It’s always amusing and sometimes frustrating to see NASA doing something I have suggested in these columns – usually after wasting millions of dollars and years of time on another option. Exactly that has happened with the boosters being designed as part of NASA’s plan for manned missions to the Moon and Mars.
Over two years ago I wrote about “Shuttle-derived” launch vehicles and concluded:
“Any heavy-lift booster based on the failed technology of the Space Shuttle will certainly be too expensive and dangerous to be the basis of a viable manned Moon or Mars program. Any short-term answer to the lift deficit should be based on the newer and cheaper technology developed in the EELV program.”
I received considerable abuse from the Shuttle sympathizer community for this statement, especially after the release of the famous ESAS study.
Here a blue-ribbon panel of experts had “objectively” evaluated every possible booster option and concluded that a CaLV closely based on Shuttle technology and even using major Shuttle components was the optimum solution. Anybody who dared to hold another opinion was shown the 723-page ESAS report and told to shut up.
And it wasn’t just armchair critics like me who were snubbed. NASA contractors presented designs similar to the current May 2006 CaLV design in confidential briefings at NASA HQ throughout the year 2005 – only to have them rejected as totally unsuitable!
By now, almost every element of the CLV and CaLV boosters recommended by ESAS has been changed. The Shuttle heritage has been progressively reduced in favor of Apollo-based and EELV-based components. NASA has gone down exactly the route that I outlined in April 2004.
First they discovered that the super-complex SSME can’t be started up without a roomful of ground support equipment, and replaced it as the CLV upper-stage engine with Apollo-derived J-2X engines. To make up for their lower thrust, the Shuttle-derived 4-segment SRB planned for the CLV first stage was replaced with a new 5-segment SRB.
SRB-5 is a very different beast from SRB-4 currently used. Solid rocket motors can’t be easily stretched or shortened like liquid-fuel tankage. If you merely inserted a 5th segment into the current SRB you would have 25% more burn area and 25% more gas trying to get out through the same nozzle. SRB-5 has to have a different central cavity in the fuel, a larger nozzle, and a slower-burning fuel mix.
The heavier booster needs larger recovery parachutes that can deploy at higher speeds. There is also a persistent rumor that NASA is dissatisfied with the projected costs of refurbishing SRB-5 and may go to an expendable design.
Also, it appears that MSFC and Thiokol will use this opportunity to replace some of the more problem-ridden SRB-4 hardware. The hydrazine APUs will probably be replaced with pneumatic controls powered from a big tank of compressed N2.
Because of all these changes, SRB-5 is essentially a new product that needs to be designed and flight-qualified from scratch. Thiokol’s “Safe, Simple, Soon” sales pitch sounds like a sick joke now.
Having purged the CLV of any Shuttle heritage, NASA began the same process on the CaLV. It was suddenly discovered that the projected “expendable” version of the SSME is still too expensive to expend. The only possible replacement was the RS-68 engine designed for the Delta 4. But this engine achieves low cost and high reliability at the cost of lower ISP and greater weight than the SSME.
This means that more fuel must be burned to achieve the same performance. The original CaLV core tankage was a stretched version of the Shuttle ET that would have required major re-engineering but at least could be fabricated on the ET tooling at Michoud Assembly Facility. The switch to RS-68 means that the CaLV core stage will be enlarged to 10m diameter to accommodate the extra fuel within the VAB height limit.
If we summarize the changes announced to date, we see that neither the CLV or the CaLV retains any Space Shuttle heritage.
Component ESAS Plan Current Plan
——————— —————————- ———————
CLV Stage 1 Shuttle SRB-4 New SRB-5
CLV Stage 2 Shuttle Main Engine New J-2X
CaLV Booster New SRB-5 New SRB-5
CaLV Core Eng. Shuttle Main Engine RS-68
CaLV Core Tank Stretched Shuttle ET New Tankage
This total abandonment of the original Shuttle-derived booster concept has received surprisingly little comment. The earlier deletion of the methane engines for the CEV-SM and LSAM-AS provoked a torrent of criticism, but the space community seems to have accepted the booster switch without looking at the implications.
There were three basic arguments for retaining Shuttle elements in the VSE:
1) reduce development costs for new hardware
2) accelerate CLV development to close the spacflight gap after Shuttle retirement
3) keep the Shuttle workforce employed at the same factories in the same Congressional districts.
The short-term fiscal effect of the CLV changes is that SRB-5 and J-2X have to be developed much sooner. Peak development costs will probably move up to the 2007-2010 fiscal years where they conflict directly with Shuttle and ISS. The already severe budget crunch will be worsened by this change.
Of course if you believe that Mike Griffin wants to rid himself of the Shuttle and ISS programs, this budget crunch is just another element of his secret plan to cancel them. Another possible solution is that the CLV itself will be cancelled and replaced with a modified Delta or Atlas as many critics have proposed.
The new CLV requires far more work than the original and certainly will come on-line later. This is totally inconsistent with the proclaimed need to minimize the post-2010 gap in US manned flight – but you hear fewer and fewer complaints about this as the current flight gap approaches the 4-year mark without any catatstrophic results to the nation.
The political argument for the Shuttle-derived boosters was always the strongest. Mike Griffin’s many cheerleaders cited them as an example of his political acumen. Even some critics accepted them as an inevitable result of the pork-barrel politics that keeps the manned space program alive in the absence of any real national need.
But there hasn’t been any outcry from space-district congressmen at these radical changes in a program that was supposedly optimized to satisfy them. Nobody is denouncing Mike Griffin for what seems to be a blatant example of bait-and-switch tactics.
It’s easy to see why. None of these changes actually diverts any money to another district.
The SRB-5 is still remanufactured in Utah and will actually cost more than SRB-4. Two moon missions per year will need a total of 30 segments recast. This is equivalent to 3.75 Shuttle missions, about equal to the average flight rate.
The RS-68 is a Pratt&Whitney/Rocketdyne engine like the SSME. Ten $20M+ CaLV engines per year means over $200M/yr of income for PWR, equivalent to 3.3 new SSMEs.
The new 10-meter CLV core stage can still be built at Michoud, and the new tooling required will give the workforce something to do during the Shuttle-CaLV production gap.
So these new boosters achieve the same political goals as the original ones. NASA hasn’t made any change which would upset any apple carts (e.g. replacing SRB-5 with an Atlas-based liquid stage). Which leads to the $64,000,000,000 question:
Why did NASA waste over two years fiddling with a design concept that almost everybody else recognized as fundamentally wrong? What political advantage was gained by this?
Could it really be true that the big booster switch is not an example of Mike Griffin’s political acumen, but just more of the technical incompetence we have seen from NASA over the past 30 years? Could the emperor really be naked?