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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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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Contribution towards a draft revision of recommendations 681: Propagation data required for the design of Earth-space land mobile telecommunications systems

Propagation models that can be used for the design of earth-space land mobile-satellite telecommunications systems are presented. These models include: empirical roadside shadowing, attenuation frequency scaling, fade and non-fade duration distribution, multipath in a mountain environment, and multipath in a roadside tree environment. Propagation data from helicopter-mobile and satellite-mobile measurements in Australia and the United States were used to develop the models.

Davarian, Faramaz↗
NASA NTRS1993

Contribution Towards a Draft Revision of Recommendation 681 Propogation Data Required for the Design of Earth-Space Land Mobile Telecommunications Systems

Propogation models that can be used for the design of Earth-space land mobile-satellite telecommunications systems are presented. These models include: empirical roadside shadowing, attenuation frequency scaling, fade and non-fade duration distribution, multipath in a mountain environment, and multipath in a roadside tree environment. Propogation data from helicopter-mobile and satellite-mobile measurements in Australia and the United States were used to develop the models.

propogation propogation models satellite telecommu↗
NASA NTRS1986

Thrust vectoring for single-stage-to-orbit, horizontal takeoff, horizontal landing, space vehicles

The preliminary design of a horizontal takeoff, horizontal landing, single-stage-to-orbit, rocket-powered space vehicle was performed. The purpose was to examine technology requirements for future small payload launch vehicles. The distinguishing aspect of the design was the utilization of thrust vectoring to provide half of the lift at takeoff. The inclusion of a canard was necessary to provide additional lift at takeoff and to balance the moments produced with thrust vectoring. A weights estimation, an aerodynamic assessment, a trajectory analysis, and a gear weight analysis were performed. The takeoff weight of the resulting vehicle was approximately 1.26 million pounds, based on advanced technology structures and subsystems. The vehicle was designed to deliver a 5000-pound payload to a polar orbit.

Cunningham, M. J.↗
NASA NTRS2010

Midodrine as a Countermeasure to Orthostatic Hypotension Immediately After Space Shuttle Landing

Midodrine prevents post-space flight orthostatic intolerance when testing is conducted in a controlled laboratory setting within 2-4 hours after Space Shuttle landing. It is unknown if midodrine is as effective during re-entry and immediately following landing. METHODS: Cardiovascular responses to 10 minutes of 80 head-up tilt in five male astronauts were compared before and immediately after Space Shuttle missions. Preflight tests were conducted in the Johnson Space Center Cardiovascular Laboratory without midodrine. Post-flight testing was performed in the Crew Transport Vehicle on the Space Shuttle runway within 60 minutes of landing; midodrine was self-administered before re-entry. Survival analysis was performed (Gehan-Breslow test) to compare presyncope rates pre- to post-flight. Cardiovascular responses (last minute standing minus supine) to tilt before and after space flight were compared using paired t-tests. RESULTS: Midodrine did not prevent post-flight orthostatic hypotension in two of the five astronauts, but the rate of presyncope across the group did not increase (p=0.17) from pre- to post-flight. Also, although the change in heart rate from supine to the last minute of standing was not affected by space flight, systolic blood pressure decreased more (p=0.05) and diastolic blood pressure tended to decrease (p=0.08) after space flight. CONCLUSIONS: Accurate interpretation of the current results requires that similar data be collected in control subjects (without midodrine) on the CTV. However, drug interaction concerns with commonly used anti-emetics and potentiation of prolonged QTc intervals observed in long duration astronauts make the routine use of midodrine for immediate post-flight orthostatic hypotension unlikely. 2

Platts, Steven H.↗
NASA NTRS1975

Flight performance of a navigation, guidance, and control system concept for automatic approach and landing of space shuttle orbiter

Unpowered automatic approaches and landings were conducted to study navigation, guidance, and control problems associated with terminal area approach and landing for the space shuttle vehicle. The flight tests were performed in a Convair 990 aircraft equipped with a digital flight control computer connected to the aircraft control system and displays. The tests were designed to evaluate the performance of a navigation and guidance concept that utilized blended radio/inertial navigation with VOR, DME, and ILS as the ground navigation aids. Results from 36 automatic approaches and landings from 11,300 m (37,000 ft) to touchdown are presented. Preliminary results indicate that this concept may provide sufficient accuracy to accomplish automatic landing of the shuttle orbiter without air-breathing engines.

Edwards, F. G.↗
NASA NTRS1962

Compilation of Papers Presented to Meeting on Space Vehicle Landing and Recovery Research and Technology

A meeting on Space Vehicle Landing and Recovery was held on July 10-11, 1962 at NASA Headquarters. The Centers were asked to participate in this meeting in accordance with their interest, activities, and requirements in the subject area. Primary emphasis was directed toward parachutes, parachute-rocket systems, paragliders, and lifting rotor concepts applicable to bothe booster and spacecraft landing and recovery.

Source record↗
NASA NTRS1970

Navigation for Apollo lunar landings

Space navigation for Apollo 11 mission, emphasizing ground and onboard systems, interfaces with guidance and use in phases of lunar landing

Mayer, J. P.↗
NASA NTRS1972

Space Shuttle landing navigation using precision distance measuring equipment.

Precision distance measuring equipment (DME) aiding onboard inertial navigation can be used to meet the stringent landing navigation requirements of the Space Shuttle. The required accuracy is achieved by using a ten-state-variable Kalman filter to process the measured range and delta-range data from the DME. The DME transponders are required to meet the accuracy requirements: two are deployed under the final approach path and one is deployed to the side. Failure considerations require deployment of additional redundant transponders. Initialization of the landing navigation after hypersonic entry is accomplished using the transponders at the airport.

Widnall, W. S.↗