NASA Technical NoteNational Aeronautics and Space Administration., 1963 |
Other editions - View all
Common terms and phrases
aerodynamic Aeronautics and Space air-flow separation Altair altitude angle of attack atmosphere calculated Central Control Station coefficient command configuration control deflection Cygnus 15 DISTANCES FROM SLOT drev electron elliptic elliptic integrals environmental test Equation Explorer XII flap Flux relative fourth-stage rocket frequency ft/sec function Goddard Space Flight GSFC H₂ ignition inlet width ratio ion chamber Jacobian elliptic functions launch Length to inlet magnetometer mass spectrometer measurements mechanical impedance MERCURY-ATLAS NASA NASA TN NASA TECHNICAL NOTE National Aeronautics nominal trajectory obtained optical orbit ORBITING ASTRONOMICAL OBSERVATORY OTS price paddle parameters payload planar motion plane radar range reentry region relative to centerplane remote control stations rocket motor satellite spin shown in figure simulation sin² slot exit solution Space Administration spacecraft stable star telemeter third-stage Three Body Problem tion Trailblazer IIa values vehicle velocity package w₁ Wall half-angle
Popular passages
Page 5 - ... verification, these commands are passed to the Project Operations Center. The commands are then sent by teletype or by microwave to the remote control station which actually communicates with the satellite. In addition to a radio beacon which is used for tracking, three radio links are used to communciate with the OAO. The remote control stations are all identical in their functions and equipment. They normally only secure data from the satellite and transmit predetermined commands to the satellite....
Page 4 - OAO system. desired accuracy of 0.1 second of arc (corresponding to a displacement of 0.03 inch at a distance of 1 mile) , it is near the limit obtainable without using error signals taken from the experimenter's optics. The OAO-II will contain an absolute spectrophotometry experiment designed by a GSFC team headed by Dr. James Milligan. The optical system will employ a 36-inch primary mirror and will use both the spacecraft's coarse and fine control capabilities. However, the experiment is designed...
Page 11 - Figure 10 make up the console. Figure 15 is a block diagram of the Central Control Station equipment not including the large scale digital computer. The functions of the Central Control Station are: 1. Generate commands, predicted status values, contact times, and instructions. 2. Convert commands and other data to TWX format and transmit to remote control stations. 3. Generate and store alternate program for quick takeover. 4. Receive the previous OAO contact data from the remote control stations...
Page 10 - ... simple go, no-go signal which indicates the readiness of particular pieces of equipment. The system functional test controls initiate actions which establish the operating readiness of the Ground Operation Equipment. The mode selector control is present only on the North Carolina station and transfers control to the Central Control Station via the microwave link. Central Control Station The foundation of the OAO ground operations is a large-scale computer which keeps track of astronomical and...
Page 14 - ... commands. The commands transmitted to the OAO from the remote stations are in a PCM NRZ format at a 1-kilobit rate. The data transmitted consist of the command words and their complements to provide error checking. The complement form simplifies the on-board command verification. After verification by the electronic equipment in the satellite, the commands and their complements are echoed (retransmitted) to the ground where the ground operation equipment compares the echo from the satellite with...
Page 3 - OAO-I will carry two prime experiments complementary in their use of the spacecraft systems : (1) a mapping study of the celestial sphere in three ultraviolet ranges (as shown in Figure 4) under the direction of Dr. Fred Whipple of the Smithsonian Astrophysical Observatory, and (2) a broadband photometry study of individual stars and nebulae using the equipment shown in Figure 5 which will be developed by the University of Wisconsin team headed by Dr. Arthur Code. The sky mapping experiment will...
Page 15 - ... a readout of current status from the OAO. Necessary gating signals are sent to the PCM data handling equipment to define the format and word size for proper signal flow in and from the PCM data handling equipment. The computer program causes current and predicted status to be compared word-by-word. In the comparison, the limits of predicted status are extracted from storage an item at a time and the difference between limits and actual values for that parameter are computed and evaluated. If...
Page 19 - ... revolutions, thus turning the spacecraft through a predetermined angle. While moving to this new position, a star tracker may reach its gimbal limit, but this will be anticipated on the ground and the error signal source will be commanded to another star tracker, again by the output from command memory. On reaching the new orientation, the star tracker error signals are connected to the small inertia wheels to maintain attitude. Alternatively, by using the satellite as the reference, the error...
Page 18 - ... accomplish this, the satellite carries core-storage command memory of 256 30-bit words, a star-tracker gimbal-angle digital logic, an analog coordinate transformer, and a system clock. As soon as the initial reference is acquired, the command memory sends new gimbal angles to the proper star trackers. The large inertia wheels are commanded to rotate through a specified number of revolutions, thus turning the spacecraft through a predetermined angle. While moving to this new position, a star tracker...