The Exploration Systems Architectural Study

Another development at NASA occurred in 2005 that profoundly affected the direction and pace of the Vision for Space Exploration. NASA Administrator Sean O'Keefe had announced his desire to pursue interests in the private sector, and President George W. Bush nominated Dr. Michael Griffin for the role on 14 March 2005. He was confirmed by the U.S. Senate the following month. At the confirmation hearing, Dr. Griffin made positive statements regarding America's role in space and what it meant for the nation.

''In the twenty-first century and beyond, for America to continue to be preeminent among nations, it is necessary for us also to be the preeminent space-faring nation. My conclusion is that we as a nation can clearly afford well-executed, vigorous programs in both robotic and human space exploration, as well as in aeronautics. I believe that, if money is to be spent on space, there is little doubt that the huge majority of Americans would prefer to spend it on an exciting, outward-focused, destination-oriented program. And that is what the President's Vision for Space Exploration is about.''

In May 2005, Administrator Griffin requested an Exploration Systems Architectural Study (ESAS) of the best hardware and facilities required to fulfill the Vision for Space Exploration. The preliminary report was issued in September of that year and the final report, nearly 800 pages long, was presented in November. This report detailed the configuration of the Crew Exploration Vehicle (CEV), the Crew Launch Vehicle (CLV) that would employ a modified Shuttle RSRM with a liquid fuel upper stage, and the Cargo Launch Vehicle (CaLV). The CaLV features a liquid fuel core booster and upper stages with two five-segment SRBs. The first stage was originally proposed to be powered by five Space Shuttle Main Engines (SSME) but NASA may also consider using five RS-68 engines (the Rocketdyne RS-68 is

Dr. Dean Eppler, a geologist at the Johnson Space Center, is shown wearing a Mark III

EVA suit and operating the controls of Matilda, another robotic testbed vehicle, during tests near Flagstaff, Arizona conducted by the Desert RATS. (NASA/JSC/GRC)

Dr. Dean Eppler, a geologist at the Johnson Space Center, is shown wearing a Mark III

EVA suit and operating the controls of Matilda, another robotic testbed vehicle, during tests near Flagstaff, Arizona conducted by the Desert RATS. (NASA/JSC/GRC)

used on the Boeing Delta IV). The Mobile Launch Platforms used for launching the Space Shuttle would be reconfigured to accommodate launching either the CLV or the CaLV from either Launch Complex 39A or 39B at the Kennedy Space Center.

The ESAS report also detailed the Earth Departure Stage that would take the CEV, the Lunar Surface Access Module, (LSAM) and other equipment to the Moon. The need for modular components was outlined and broken down into three weight classifications: Less than 2,000 kg, 2,000 to 10,000 kg, and greater than 10,000 kg. An unpressurized rover was classed in the less than 2,000 kg class, requiring no modular design or assembly on the Moon, while the pressurized rover was classed at over 10,000 kg and would require such options. The pressurized rover came under considerable scrutiny in this report due to the problems involved in getting the components to the lunar surface and their subsequent assembly, as the ESAS report stated:

• After severing all power, data, fluid, and structural connections with the LSAM descent stage, the habitable module must be unloaded from the descent stage (e.g., crane, placed on wheels)

• The habitable volume must be moved to the vicinity of the pressurized rover chassis

• The habitable volume must be lifted (e.g., crane) and placed onto the chassis, and all required connections must be made - power, data, fluid, structural

• The habitable volume will require all systems (Environment Control and Life Support System, Thermal Control System, etc.) that are required to create a surface habitable volume. This means that duplicate systems will be required between the ascent stage and the habitable volume that is left behind

• The habitable volume's systems must be designed with a significantly longer lifetime than is needed to support sortie missions and must be able to accommodate multiple reuses

• No Earth-based integrated validation of the final configuration will be possible

The report went on to explain other problematic issues with the pressurized rover that strongly weighed against it being employed in the first years of missions returning to the Moon:

"Firstly, the pressurized rover chassis will probably be designed from lessons learned from the unpressurized rover design after years of operations. Secondly, pressurized rovers are not needed until several years into the lunar surface program; therefore, there will probably not be an element of intense design scrutiny until several years after the LSAM design is underway (or is already developed).''

Employing a pressurized rover would directly impact the design of the LSAM since the habitable volume would be integrated with it. This report did suggest designing the LSAM in such a way that none of the pressurized rover's operational components interfaced with the LSAM. There was still the issue of removing the main components of the pressurized rover from the LSAM and then assembling them on the lunar surface, however. In the final analysis, the ESAS report made it clear that the next generation lunar rover would be unpressurized. While the design of much of the human-rated hardware described in the report took into account its future use in Mars missions, the approach was to gain experience with this equipment during long-duration lunar missions and apply the experience gained to improved hardware applicable to Martian missions.

In the report's Summary and Recommendations, the last two New Projects listed were No. 51 for surface handling, transportation, and operations equipment (Lunar or Mars), and No. 52 for surface mobility. The first diligent engineering work will be devoted to the Crew Exploration Vehicle, the Crew Launch Vehicle, the Cargo Launch Vehicle and Earth Departure Stage, and then the Lunar Lander and its many science experiments. Eventually, the Request for Proposals will be issued for the second-generation Lunar Roving Vehicle. A wealth of engineering data and actual lunar experience with LRVs can be brought to bear on the next, improved lunar roving vehicles and the experience gained from these new vehicles will be applied to the design of the human-rated Martian roving vehicles.

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