[New] Space Launch System / Orion Discussion Thread

[Space Nerd]

Good point, I did not think about that.

[tater]

3 minutes ago, Space Nerd said:

Good point, I did not think about that.

So there is a legit set of testing unrelated to just exposing the astronauts to more radiation. In some ways it's an easier problem than LEO, though, because it is constant. Point radiators away from sun. Wonder of Gateway should have a sun shield? Apollo did the barbecue roll, but Gateway won't.

[RCgothic]

Both those points - radiation study and deep space temperature regulation can be done unmanned. Sure, you'd do them if you had a good reason to be there anyway, but they are not by themselves a good reason to go.

Endurance is best tested in LEO where if anything goes seriously wrong help is under an hour away. You simply don't schedule resupply, and if you don't make it to the planned endurance it's no big deal.

[sevenperforce]

6 hours ago, Space Nerd said:

How does the radiation strength in NRHO compare to that in the Van Allen belts and interplanetary space/around mars? (Isn't the moon usually in the earth's magnetic field?)

IIRC the moon is in the shadow of the Earth's magnetic field about a third of the time. Van Allen belt radiation is higher than interplanetary space. Mars has no magnetic field so radiation is the same there as interplanetary space.

 

[tater]

18 minutes ago, RCgothic said:

Endurance is best tested in LEO where if anything goes seriously wrong help is under an hour away. You simply don't schedule resupply, and if you don't make it to the planned endurance it's no big deal.

Yeah, being far away is not a feature.

[Silavite]

On 5/22/2020 at 9:56 AM, tater said:

The primary benefit of the cislunar region probably relates to spacecraft temperature regulation studies since it's a more constant environment than LEO day/night cycles (and light reflection from Earth), so there is some real utility there, I suppose.

You could get the same, constant sunlight from a sun-synchronous orbit with an inclination of 113.5 degrees (90 deg + Earth's equatorial tilt of 23.5 deg w.r.t. the ecliptic) and altitude of 3127 km. The path of the orbit follows the Earth's terminator, so the spacecraft would be under constant illumination.

Spoiler

Courtesy of Principia and RO

The downside is that this orbit is smack inside the inner Van Allen belt. That said, if you're looking to test the durability of a space system, this could be viewed as a positive.

Ignore this

Edited May 23, 2020 by Silavite
Orbital mechanics is hard, man

[tater]

19 minutes ago, Silavite said:

You could get the same, constant sunlight from a sun-synchronous orbit with an inclination of 113.5 degrees (90 deg + Earth's equatorial tilt of 23.5 deg w.r.t. the ecliptic) and altitude of 3127 km. The path of the orbit follows the Earth's terminator, so the spacecraft would be under constant illumination.

Wonder of either crew launch vehicle can insert them into SSO.

[Silavite]

4 hours ago, tater said:

Wonder of either crew launch vehicle can insert them into SSO.

@tater Ignore my previous post. Just realized that the precession will occur about the equator, not about the ecliptic. Thus the orbit will become misaligned from the terminator as the Earth revolves around the sun.

Edited May 23, 2020 by Silavite

[EchoLima]

Remember when Bolden said SLS was real, and Falcon Heavy was not? Well I found the source...

Edited May 26, 2020 by EchoLima

[tater]

 

[.50calBMG]

So for everyone saying SLS is a complete rocket, they still don't have a production piece for mating stage one with stage two. They have a quarter of a pathfinder test article. You may counter with the fact that it is a fairly simple thing to make relative to the rest of the rocket, to which I respond "then what took so long?"

Edited May 26, 2020 by .50calBMG

[tater]

If I am reading this : https://oig.nasa.gov/docs/IG-20-012.pdf right, the SRBs have had 3.4 billion contracted which includes one booster to test, then the 6 boosters for the first 3 Artemis missions.

That's 971 million per Artemis flight just for SRBs. I've been assuming they were "really expensive" at ~50M$ each (as much as an entire, real launch vehicle!). I've been off by an order of magnitude?

Maybe somehow because magic, going from a 4 segment to a 5 segment SRB took additional billions?

I've see other claims now that they are "only" 200M$ each.

584M$ in RS-25s. 400M$ (min) to 900M$ in SRBs. Plus ICPS (175M$). Is there any chance that the core stage itself costs less than either of those other components? I think not.

Anyway, a lower bound for marginal cost is over a billion just for SLS.

[sevenperforce]

27 minutes ago, tater said:

If I am reading this : https://oig.nasa.gov/docs/IG-20-012.pdf right, the SRBs have had 3.4 billion contracted which includes one booster to test, then the 6 boosters for the first 3 Artemis missions.

That's 971 million per Artemis flight just for SRBs. I've been assuming they were "really expensive" at ~50M$ each (as much as an entire, real launch vehicle!). I've been off by an order of magnitude?

Maybe somehow because magic, going from a 4 segment to a 5 segment SRB took additional billions?

I've see other claims now that they are "only" 200M$ each.

584M$ in RS-25s. 400M$ (min) to 900M$ in SRBs. Plus ICPS (175M$). Is there any chance that the core stage itself costs less than either of those other components? I think not.

Anyway, a lower bound for marginal cost is over a billion just for SLS.

Constellation really was a good idea, from a purely functional standpoint. Man-rate the thing that gets you to LEO, not the thing that needs to lift a bunch of cargo and fuel to LEO. Use common elements on your heavy lifter and your crew launcher wherever possible. Would have been even better if it had used a common upper stage, like how the second stage of the Saturn 1B was the third stage of the Saturn V.

Trouble was that the Shuttle's SRBs really weren't designed to launch single-stick.

Edited May 28, 2020 by sevenperforce

[tater]

Ares I was supposedly over a billion a flight, too.

Given SRB costs for SLS, now I am not surprised.

[sevenperforce]

22 minutes ago, tater said:

Ares I was supposedly over a billion a flight, too.

Given SRB costs for SLS, now I am not surprised.

If NASA had taken the DIRECT route with the Ares distributed-launch architecture, using the basic Shuttle SRBs, the SLWT with three SSMEs, and an S-IVB-derived common upper stage, it would have been able to launch a 16-tonne crew vehicle to LEO on the single-stick and send up 40 tonnes to LEO on the cargo lifter, then send the whole stack on TLI. That's 37% more payload to TLI than Saturn V or SLS Block 2, for the cost of a shuttle launch, an extra SRB, and two S-IVB upper stages (that assumes the cost of the shuttle would be comparable to the cost of the payload, which is probably a decent estimate).

[tater]

 

[wumpus]

On 5/20/2020 at 3:08 AM, Shpaget said:

Not exactly SLS related, but...

Doug Loverro, NASA's head honcho for human spacefligh, resigned. Ken Bowersox to take the seat, at least until permanent replacement is found.

https://www.nasaspaceflight.com/2020/05/loverro-resigns-bowersox-acting-heo-lead/

Looks like some information was passed to Boeing.  Which was always a pretty good guess for this type of thing.

https://www.washingtonpost.com/technology/2020/06/20/nasa-boeing-bid-probe/

(not sure which thread this belongs, but found the quoted text in this thread...).

[StrandedonEarth]

10 minutes ago, wumpus said:

https://www.washingtonpost.com/technology/2020/06/20/nasa-boeing-bid-probe/

Paywalled 

[mikegarrison]

According to the article, Boeing wanted to make some changes to their proposal after the deadline. The specific nature of the proposed changes raised some red flags that indicated possible insider information. That investigation led to Loverro's resignation. Further investigations continue.

[StrandedonEarth]

 

[Nightside]

My hot take:

They've been working on this thing HOW LONG and they just now tested it?

[RealKerbal3x]

9 minutes ago, Nightside said:

My hot take:

They've been working on this thing HOW LONG and they just now tested it?

Indeed. 

Also, Starship prototypes popping is still more impressive

[V_Bomb2001]

33 minutes ago, RealKerbal3x said:

Indeed. 

Also, Starship prototypes popping is still more impressive

Personally, I prefer a successful test to constant failures, but hey, that’s just me...

 

[RealKerbal3x]

14 minutes ago, V_Bomb2001 said:

Personally, I prefer a successful test to constant failures, but hey, that’s just me...

 

So do I, but that doesn't mean I don't find the failures impressive when they do happen

[tater]

It's a good test, and something that needed to happen, but to be honest when I saw the SLS tweet earlier and watched the vid, I didn't read the text, and I assumed SLS had retweeted (as they often do) a test that had happened years ago, because it never occurred to me this had not already been done.