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NASA SLS/Orion/Payloads

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13 minutes ago, sh1pman said:

Ok, I didn’t really want to participate in this debate, but... @ZooNamedGames, come on. First you say this:

Then, when you’re told about Yusaku Maezawa and his flight, you dismiss it as “not pushing exploration forward”.

He is a person that has an interest in utilizing Starship/Super Heavy rocket. Here’s your answer, there is a demand for such a rocket. Why bringing up exploration here? That’s a very different topic which doesn’t help you support your original statement (that SS/SH has no commercial customers).

Passenger is not commercial customer. A seat that would be used, even if no one payed for it. Only one SpaceX’s dollar.

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Just now, ZooNamedGames said:

Passenger is not commercial customer. A seat that would be used, even if no one payed for it. Only one SpaceX’s dollar.

He paid money for it, right? In my book that counts as being a “commercial customer”. SpaceX use that money to make Starship that will be able to go to the Moon, Mars, etc. This is the example of a commercial passenger benefiting future exploration goals of other SpaceX customers like NASA. 

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1 hour ago, sh1pman said:

He paid money for it, right? In my book that counts as being a “commercial customer”. SpaceX use that money to make Starship that will be able to go to the Moon, Mars, etc. This is the example of a commercial passenger benefiting future exploration goals of other SpaceX customers like NASA. 

One customer does not make a business.

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On the topic of Orion in general: if anyone wants to forward this on to Bridenstine, send it to someone you know in the industry, or simply post on social media, I'd greatly appreciate it:

https://medium.com/@davidstarlingm/back-to-the-moon-61a47c60f78d

Quote

The solution is to utilize Delta IV Heavy’s proven capability to launch Orion along with Dragon 2’s docking abilities and the extraordinarily high payload capacity of Falcon Heavy.

In a near-repeat of the EFT-1 launch, a Delta IV Heavy operating out of SLC-37 would send Orion and its service module into an elliptical orbit with a stable perigee. Orion would separate and validate its systems in this orbit. Immediately after Orion’s systems checked out and orbital inclinations aligned, Falcon Heavy would launch expendable, carrying an unmanned Dragon 2, into the same orbit. However, Dragon 2 would remain mated to the Falcon Heavy upper stage. Expending all three cores of Falcon Heavy would leave 45.3 tonnes of propellant residuals in low Earth orbit, of which 29.9 tonnes would still remain after matching orbits with Orion. The Falcon Heavy upper stage would have the same modifications used in its inaugural test flight to allow extended restart of the Merlin 1D Vacuum engine.

Orion would use its own thrusters to match orbits with the other vehicle, then hold position. Dragon 2, with its software updated to allow maneuvering while still attached to the Falcon upper stage, would execute autonomous docking. Although Dragon 2 previously docked while flying free of the upper stage, it is already able to compensate for shifts in the center of mass in order to carry externally-manifested payloads.

 
1*6YrLAHrAK9_JImcT45rxxg.png
Mockup courtesy KSP

Once Dragon 2 has firmly mated to the docking adapter on the nose of Orion, the Falcon Heavy upper stage would reorient using cold gas thrusters and then fire at perigee to push both Dragon 2 and Orion onto TLI. The combined stack, with Dragon 2, Orion, and the upper stage, would mass 71.1 tonnes at startup, and the M-1D would provide 1,860 m/s of additional impulse at minimum residual shutdown.

From an orbit with the same apogee as EFT-1, this would be enough to commit the stack to a lunar flyby with 80 m/s of margin. Dragon 2, Orion, and the upper stage would separate. The upper stage would be left on a disposal trajectory, while Dragon 2 and Orion would adjust their own paths independently: Dragon 2 to line up for free-return and Orion to orient for injection into the desired lunar orbit.

 

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1 hour ago, ZooNamedGames said:

Passenger is not commercial customer. A seat that would be used, even if no one payed for it. Only one SpaceX’s dollar.

He's literally buying the entire flight. He's a commercial customer. There is no seat to the Moon and back without him, it's a charter.

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21 minutes ago, tater said:

He's literally buying the entire flight. He's a commercial customer. There is no seat to the Moon and back without him, it's a charter.

If Musk wanted it that badly he’d use SpaceX’s dollar. This flight just happens to be a good way to test the vehicle and show what it’s capable of.

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14 minutes ago, ZooNamedGames said:

If Musk wanted it that badly he’d use SpaceX’s dollar. This flight just happens to be a good way to test the vehicle and show what it’s capable of.

It’s a paying customer. Not his problem or concern, really, just like they don’t care what Arabsat will broadcast.

Dearmoon is a customer. That it happens to be cool... happy plus.

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amazing. TBH, if he is still administrator, when SS/SH is done, he will probably make good use of it.

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17 minutes ago, Barzon Kerman said:

amazing. TBH, if he is still administrator, when SS/SH is done, he will probably make good use of it.

I looked it up. Not counting acting administrators, the average term is 1536 days (not counting Bridenstine) or just over 4 years. Term length is decided by the President, but many administrators have served across multiple presidents and a good chunk of them have served across party changes, so if he keeps doing good things and politically wise things, he should be in office for a while.

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I remember seeing something about him proposing to lengthen the administrator term to 10 years, and make it permanent, not changing on the whim of POTUS

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Posted (edited)
1 hour ago, Barzon Kerman said:

I remember seeing something about him proposing to lengthen the administrator term to 10 years, and make it permanent, not changing on the whim of POTUS

I like Bridenstine a lot. Guy's got an actual enthusiasm for his job. He's reasonably adept at navigating changing political winds, which is a plus. I don't always see eye-to-eye with him, but he's grown on me. It's nice to have a NASA administrator put so much effort into everything he does.

If Trump gets booted out of office in the next election, I hope whoever replaces him asks Bridenstine to not tender a resignation and to stay on NASA during the next administration.

Edited by jadebenn

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Posted (edited)

This thread might someday need splitting into Gateway/lunar vs SLS/Orion (seems OK for now, as Gateway is the current raison d'être for the system). That said, 5m Centaur (Vulcan upper stage) seems like a good starting point for a reusable system near the Moon, eventually moving to ACES. Related to SLS, it would be nice if NASA got POed enough to dump Boeing for the upper stage (EUS), and let LockMart have it (Centaur). Centaur is flat out better than DCSS, which is all EUS and ICPS are, writ larger. An 8.4m Centaur would be a heck of a thing.

Edited by tater

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Posted (edited)
19 minutes ago, tater said:

Centaur is flat out better than DCSS

How? RL10B-02 has 12 seconds more ISP than RL10C-1 (462s vs 450s), and 5m DCSS has more props (27.2t vs 20.8t). Centaurs dry mass is slightly lower, though (2.5t vs 3.5t). Centaur can only outperform DCSS with the lightest payloads (<1t) on super high energy interplanetary trajectories (where lower dry mass matters the most).

Edited by sh1pman

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41 minutes ago, tater said:

This thread might someday need splitting into Gateway/lunar vs SLS/Orion (seems OK for now, as Gateway is the current raison d'être for the system). That said, 5m Centaur (Vulcan upper stage) seems like a good starting point for a reusable system near the Moon, eventually moving to ACES. Related to SLS, it would be nice if NASA got POed enough to dump Boeing for the upper stage (EUS), and let LockMart have it (Centaur). Centaur is flat out better than DCSS, which is all EUS and ICPS are, writ larger. An 8.4m Centaur would be a heck of a thing.

We head butt a lot but I agree for any future hardware Boeing should be dropped. Recent developments and the lack thereof in other aspects has proven they can’t meet requirements and milestones and if they do, sacrifice safety in their designs and builds.

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21 minutes ago, sh1pman said:

How? RL10B-02 has 12 seconds more ISP than RL10C-1 (462s vs 450s), and 5m DCSS has more props (27.2t vs 20.8t). Centaurs dry mass is slightly lower, though (2.5t vs 3.5t). Centaur can only outperform DCSS with the lightest payloads (<1t) on super high energy interplanetary trajectories (where lower dry mass matters the most).

I don't mean a current Centaur, a larger, nonexistent Centaur (a full 8.4m dia version). You've just compared 5m DCSS to 3m Centaur. A 5m Centaur will hold substantially more propellant, but yeah, they are opting for a higher TWR (and slightly lower Isp) version.

 

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Posted (edited)
34 minutes ago, sh1pman said:

How? RL10B-02 has 12 seconds more ISP than RL10C-1 (462s vs 450s), and 5m DCSS has more props (27.2t vs 20.8t). Centaurs dry mass is slightly lower, though (2.5t vs 3.5t). Centaur can only outperform DCSS with the lightest payloads (<1t) on super high energy interplanetary trajectories (where lower dry mass matters the most).

Centaur pretty much always outperforms the lighter DCSS, and a larger Centaur would likely outperform the 5m DCSS as well - despite the lower ISP.

I asked one of the engineers working on SLS why they aren't using Centaur for ICPS a while back. After some time he came back and told me it was apparently for no reason at all. According to some performance simulations Centaur could outperform DCSS on some missions. Also, DCSS is limited to a single engine from what I remember.

A 5.4m Centaur is under development, apparently - Centaur V.

Also, from my understanding Centaur is effectively man-rated, at least the current version is. A 5m version would probably need to go through that process again.

Oh, and:

Centaur (all variants): 245 launches

DCSS (all variants): 39 launches

45 minutes ago, tater said:

This thread might someday need splitting into Gateway/lunar vs SLS/Orion (seems OK for now, as Gateway is the current raison d'être for the system). That said, 5m Centaur (Vulcan upper stage) seems like a good starting point for a reusable system near the Moon, eventually moving to ACES. Related to SLS, it would be nice if NASA got POed enough to dump Boeing for the upper stage (EUS), and let LockMart have it (Centaur). Centaur is flat out better than DCSS, which is all EUS and ICPS are, writ larger. An 8.4m Centaur would be a heck of a thing.

Centaur is honestly my favorite rocket stage. I wonder what would have happened if the Saturn I Centaur ever flew. Could've been cool...

They'd probably have to use Centaur V to get the most out of it on SLS.

Edited by Bill Phil

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Don’t think it would be wise to redesign the core stage of the SLS though. Simply because that would string out development time and costs out further.

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Just now, ZooNamedGames said:

We head butt a lot but I agree for any future hardware Boeing should be dropped. Recent developments and the lack thereof in other aspects has proven they can’t meet requirements and milestones and if they do, sacrifice safety in their designs and builds.

And Centaur will already be man rated for CST-100, anyway.

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Just now, ZooNamedGames said:

Don’t think it would be wise to redesign the core stage of the SLS though. Simply because that would string out development time and costs out further.

They have to redesign the core stage - otherwise they will suffer tremendous gravity losses on later variants. 

4 engines just doesn't cut it.

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Posted (edited)
3 minutes ago, ZooNamedGames said:

Don’t think it would be wise to redesign the core stage of the SLS though. Simply because that would string out development time and costs out further.

Yeah, there's no way that happens. SLS flies with the core stage and SRBs, at least until it looks like a waste of money to keep flying it.

2 minutes ago, Bill Phil said:

They have to redesign the core stage - otherwise they will suffer tremendous gravity losses on later variants. 

4 engines just doesn't cut it.

Wasn't the plan to dump the Shuttle SRBs in favor of better side boosters (to avoid redesign of the core)?

(BTW, looks like with liquid side boosters, SLS Block 2 is actually useful)

Edited by tater

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4 minutes ago, tater said:

Wasn't the plan to dump the Shuttle SRBS in favor of better side boosters (to avoid redesign of the core)?

And because they still don't entirely trust ATK's boosters.

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2 minutes ago, tater said:

Wasn't the plan to dump the Shuttle SRBs in favor of better side boosters (to avoid redesign of the core)?

Maybe, but if I recall they haven't done really any work on that, since Block 2 is basically dead. 

Even with such boosters the core is still flying alone for quite some time. It's not an optimal design in terms of staging either (neither was Shuttle, though).

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What would it take to make SLS/Orion more useful?

1a. Block 2, though that was only supposed to be cargo, so no need to man rate the new side boosters.

1b. If The advanced boosters were the liquid type proposed, cargo goes to 150t. Loft Orion some other way, and you can do whatever with that.

2. A better upper stage. EUS is pretty marginal, and boiloff is still a serious issue, so EUS is just a TLI stage, with any excess capacity wasted (ie: a small mass comanifested payload). Pushing for 8.4m ACES, instead? If the comanifested payload on Block 1b was underweight (likely), then Stage 2 will do TLI, while having residual propellants. If those props can be maintained for days, then S2 can potentially do a LOI burn. Given the weak Orion SM, this matters.

3. Orion could get a better SM. When used for Gateway, it doesn't really need it, but assume that a comanifested payload is never needed, since the extra 11t Block 1b offers can't get enough lander there (or a segment). Send lander parts ahead, and use extra 11t to make a SM that allows Orion to go directly to LLO, to meet with lander system in LLO?

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15 minutes ago, tater said:

BTW, looks like with liquid side boosters, SLS Block 2 is actually useful

Probably a stupid question, but is it possible for SLS to launch with more than 2 side boosters?

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