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SLS / Orion / Beyond-LEO HSF - Constellation => Heavy Lift Launch Vehicle (HLV/SLS) => Topic started by: Chris Bergin on 02/24/2012 05:24 am

Title: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Chris Bergin on 02/24/2012 05:24 am
http://www.nasaspaceflight.com/2012/02/acronyms-ascent-sls-managers-create-developmental-milestone-roadmap/

Acronym soup time! Really enjoyed writing this one up, and I hope it's readable. Just thought it really important to get this info out there as we're watching a Launch Vehicle being born and it's good to get the review milestone and vehicle designation info out there.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Moonwalker on 02/24/2012 06:19 am
Interesting article, thank you - especially part about MPTA tests at KSC, interesting idea. Also, I can't wait to find out something more about SLS-3 (EM-3) mission and exploration roadmap.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Steven Pietrobon on 02/24/2012 07:12 am
Wow! Back down to four engines, which is what Direct recommended. Now they just have to shorten the core and fly with three engines for Block I and Block IA. According to Direct, this will put 95 t into LEO for Block I. Not sure what the new boosters will do with a shortened core and three engines for Block IA, but if 35 t were added from Block I to Block IA with a stretched core and four engines, then possibly NASA could get 95+35 = 130 t for Block IA. Oops! no need for Block II then. :-)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: rusty on 02/24/2012 08:19 am
Very good outline Chris.

Two points -
1) "Because this (booster) competition isn’t set to end until 2015, SLS teams have had to analyze both versions of the Block 1A, given the differences in their performance characteristics and environments – such as aerodynamic factors like Max Q, as well as vibration, acceleration, acoustics – thus the engineers need to ensure the core stage design is compatible with both options."

That seems like backward thinking - to design something for any/all or no future options. While it's a nice ability, it doesn't seem to be a necessary one.
Unless things have changed since the end of last year, ATK can support 11 launches with their current stockpile of SRBs and no recovery. Considering one launch every two years (starting with a possible hold down test in 2015), that means more/upgraded boosters won't be needed until the mid-2030's.
I don't think the booster competition is needed at this time, especially with budgets/timelines as tight as they are, and in 20yrs when more/better boosters are needed the burden should fall on the competitors to match the existing vehicle.


2) "The current plan is to use the (16) RS-25Ds on the (two Block 1 and) first two Block 1A flights, prior to switching to the expendable version of the engine, known as the RS-25E."

i) I'd assuming the RS-25D engines used in the 2015 hold down test will be refurbished and used on one of those flights.
ii) For years I have, and still think the selection of the RS-25 is a mistake. While the heritage is there, starting RS-25E production is an entirely new engine program (To say it's a modification of an existing program is as fallacious as saying the J-2X is a modification of the J-2S program). If a new engine is the route taken, why not make the RS-25 design much simpler while adding 150,000flb -- the STME. Or even better, use an existing production line based on RS-25 heritage, one that shares cost with another launch vehicle and is even simpler still and has an additional 150,000flb -- the RS-68.
iii) A question; Are the performance figures of a possible RS-25E close enough to state?
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: MATTBLAK on 02/24/2012 08:38 am
With the RS-68, clustering them close together was a base-heating concern on the various Ares V configurations. I presume SLS wouldn't be much different. Since the regeneratively-cooled RS-25 was clustered close on Shuttle, this made it better suited for the SLS corestage - along with their much higher Isp than RS-68.

Also, I recall that on the 'Shannon Side-Mount', the documentation shows one configuration using the RS-25's at an 111% percent throttle setting.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/24/2012 11:47 am
Very good outline Chris.

Two points -
1) "Because this (booster) competition isn’t set to end until 2015, SLS teams have had to analyze both versions of the Block 1A, given the differences in their performance characteristics and environments – such as aerodynamic factors like Max Q, as well as vibration, acceleration, acoustics – thus the engineers need to ensure the core stage design is compatible with both options."

That seems like backward thinking - to design something for any/all or no future options. While it's a nice ability, it doesn't seem to be a necessary one.
Unless things have changed since the end of last year, ATK can support 11 launches with their current stockpile of SRBs and no recovery. Considering one launch every two years (starting with a possible hold down test in 2015), that means more/upgraded boosters won't be needed until the mid-2030's.
I don't think the booster competition is needed at this time, especially with budgets/timelines as tight as they are, and in 20yrs when more/better boosters are needed the burden should fall on the competitors to match the existing vehicle.


2) "The current plan is to use the (16) RS-25Ds on the (two Block 1 and) first two Block 1A flights, prior to switching to the expendable version of the engine, known as the RS-25E."

i) I'm assuming the RS-25D engines used in the 2015 hold down test will be refurbished and used on one of those flights.

(ii) For years I have, and still think the selection of the RS-25 is a mistake. While the heritage is there, starting RS-25E production is an entirely new engine program (To say it's a modification of an existing program is as fallacious as saying the J-2X is a modification of the J-2S program). If a new engine is the route taken, why not make the RS-25 design much simpler while adding 150,000flb -- the STME.

(iii) Or even better, use an existing production line based on RS-25 heritage, one that shares cost with another launch vehicle and is even simpler still and has an additional 150,000flb -- the RS-68.

(iv) A question; Are the performance figures of a possible RS-25E close enough to state?

1. It's more forward thinking than backward thinking. It's looking at the entire program from a decadal pov rather than the short term. What LRB's can potentially bring to the table significantly outweigh the advantages of the SRB's, depending of course on their final design parameters, but they cannot be ready in time to drive the SLS design. So it is an appropriate decision to design the core to support either, so long as performance is not compromised by that decision, which it is not. We only want to build one core design – for the entire life of the program (3 to 5 decades). We're going to be flying this vehicle for the next 30-50 years, not just 11 flights. It's far better to take the time up front to make sure we make the correct configuration choices than to succumb to “we have enough SRB's for 11 flights so let's just down-select to them right away. Forget LRB's”. That is short-sighted thinking.

2. (i) Yes

    (ii) RS-25E is not an entirely new engine program. This design has been underway for many years now and is essentially at the point where the only big change remaining is the nozzle. Even that has already been conceptually designed and awaits only the production design and tooling to be put in place to build it (big picture).

    (iii) RS-68 has become a non-viable engine choice for SLS principally because of the use of SRB's. The ablatively cooled nozzle would not survive long enough for the vehicle to reach MECO because of the thermal environment at the base of the vehicle. A man rated regenerativly cooled version can certainly be designed and built. In fact that is what DIRECT v2 intended to do. But the door has already been closed to that and the Air Force is not amicable to reopening it. This was the final straw that broke the back of the Ares-V.

    (iv) They are but that data is still FOUO.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: sewand on 02/24/2012 01:36 pm
As to the LRB competition - is it firm knowledge that only Aerojet will bid, or would an RD-180-based solution still be possible? 
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Chris Bergin on 02/24/2012 02:15 pm
Thanks to the nice comments! :)

As to the LRB competition - is it firm knowledge that only Aerojet will bid, or would an RD-180-based solution still be possible? 

Not entirely certain, but it is "likely" to be an Aerojet vs ATK shoot out.

I've got comments from Aerojet, which are somewhat cagey. ATK aren't responding yet (and usually do, so they'll be carefully wording a response too). Will be an article.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: renclod on 02/24/2012 06:19 pm
    (iii) RS-68 has become a non-viable engine choice for SLS principally because of the use of SRB's.

So what if a LRB replaces the SRB ; would the RS-68 be re-considered ?

Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Chris Bergin on 02/24/2012 06:36 pm
    (iii) RS-68 has become a non-viable engine choice for SLS principally because of the use of SRB's.

So what if a LRB replaces the SRB ; would the RS-68 be re-considered ?



I'm thinking not. They seem very set on the RS-25s.

Of course, you never know! :)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: aquanaut99 on 02/24/2012 06:50 pm

I'm thinking not. They seem very set on the RS-25s.

Of course, you never know! :)

Well, the RS-25 is superior to the RS-68 in many ways. And I think that the RS-25E is supposed to be able to run at 111% rated performance, since it is not required to be reusable.

The RS-25 is one of the finest rocket engines ever made. The fact that NASA plans to keep on using it is a good idea, IMO.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: renclod on 02/24/2012 07:13 pm
Quote
They seem very set on the RS-25s.

The "Direct" advocates argued the case for RS-25s in the context of a large number of engines consumed per year, being as cheap as RS-68s (!).
However SLS as currently funded is anything but... large number of engines consumed per year.

Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Paul Howard on 02/24/2012 07:41 pm
I really enjoyed that article. This site's coverage of SLS is unrivalled.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/25/2012 02:42 am
    (iii) RS-68 has become a non-viable engine choice for SLS principally because of the use of SRB's.

So what if a LRB replaces the SRB ; would the RS-68 be re-considered ?



No.
SLS is a man-rated launch vehicle and the Air Force closed the door on RS-68 changes needed to man-rate the engine.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: rusty on 02/25/2012 05:06 am
Re;
A) RS-25E is not an entirely new engine program. This design has been underway for many years now and is essentially at the point where the only big change remaining is the nozzle. Even that has already been conceptually designed and awaits only the production design and tooling to be put in place to build it (big picture).

B) RS-68 has become a non-viable engine choice for SLS principally because of the use of SRB's. The ablatively cooled nozzle would not survive long enough for the vehicle to reach MECO because of the thermal environment at the base of the vehicle.

C) ...But the door has already been closed to that and the Air Force is not amicable to reopening it.

a) SSME, RS-25E, STME and RS-68 all spent years being designed. Two went through testing, production and flight. One no longer has a production line and the other is in production. By those measures, of the remaining two, the STME designed decades ago is as close/closer to flight than the RS-25E.

b) I have and do disagree with that statement. As I could design and prototype an effective, simple solution in 60 days, I find the assertion the RS-68 is "a non-viable engine choice" to be BaselesS hand waiving. You determine the "who" and "why" for the claims.

c) Would you consider the 'door closed' for a human-rated RS-68, thus the door closed on Delta IV as well? A few links/quotes;
http://www.nasaspaceflight.com/2009/09/ula-claim-gap-reducing-solution-via-eelv-exploration-master-plan/
In regards to the entire Delta IVH - " Numerous upgrades and modifications are listed, but also with cited uncertainty as to how many of the modifications would be required. ...
“Of note is that quite a few of the requirements are not driven by explicit redundancy requirements, but on other anticipated safety criteria as the desire to reduce the release of burning H2 at RS-68 start,” added the paper.
“Also, in some cases different redundancy upgrades (RS-68 backup valves, feedline prevalves, and hydraulics redundancy) need to be traded off to find the smartest implementation path. This makes the final suite of upgrades somewhat uncertain. However, the anticipated total scope and cost of these safety upgrades is programmatically small, with engine mods the most expensive due to high intrinsic recertification cost." "
http://www.floridatoday.com/content/blogs/space/EELVHumanRating.pdf
Pg 8/9 on RS-68 Human-Rating - "A representative list includes: 1) improving the reliability of the engine controller; 2) furtherevluating and mitigating any structural margin issues that do not comply with "Strength and Life Assessment Requirements for Liquid Fueled Space Propulsion System Engines," NASA-STD-5012, 13 June 2006; 3) developing redundant actuators and valves, and installing triple-redundant sensors for more robust fault detection; 4) improving quality control to meet human-rating requirements; 5) implementing a cross-strapped pressurization system; and 6) additional qualification testing to determine reliability."
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/25/2012 12:47 pm

a) SSME, RS-25E, STME and RS-68 all spent years being designed. Two went through testing, production and flight. One no longer has a production line and the other is in production. By those measures, of the remaining two, the STME designed decades ago is as close/closer to flight than the RS-25E.

b) I have and do disagree with that statement. As I could design and prototype an effective, simple solution in 60 days, I find the assertion the RS-68 is "a non-viable engine choice" to be BaselesS hand waiving. You determine the "who" and "why" for the claims.

c) Would you consider the 'door closed' for a human-rated RS-68, thus the door closed on Delta IV as well? A few links/quotes;
http://www.nasaspaceflight.com/2009/09/ula-claim-gap-reducing-solution-via-eelv-exploration-master-plan/
In regards to the entire Delta IVH - " Numerous upgrades and modifications are listed, but also with cited uncertainty as to how many of the modifications would be required. ...
“Of note is that quite a few of the requirements are not driven by explicit redundancy requirements, but on other anticipated safety criteria as the desire to reduce the release of burning H2 at RS-68 start,” added the paper.
“Also, in some cases different redundancy upgrades (RS-68 backup valves, feedline prevalves, and hydraulics redundancy) need to be traded off to find the smartest implementation path. This makes the final suite of upgrades somewhat uncertain. However, the anticipated total scope and cost of these safety upgrades is programmatically small, with engine mods the most expensive due to high intrinsic recertification cost." "
http://www.floridatoday.com/content/blogs/space/EELVHumanRating.pdf
Pg 8/9 on RS-68 Human-Rating - "A representative list includes: 1) improving the reliability of the engine controller; 2) further evaluating and mitigating any structural margin issues that do not comply with "Strength and Life Assessment Requirements for Liquid Fueled Space Propulsion System Engines," NASA-STD-5012, 13 June 2006; 3) developing redundant actuators and valves, and installing triple-redundant sensors for more robust fault detection; 4) improving quality control to meet human-rating requirements; 5) implementing a cross-strapped pressurization system; and 6) additional qualification testing to determine reliability."

A) Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25). STME is a non-consideration.

B) 60 days? Then you are disagreeing with all the thermal analyses performed on the engine by PWR. RS-68 has an ablativly cooled nozzle. It will not survive the thermal environment at the base of the SLS with SRB’s. Only a regenerativly cooled nozzle will.

C) All the studies in the world do not change the fact that the Air Force has closed the door on any further changes to its engine. They own it – it is their engine and they don’t want anyone touching it.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: daver on 02/25/2012 01:52 pm
  Great article Chris.    My reaction is very similar to when the Ares V was being designed.  Three years in and still debating what engines to use.

  (HLV / SLS / Orion / Constellation / Missions To Mars (HSF) / Re: Return to SSME - Ares V undergoes evaluation into potential switch)    on: 12/27/2008 09:05 AM

"It amazes me that Ares V has been on the drawing board for over 3 years and they don't know what engines they are going to use yet.  Don't they have rocket formulas that calculate out how much thrust puts how much weight into orbit?  From there they could figure out how much weight they need to launch and pick the correct engines."


  If they don't pick the engines and bend metal this rocket will suffer the same fate.  Time and money are limited.  I can't imagine an auto company designing a car this way.   
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/25/2012 02:08 pm
  Great article Chris.    My reaction is very similar to when the Ares V was being designed.  Three years in and still debating what engines to use.

  (HLV / SLS / Orion / Constellation / Missions To Mars (HSF) / Re: Return to SSME - Ares V undergoes evaluation into potential switch)    on: 12/27/2008 09:05 AM

"It amazes me that Ares V has been on the drawing board for over 3 years and they don't know what engines they are going to use yet.  Don't they have rocket formulas that calculate out how much thrust puts how much weight into orbit?  From there they could figure out how much weight they need to launch and pick the correct engines."


  If they don't pick the engines and bend metal this rocket will suffer the same fate.  Time and money are limited.  I can't imagine an auto company designing a car this way.   

The engines have been officially selected.
It is only some posters here that won't let it alone.
The down select is complete and NASA has made the final choice. 
SLS will be powered by the RS-25.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: daver on 02/25/2012 03:17 pm
   This is the part that seemed similar.  IMO

  " SLS VCR 11000 sports two solid-propellant Advanced Composite Boosters (ACBs), the same core stage as the 10000 vehicle, with a cargo adapter and fairing on top.

SLS VCR 12000 is the same vehicle as the 11000, except this version would use Liquid Rocket Boosters (LRBs) instead of the ACBs. Only one version – be it the 11000 or the 12000 "


  They are designing it for both (solid and liquid).  Why not pick one and live with it.   That would eliminate a lot of cost.   It seems to me they are trying to please everyone and ultimately we will get nothing. 
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/25/2012 03:57 pm
   This is the part that seemed similar.  IMO

  " SLS VCR 11000 sports two solid-propellant Advanced Composite Boosters (ACBs), the same core stage as the 10000 vehicle, with a cargo adapter and fairing on top.

SLS VCR 12000 is the same vehicle as the 11000, except this version would use Liquid Rocket Boosters (LRBs) instead of the ACBs. Only one version – be it the 11000 or the 12000 "


  They are designing it for both (solid and liquid).  Why not pick one and live with it.   That would eliminate a lot of cost.   It seems to me they are trying to please everyone and ultimately we will get nothing. 

From a previous post to a similar question:

Quote
1. It's more forward thinking than backward thinking. It's looking at the entire program from a decadal pov rather than the short term. What LRB's can potentially bring to the table significantly outweigh the advantages of the SRB's, depending of course on their final design parameters, but they cannot be ready in time to drive the SLS design. So it is an appropriate decision to design the core to support either, so long as performance is not compromised by that decision, which it is not. We only want to build one core design – for the entire life of the program (3 to 5 decades). We're going to be flying this vehicle for the next 30-50 years, not just 11 flights. It's far better to take the time up front to make sure we make the correct configuration choices than to succumb to “we have enough SRB's for 11 flights so let's just down-select to them right away. Forget LRB's”. That is short-sighted thinking.

Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Jason1701 on 02/25/2012 06:13 pm
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: edkyle99 on 02/25/2012 08:19 pm
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

As I understand it, the future SLS core stage engine will be competed, in a "full and open" contract competition.  As you suggest, there is no guarantee that PWR will win that competition. 

 - Ed Kyle
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Ben the Space Brit on 02/25/2012 08:37 pm
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

As I understand it, the future SLS core stage engine will be competed, in a "full and open" contract competition.  As you suggest, there is no guarantee that PWR will win that competition. 

I thought that the competition was for the second-generation booster, not the core engine.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/25/2012 09:07 pm
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

As I understand it, the future SLS core stage engine will be competed, in a "full and open" contract competition.  As you suggest, there is no guarantee that PWR will win that competition. 

I thought that the competition was for the second-generation booster, not the core engine.

That is correct. The competition is for the boosters, not the core engine, which will be a non-compete RS-25.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: edkyle99 on 02/26/2012 01:04 am
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

As I understand it, the future SLS core stage engine will be competed, in a "full and open" contract competition.  As you suggest, there is no guarantee that PWR will win that competition. 

I thought that the competition was for the second-generation booster, not the core engine.

That is correct. The competition is for the boosters, not the core engine, which will be a non-compete RS-25.
Thought I read compete for core, alas.  Since it is more than a decade away, I think RS-25E should be competed

-Ed Kyle
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/26/2012 05:03 am
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

As I understand it, the future SLS core stage engine will be competed, in a "full and open" contract competition.  As you suggest, there is no guarantee that PWR will win that competition. 

I thought that the competition was for the second-generation booster, not the core engine.

That is correct. The competition is for the boosters, not the core engine, which will be a non-compete RS-25.
Thought I read compete for core, alas.  Since it is more than a decade away, I think RS-25E should be competed

-Ed Kyle
Where are you guys getting your information from?
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Jason1701 on 02/26/2012 07:30 am
RS-25E is Rocketdyne by definition. It can't be competed.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: edkyle99 on 02/26/2012 03:52 pm
Where are you guys getting your information from?
I'm reading the SLS Industry Day presentation, linked in the following message.  This document is essential reading for SLS followers.

http://forum.nasaspaceflight.com/index.php?topic=26853.msg864885#msg864885

On the bottom of Page 23, the following text is presented.

"Advanced Development
Broad Agency Announcement (BAA)/NASA Research Announcement (NRA):
Full and Open Competition
Future Core Stage Engine: Separate contract activity to be held in the future."

It was the bold text (my bold highlighting) that made me expect a competed RS-25 future core engine.

 - Ed Kyle
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/27/2012 04:27 am
Where are you guys getting your information from?
I'm reading the SLS Industry Day presentation, linked in the following message.  This document is essential reading for SLS followers.

http://forum.nasaspaceflight.com/index.php?topic=26853.msg864885#msg864885

On the bottom of Page 23, the following text is presented.

"Advanced Development
Broad Agency Announcement (BAA)/NASA Research Announcement (NRA):
Full and Open Competition
Future Core Stage Engine: Separate contract activity to be held in the future."

It was the bold text (my bold highlighting) that made me expect a competed RS-25 future core engine.

 - Ed Kyle
Okay, now where is Chuck getting his information?
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/27/2012 10:13 am
Where are you guys getting your information from?
I'm reading the SLS Industry Day presentation, linked in the following message.  This document is essential reading for SLS followers.

http://forum.nasaspaceflight.com/index.php?topic=26853.msg864885#msg864885

On the bottom of Page 23, the following text is presented.

"Advanced Development
Broad Agency Announcement (BAA)/NASA Research Announcement (NRA):
Full and Open Competition
Future Core Stage Engine: Separate contract activity to be held in the future."

It was the bold text (my bold highlighting) that made me expect a competed RS-25 future core engine.

 - Ed Kyle
Okay, now where is Chuck getting his information?
Chuck didn't see that and is looking into it.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: RyanC on 02/27/2012 06:14 pm
The down select is complete and NASA has made the final choice. 
SLS will be powered by the RS-25.

It's worth noting that P&W/UTC keeps investigating selling Rocketdyne. They wouldn't be doing that route of investigation if they were bullish about SLS' future prospects, which currently uses both RS-25 and J-2X.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: manboy on 02/27/2012 07:34 pm
"At present, SLS-3 is set to fly as the Block 1A configuration. No missions have yet been allocated past EM-2, although teams continued to work towards an exploration roadmap, which is now likely to feature an Exploration Platform “Gateway” at Earth-Moon Lagrange (EML) point 2 – based on what are an increasing number of international meetings on the proposal (L2 Link to SLS Exploration Roadmap Updates)."

I just hope there's enough funding for a lunar lander.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: aquanaut99 on 02/27/2012 07:40 pm
I just hope there's enough funding for a lunar lander.

Highly unlikely. Lunar landings are not currently in the plan, for several reasons (lack of money for a lander being one of them). And NASA's budget is likely to go down, not up, over the next few years.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: manboy on 02/27/2012 07:42 pm
I just hope there's enough funding for a lunar lander.

Highly unlikely.
Then why waste all this time and money going no where?
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: aquanaut99 on 02/27/2012 07:47 pm
Then why waste all this time and money going no where?

EML-2 and (eventually) a NEA are not "nowhere".

Also, the current administration has decided that the Moon is "been there, done that". And the potential GOP candidates have all shown their hostility to a lunar return, thanks to Newt actually proposing it. Unless Gingrich is elected, I see no chance of a lunar return anytime soon.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: manboy on 02/27/2012 07:58 pm
Then why waste all this time and money going no where?

EML-2 and (eventually) a NEA are not "nowhere".

Also, the current administration has decided that the Moon is "been there, done that". And the potential GOP candidates have all shown their hostility to a lunar return, thanks to Newt actually proposing it. Unless Gingrich is elected, I see no chance of a lunar return anytime soon.
I was talking about the Exploration Gateway Platform (the Boeing moonlanding proposal) which Chris seemed to infer was gaining traction. With no additional hardware EML-2 might as be nowhere.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: edkyle99 on 02/27/2012 09:27 pm
Then why waste all this time and money going no where?

EML-2 and (eventually) a NEA are not "nowhere".

Also, the current administration has decided that the Moon is "been there, done that". And the potential GOP candidates have all shown their hostility to a lunar return, thanks to Newt actually proposing it. Unless Gingrich is elected, I see no chance of a lunar return anytime soon.

Lagrange points are "somewhere" for unmanned science missions, but they are definitely "nowhere" for crewed missions.  There is literally nothing there to see or visit!

Asteroid is a one-time mission, and opportunities for such missions come along infrequently.  It will be interesting to the public for about an hour.

Those responsible for SLS should stop trying to obfuscate its real purpose.  There is only one reason to create such a powerful machine.  There is only one place in space for which it is needed to visit - a place with red rocks, sand, and sky.

 - Ed Kyle
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/27/2012 09:55 pm
Then why waste all this time and money going no where?

EML-2 and (eventually) a NEA are not "nowhere".

Also, the current administration has decided that the Moon is "been there, done that". And the potential GOP candidates have all shown their hostility to a lunar return, thanks to Newt actually proposing it. Unless Gingrich is elected, I see no chance of a lunar return anytime soon.

Lagrange points are "somewhere" for unmanned science missions, but they are definitely "nowhere" for crewed missions.  There is literally nothing there to see or visit!

Asteroid is a one-time mission, and opportunities for such missions come along infrequently.  It will be interesting to the public for about an hour.

Those responsible for SLS should stop trying to obfuscate its real purpose.  There is only one reason to create such a powerful machine.  There is only one place in space for which it is needed to visit - a place with red rocks, sand, and sky.

 - Ed Kyle
...butterscotch sky. ;)

(By the way, I have a sort of feeling that if SLS survives, it will be in a cargo-only role with Orion launching on Delta IV Heavy... D4H serving the same role as Ares I did...)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: spectre9 on 02/27/2012 11:57 pm
DIV-H Orion MPCV can't go beyond LEO without a prop depot.

NASA wants all up and all their studies tell us all up is the way to go.

They want to launch Orion with CPS and this requires a HLV.

I'm not saying it's right or wrong because I really don't know.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/28/2012 12:18 am
DIV-H Orion MPCV can't go beyond LEO without a prop depot....
DIV-H can function the same as Ares I did in Constellation. Did you bother reading what I actually wrote? ;)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: spectre9 on 02/28/2012 03:18 am
Yes I know exactly what you're talking about. The Altair/Ares V upper stage whatever it was IS the prop depot.

Added video.

http://www.youtube.com/watch?v=_9JxSrwlTA4
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: spectre9 on 02/28/2012 05:21 am
I found a nice website of NASA putting together their all up stack for Apollo.

http://www.hq.nasa.gov/office/pao/History/SP-4204/ch19-3.html

Thanks Robotbeat for having this discussion and leading to me to look into this.

Seems they like to attach their depot/S-IVB in the safety of the VAB.

This is something they've done before and something they're more comfortable with doing.

I can just imagine guys like those in the pictures up in that high bay dropping the ICPS down onto the first SLS core stage.  ;D
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: aquanaut99 on 02/28/2012 05:42 am
Lagrange points are "somewhere" for unmanned science missions, but they are definitely "nowhere" for crewed missions.  There is literally nothing there to see or visit!

Asteroid is a one-time mission, and opportunities for such missions come along infrequently.  It will be interesting to the public for about an hour.

Those responsible for SLS should stop trying to obfuscate its real purpose.  There is only one reason to create such a powerful machine.  There is only one place in space for which it is needed to visit - a place with red rocks, sand, and sky.

 - Ed Kyle

NVM the public. The public doesn't give a hoot one way or the other. Even if we went back to the moon; there might be some interest during the first flight, after that, [insert favorite moronic TV show here] becomes more important and the lunar missions will find mention in the media (if at all) mainly due to controversies regarding excessive cost.

The same goes for Mars. Don't fool yourself, a first human landing on Mars will generate nowhere near the interest Apollo 11 did. Why? Because the moon is special, an object of human desire since the dawn of time. Mars is just a pinpoint in the sky. And once those first TV pics of astronauts on Mars come back, the public reaction will be: "hey, it's just like the old moon landings, except in red! This what we payed all those hundreds of billions for? What a let-down!". And, ofc, there will be plenty of conspiracy theory nutters who will claim it was all flimed in a Holywood studio anyway.

If we are to do human exploration of the Solar System (and there isn't that much reason for doing it in the first place), I would hope it is for better reasons than one-off "flags and footprints" stuff; which is what a human Mars mission would be (at least in the next 50 years). We did that with Apollo, and look where it got us.

No, I firmly believe that the prime real estate in the Solar System are the asteroids and minor planets, without those annyoing deep gravity wells. Human Space exploration should focus more on adapting humans to live in deep space (absence of gravity, hard radiation). This will probably require that we evolve beyond homo sapiens, into a new species. Before that, all human exploration is bound to be a dead-end.

Which is why I support the flexible path architecture (be it with SLS or something else). The progression should be:
- a sucessor to ISS in deep space (EML-2), where we can study the effects of prolonged exposure to GCR on humans.
- a series of flights to NEA, to explore the feasibilty of one day exploiting them for resources or using them as improvised deep-space habitats (maybe hollowing out a small rock is better than assembling a spacecraft in orbit)
- long-duration deep-space flights (1 year +). This can be things such as a Venus/Mars flyby, missions to Phobos and Deimos, and eventually out into the asteroid belt and maybe even beyond.

A Mars or moon landing does not fit into my schedule. Been there, done that, dead end.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: MATTBLAK on 02/28/2012 06:54 am
I actually firmly agree with some of what you said in the post above.

BUT: "Dead End" is dangerously close to myth territory. Just because Apollo didn't lead to anything better doesn't mean we should let any other exploration program end up the same, too. I thought the idea was to push for more sustainable, meaningful exploration? Or are we going to - again - throw up our hands and say it's all too hard?

The problem is; in an era when both manned and unmanned Space Exploration struggles for funding as never before, it is very, very easy to just negatively bray "Its all a dead end! It has no value" or other partisan and apocryphal sayings.

And if there's one thing I'm heartily sick of is the 'been there, done that' as pertains to the Moon. We landed only Six times and sent only a handful of probes there. Its like landing at six U.S. airports, driving around the runway then saying "We've explored America - been there, done that!"

Rubbish!! ::)

There are millions of square kilometers of unexplored land and resources there. Billions of years of geology in the rocks and regolith!!

And the same goes for Mars, only more so - and possibly paleontology there, too.

They are Worlds. Oh sure, they aren't 'Class-M' planets like from Star Trek. We cannot truly compare them to the Earth - that is pointless; maybe even inappropriate. We should stop trying to compare the Moon and Mars to Earthly standards of usefulness. You can't. They are worlds in their own right. There is only one Earth in this Solar system. We need to explore other worlds on their own terms.

We are not finished with any of them - we've barely started. Anyone who claims otherwise is being strangely subversive. But Space needs more money - starting with Taxpayer funding but ending I hope with Private Industry ventures. Space Exploration started unmanned in 1957 and manned in 1961. It aint that 'new-fangled' - its been with us for decades now. It's time to start treating it as something that's a part of us, part of human history - because it IS.

But will it ever become 'normal', maybe not even extraordinary? I don't think so.

And I rather hope not...
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: woods170 on 02/28/2012 09:56 am
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

Aquanaut99 hit the nail squarely on the head. It does not matter that there are many worlds out there to explore. It does not matter that the vast majority of the lunar surface is terra incognita. None of it matters as long as there is zero interest from the general public for Exploration. And that is precisely were we are today.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: clongton on 02/28/2012 10:36 am
Don't kid yourself.

Throughout all of human history there has been absolutely zero public interest in exploration. It was always - ALWAYS - the few visionaries who understood the value of exploration and pulled out all the personal stops to engage in it while the vast - VAST - majority went about their daily lives of chopping wood, scratching ground and cooking gruel.

The fact that the general public isn't engaged doesn't mean anything, because the general public have never been, and likely never will be, engaged. It's only the visionary that matters, It's only the visionary that has ever mattered. It is only the visionary who was willing to risk everything to see what was over the next hill or on the other side of the ocean while the general public went about their daily lives - at home, uninterested in what that fool was doing trying to get to the other side to see what was there.

Exploration will happen only so long as there are visionaries willing to engage, and the general public is not part of the equation - they never really have been. The visionary will explore, find, catalog, and report. Only then will the public become involved, at the economic level, as the visionaries uncover economic opportunity and make it available to the next level of visionary - the entrepreneur. The entrepreneur will see opportunity where the explorer saw real estate, and will pull out all their own personal stops and go for it. Then other entrepreneurs will join the field, following their own vision of opportunity, until finally it begins to  filter down to the general public in the form of a better wood chopping tool, a better way to scratch the ground, a better way to cook gruel.   In the mean time, the general public will go about their daily lives of chopping wood, scratching ground and cooking gruel, and now watching NASCAR and Brittany Spears.

It has always been this way and it likely always will be this way. The only involvement the general public has ever had in exploration is to be the source of the very small pool of visionaries. Other than that the general public has never been part of the equation and likely never will be - no matter how far we go in the solar system, or even the stars someday.

This is not a good or a bad thing. It's just the way it is.

It is what it is.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: QuantumG on 02/28/2012 11:04 am
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

I think you mean: does the public want to be forced to pay for Exploration?

So long as the costs involved in spaceflight are absurdly high, as they are now, voluntary funding for exploration will be insufficient.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: HappyMartian on 02/28/2012 01:28 pm
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

Aquanaut99 hit the nail squarely on the head. It does not matter that there are many worlds out there to explore. It does not matter that the vast majority of the lunar surface is terra incognita. None of it matters as long as there is zero interest from the general public for Exploration. And that is precisely were we are today.


New model provides different take on planetary accretion
February 28, 2012 By Tony Fitzpatrick
At: http://www.physorg.com/news/2012-02-planetary-accretion.html

It seems quite likely that we don't know enough to confidently declare "None of it matters..." when it comes to space exploration.

On a personal level, our space exploration efforts have meant alot for many folks.

One of NASA’s top planet hunters talks about the past, present and future of Kepler
http://blog.chron.com/sciguy/2012/02/one-of-nasas-top-planet-hunters-talks-about-the-past-present-and-future-of-kepler/
At:
"Neither of my parents went to college, and I didn’t understand what it meant to be a scientist at all. But I always excelled in math. And in the background, growing up in the ‘80s, the shuttle program was going on and that was an exciting time. It seemed to me that the most exciting job that anyone could have would be to work for NASA and support the space program."


Well, space exploration by Earthlings may or may not seem to matter much to those citizens of countries that have had a good century or two to benefit from how superior technology allowed some of our ancestors to take whatever they wanted from various native folks. However, some of those former natives are today getting money and fancy toolkits and may also have some members of the "general public" and government that remember their very hard lessons in how the universe may bestow rich benefits on those who reach out in a determined manner with a sophisticated toolkit.

There are a whole lot of planets beyond our Solar System. It sure would be a shame to discover someday that one of those planets had a nasty individual that coveted our pretty blue sphere and had a sufficiently advanced toolkit to make its desire for ownership a reality. Late discovery of such vital information would be a poor way to ensure humanity's future. Many members of our species may only realize the importance our 'space exploration toolkit insurance' if or when we come face to face with some really bad news.

Does the history of our species strongly hint that humans need extensive plans, tools, and abilities to deal with both the uncertainty embedded in the universe and the potential actions of any unsavory newcomer to our Solar System? Is it the unknown that could really mess up what should have been a nice day or a great millennium for our species?

The SLS/Orion combination is one of our tools to find affordable answers to questions we currently lack the ability to fully formulate.

Cheers!





Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: edkyle99 on 02/28/2012 01:35 pm
So long as the costs involved in spaceflight are absurdly high, as they are now, voluntary funding for exploration will be insufficient.

That's the reason SLS is so stretched on the development schedule.  NASA is focused on keeping its budget steady (Shuttle-esq) and below the public radar, when a surge of dollars is common for development.  It is a good plan - if it works.

The U.S. spends nearly one-half billion dollars per year on Arctic and Antarctic research, much of which goes to PhD types.  Does the public support that, I wonder?  Or does the public even know such spending exists?

 - Ed Kyle
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: MATTBLAK on 02/28/2012 06:31 pm
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

Aquanaut99 hit the nail squarely on the head. It does not matter that there are many worlds out there to explore. It does not matter that the vast majority of the lunar surface is terra incognita. None of it matters as long as there is zero interest from the general public for Exploration. And that is precisely were we are today.

NOT Zero interest, more like insufficient interest to sustain anything meaningful. As it pertains to Exploration, our culture is broken. People digress and get distracted far too easily. Wars and other cultural and political clashes suck up attention and money. Also, the antics of celebrities and social networking are far more important to people than Mike Massimino or Cady Coleman's next mission. The Earth's ocean floors and deep trenches have been explored by humans far LESS than the Moon's surface. Yet if a multi-billion dollar project was announced to send people to live - NEEMO style - on a deep ocean floor, there'd be howls of outrage over the amounts of money being spent: "There are people starving around the world, you know!!"

Different thing, different problem. But like I said: how can exploration survive if people wallow in distractions or more to the nail-on-the-head of my point - negativity?
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/28/2012 06:38 pm
It's the economy, stupid.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: MATTBLAK on 02/28/2012 06:44 pm
I know; I aint stupid, brother ;) But when the U.S. economy was at its (modern) strongest more than a decade ago, what happened? John Glenn flew again and billions were given to Russia to fly Astronauts and Shuttles to Mir. Also, ISS barely survived cancellation and NASA's budget was cut again and again and again.

The economy has been and will again be an excuse. It's far more to do with ideology and (perceived) priorities.

Er... What was the title of this thread again? ;)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/28/2012 06:51 pm
I know; I aint stupid, brother. ...
(Sorry, that wasn't supposed to be directed at you or anyone in particular, it's a common phrase in American political culture... when the economy is in recession, that's what successful politicians focus on.)
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Lobo on 02/28/2012 06:51 pm
So long as the costs involved in spaceflight are absurdly high, as they are now, voluntary funding for exploration will be insufficient.

That's the reason SLS is so stretched on the development schedule.  NASA is focused on keeping its budget steady (Shuttle-esq) and below the public radar, when a surge of dollars is common for development.  It is a good plan - if it works.

The U.S. spends nearly one-half billion dollars per year on Arctic and Antarctic research, much of which goes to PhD types.  Does the public support that, I wonder?  Or does the public even know such spending exists?

 - Ed Kyle

Agreed.  You could trim just 2% from the Medicare or Defense budgets, those programs would never even miss it, they waste far more than that anyway, and literally double NASA's budget.  If NASA's budget were doubled, we'd actually see some really high-profile, amazing things that would generate a certain degree of public interest, and good PR for the US. 
Heck, just 5% of Obama's "stimulus" bill directed to NASA, and parcelled out over say 5 years, would be almost a 50% increase in their budget for 5 years, and would probably have paid for all of SLS development, KSC upgrades, Orion development, and some type of lunar lander development.  So when NASA's budget came back down to normal, they should be able to sustain all of that going forward as all the development and infrastructure would be paid for already.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Robotbeat on 02/28/2012 06:53 pm
Lobo: Part of the stimulus was supposed to be spent on commercial crew... but it was redirected by a certain Senator... (http://en.wikipedia.org/wiki/Richard_Shelby) to the blackhole of Constellation. Didn't seem to do much good for Constellation.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: deltaV on 02/28/2012 07:00 pm
This thread is getting rather off-topic.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: MATTBLAK on 02/28/2012 07:09 pm
That's what I said! But sometimes they digress because of natural, related branching-out of the subject matter: when the initial, pure subject matter exhausts the known facts, that's often what happens.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Ox on 02/28/2012 08:54 pm
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

Aquanaut99 hit the nail squarely on the head. It does not matter that there are many worlds out there to explore. It does not matter that the vast majority of the lunar surface is terra incognita. None of it matters as long as there is zero interest from the general public for Exploration. And that is precisely were we are today.

I think there are some minor but important distinctions that are necessary with your statement.

Who pays for that? Congress
Does Congress give anything about Exploration? Yes
Does the Congress want to pay for Exploration? Remains to be seen.
Will Exploration happen, taking into account the points above? Remains to be seen.

Congress is the important party here (along with the President obviously). Regardless of what the general public believes (and I think you're underestimating the public's opinion on NASA and exploration) Congress frequently funds things the public does not approve of.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Lars_J on 02/28/2012 10:47 pm
Do Exploration? Fine.
Who pays for that? The public.
Does the public give anything about Exploration? No
Does the public want to pay for Exploration? Big No.
Will Exploration happen, taking into account the points above? Very big No.

Aquanaut99 hit the nail squarely on the head. It does not matter that there are many worlds out there to explore. It does not matter that the vast majority of the lunar surface is terra incognita. None of it matters as long as there is zero interest from the general public for Exploration. And that is precisely were we are today.

I think there are some minor but important distinctions that are necessary with your statement.
...
Does Congress give anything about Exploration? Yes

Since when? Them funding exploration only occurs if it is a happy coincidence with their primary objective(s).
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Ox on 02/29/2012 02:35 am

I think there are some minor but important distinctions that are necessary with your statement.
...
Does Congress give anything about Exploration? Yes

Since when? Them funding exploration only occurs if it is a happy coincidence with their primary objective(s).

Over the last decade it's been pretty obvious that Congress has wanted both a large rocket and a deep space capable capsule. Given the response to the President's FY '11 budget proposal and the ensuing compromise I think Congress does indeed want an exploration program. Now, you seem to have the same feeling that I do and that is they haven't shown any commitment to funding this program at the necessary levels, hence the "Remains to be seen" comments if this will change in the future.

So, just to be clear, I think they want an exploration program but up to this point have been unwilling to actually pay what NASA believes it will cost.


Bolding my emphasis.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Ronsmytheiii on 02/29/2012 02:48 am
Two production lines exist - RS-68 (Delta-IV) and RS-25 (STS & SLS). 1 is actively building (RS-68) and 1 is primed for production (RS-25).

I do not believe Rocketdyne is anything like "primed" for RS-25E.

RS-25D can restart construction in the meantime, all that RS-25E would be is a more economic expendable version to decrease carrying costs of the core engine.  The J-2x was only in the J-2 family in name only, pretty much was a brand new engine. RS-25E will basically still function as the current engine, but changes will be made based on availability of funds and potential savings.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Fred M on 04/09/2012 11:35 am
What a great article. Enjoying going through what appears to be a huge amount of SLS articles. So glad I found this site, even if I was late to the party.
Title: Re: Acronyms to Ascent – SLS managers create development milestone roadmap
Post by: Chris Bergin on 04/10/2012 11:53 pm
What a great article. Enjoying going through what appears to be a huge amount of SLS articles. So glad I found this site, even if I was late to the party.

Nice one Fred, thanks!