Ground tracking of Apollo.
Apollo Manned Space Flight Network /MSFN/ TRACKING and communications systems for tracking lunar spacecraft
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Apollo Manned Space Flight Network /MSFN/ TRACKING and communications systems for tracking lunar spacecraft
The design and requirements for the proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer (COLD-SAT) satellite experiment, which is to be launched by Atlas I, are examined. The COLD-SAT experiments are categorized as class I and II; class I involves technology related to space transportation missions and class II represents alternative fluid management operations and data. The hardware for the COLD-SAT experiments consists of three hydrogen tanks contained in the experimental module; the experimental module is connected to a three-axis-controlled spacecraft bus, and thrusters are positioned on the forward and aft ends of the spacecraft and on the cylindrical portion of the experimental module. The components and systems of the experiment module and the types of experiments that can be conducted in each tank are described. Diagrams of the spacecraft configuration are provided.
Computerized mathematical analysis for dynamic behavior prediction of Apollo command module during earth landing
The conclusions of the analyses of the inflight performance of the Apollo 13 spacecraft guidance, navigation, and control equipment are presented. The subjects discussed are: (1) the command module systems, (2) the lunar module inertial measurement unit, (3) the lunar module digital autopilot, (4) the lunar module abort guidance system, (5) lunar module optical alignment checks, and (6) spacecraft component separation procedures.
This paper presents an overview of the development and qualification test campaign for the primary structure of the European Service Module of ORION, the NASA spacecraft which will serve the future human exploration missions to the Moon, Mars and beyond. Under an agreement between NASA and ESA, the ORION will be powered by a European Service Module (ESM), providing also water and oxygen for astronauts' life sustainability. The development and qualification of the European Service Module (ESM) is under ESA responsibility with Airbus Defense and Space as the prime contractor. Thales Alenia Space Italia is responsible for design development, manufacturing, assembly and qualification of the Structure subsystem. The European Service Module, installed onto the launch adapter, shall support the crew module with its adapter and a launch abort system. It shall sustain: - A combination of global and local launch loads during lift off and ascent phases, - On orbit loads induced by engine firing for orbital transfers and attitude control. The ESM structure is based on a core made of Composite Fiber Reinforced Polymer (CFRP) sandwich panels complemented by aluminum alloy platforms, longerons and secondary structures. A development campaign has been implemented in order to define and validate composite parts' strength allowable values for design: coupon tests at material level, test at component level up to breadboards tests performed on main structural components (composite to metallic joints, and at panels' discontinuities). An incremental approach as defined in [1] has been followed. A qualification static test campaign at primary structure assembly level has been implemented in order to validate the design against static stiffness and ultimate strength as well as to correlate the structural Finite Element Model (FEM) used for sizing and confirm the margins of safety. The tests have been performed successfully by Thales Alenia Space Italia (TAS-I) on two flight representative structural models (STA1, STA2), in Turin facilities (Italy) between August 2015 and March 2017, with engineering support of technical representatives from Airbus, ESA, NASA and LMCO. The main development and qualification test activities and associated results are presented and discussed in the paper
The Wide-Field Infrared Explorer (WIRE), currently scheduled for launch in September 1998, is the fifth of five spacecraft in the NASA/Goddard Small Explorer (SMEX) series. This paper presents the design of WIRE's Attitude Control System flight software (ACS FSW). WIRE is a momentum-biased, three-axis stabilized stellar pointer which provides high-accuracy pointing and autonomous acquisition for eight to ten stellar targets per orbit. WIRE's short mission life and limited cryogen supply motivate requirements for Sun and Earth avoidance constraints which are designed to prevent catastrophic instrument damage and to minimize the heat load on the cryostat. The FSW implements autonomous fault detection and handling (FDH) to enforce these instrument constraints and to perform several other checks which insure the safety of the spacecraft. The ACS FSW implements modules for sensor data processing, attitude determination, attitude control, guide star acquisition, actuator command generation, command/telemetry processing, and FDH. These software components are integrated with a hierarchical control mode managing module that dictates which software components are currently active. The lowest mode in the hierarchy is the 'safest' one, in the sense that it utilizes a minimal complement of sensors and actuators to keep the spacecraft in a stable configuration (power and pointing constraints are maintained). As higher modes in the hierarchy are achieved, the various software functions are activated by the mode manager, and an increasing level of attitude control accuracy is provided. If FDH detects a constraint violation or other anomaly, it triggers a safing transition to a lower control mode. The WIRE ACS FSW satisfies all target acquisition and pointing accuracy requirements, enforces all pointing constraints, provides the ground with a simple means for reconfiguring the system via table load, and meets all the demands of its real-time embedded environment (16 MHz Intel 80386 processor with 80387 coprocessor running under the VRTX operating system). The mode manager organizes and controls all the software modules used to accomplish these goals, and in particular, the FDH module is tightly coupled with the mode manager.
Results are presented of the planetary radio astronomy observations conducted on board Voyager 2, with emphasis placed on the characteristics of the strong (3 to 6 dB) modulations of the broadband smooth Uranian radio emissions recorded from January 27-30, 1986, when the spacecraft was outbound from Uranus. The modulations were characterized by two superposed periods of about 100 sec and about 10 sec. It is suggested that the long-period modulation is due to the magnetopause surface waves, while the short-period modulations are due to the signature of ion cyclotron turbulence above the proton gyrofrequency, related to the magnetopause boundary layer.
Portions of the combined Apollo spacecraft (the command and service module and the lunar module) are subjected to the impingement of hot exhaust gases from the various propulsion systems of the modules. The configurations of the vehicles and the sources of impinging engine plumes are described. A typical Apollo mission is outlined. Protection and design-verification methods are discussed. Finally, recommendations are made for future spacecraft programs.
Structural features of Apollo spacecraft, its subsystems, configurations and functions
The mathematical formulation of orbital spacecraft sloshing dynamics for a partially filled cryogenic superfluid liquid helium II in a dewar container actuated by the gravity gradient acceleration associated with slew motion is studied. The Advanced X-Ray Astrophysics Facility-Spectroscopy (AXAF-S) spacecraft is chosen as a practical example in this study. Explicit mathematical expressions which manage orbital galaxy gradient acceleration with slew motion which is acting on the spacecraft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinates and the solution of time-dependent, three-dimensional formulations of partial differential equations subject to initial and boundary conditions. This study discloses the capillary effect of sloshing dynamics governed liquid-vapor interface fluctuations, angular momentum and moment fluctuations of fluid system, and also buble mass center fluctuations driven by the gravity gradient acceleration associated with slew motion which affects the stability of the orbital spacecraft fluid system in a microgravity environment.
The Orion spacecraft is part of NASA’s Artemis program to establish a permanent human presence on the lunar surface and further enable future crewed missions to Mars. One of the key safety features of Orion is the Launch Abort System (LAS) which pulls the Orion Crew Module (CM) away in the event of a launch vehicle malfunction. It was necessary to design a LAS hatch that allows for crew access to the CM during pad operations. This paper describes the background and evolution of the LAS hatch design, the features used to address the crew safety requirements, the testing challenges in preparation for the Artemis crewed missions, and lessons learned.
The Orion spacecraft is part of NASA’s Artemis program to establish a permanent human presence on the lunar surface and further enable future crewed missions to Mars. One of the key safety features of Orion is the Launch Abort System (LAS) which pulls the Orion Crew Module (CM) away in the event of a launch vehicle malfunction. It was necessary to design a LAS hatch that allows for crew access to the CM during pad operations. This paper describes the background and evolution of the LAS hatch design, the features used to address the crew safety requirements, the testing challenges in preparation for the Artemis crewed missions, and lessons learned.
Since Mariner, NASA-JPL planetary missions have been supported by ground software to plan and design remote sensing science observations. The software used by the science and sequence designers to plan and design observations has evolved with mission and technological advances. The original program, PEGASIS (Mariners 4, 6, and 7), was re-engineered as POGASIS (Mariner 9, Viking, and Mariner 10), and again later as POINTER (Voyager and Galileo). Each of these programs were developed under technological, political, and fiscal constraints which limited their adaptability to other missions and spacecraft designs. Implementation of a multi-mission tool, SEQ POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions as they were being adapted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required. The current and planned capabilities of the tool will be discussed. The presentation will also include a 5-10 minute video presentation demonstrating the capabilities of a proto-Cassini Project version that was adapted to test the tool. The work described in this abstract was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.
Implementation of a multimission tool, SEQ_POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions when being adopted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ_POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required.
Wire-connected electronic module as standard configuration for operational tests of spacecraft components
The Apollo command module was the first manned spacecraft to be designed to enter the atmosphere of the earth at lunar-return velocity, and the design of the thermal protection subsystem for the resulting entry environment presented a major technological challenge. Brief descriptions of the Apollo command module thermal design requirements and thermal protection configuration, and some highlights of the ground and flight testing used for design verification of the system are presented. Some of the significant events that occurred and decisions that were made during the program concerning the thermal protection subsystem are discussed.
In situ observations of the cusp/cleft are important as they allow a direct investigation of coupling solar wind energy to the ionosphere, plus they provide an opportunity for the remote sensing of the magnetopause. High time resolution observations from Dynamic Explorer 1 are used to investigate these processes. It is shown that in the spacecraft frame the injection is modulated or pulsating with a period of approximately 18-30 s with the injection duration possibly being as short as 6 s. This modulation indicates that there may be fast time scale and/or short scale length processes modulating the injection of the magnetosheath plasma across the magnetopause. In addition, the pulsating injection is seen to modulate the outflow of upwelling ionospheric ions to the magnetosphere. These upwelling ions are seen prior to the magnetosheath ion injection and therefore are not directly created by the injection. During the injection itself, the intensity of the upwelling ions is seen to dramatically decrease but their average energy increases. At end of the magnetosheath injections, the intensity of the upwelling ion flux is seen to increase to levels comparable to levels prior to the magnetosheath injection. On two occasions during the encounter, the particle fluxes are sufficiently high that enhanced downward flows of perpendicularly heated ions, of presumably ionospheric origin, are observed in association with a reduction in the intensity of the upwelling ions. These observations are probably the first detection of downward conics and suggest that there is momentum transfer between the magnetosheath and ionospheric ions. This momentum transfer eventually leads to an enhanced outflow of heated ionospheric plasma where their energy has been raised from a few tens of eV to a few hundred eV.
The Automated Scheduling and Planning Environment (ASPEN) computer program has been updated to version 3.0. ASPEN as a whole (up to version 2.0) has been summarized, and selected aspects of ASPEN have been discussed in several previous NASA Tech Briefs articles. Restated briefly, ASPEN is a modular, reconfigurable, application software framework for solving batch problems that involve reasoning about time, activities, states, and resources. Applications of ASPEN can include planning spacecraft missions, scheduling of personnel, and managing supply chains, inventories, and production lines. ASPEN 3.0 can be customized for a wide range of applications and for a variety of computing environments that include various central processing units and randomaccess memories. Domain-specific reasoning modules (e.g., modules for determining orbits for spacecraft) can easily be plugged into ASPEN 3.0. Improvements over other, similar software that have been incorporated into ASPEN 3.0 include a provision for more expressive time-line values, new parsing capabilities afforded by an ASPEN language based on Extensible Markup Language, improved search capabilities, and improved interfaces to other, utility-type software (notably including MATLAB).