Propellant Selection for Spacecraft Propulsion Systems. Volume 2 - Missions and Vehicles Final Report
Voyager and Mars Excursion Module baseline mission and stage analyses - spacecraft propulsion
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Voyager and Mars Excursion Module baseline mission and stage analyses - spacecraft propulsion
In the preliminary design of spacecraft, spreadsheets are often used to scale and size components. While offering some benefits, using spreadsheets does have some drawbacks. In particular, since time is typically not one of the input values, overly conservative designs can result because scheduling issues are not considered. To overcome this problem, the Space Systems Concepts Division is developing a time dependent, virtual spacecraft simulation system. Since the performance of many components on the spacecraft are sensitive to the attitude of the spacecraft, a method or function is needed to determine the attitude of a part. Thus, the primary goal of this research was to develop a software module that calculates the attitude of an arbitrary part on the spacecraft. This module is then used by subsystem engineers, e.g. the power subsystem, to compute the attitude relative to the spacecraft, the sun, the Earth, or a user specified target.
The Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer Satellite (COLD-SAT) will perform subcritical liquid hydrogen handling experiments under low gravity conditions to provide engineering data for future space transportation missions. Comprising the four Class 1 enabling experiments are tank press control, tank chilldown, tank no-vent fill, and liquid acquisition device fill/refill. The nine Class 2 enhancing experiments are tanker thermal performance, pressurization, low-gravity setting and outflow, liquid acquisition device performance, transfer line chilldown, outflow subcooling, low-gravity vented fill, fluid dumping, and advanced instrumentation. Consisting of an experiment module mated to a spacecraft bus, COLD-SAT will be placed in an initial 1300 km circular orbit by an Atlas commercial launch vehicle, and will perform experiments in a semi-autonomous mode for a period of up to six months. The three-axis controlled spacecraft bus provides electric power, control and data management, communications, and attitude control along with propulsive acceleration levels ranging from 10(exp -6) to 10(exp -4) g. It is desired to understand the effects that low acceleration levels might have on the heat and mass transfer processes involved in some of the experiments. The experiment module contains the three liquid hydrogen tanks, valves, pressurization and pumping equipment, and instrumentation. Within the highly insulated tanks are specialized fluid management equipment that might be used in future space transportation systems. At launch all the liquid hydrogen for the experiments is contained in the largest tank, which has helium-purged insulation to prevent cryo-pumping of air on the launch pad. The tank is loaded by the hydrogen tanking system used for the Centaur upper stage of the Atlas. After reaching orbit the two smaller tanks become receivers for fluid transfers, and when tanked, become the vessels for performing many of the experiments.
The ICE spacecraft observed in the vicinity of Comet Giacobini-Zinner electrostatic noise with burstlike features seemingly modulated by the relative orientation of the interplanetary magnetic field and the solar wind velocity. The adequacy of ion acousticlike instabilities stimulated by photoelectron or newborn ion beams to the interpretation of the electrostatic bursts is discussed. It is concluded that the mode fed by the photoelectrons exhibits characteristics compatible with the observations.
This video shows footage of the Expedition 1 crew, William Shepherd, Yuri Gidzenko, and Sergei Krikalev, training for their stay on the International Space Station. Shepherd is seen training in the Soyuz spacecraft and inspecting the Service Module and Node 1. The three crewmembers are seen training for winter survival and extravehicular activity (in the Neutral Buoyancy Lab). They are taught how to use the fire extinguishers and extravehicular activity tools. Scenes show Gidzenko training in the crew compartment trainer and on the Mir Space Station and Krikalev on the STS-60 mission. A computer animation shows the Soyuz spacecraft docking with the Service Module.
The large-signal behaviors of a regulator depend largely on the type of power circuit topology and control. Thus, for maximum flexibility, it is best to develop models for each functional block a independent modules. A regulator can then be configured by collecting appropriate pre-defined modules for each functional block. In order to complete the component model generation for a comprehensive spacecraft power system, the following modules were developed: solar array switching unit and control; shunt regulators; and battery discharger. The capability of each module is demonstrated using a simplified Direct Energy Transfer (DET) system. Large-signal behaviors of solar array power systems were analyzed. Stability of the solar array system operating points with a nonlinear load is analyzed. The state-plane analysis illustrates trajectories of the system operating point under various conditions. Stability and transient responses of the system operating near the solar array's maximum power point are also analyzed. The solar array system mode of operation is described using the DET spacecraft power system. The DET system is simulated for various operating conditions. Transfer of the software program CAMAPPS (Computer Aided Modeling and Analysis of Power Processing Systems) to NASA/GSFC (Goddard Space Flight Center) was accomplished.
Packaging, machine organization, error detection, and fabrication and test in determining solution to long-term and time-critical reliability of Apollo command module guidance-control computer
A multireceiver configuration for the purpose of carrier arraying and/or signal arraying is presented. Such a problem arises for example, in the NASA Deep Space Network where the same data-modulated signal from a spacecraft is received by a number of geographically separated antennas and the data detection must be efficiently performed on the basis of the various received signals. The proposed configuration is arrived at by formulating the carrier and/or signal arraying problem as an optimal estimation problem. Two specific solutions are proposed. The first solution is to simultaneously and optimally estimate the various phase processes received at different receivers with coupled phase locked loops (PLLs) wherein the individual PLLs acquire and track their respective receivers' phase processes, but are aided by each other in an optimal manner. However, when the phase processes are relatively weakly correlated, and for the case of relatively high values of symbol energy-to-noise spectral density ratio, a novel configuration for combining the data modulated, loop-output signals is proposed. The scheme can be extended to the case of low symbol energy-to-noise case by performing the combining/detection process over a multisymbol period. Such a configuration results in the minimization of the effective radio loss at the combiner output, and thus a maximization of energy per bit to noise-power spectral density ration is achieved.
Preliminary designs of the Bioexplorer spacecraft, developed in an earlier study program, are analyzed and updated to conform to a new specification which includes use of both the Scout and the space shuttle vehicle for launch. The updated spacecraft is referred to as bioresearch module. It is capable of supporting a variety of small biological experiments in near-earth and highly elliptical earth orbits. The baseline spacecraft design is compatible with the Scout launch vehicle. Inboard profile drawings, weight statements, interface drawings, and spacecraft parts and aerospace ground equipment lists are provided to document the design. The baseline design was analyzed to determine the design and cost impact of a set of optional features. These include reduced experiment power and thermal load, addition of an experiment television monitor, and replacement of VHF with S-band communications. The impact of these options on power required, weight change and cost is defined.
A bubble memory module design providing flexibility for many user applications in spacecraft data recording is described. The memory module can be used with user-designed controllers with the memory organization determined by the application. Asynchronous data rates from zero to 1.33 Mbits/sec at minimum power are accomplished by using 8-chip memory cells with 100 K bit serial chips. The memory module is expandable from a 4 x 2 cell matrix to a 4 x 16 cell matrix corresponding to an expandable capacity of 6.55 M to 52.4 M bits. The module's design, utility in various memory systems, and user clocking scheme are described.
Telemetry and television capabilities of command module and Lunar Excursion Module /LEM/
Problems and technology requirements for design of unmanned Mars probe and lander
Intensity display system similar to radar output, showing real time intensity and pattern variations created by solar lamp modules in testing of spacecraft systems in simulation facilities
Cassegrain monopulse tracking antenna for LEM and Command Module rendezvous guidance
Full-size pilot-controlled docking simulation of Apollo command and service module with lunar module using only visual information
Flight test evaluation of on-off rate command attitude control system of manned lunar landing research vehicle
Design concept of combined counter/shift register module and applications as spacecraft telemetry encoders and logarithmic data compressor
Ultrasonic modeling system for simulating lunar excursion module landing trajectory on lunar surface