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At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

The elements of a space operations system

The Space Shuttle has completed its flight test program and is entering operational service with its fifth flight in November 1982. With the completion of Shuttle development, its entry to operational service, and delivery of additional units into field service, it is timely to initiate development of the next elements of the system. The elements of a Space Operations System are the Shuttle, a Station in low earth orbit, and upper stages for low and high energy orbit delivery. To design these elements properly will require a substantial operations analysis effort to characterize the most effective performance tradeoffs among the discrete elements. The Shuttle establishes a new context for the design and execution of operations in space. The components of the Shuttle, Space Station, and upper stages will need to share technology and components to minimize the cost and complexity of the logistics of ownership and operation.

Loftus, J. P., Jr.↗
NASA NTRS1984

Preprototype SAWD subsystem

A regenerable, three man preprototype solid amine, water desorbed (SAWD) CO2 removal and concentation subsystem was designed, fabricated, and successfully acceptance tested by Hamilton Standard. The preprototype SAWD incorporates a single solid amine canister to perform the CO2 removal function, an accumulator to provide the CO2 storage and delivery function, and a microprocessor which automatically controls the subsystem sequential operation and performance. The SAWD subsystem was configured to have a CO2 removal and CO2 delivery capability at the rate of 0.12 kg/hr (0.264 lb/hr) over the relative humidity range of 35 to 70%. The controller was developed to provide fully automatic control over the relative humidity range via custom software that was generated specifically for the SAWD subsystem. The preprototype SAWD subsystem demonstrated a total of 281 hours (208) cycles of operation during ten acceptance tests that were conducted over the 3 to 70% relative humidity range. This operation was comprised of 178 hours (128 cycles) in the CO2 overboard mode and 103 hours (80 cycles) in the CO2 reduction mode. The average CO2 removal/delivery rate met or exceeded the design specification rate of 0.12 kg/hr (0.254 lb/hr) for all ten of the acceptance tests.

Nalette, T. A.↗
NASA NTRS1984

Analytical fuel property effects: Small combustors

The study performed in Phase 1 of this program applies only to a T700/CT7 engine family type combustor functioning in the engine as defined and does not necessarily apply to other cycles or combustors of differing stoichiometry. The study was not extended to any of the fuel delivery accessories such as pumps or control systems, nor was there any investigation of potential systems problems which might arise as a consequence of abnormal properties such as density which might affect delivery schedules or aromatics content which might affect fuel system seals. The T700/CT7 engine is a front drive turboshaft or turboprop engine in the 1500-1800 shp (1120-1340 kW) class as currently configured with highpower core flows of about 10 lb/sec (4.5 kg/sec). It employs a straight-through annular combustion system less than 5 in. (12.5 cm) in length utilizing a machined ring film cooled construction and twelve low-pressure air blast fuel injectors. Commercial and Naval versions employ two 0.5 Joule capacitive discharge surface gap ignitors.

Cohen, J. D.↗
NASA NTRS1984

Galileo Jupiter approach orbit determination

Orbit determination characteristics of the Jupiter approach phase of the Galileo mission are described. Predicted orbit determination performance is given for the various mission events that occur during Jupiter approach. These mission events include delivery of an atmospheric entry probe, acquisition of probe science data by the Galileo orbiter for relay to earth, delivery of an orbiter to a close encounter of the Galilean satellite Io, and insertion of the orbiter into orbit about Jupiter. The orbit determination strategy and resulting accuracies are discussed for the data types which include Doppler, range, optical imaging of Io, and a new Very Long Baseline Interferometry (VLBI) data type called Differential One-Way Range (DOR).

Miller, J. K.↗
NASA NTRS1984

Moderate lift-to-drag aeroassist

Significant performance benefits are realized via aerodynamic braking and/or aerodynamic maneuvering on return from higher altitude orbits to low Earth orbit. This approach substantially reduces the mission propellant requirements by using the aerodynamic drag, D, to brake the vehicle to near circular velocity and the aerodynamic lift, L, to null out accumulated errors as well as change the orbital inclination to that required for rendezvous with the Space Shuttle Orbiter. Broad concept evaluations were performed and the technology requirements and sensitivities for aeroassisted OTV's over a range of vehicle hypersonic L/D from 0.75 to 1.5 were systematically identified and assessed. The aeroassisted OTV is capable of evolving from an initial delivery only system to one eventually capable of supporting manned roundtrip missions to geosynchronous orbit. Concept screening was conducted on numerous configurations spanning the L/D = 0.75 to 1.5 range, and several with attractive features were identified. Initial payload capability was evaluated for a baseline of delivery to GEO, six hour polar, and Molniya (12 hours x 63.4 deg) orbits with return and recovery of the aeroassist orbit transfer vehicle (AOTV) at LEO. Evolutionary payload requirements that were assessed include a GEO servicing mission (6K up and 2K return) and a manned GEO mission (14K roundtrip).

Florence, D. E.↗
NASA NTRS1985

Design study of an integrated aerobraking orbital transfer vehicle

An aerobraking orbital transfer vehicle (AOTV) concept, which has an aerobrake structure that is integrated with the propulsion stage, is discussed. The concept vehicle is to be assembled in space and is space-based. The advantages of aeroassist over an all propulsive vehicle are discussed and it is shown that the vehicle considered is very competitive with inflatable and deployable concepts from mass and performance aspects. The aerobrake geometry is an ellipsoidally blunted, raked-off, elliptical wide-angle cone with a toroidal skirt. Propellant tanks, engines, and subsystems are integrated into a closed, isogrid aerobrake structure which provides rigidity. The vehicle has two side-firing, gimbaled RL-10 type engines and carries 38,000 kg of useable propellant. The trajectory during aerobraking is determined from an adaptive guidance logic, and the heating is determined from engineering correlations as well as 3-D Navier-Stokes solutions. The AOTV is capable of placing 13,500 kg payload into geosynchronous Earth orbit (GEO) or carrying a LEO-GEO-LEO round-trip payload of 7100 kg. A two-stage version considered for lunar missions results in a lunar surface delivery capability of 18,000 kg or a round-trip capability of 6800 kg with 3860 kg delivery-only capability.

Scott, C. D.↗
NASA NTRS1984

Intermediate load modules for test and evaluation

Photovoltaic modules were tested for qualification. Tests involved the following: (1) delivery of 20 solar cells for use as reference cells; (2) module documentation and inspection plans specifying the 10 Group I modules; (3) design review of module documentation from Group I modules; (4) revise module documentation to overcome any problems of deficiencies associated with the Group I modules; (5) delivery of 10 Group II modules built to revised specifications; (6) testing of Group II modules to the criteria as outlined in qualification specification. It is found that the solarvolt MSP43E40B satisfies the design criteria of qualification specification for intermediate load modules. Design changes were made in the Group I modules to overcome the deficiencies which allowed Group II modules to pass the qualification tests.

Source record↗
NASA NTRS1984

Development of solid amine CO2 control systems for extended duration missions

This paper briefly discusses the development history of solid amine CO2 control systems, describes two distinct CO2 control system concepts, and presents the performance characteristics for both system concepts. The first concept (developed under NASA Contract NAS9-13624) incorporates a solid amine canister, an automatic microprocessor controller, and an accumulator to collect CO2 and to provide regulated CO2 delivery to an oxygen recovery system. This system is currently operating in the Crew Systems Division's Advanced Life Support Development Laboratory (ALSDL). The second system concept (being developed under NASA Contract NAS9-16978) employs multiple solid amine canisters, an advanced automatic controller and system status display, the ability to regulate CO2 delivery for oxygen recovery, and energy saving features that allow system operation at lower power levels than the first concept.

Dresser, K. J.↗
NASA NTRS1984

An evolutionary GEO transportation system

Several transportation system options that utilize the Space Station as a base for delivery of payloads to geosynchronous earth orbit are examined and compared to each other as well as to the reference case, which uses the orbiter as the staging base. The factors evaluated include impact on Kennedy Space Center (KSC) flow, STS traffic, load factor, and the cost effectiveness of each transportation system option. With respect to KSC flow, it is determined that utilizing the Space Station as a staging base could lead to a reduction of 3000 man-hours off-line and an additional 475 man-hours on-line. Launch costs for STS are reduced by 10 percent. The actual number of STS flights varies depending on the transportation system option, and the delivery of multiple payloads results in the least cost.

Markus, G.↗
NASA NTRS1985

Shuttle derived launch vehicle wind tunnel tests

Studies are being conducted regarding new launch vehicle configurations which may effectively and economically share the delivery of payloads to orbit with the present Space Transportation System (STS). The role envisaged for these launch vehicles is related to the execution of missions whose requirements exceed the STS Shuttle capabilities, taking into account the delivery of much heavier or larger payloads. One class of advanced launch vehicles is configured to take advantage of the existing Shuttle hardware and facilities. Such vehicles are referred to as Shuttle Derived Vehicles (SDV). One version of an SDV consists of two STS elements, including the external tank (ET) and solid rocket boosters, and a cargo carrier. Attention is given to wind tunnel tests, which are being conducted with SDV sidemount configurations incorporating various size payload modules.

Tewell, J. R.↗
NASA NTRS1986

Metal powder production by gas atomization

The confined liquid, gas-atomization process was investigated. Results from a two-dimensional water model showed the importance of atomization pressure, as well as delivery tube and atomizer design. The atomization process at the tip of the delivery tube was photographed. Results from the atomization of a modified 7075 aluminum alloy yielded up to 60 wt pct. powders that were finer than 45 microns in diameter. Two different atomizer designs were evaluated. The amount of fine powders produced was correlated to a calculated gas-power term. An optimal gas-power value existed for maximized fine powder production. Atomization at gas-power greater than or less than this optimal value produced coarser powders.

Ting, E. Y.↗
NASA NTRS1986

Titan Probe navigation analysis

In the proposed Cassini mission, a combined Saturn Orbiter/Titan Probe spacecraft will be launched from the Space Shuttle to arrive at Saturn around 2002, by means of a delta-VEGA trajectory. After Saturn-orbit insertion and a pericrone raise maneuver, the probe will be released to enter the Titan atmosphere and impact onto its surface. During its descent phase and impact onto Titan, the probe will maintain radio contact with the orbiter. Since the Titan-probe experimental phase lasts for only about four hours, probe-orbiter geometry and probe-delivery accuracy are critical to successful completion of this part of the mission. From a preliminary navigation analysis for probe delivery accuracy, it seems feasible to deliver the probe within 50 km (1-sigma value) of the desired aim-point in the Titan B-plane. The covariance study, however, clearly indicates the need for optical data, in addition to radio metric data. A Monte Carlo study indicates that a Delta-V capability of 98 m/sec for trajectory correction maneuvers will be sufficient to cover 99 percent of all contingencies during the segment from Saturn-orbit insertion to Titan-probe release.

Vijayaraghavan, A.↗
NASA NTRS1985

System technology analysis of aeroassisted orbital transfer vehicles: Moderate lift/drag (0.75-1.5),volume 1B, part 1, study results

Significant performance benefits can be realized via aerodynamic breaking and/or aerodynamic maneuvering on return from higher altitude orbits to low Earth orbit. This approach substantially reduces the mission propellant requirements by using the aerodynamic drag, D, to brake the vehicle to near circular velocity and the aerodynamic lift, L, to null out accumulated errors as well as change the orbital inclination to that required for rendezous with the Space Shuttle Orbiter. A study was completed where broad concept evaluations were performed and the technology requirements and sensitivities for aeroassisted Orbital Transfer Vehicles (AOTVs) over a range of vehicle hypersonic L/D from 0.75 to 1.5 were systematically identified and assessed. The AOTV is capable of evolving from an initial delivery only system to one eventually capable of supporting manned roundtrip missions to geosynchronous orbit. Concept screenings were conducted on numerous configurations spanning the L/D = 0.75 to 1.5 range, and several with attractive features were identified. Initial payload capability was evaluated for a baseline of delivery to GEO, six hour polar, and Molniya orbits with return and recovery of the AOTV at LEO. Evolutionary payload requirements that were assessed include a GEO servicing mission and a manned GEO mission.

Source record↗
NASA NTRS1987

On-board processing satellite network architecture and control study

For satellites to remain a vital part of future national and international communications, system concepts that use their inherent advantages to the fullest must be created. Network architectures that take maximum advantage of satellites equipped with onboard processing are explored. Satellite generations must accommodate various services for which satellites constitute the preferred vehicle of delivery. Such services tend to be those that are widely dispersed and present thin to medium loads to the system. Typical systems considered are thin and medium route telephony, maritime, land and aeronautical radio, VSAT data, low bit rate video teleconferencing, and high bit rate broadcast of high definition video. Delivery of services by TDMA and FDMA multiplexing techniques and combinations of the two for individual and mixed service types are studied. The possibilities offered by onboard circuit switched and packet switched architectures are examined and the results strongly support a preference for the latter. A detailed design architecture encompassing the onboard packet switch and its control, the related demand assigned TDMA burst structures, and destination packet protocols for routing traffic are presented. Fundamental onboard hardware requirements comprising speed, memory size, chip count, and power are estimated. The study concludes with identification of key enabling technologies and identifies a plan to develop a POC model.

Campanella, S. Joseph↗
NASA NTRS1987

Plant Growth Module (PGM) conceptual design

The Plant Growth Module for the Controlled Ecological Life Support System (CELSS), designed to answer basic science questions related to growing plants in closed systems, is described functionally with artist's conception drawings. Subsystems are also described, including enclosure and access; data acquisition and control; gas monitor and control; heating, ventilation, and air conditioning; air delivery; nutrient monitor and control; microbial monitoring and control; plant support and nutrient delivery; illumination; and internal operations. The hardware development plan is outlined.

Schwartzkopf, Steven H.↗
NASA NTRS1987

A space transportation system operations model

Presented is a description of a computer program which permits assessment of the operational support requirements of space transportation systems functioning in both a ground- and space-based environment. The scenario depicted provides for the delivery of payloads from Earth to a space station and beyond using upper stages based at the station. Model results are scenario dependent and rely on the input definitions of delivery requirements, task times, and available resources. Output is in terms of flight rate capabilities, resource requirements, and facility utilization. A general program description, program listing, input requirements, and sample output are included.

Morris, W. Douglas↗
NASA NTRS1987

Apollo Lightcraft project

The detailed design of a beam-powered transatmospheric vehicle, the Apollo Lightcraft, was selected as the project for the design course. The principal goal is to reduce the LEO payload delivery cost by at least three orders of magnitude below the Space Shuttle Orbiter in the post 2020 era. The completely reusable, single-stage-to-orbit shuttlecraft will take off and land vertically, and have a reentry heat shield integrated with its lower surface. At appropriate points along the launch trajectory, the combined cycle propulsion system will transition through three or four airbreathing modes, and finally use a pure rocket mode for orbital insertion. The objective for the Spring semester propulsion source was to design and perform a detailed theoretical analysis on an advanced combined-cycle engine suitable for the Apollo Lightcraft. The preliminary theoretical analysis of this combined-cycle engine is now completed, and the acceleration performance along representative orbital trajectories was simulated. The total round trip cost is $3430 or $686 per person. This represents a payload delivery cost of $3.11/lb, which is a factor of 1000 below the STS. The Apollo Lightcraft concept is now ready for a more detailed investigation during the Fall semester Transatmosphere Vehicle Design course.

Myrabo, Leik N.↗
NASA NTRS1987

Mass flow meter using the triboelectric effect for measurement in cryogenics

The use of triboelectric charge to measure the mass flow rate of cryogens for the Space Shuttle Main Engine was investigated. Cross correlation of the triboelectric charge signals was used to determine the transit time of the cryogen between two sensor locations in a .75-in tube. The ring electrode sensors were mounted in a removable spool piece. Three spool pieces were constructed for delivery, each with a different design. One set of electronics for implementation of the cross correlation and flow calculation was constructed for delivery. Tests were made using a laboratory flow loop using liquid freon and transformer oil. The measured flow precision was 1 percent and the response was linear. The natural frequency distribution of the triboelectric signal was approximately 1/f. The sensor electrodes should have an axial length less than approximately one/tenth pipe diameter. The electrode spacing should be less than approximately one pipe diameter. Tests using liquid nitrogen demonstrated poor tribo-signal to noise ratio. Most of the noise was microphonic and common to both electrode systems. The common noise rejection facility of the correlator was successful in compensating for this noise but the signal was too small to enable reliable demonstration of the technique in liquid nitrogen.

Bernatowicz, Henry↗