory and LES probably impact that... call it 38-40t with "not Orion" as the spacecraft).

That would leave about 28t in LLO after the LOI burn. How big a lander is required?

 

 

Link to post
Share on other sites
3 minutes ago, tater said:

They are not at all capable of a useful BLEO mission at this time. They cannot get back (lack of dv). They have SMs designed explicitly for LEO operations, and indeed ISS as the target, not long flight LEO missions.

I think it wouldn't be too difficult for Dragon to be modified.

The place where the trunk is could be extended, and almost completely filled with fuel, and perhaps SpaceX could derived the SM engine based on the SuperDraco. 

(with a bigger nozzle)

Link to post
Share on other sites
7 minutes ago, Spaceman.Spiff said:

I think it wouldn't be too difficult for Dragon to be modified.

The place where the trunk is could be extended, and almost completely filled with fuel, and perhaps SpaceX could derived the SM engine based on the SuperDraco. 

(with a bigger nozzle)

SuperDraco would actually be massively overpowered.

Link to post
Share on other sites
6 minutes ago, Spaceman.Spiff said:

I think it wouldn't be too difficult for Dragon to be modified.

The place where the trunk is could be extended, and almost completely filled with fuel, and perhaps SpaceX could derived the SM engine based on the SuperDraco. 

(with a bigger nozzle)

It's certainly possible, the question is one of capability. ~38-40t to TLI is what Block 1B can do (minus the heavy Orion LES). So you need to get Starliner or Dragon on top, AND consumables for the trip duration, AND a lander.  The Apollo LEM was ~16t. So assuming that sort of sortie lander (larger, perhaps?) you have ~20-22t to play with. Looks like you could just do it assuming the dry mass* of the improved Dragon/Starliner CSM combo is ~8.5t (*I mean the mass minus props, wet with consumables like O2, water, etc)

Link to post
Share on other sites
1 hour ago, The Doodling Astronaut said:

But I don't agree with the  bold [variant of Starship to land crew on the Moon (...) With orbital refuelling and maybe some light aerobraking it could probably be done]. That's a new design that would take months or years to test and try. Why not do both? have something that's been proven and tested AND something innovative at the same time. 

Landing a Starship on the Moon or fueling it in orbit would take months or years to test and try, sure ... but that's also true of the SLS. It doesn't currently have a lander to send anywhere, and the spacecraft it is built to lift, it can't even send to the Moon. Orbital refueling isn't even on the table. Arguably Starship lacks those capabilities at the moment, but they are not even within the design specs of the SLS, so I'd say that puts them on even footing. 

Overall, I can agree that the SLS doesn't necessarily "suck" per se, but it definitely lacks a sensible purpose, and it's so incredibly expensive. That's why people ridicule it. It can't do anything useful, but it still costs oceans of money doing nothing useful. 

I mean, I've only done back-of-the-envelope math here, but I found you could build a to-scale model of the SLS out of chicken wire, stuff it with dollar bills, and light the whole thing on fire, and you'd have spent less money than the marginal cost of a launch - depending  slightly on how tightly the dollar bills are packed, of course.

Link to post
Share on other sites

FH is theoretically about 32t to TLI assuming the 32t makes is own way to LEO, which considering an F9 (ASDS recovery) is about 16t, is a nice multiple.

Edited by RCgothic
Link to post
Share on other sites
26 minutes ago, RCgothic said:

FH is theoretically about 32t to TLI assuming the 32t makes is own way to LEO, which considering an F9 (ASDS recovery) is about 16t, is a nice multiple.

?

Payload to GTO is 26.6t, and to Mars is 16.8t. TLI is in between.

Link to post
Share on other sites
2 minutes ago, tater said:

?

Payload to GTO is 26.6t, and to Mars is 16.8t. TLI is in between.

He means that a naked FHe can reach LEO with enough propellant to boost 32 tonnes to TLI "assuming the 32t makes its own way to LEO"

Link to post
Share on other sites
6 minutes ago, tater said:

?

Payload to GTO is 26.6t, and to Mars is 16.8t. TLI is in between.

 

6 minutes ago, tater said:

 

Yes, if the payload goes up on FH. If it goes up on two F9's, then that's 32t of spacecraft in LEO. 

FH then goes up with nothing but a fairing and a basic docking target, the combined spacecraft autonomously docks to it, and 63t of fuel residuals sends 32t to the moon from LEO easy.

EOR.

I'd like sevenperforce but I'm out for today.

Edited by RCgothic
Link to post
Share on other sites

Except all the replies about FH were in response to my reply to a specific suggestion of Dragon or Starliner on top of SLS. The point was single stack.

Link to post
Share on other sites

Think Tim (Everyday astronaut) summed it up well, its an impressive rocket, starship and long march 9  might be the only one heavier under development, starship is less payload to orbit and not sure about LM9.  
It would have been nice 10 years ago, it would been very nice if they could cheaply add engines below the drop tank and an second stage on top KSP style. 

But its not that much better than falcon heavy today who is  flying, New Glen and Starship is upcoming.  Give SpaceX an billion or half of it and they focus on getting the stack into LEO rather than reusing second stage. 
Second stage reuse is space shuttle only. Again impressive craft, nothing today have the capability but it was expensive. 
 

Link to post
Share on other sites

Starship Superheavy will blow SLS away.

SLS's payload to LEO is about 50t max (Block 2) plus a lot of fuel and stage (~130t total).

Starship is 100t payload plus 80t starship plus ~30t landing fuel 210t total without even considering expending Superheavy (which would still be cheaper than SLS).

Link to post
Share on other sites
4 hours ago, The Doodling Astronaut said:

While I see SLS a good idea, I don't fully agree with the Orion concept. Seems obsolete when we already have Starliner or Dragon that can be put on top with a few modifications. 

Neither Starliner nor Dragon are designed for long-duration flights.

Link to post
Share on other sites
16 hours ago, tater said:

Ares I to put Orion in LEO

As much as this would've been a fairly capable launcher I'm glad we didn't follow through with that one.

I honestly wonder what would be the 'easiest' way out for NASA to uprate SLS so it'd actually be useful to send a cargo to land once a la Apollo. Extra SRB segment ?

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...