Author Topic: Griffin speech - EELV would not work for Constellation  (Read 44533 times)

Offline jongoff

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RE: Griffin speech - EELV would not work for Constellation
« Reply #20 on: 01/23/2008 07:18 pm »

Norm,

Quote
I would like to challenge both the DIRECT group and the EELV group to respond to this speech on a point-by-point basis.

As I'm at work at the moment, I need to keep this short.  Also, I'm not really in either the EELV or DIRECT groups (though I've got friends in both camps), even though it may sound like it at times.

I'd like to comment on just one thing first (from page 17, emphasis mine).  This was one of the main rationales Griffin gave for rejecting a two launch technique which used equal sized launchers (ie DIRECT):

But if we split the EOR lunar architecture into two equal but smaller vehicles, we will need ten or more launches to obtain the same Mars-bound payload in LEO, and that is without assuming any loss of packaging efficiency for the launch of smaller payloads. When we consider that maybe half the Mars mission mass in LEO is liquid hydrogen, and if we understand that the control of hydrogen boiloff in space is one of the key limiting technologies for deep space exploration, the need to conduct fewer rather than more launches to LEO for early Mars missions becomes glaringly apparent.

While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion.  The conclusion I would draw is that if cryogenic propellant storage technologies are so critical--develop them.  Don't let the existing state of the art in propellant handling drive transportation system decisions for projects that won't be undertaken for 15-20 years!  

There are current technologies under development that could yield very low to zero boiloff of cryogenic propellants.  For a six launch architecture, especially if the LH2 is being used in some sort of nuclear or solar thermal system (where the hydrogen is used gradually over the course of the trip to and from Mars), you already need a system that can keep LH2 for months to years, so extending that technology further so that boiloff during mission assembly isn't an issue.

Is 2025-2030 really so close that we can't afford to do this right and actually develop the technologies we need instead of trying to kludge by with existing technologies? 

Once you have the boiloff issue reduced or solved, that ~500klb of hydrogen ceases to be a headache, and begins to be an opportunity.  That's a lot of demand for propellant in orbit, and it can be supplied commercially.  You're already going to need propellant transfer technologies anyway if you have to launch the hydrogen in multiple launches, so what's to stop launching it in even smaller launches?  Use a depot if you're worried about too many docking events with your mars ship. 

I'm sure the DIRECT guys can bring up other points, but that's one that stuck out to me.  If one of his key arguments for why you need Ares V is hydrogen boiloff, he's going about it in the wrong way.

~Jon


Offline texas_space

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RE: Griffin speech - EELV would not work for Constellation
« Reply #21 on: 01/23/2008 07:26 pm »
Jon may have something here.  Propellant boiloff is an issue, but it does scream out as a problem to be solved by a new technology or strategy and not by a new and expensive hulking rocket.  Griffin does seem to assume that technology for various things including propellant storage will remain static.  Without money they may remain static anyway, but if there's no money then it's a moot point IMO.

Personally, I'm convinced that nuclear propulsion will be needed to really go to Mars (and keep going back).  Unless a reactor or its components can't be broken down into smaller components (wise anyway from a safety standpoint), then that couldn't be used as a justification for a heavy lift vehicle either.
"We went to the moon nine times. Why fake it nine times, if we faked it?" - Charlie Duke

Offline savuporo

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RE: Griffin speech - EELV would not work for Constellation
« Reply #22 on: 01/23/2008 07:28 pm »
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jongoff - 23/1/2008  10:18 AM
the control of hydrogen boiloff in space is one of the key limiting technologies for deep space exploration, the need to conduct fewer rather than more launches to LEO for early Mars missions becomes glaringly apparent.

While one could definitely draw the conclusion that Griffin drew, ie. that hydrogen boiloff issues imply it would be better to launch the system in fewer pieces, one could also draw a different conclusion.  

Exactly. Either deal with the boiloff problem or dont use hydrogen. Justifying a multibillion decades long project, launchers and basically every other technical decision in the program with something so trivial and obviously solvable .. he calls himself an engineer ?

And thats by far not the only "logical" conclusion drawn in his speech that just does not click.
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Offline Thomas

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Re: Griffin speech - EELV would not work for Constellation
« Reply #23 on: 01/23/2008 07:33 pm »
The SSME airstart issue was not a "problem" or a "weakness". Everyone knew that the SSME as designed was not air-startable. Turning it into an air-startable engine would take time and money--again everyone knew this from the get go. What the 5 segment SRB + J-2x solution did was allow more money to go towards eventual Ares V hardware and less into turning the SSME into a second stage engine. Since the Ares V has been identified as essential to Constellation and beyond it seems like a good trade off to me anyway

Offline clongton

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Re: Griffin speech - EELV would not work for Constellation
« Reply #24 on: 01/23/2008 07:33 pm »
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Thomas - 23/1/2008  2:46 PM

I'm glad to see Griffin emphasizing that the switch to the 5 segment booster/J-2X upper stage was for the purposes of reducing the cost/development time of the Ares V and not due to any inherent weakness in the SRB or SSME. Too many Ares I detractors either don't realize this or intentionally mislead their audience.

The following is a small portion of what was written by me, in concert with the rest of the DIRECT team, in the Summer 2007 issue of Horizons. You are new to posting (don’t know how long you’ve been reading) so you may not be aware that we have been constantly stating this, over and over again, for the past almost 2 years now. We go out of our way to make sure that we present the facts as they actually are and do not ever intentionally mislead anyone. We don't have to because the facts speak for themselves. When we have discovered that we have misspoken we have gone back to the thread(s) and corrected our mistakes, in plain view.

{begin quote}
Theoretically, the Ares-I / Ares-V launch concept is a good idea. Too often missed in the conversations of pro and con for Ares-I is the Saturn-V class heavy lift vehicle for the Moon and Mars. Crewed missions to the Moon and Mars are mandated in the VSE, but bringing such an expensive new launch vehicle online in today’s economic and political climate would prove to be extremely difficult at best. To his credit, the new administrator of NASA, Dr. Michael Griffin, together with other notables, was able to devise an architecture that enabled this lifter, while addressing the additional VSE requirements of a Shuttle replacement and continued servicing of the ISS. The solution was the pair of Ares launch vehicles, where a small launcher, constructed almost entirely of active and flight-proven hardware, is deployed to replace the crew transport functions of Shuttle and provide service to the ISS, and at the same time, to be the financial stalking horse for the flight articles needed for the heavy lift. The Ares-V would be too expensive to navigate Congressional authorization by itself, but if some of its development costs could be shared by a second, less expensive vehicle that addressed the immediate need to replace Shuttle and service the ISS, then the heavy lifter drops into the realm of the affordable. Thus was the Ares 1.5 launch concept born. It was a good idea.
{end quote}

The entire article is located here:
http://www.aiaa-houston.org/newsletter/aug07/aug07.pdf
The entire issue is a good read. I would recommend getting all of the issues as they come out. They are all, every one, good reads.

Returning you now to Mike's speech.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Tim S

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RE: Griffin speech - EELV would not work for Constellation
« Reply #25 on: 01/23/2008 07:39 pm »
Well said Mr Griffin.

We're not talking about U-Haulers for cargo here. We're talking manned space flight.

EELV folks on here need to stick to what they know.

Offline jongoff

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RE: Griffin speech - EELV would not work for Constellation
« Reply #26 on: 01/23/2008 07:43 pm »
Texas Space,
Quote
Jon may have something here.  Propellant boiloff is an issue, but it does scream out as a problem to be solved by a new technology or strategy and not by a new and expensive hulking rocket.  Griffin does seem to assume that technology for various things including propellant storage will remain static.  Without money they may remain static anyway, but if there's no money then it's a moot point IMO.

It's one thing to assume that the technology over say a 5 year period will remain relatively static.  But by the time you get to 10, 15, and 20 years out, it becomes a lot more unrealistic.  Especially when there are multiple NASA and industry groups working on this very problem.  As it is, Ares V and LSAM are required to have long loiters with minimal boiloff.  In order to meet those requirements, advances in the state of the art are already required.  But taking it from there to ultra-low-boiloff systems and/or Zero Boiloff Systems just means some continued investment.  The fact that there are several groups (many headed up by Glenn Research Center or by ULA or by both) attacking this problem from different angles gives me very high confidence that a workable solution will be found, and probably not too far in the future.

If cryogenic fluid management (ie handling, storage, and transfer) technologies were funded at a reasonable rate (say a couple tens of millions per year), a *lot* of those issues would be worked out in before Ares I even gets a chance to fly.

~Jon

Offline PhalanxTX

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RE: Griffin speech - EELV would not work for Constellation
« Reply #27 on: 01/23/2008 07:45 pm »
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Tim S - 23/1/2008  2:39 PM

Well said Mr Griffin.

We're not talking about U-Haulers for cargo here. We're talking manned space flight.

EELV folks on here need to stick to what they know.

Wouldn't that be EELVs?  And what's with the confrontational attitude?  I thought we're all working towards the same goal.  Why do you seem dead set on antagonizing those that disagree with the ESAS approach?
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Offline Jim

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RE: Griffin speech - EELV would not work for Constellation
« Reply #28 on: 01/23/2008 07:56 pm »
Quote
Tim S - 23/1/2008  3:39 PM

Well said Mr Griffin.

We're not talking about U-Haulers for cargo here. We're talking manned space flight.

EELV folks on here need to stick to what they know.

They know how to manrate vehicles, they know how to launch rockets

But  apparently MSFC doesn't know how to do either

Offline yinzer

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RE: Griffin speech - EELV would not work for Constellation
« Reply #29 on: 01/23/2008 07:57 pm »
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Tim S - 23/1/2008  12:39 PM

Well said Mr Griffin.

We're not talking about U-Haulers for cargo here. We're talking manned space flight.

EELV folks on here need to stick to what they know.

Are you suggesting that the EELV guys stick to building rockets and leave the powerpoint wrangling to NASA?  Admittedly that's the happy state of affairs that has existed for the past twenty years, but at some point the Shuttle is going to go away and we'll need a replacement.
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RE: Griffin speech - EELV would not work for Constellation
« Reply #30 on: 01/23/2008 08:21 pm »
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Chris Bergin - 23/1/2008  11:30 AM

http://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdf

Here's the part that will make many a coffee be spat over screens in Denver etc. ;)

snip

The Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission.  EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I.  We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.

ship


What is the lift capability of Delta and Atlas heavy?  I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.

Danny Deger
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Online edkyle99

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RE: Griffin speech - EELV would not work for Constellation
« Reply #31 on: 01/23/2008 08:32 pm »
Quote
Norm Hartnett - 23/1/2008  1:57 PM

Not the Moon and not Mars but beyond, in other words a system that has the versatility to go to any place in space that is reasonable within the framework of the next thirty years.

Mars explains why Griffin's NASA is planning for Ares V.  It doesn't make sense for LEO.  It doesn't look like the most sensible way to do a lunar mission either.  But for Mars, since NASA would need the biggest launch vehicle available, the reasoning for Ares V begins to come into focus.  

Griffin says:  "I have written that a careful analysis of what we can do at NASA on constant-dollar budgets leads me to believe that we can realistically be on Mars by the mid-2030’s.  ...  We’ll be on Mars in thirty years, and when we go, we’ll be using hardware that we’re building today.  So we need to keep Mars in mind as we work, even now."

Quote
As to the Constellation architecture looking better cost-wise than any alternative for Mars IMO Ross has already addressed this in the DIRECT discussion. And to address your question, if it is not used for Mars there are still the NEOs, Mars' moons, and Venus.

A bigger launch vehicle is always going to cost less on a $/kg payload basis when it is compared to a smaller launch vehicle if the payload requirements are large enough or the program time frame is long enough, or both.  Ares V outhauls Direct, and so will always beat it at that cost-comparison game when it comes to Mars missions that start in 2030, require a million pounds of payload in LEO for each mission, and are part of a Mars exploration program that continues forever.

 - Ed Kyle

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RE: Griffin speech - EELV would not work for Constellation
« Reply #32 on: 01/23/2008 08:38 pm »
Quote
Danny Dot - 23/1/2008  3:21 PM

Quote
Chris Bergin - 23/1/2008  11:30 AM

http://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdf

Here's the part that will make many a coffee be spat over screens in Denver etc. ;)

snip

The Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission.  EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I.  We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.

ship


What is the lift capability of Delta and Atlas heavy?  I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.

Danny Deger

My recollection is that NASA's study showed that the EELVs couldn't lift the payload when restricted to the low-loft ascent profiles.  They would also carry a lot of LAS mass, etc., that would limit them compared to a typical satellite in a shroud type payload.  Together, these factors dramatically cut the EELV mass delivery capabilities for a CEV.  

 - Ed Kyle

Offline Thomas

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Re: Griffin speech - EELV would not work for Constellation
« Reply #33 on: 01/23/2008 08:38 pm »
Why do people seem so surprise that the ARES (hello!!!!!!) series of vehicles have Mars as an ultimate destination? ;)

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Re: Griffin speech - EELV would not work for Constellation
« Reply #34 on: 01/23/2008 08:43 pm »
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Thomas - 23/1/2008  3:38 PM

Why do people seem so surprise that the ARES (hello!!!!!!) series of vehicles have Mars as an ultimate destination? ;)

Then why is NASA betting its foreseeable future on lunar exploration?

 - Ed Kyle

Offline clongton

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Re: Griffin speech - EELV would not work for Constellation
« Reply #35 on: 01/23/2008 08:47 pm »
Quote
edkyle99 - 23/1/2008  4:43 PM

Quote
Thomas - 23/1/2008  3:38 PM

Why do people seem so surprise that the ARES (hello!!!!!!) series of vehicles have Mars as an ultimate destination? ;)

Then why is NASA betting its foreseeable future on lunar exploration?

 - Ed Kyle
Basically because right now the moon is reachable, while Mars is not (yet).
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Herb Schaltegger

Come on, Ed - while I'm certainly not an Ares fan, let's be honest about that: they're betting the foreseeable future on lunar goals because #1) Congress has told them to, and #2) there's simply no money to go to Mars yet (if there ever will be).  This whole plan and subsequent architecture fight is politics and while Griffin has much to be held accountable for, so too does the administration and Congress for the current technical mess.
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Offline jongoff

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RE: Griffin speech - EELV would not work for Constellation
« Reply #37 on: 01/23/2008 08:50 pm »
Ed,
Quote
A bigger launch vehicle is always going to cost less on a $/kg payload basis when it is compared to a smaller launch vehicle if the payload requirements are large enough or the program time frame is long enough, or both.  Ares V outhauls Direct, and so will always beat it at that cost-comparison game when it comes to Mars missions that start in 2030, require a million pounds of payload in LEO for each mission, and are part of a Mars exploration program that continues forever.

Well....I would quibble with the "a bigger launch vehicle is always going to cost less on a $/kg basis" comment.  It depends a lot on assumptions.  Even after factoring the higher overhead of dealing with more launches, it may very well be that an RLV flying 50x per year at 10000lb LH2 per flight is going to cost a whole lot less per kg than an HLV that does it in only three flights.

For existing, very low launch rate vehicles (EELV, SDVs, etc), you might have a point, but I'd be careful with generalities like that.

~Jon

Offline libs0n

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RE: Griffin speech - EELV would not work for Constellation
« Reply #38 on: 01/23/2008 08:58 pm »
Quote
edkyle99 - 23/1/2008  4:38 PM

Quote
Danny Dot - 23/1/2008  3:21 PM

Quote
Chris Bergin - 23/1/2008  11:30 AM

http://www.nasa.gov/pdf/208916main_Space_Transportation_Association_22_Jan_08.pdf

Here's the part that will make many a coffee be spat over screens in Denver etc. ;)

snip

The Ares I lift requirement is 20.3 mT for the ISS mission and 23.3 mT for the lunar mission.  EELV lift capacity for both the Delta IV and Atlas V are insufficient, so a new RL-10 powered upper stage would be required, similar to the J-2X based upper stage for Ares I.  We considered using additional strap-on solid rocket boosters to increase EELV performance, but such clustering lowers overall reliability.

ship


What is the lift capability of Delta and Atlas heavy?  I am certain Atlas Heavy can lift this much and it is already at CDR with a very low risk to first flight.

Danny Deger

My recollection is that NASA's study showed that the EELVs couldn't lift the payload when restricted to the low-loft ascent profiles.  They would also carry a lot of LAS mass, etc., that would limit them compared to a typical satellite in a shroud type payload.  Together, these factors dramatically cut the EELV mass delivery capabilities for a CEV.  

 - Ed Kyle

One thing I don't think is being considered is that we're not talking about the Delta 4 Heavy of today, but a post-2012 one with its engines upgraded, which will supposedly boost its payload to LEO to 27,000kg.  That, I think, changes the parameters of discussion significantly when we start talking performance hits from safer ascent profiles and launch abort systems.

Offline savuporo

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RE: Griffin speech - EELV would not work for Constellation
« Reply #39 on: 01/23/2008 09:17 pm »
Quote
jongoff - 23/1/2008  11:50 AM
For existing, very low launch rate vehicles (EELV, SDVs, etc), you might have a point, but I'd be careful with generalities like that.
Considering Dnepr vs EELV launch costs per pound, the point just does not work.
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