Axisymmetric Capsule Shape Variations
One way to achieve the required L D is to use a nonaxisymmetric shape similar to the AFE shape mentioned previously. A computer-generated shape optimization approach was pursued to attempt to optimize an OML that exhibited some of the desirable characteristics without necessarily being axissymmetric. The investigation of various optimized shapes used the optimization capabilities of the CBAERO computer code. These optimized shapes held the aft-body shape fixed, while the heat shield shape was...
Blunt Bodies Versus Slender Bodies Trade
The shape study trade was initiated between major vehicle classes. The primary classes considered were capsules blunt bodies , slender bodies, lifting bodies, and winged vehicles. Winged bodies and lifting bodies such as X-38, X-24, HL-10, etc. were eliminated at the outset due to several factors, including 1 the extreme heating especially on empennages these would encounter on lunar return entries, 2 the additional development time required due to multiple control surfaces, and 3 the increased...
Heat Transfer Analysis and TPS Sizing
The TPS sizing analysis was conducted using a transient 1-D Plug model. The required TPS insulation thicknesses were computed by a TPS Sizer using the Systems Improved Numerical Differencing Analyzer SINDA Fluid Integrator FLUINT software solver for the reusable concepts and the FIAT software code for the ablative TPS materials. For the aft portion of the capsule, a full soak-out condition was imposed for TPS insulation sizing. Because the heat shield for all capsule configurations was assumed...
ESAS LSAM Configuration
Based on the results of the LSAM configuration trade studies, a combined CM design was chosen as a POD for future lander design studies. This concept was chosen to both provide the required airlock function and simplify ascent and descent stage interfaces. The description and mass property breakouts presented in this section are the result of additional lander analysis and refined subsystem mass estimation using the Envision sizing tool. It was recognized, however, that returning this large...
CharterPurpose
The Exploration Systems Architecture Study ESAS team developed candidate Launch Vehicle LV concepts, assessed these concepts against the ESAS Figures of Merit FOMs e.g., cost, reliability, safety, extensibility , identified and assessed vehicle subsystems and their allocated requirements, and developed viable development plans and supporting schedules to minimize the gap between Shuttle retirement and the Crew Exploration Vehicle CEV Initial Operational Capability IOC . The team was directed to...
Crew Launch Vehicle
An array of options was assessed to determine their individual abilities to meet the stated requirements for the CLV. Those that most closely support the necessary demands are provided here. The remaining CLV options that were not evaluated further are discussed in more detail in Appendix 6A, Launch Vehicle Summary. Table 6-3. Shuttle-Derived CLV Options Assessed in Detail
LSAM Reference Design
The ESAS team examined the unique architecture of the lunar lander, or LSAM. Other architecture element designs and trade studies were also accomplished by the team. The reference LSAM concept, shown in Figure 1-16, for the ESAS 1.5-launch EOR-LOR architecture is a two-stage, single-cabin lander similar in form and function to the Apollo LM. The LSAM ascent stage, in conjunction with the descent stage, is capable of supporting four crew members for 7 days on the lunar surface and transporting...
Lunar Mission Mode
The lunar mission mode is the fundamental lunar architecture decision that defines where space flight elements come together and what functions each of these elements perform. Mission mode analysis had its genesis early in the design of the Apollo Program, with notable NASA engineers and managers such as Wernher Von Braun, John Houbolt, Joe Shea, and Robert Seamans contributing to the decision to use LOR as the Apollo mission mode. This study built on the foundation of the Apollo decision but...
DRM Description Lunar Sortie Crew with Cargo
The architecture provides the capability for up to four crew members to explore any site on the Moon i.e., global access for up to 7 days. These missions, referred to as lunar sorties, are analogous to the Apollo surface missions and demonstrate the capability of the architecture to land humans on the Moon, operate for a limited period on the surface, and safely return humans to Earth. Sortie missions also allow for exploration of high-interest science sites or scouting of future lunar outpost...
Overall Mass Properties
Table 5-1 provides overall vehicle mass properties for the lunar CEV CM. The mass properties reporting standard is outlined in JSC-23303, Design Mass Properties. A detailed mass statement is provided in Appendix 5A, CEV Detailed Mass Breakdowns. Vehicle Mass Properties for the Lunar CEV CM Vehicle Mass Properties for the Lunar CEV CM
Ascent Stage Description
The reference LSAM concept for the ESAS 1.5-launch EOR-LOR architecture is a two-stage, single-cabin lander similar in form and function to the Apollo LM. The LSAM ascent stage, in conjunction with the descent stage, is capable of supporting four crew members for 7 days on the lunar surface and transporting the crew from the surface to lunar orbit. The ascent stage assumes an integrated pressure-fed oxygen methane propulsion system, similar to the CEV SM, to perform coplanar ascent to a 100-km...
Lunar CEV SM Vehicle Description
The Lunar CEV SM is included in the ESAS exploration architecture to provide major trans-lational maneuvering capability, power generation, and heat rejection for the CEV CM. The SM assumes an integrated pressure-fed oxygen methane service propulsion system and RCS to perform rendezvous and docking with the LSAM in Earth orbit, any contingency plane changes needed prior to lunar ascent, TEI, and self-disposal following separation from the CM. One 66.7 kN 15,000 lbf service propulsion system and...
Overview 1
A safe, reliable means of human access to space is required after the Space Shuttle is retired in 2010. As early as the mid-2010s, a heavy-lift cargo capability will be required, in addition to the crew launch capability to support manned lunar missions and follow-on missions to Mars. It is anticipated that robotic exploration beyond Earth orbit will have an annual manifest of five to eight spacecraft. The ESAS team was chartered to develop and assess viable launch system configurations for a...
CM Net Habitable Volume Trades
In the history of human spacecraft design, the volume allocated for crew operations and habit-ability has typically been the remaining excess after all of the LV constraints and vehicle design, weight, CG, and systems requirements were met. As a result, crew operability has often been compromised as crew sizes are increased, mission needs changed, and new program requirements implemented. CM habitability considerations have often been relegated to a second level behind engineering convenience...
Protection
The CEV CM spacecraft protection consists of the materials dedicated to providing passive spacecraft thermal control during all mission phases including ascent, ascent aborts, in-space operations, and atmospheric entry, and includes the following components External TPS and internal insulation. For the CEV CM, spacecraft protection is the TPS that includes ablative TPS on the windward aft side of the vehicle, reusable surface insulation for the external leeward central and forward TPS, and...
Entry Trajectory for CEV CM Returning from ISS
An evaluation of the CEV returning from the ISS was conducted as part of the ESAS. A simplified CEV vehicle model was used in the 4-DOF Simulation and Optimization of Rocket Trajectories SORT . The vehicle model consisted of an L D of 0.4 which included constant lift-and-drag coefficients as well as a constant ballistic number throughout the entry. A complete list of the simplified CEV model can be seen in Table 5-20. All entry scenarios were flown assuming two entry techniques, guided and...
TPS and AeroShell Material and Properties
A summary of the structural and carrier panel aero-shell materials is presented in Table 5-11, which includes material selection and representative thicknesses. A similar summary of the TPS materials is presented in Table 5-12. For the reusable TPS concepts, the thermal, optical and mechanical properties were taken from the Thermal Protection Systems eXpert TPSX online database. A detailed listing of the benefits and concerns associated with each TPS material is given in Table 5-13. Table 5-11....
CEV Design Evolution
The design and shape of the CEV CM evolved in four design cycles throughout the study, beginning with an Apollo-derivative configuration 5 m in diameter and a sidewall angle of 30 deg. This configuration provided an OML volume of 36.5 m3 and a pressurized volume of 22.3 m3. The CM also included 5 g cm2 of supplemental radiation protection on the cabin walls for the crew's protection. Layouts for a crew of six and the associated equipment and stowage were very constrained and left very little...
Info
Rocketdyne has performed LOX LCH4 tests on various contracts primarily related to large engine chambers and gas generators. The High-Pressure LOX CH4 Injector Program, NASA Marshall Space Flight Center MSFC contract NAS8-33206 1978-1979 , examined coaxial and impinging elements for high-pressure LOX CH4 operation with an existing 40 klb-thrust chamber. The shear coaxial element injector was fabricated, flow-tested, and delivered to MSFC for hot-fire testing. In 1988, MSFC tested the 82-element...
Lunar return heating is extremely high heavy heat shield Blunt Bodies versus
To summarize the results, it appeared that the capsule configurations have more desirable features and fewer technical difficulties or uncertainties than the slender body class of vehicles. Because one of the primary drivers for the selection was the minimal time frame desired to produce and fly a vehicle, the blunt bodies had a definite advantage. All the human and robotic experience NASA has had with blunt bodies has led to a wealth of knowledge about how to design, build, and fly these...