Apollo entry radar acquistion study
Apollo entry radar acquisition of command module for tracking during ionization blackout
COMMAND MODULE↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Hypersonic aerodynamic problems at re-entry of space vehicles
Hypersonic aerodynamic problems at space vehicle reentry - plasma effects on communications blackout, hypersonic flow, and atmospheric entry
PLASMA PHYSICS↗
Electron attachment to atomic fluorine in thermally ionized air
Electron attachment to atomic fluorine in thermally ionized air for application to reentry radio communications blackout
REENTRY COMMUNICATION↗
Apollo plasma sheath in-flight diagnostics
Electron density probes for potential application to Apollo in-flight plasma sheath diagnostics in reentry radio blackout investigations
BLACKOUT↗
Communications elements research
Planetary entry blackout, instrumentation and data reduction for lunation experiment, spacecraft communications system, and low noise transponder preamplifier
PREAMPLIFIER↗
Entry trajectory, entry environment, and analysis of spacecraft motion for the RAM C-3 flight experiment
The RAM C-3 flight experiment was launched to study the problem of radiofrequency blackout at an entry velocity of 24,300 ft/sec. The flight is described, and data for the entry trajectory and environment, which include the effects of actual temperature measured the day of launch, are presented. An analysis of entry spacecraft motions was performed. This analysis included the determination of wind angles from measured accelerations and estimates of wind angles at high altitudes from gyro-measured rotation rates. The maximum wind angles were found to be less than 5 deg to the point of pitch-roll resonance where the total wind angle increased to 8.5 deg and the roll rate started decreasing. A plausible cause for the decrease in roll rate was shown to be a combination of trim angle and an offset center of gravity.
RAM↗
High Altitude Re-entry Plasma Emulation Experiment (HARPEE)
A table-top apparatus has recently been constructed at the NASA Glenn Research Center to investigate potential solutions for the radio-frequency communication blackout problem -- experienced by landing modules during high-speed atmospheric entry. This customized plasma chamber was designed to emulate Earth-based atmospheric entry plasmas with electron densities in the range of 10^16 m^-3 to 10^19 m^-3. The system makes use of a 40-kHz, perforated coaxial electrode pair to generate a disk-shaped, static plasma with an approximate diameter and thickness of 405 mm and 100 mm, respectively. A translatable Langmuir probe was employed to characterize the radial profile of electron temperature and density as a function the 40-kHz power (< 1 kW) and dry-nitrogen flow rate (< 160 SCCM).
plasma↗
A SOLID-STATE DATA-STORAGE DIGITAL TELEMETRY SYSTEM FOR OBTAINING REENTRY RESEARCH DATA USING SOLID-FUEL ROCKET VEHICLES
Solid state data storage digital telemetry system which makes it possible to store and retransmit after reentry blackout
SOLID STATE DEVICE↗
Entry acquisition and radio visibility computer program
Entry acquisition and radio visibility computer program for optimization of tracking station locations - blackout prediction
COMPUTER PROGRAM↗
Apollo omnidirectional antenna design with reentry considerations.
Apollo antenna design before and after reentry, discussing radio blackout problems and S band helices performance
Leopold, L.↗
Radiation from a circularly polarized antenna through the ionized wake of a Mars-entry capsule.
Mars entry capsule ionized wake producing circularly polarized antenna radiation null region, noting effect on communication blackout time
Ishimaru, A.↗
Electrostatic Probe Measurements of Plasma Surrounding Three 25,000 Foot Per Second Reentry Flight Experiments
A high-altitude electrostatic probe experiment is described and data are presented for three RAM C reentries at velocities of approximately 25 OOO feet per second. The electron density profiles inferred from the probe measurements are compared with theoretical calculations, and the probable cause of significant disagreement is briefly discussed. Probe measurements during material-addition sequences for radio-blackout alleviation are presented, and comparisons of probe measurements with other pertinent diagnostic measurements are made.
W Linwood Jones, Jr↗
Convective effects on microwave break-down of gases
Communication blackout during missile and spacecraft high altitude flight, considering convective effects on gas breakdown by microwaves
Mohanty, A. K.↗
Systems-level study of a nonsurvivable Jupiter turbopause probe. Volume 1: Summary
The design of a space probe to explore the atmosphere of the planet Jupiter is discussed. Five major areas were considered: (1) definition of science requirements, (2) mission evaluation, (3) definition of probe system, (4) definition of spacecraft support requirements, and (5) nonequilibrium flow field analysis for communications blackout evaluation. The overall mission and system design are emphasized. The integration of the various technologies into complete systems designs is described. Results showed that a nonsurvivable turbopause probe mission to Jupiter with adequate data return to meet the science objectives is feasible and practical.
Wiltshire, R. S.↗
Autonomous power subsystem design for an Outer Planet Spacecraft.
This paper describes the overall design of the Thermoelectric Outer Planet Spacecraft (TOPS) power subsystem. It discusses the implementation of spacecraft requirements into a fault-tolerant design in which an on-board self-test and repair computer is utilized to provide autonomous operation. Development of a protected bus concept is discussed whereby electrical power supplied to essential spacecraft loads is maintained in the event of major on-board power blackouts. Particular attention is given to describing the interfaces and operation of the power subsystem with the spacecraft control computer subsystem. Autonomous power management operations are discussed where the on-board computer adjusts the spacecraft load demand to provide maximum utilization of source power for a given mission mode.
Andrews, R. E.↗
Advance techniques for monitoring human tolerance to positive Gz accelerations
Tolerance to positive g accelerations was measured in ten normal male subjects using both standard and advanced techniques. In addition to routine electrocardiogram, heart rate, respiratory rate, and infrared television, monitoring techniques during acceleration exposure included measurement of peripheral vision loss, noninvasive temporal, brachial, and/or radial arterial blood flow, and automatic measurement of indirect systolic and diastolic blood pressure at 60-sec intervals. Although brachial and radial arterial flow measurements reflected significant cardiovascular changes during and after acceleration, they were inconsistent indices of the onset of grayout or blackout. Temporal arterial blood flow, however, showed a high correlation with subjective peripheral light loss.
Pelligra, R.↗
Langley Research Center entry aerothermodynamic technology development in support of Pioneer Venus multiprobe mission studies
A program of entry aerothermodynamics has been conducted to support the Pioneer Venus multiprobe mission. Aspects of the study include radiative property data, radiative blockage effectiveness measurements, heating calculations, aerodynamic and convective heating studies, and radio communications blackout models. Some of the historical background for the investigation is reviewed, and recommendations are made concerning the use of the developed technology in probe design and the continuation of certain elements of the program.
Olstad, W. B.↗
A demonstration of the value of general purpose, on-board satellite computers
Failure of the solar panels to erect and spin stabilize the TRANSIT Improvement Program (TIP) satellites is discussed, with emphasis on how the flight computer was reprogrammed to perform various control functions in order to achieve a partial mission success. These functions include: (1) power management to avoid troublesome spacecraft blackouts; (2) achieve enough spin stability to fire the OATS thruster; (3) raise the parking orbit to a workable altitude; (4) remove a high tumble rate which was the indirect result of the failure; and (5) deploy the gravity-gradient boom successfully on TIP-3.
Jenkins, R. E.↗