Internal NASA Studies Show Cheaper and Faster Alternatives to The Space Launch System
On 26 September 2011, Rep. Dana Rohrabacher (R-CA) issued a press release regarding fuel depots. This included a letter to former Administrator Mike Griffin who had dismissed the notion of fuel depots and commercial launch vehicles as being a viable alternative to the Space Launch System(SLS) during Congressional testimony.
Rohrabacher noted “When NASA proposed on-orbit fuel depots in this Administration’s original plan for human space exploration, they said this game-changing technology could make the difference between exploring space and falling short. Then the depots dropped out of the conversation, and NASA has yet to provide any supporting documents explaining the change,” says Rohrabacher.”
Well, despite what NASA may or may not have been telling Rep. Rohrabacher about its internal evaluations regarding the merits of alternate architectures that did not use the SLS (and those that incorporated fuel depots), the agency had actually been rather busy studying those very topics.
And guess what: the conclusions that NASA arrived at during these studies are in direct contrast to what the agency had been telling Congress, the media, and anyone else who would listen.
This presentation “Propellant Depot Requirements Study – Status Report – HAT Technical Interchange Meeting – July 21, 2011” is a distilled version of a study buried deep inside of NASA. The study compared and contrasted an SLS/SEP architecture with one based on propellant depots for human lunar and asteroid missions. Not only was the fuel depot mission architecture shown to be less expensive, fitting within expected budgets, it also gets humans beyond low Earth orbit a decade before the SLS architecture could.
Moreover, supposed constraints on the availability of commercial launch alternatives often mentioned by SLS proponents, was debunked. In addition, clear integration and performance advantages to the use of commercial launchers Vs SLS was repeatedly touted as being desirable: “breaking costs into smaller, less-monolithic amounts allows great flexibility in meeting smaller and changing budget profiles.”
In a time when space sector jobs are an issue this alternative architecture to the use of the SLS would create real jobs and get humans beyond low Earth orbit years sooner than what the Senate demands be done via the pork filled route.
Right now there is a slow-motion purge underway within OCT and across the agency to move anyone who thinks beyond the SLS mindset in ways that could do things in a much less costly fashion with much greater flexibility.
And if some of these words below look familiar, well they should – see “Using Commercial Launchers and Fuel Depots Instead of HLVs” (March 2011) and “The HLV Cost Information NASA Decided Not To Give To Congress” (January 2011). Studies have been bouncing around NASA for some time that cite alternatives to large government-developed Ares-V/SLS-class boosters such as the use of fuel depots and commercial launch vehicles.
Excerpts
Why Examine Propellant Depots Without HLLVs?
* Large in-space mission elements (inert) can be lifted to LEO in increments on several medium-lift commercial launch vehicles (CLVs) rather than on one Heavy Lift Launch Vehicle (HLLV)
* Over 70 percent of the exploration mission mass is propellant that can be delivered in increments to a Propellant Depot and transferred to the in-space stages
* Saves DDT&E costs of HLLV
* Low-flight-rate HLLV dominated by high unique fixed costs. Use of CLVs eliminates these costs and spreads lower fixed costs over more flights and other customers.
* Use of large re-fueled cryo stages saves DDT&E/ops costs for advanced propulsion stages (e.g., SEP)
* Provides opportunity for more easily integrated commercial and international partner mission participation
Advantages
* Tens of billions of dollars of cost savings and lower up-front costs to fit within budget profile
* Allows first NEA/Lunar mission by 2024 using conservative budgets
* Launch every few months rather than once every 12-18 months
-Provides experienced and focused workforce to improve safety
-Operational learning for reduced costs and higher launch reliability.
* Allows multiple competitors for propellant delivery
-Competition drives down costs
-Alternatives available if critical launch failure occurs
-Low-risk, hands-off way for international partners to contribute
* Reduced critical path mission complexity (AR&Ds, events, number of unique elements)
* Provides additional mission flexibility by variable propellant load
* Commonality with COTS/commercial/DoD vehicles will allow sharing of fixed costs between programs and “right-sized” vehicle for ISS
* Stimulate US commercial launch industry
* Reduces multi-payload manifesting integration issues
Issues
* Congressional language
* Requires longer storage of cryo propellants than alternatives and addition of zero-g transfer technologies
* Volume/mass constraints (e.g, fairing size)
* NASA loses some control/oversight
* Added complexity of common CPS/depot
* Launch capacity build-up
* Aligning LEO departure plane with departure asymptote location for small NEA departure windows given LAN precession
Launch Rate and Capacity Issues
* Propellant depot options eliminated during HEFT 1 because of supposed launch capacity constraints
* Current US and world-wide launch vehicles operating significantly under-capacity
-Average launch rate for each major LV family is only 2.2/year.
* Possible future LV capacity constraints is only an issue in the short term. Given a few years to invest, capacity is not a long-term problem.
* Additional capacity is a “feature”, not a “bug”, for US launch industry
* Current launch capabilities:
– Atlas V: 5-9/year. Could be doubled with modest infrastructure investment, and doubled again with additional infrastructure investments (e.g., Build a second VIF.ULA inputs at NASA HQ, 10/2010).
– Delta IV: 2-5/year. Could be doubled with modest infrastructure investment, and doubled again with additional infrastructure investments (e.g., Second launch pad,ULA inputs at NASA HQ, 10/2010).
– Falcon: 20/year by 2015, including 10 heavy, 12 already under contract, additional pads planned at WTR and ETR, less than $70M each (Musk E-Mail, Feb 2011)
– Taurus II: : 6-12/year by 2015. (Claybaugh E-Mail, March 2011)
– SeaLaunch: 5/year. Coming back on line. Capacity could be doubled with moderate infrastructure.
– International partners (Ariane5, H-II, Proton, Soyuz, Zenit, GSLV): More than 21/year for Ariane5 & Proton alone
Advantages of Propellant Depot over Refueling
* Most expensive hardware/capability can be located on the depot to be re-used over and over again rather than be expended every flight
* The expendable CPS and delivery tankers can be made as dumb/cheap as possible
* Mass of the CPS that has to be pushed through thousands of m/s of delta-V can be reduced
* All of the important and costly avionic/software/IVHM can be on the depot
* The prox-ops and rendevousand docking systems can be on the depot, rather than on CPS
* The depot could do the last prox-ops maneuvers and even berth the tanker/CPS with an RMS
* Relieves CPS of need for active boil-off control for cis-lunar missions with few burns (Injection burns are made shortly after undocking. For NEO missions that need burns after 100 days of travel, this could be done by storablesor cryotanks inside of the main tanks and conditioned via passive systems and/or fuel cells)
* Reduces risk to CPS from MMOD by reducing required time in orbit prior to departure
* Reduces number of rendezvous events required to fuel CPS from many to one, reducing risk of collision or propellant transfer failure
* Reduces risk of LOM by decoupling propellant delivery flights from delivery of mission elements (i.e., elements stay on the ground until needed for mission)
* Opens the possibility to add other in-space services (e.g., maintenance and repair)
* Potential for multiple customers and creation of new commercial industry
NEA Mission Observations – Mixed Fleet
* Costs $10s of billions less through 2030 over alternate HLLV/SEP-based architecture approaches
– Only $10B more than all Falcon Heavy approach
* Fits within conservative exploration budget through 2030 with extended ISS and budget cuts while allowing 3-4 NEA missions
* Breaking costs into smaller, less-monolithic amounts allows great flexibility in meeting smaller and changing budget profiles
* Allows first mission to NEA in 2024, potentially several years earlier than HLLV/SEP-based approaches, meeting President’s deadline and actual availability of NEA 2008EV5
* Launch capacity not much of an issue with two suppliers
– Availability risk also improved
* Use of two CLVs, similar to COTS, should reduce cost and risk through competition
* Integration of large CPS stage with multiple vehicles could reduce commonality and add complexity
Lunar Mission Observations -RP Depot/CPS
* Costs $10s of billions less through 2030 over alternate HLLV/SEP-based architecture approaches
– Only $2B more than LO2/LH2 Depot approach
* Fits within conservative exploration budget through 2030 with extended ISS and budget cuts while allowing 4-8 lunar missions
* Breaking costs into smaller, less-monolithic amounts allows great flexibility in meeting smaller and changing budget profiles
* Allows first lunar mission to in 2024, potentially several years earlier than HLLV-based approaches
* Launch capacity does not appear to be a major issue
* Dependence on a single CLV and provider likely unacceptable
* Integration of large CPS stage with small-diameter Falcon easier due to smaller stage size
* Integration of lunar lander on Falcon limits design options
* RP-based depot/CPS provides slightly higher LCC for lunar missions with lower risk
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