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NASA NTRSDate not supplied

Safety & Mission Assurance (SMA) Activities in Support of Artemis I and Plans for Artemis II

The Artemis I mission in 2022 accomplished humanity’s first venture beyond Low-Earth Orbit (LEO) with a human-rated spacecraft in over fifty years. Artemis comprises several key Program elements – Multi-Purpose Crew Vehicle (MPCV) Orion Crew Module, Service Module, Launch Abort System; the Space Launch System (SLS) and the Exploration Ground System (EGS). Much of our human spaceflight experience with crewed lunar missions is captured in historical program documents, but first-hand knowledge is limited to a few spaceflight veterans. Missions to LEO have offered the opportunity of direct, near-instantaneous communications and assistance, and the ability to return to Earth within a matter of hours in case of emergency. Outward-bound missions do not have these features and will require a more autonomous and reliable spacecraft. The assessment of compliance with applicable safety requirements and adequacy of hazard controls and verifications is the responsibility of the MPCV Safety and Engineering Review Panel (MSERP), along with a Joint [NASA/ESA] Safety and Engineering Review Panel (JSERP) for the review of the European Service Module (ESM). The MSERP has two features that are relatively unique amongst NASA safety panels. First, NASA Engineering was added as a Panel co-chair, which enhanced the Engineering organization’s engagement and level of understanding of hazard analysis methodology and results. The MSERP has representation from each office, including Flight Operations Directorate (FOD) and Health and Medical Technical Authority, supporting the Orion Program in addition to the Engineering and Safety Technical Authority co-chairs. Second, the JSERP has a second set of co-chairs from ESA Engineering and ESA Product Assurance and Safety organizations, which recognizes the international arrangement as one of partnership. This paper will focus on SMA processes, activities, and plans for the Orion element and explore unique challenges associated with Artemis II as we approach the flight of the first crewed Orion vehicle.

Paul J. Collier↗
NASA NTRS1972

An ERTS multispectral scanner experiment for mapping iron compounds

There are no author-identified significant results in this report. An experimental plan for enhancing spectral features related to the chemical composition of geological targets in ERTS multispectral scanner data is described. The experiment is designed to produce visible-reflective infrared ratio images from ERTS-1 data. Iron compounds are promising remote sensing targets because they display prominent spectral features in the visible-reflective infrared wavelength region and are geologically significant. The region selected for this ERTS experiment is the southern end of the Wind River Range in Wyoming. If this method proves successful it should prove useful for regional geologic mapping, mineralogical exploration, and soil mapping. It may also be helpful to ERTS users in scientific disciplines other than geology, especially to those concerned with targets composed of mixtures of live vegetation and soil or rock.

Vincent, R. K.↗
NASA NTRS1979

Design of a one-year lifetime, spaceborne superfluid helium dewar

The Infrared Astronomical Satellite is an Explorer Mission and a joint venture of the Netherlands, the United Kingdom, and the United States scheduled for launch into earth orbit in 1981. The cryogenic system is a major part of the satellite; it incorporated many unique and state-of-the-art design features to satisfy the requirements of a one-year orbital lifetime, a focal plane temperature less than 4K, minimal launch weight, and zero-gravity operation. The 60-centimeter diameter telescope is contained within a superfluid helium dewar having a capacity of 540 liters. The telescope aperture cover employs an independent cryogenic system containing a 54-liter supercritical helium tank. The aperture cover, which is ejected two weeks after launch, protects the telescope from contamination and provides the low-temperature background needed to perform focal plane health checks. Design and predicted performance of the cryogenic systems are discussed in detail.

Hopkins, R. A.↗
NASA NTRS1984

Development of a bipropellant propulsion module for the Galileo spacecraft

The bipropellant engine retropropulsion module (RPM) of the Jupiter-exploration Galileo spacecraft provides attitude control, trajectory correction, a deep space velocity increment, a spacecraft deflection maneuver for an entry capsule, a retromaneuver for Jupiter approach, and a 'perijove raise' maneuver for the Jovian system tour of the spacecraft. Attention is given to the design features and performance capabilities of the RPM, which uses a set of 12 10-N thrusters in conjunction with a 400-N engine. Tanks contain 935 kg of propellant to satisfy mission requirements.

Hagenest, W.↗
NASA NTRS1994

On planetary nebula nuclei of the spectral type 'continuous'

A detailed reexamination of existing and new International Ultraviolet Explorer (IUE) low-and high-resolution spectra, plus a search of recent literature, shows that for most of the central stars of planetary nebulae the spectral classification previously called 'continuous-type' does not really exist. The stellar continua show primarily photospheric absorption features of N V, O V, C IV, H, He II, Fe VII, Fe VI, and Fe V, and/or P Cygni profiles.

Feibelman, Walter A.↗
NASA NTRS1996

State modeling and pass automation in spacecraft control

The integrated monitoring and control commercial off-the-shelf system (IMACCS), which demonstrates the feasibility of automating spacecraft monitoring and control activities through the use of state modeling, is described together with its use. The use of the system for the control and ground support of the solar, anomalous and magnetic particle explorer (SAMPEX) spacecraft is considered. A key component of IMACCS is the Altair mission control system which implements finite state modeling as an element of its expert system capability. Using the finite state modeling and state transition capabilities of the Altair mission control system, IMACCS features automated monitoring, routine pass support, anomaly resolution and emergency 'lights on again' response. Automatic orbit determination and the production of typical flight dynamics products exists. These functionalities are described.

Klein, J.↗
NASA NTRS2001

Touch and Go Surface Sampler (TGSS)

The Touch and Go Surface Sampler (TGSS) is a new class of planetary and small body sample acquisition tool that can be used for the surface exploration of Europa, Titan and comets. TGSS in its basic configuration consists of a high speed sampling head attached to the end of a flexible shaft. The sampling head consists of counter rotating cutters that rotates at speeds of 3000 to 15000 RPM. The attractive feature of this if touch and go type sampler is that there are no requirements for a lander type spacecraft. Additional information is contained in the original extended abstract.

Gorevan, S. P.↗
NASA NTRS2014

Design of Two RadWorks Storm Shelters for Solar Particle Event Shielding

In order to enable long-duration human exploration beyond low-Earth orbit, the risks associated with exposure of astronaut crews to space radiation must be mitigated with practical and affordable solutions. The space radiation environment beyond the magnetosphere is primarily a combination of two types of radiation: galactic cosmic rays (GCR) and solar particle events (SPE). While mitigating GCR exposure remains an open issue, reducing astronaut exposure to SPEs is achievable through material shielding because they are made up primarily of medium-energy protons. In order to ensure astronaut safety for long durations beyond low-Earth orbit, SPE radiation exposure must be mitigated. However, the increasingly demanding spacecraft propulsive performance for these ambitious missions requires minimal mass and volume radiation shielding solutions which leverage available multi-functional habitat structures and logistics as much as possible. This paper describes the efforts of NASA's RadWorks Advanced Exploration Systems (AES) Project to design two minimal mass SPE radiation shelter concepts leveraging available resources: one based upon reconfiguring habitat interiors to create a centralized protection area and one based upon augmenting individual crew quarters with waterwalls and logistics. Discussion items include the design features of the concepts, a radiation analysis of their implementations, an assessment of the parasitic mass of each concept, and the result of a human in the loop evaluation performed to drive out design and operational issues.

Simon, Matthew↗
NASA NTRS2018

Development of a Multi-Stage Filter System for Cabin Ventilation Systems on the ISS and Future Deep Space Missions

The National Aeronautics and Space Administration's (NASA's) deep space exploration missions will be of significant duration requiring long-life and reliably performing spacecraft cabin ventilation filters. A particulate filter system is being developed at NASA Glenn Research Center (GRC) to meet the challenges of these remote and long duration missions. The capabilities and features of the filter system are expected to expand the life and reduce the maintenance requirements over that of the current ISS (International Space Station) filter by providing pre-filtration stages with novel self-cleaning and regenerable techniques. The filter provides two regenerable pre-filtration stages using a screen mesh media and an impactor collection system, and also provides intermediate stage filtration employing self-replacing filter media. The filter system is also designed to be compatible with the interfaces and performance requirements of the ISS distributed ventilation architecture in the US modules to facilitate testing on ISS type test or mock up platforms. Currently, a prototype of the filter system is undergoing tests in a custom configured filter test stand at the NASA GRC. The test stand provides the same range of flow rates produced on the ISS distributed architecture, and is equipped and instrumented to perform filter tests based on industrial test standards. The test stand has been used successfully to perform filter and flow performance test on returned ISS Bacterial Filter Elements. Similar test protocols were used to characterize the performance of the current filter system. Different performing grades of filter media will be installed and tested on the filter system, and different test particle standards will be used to simulate the range of particulate matter particles and debris the filter will see during a mission. This paper will present results and analysis of the test data to guide and provide input to the next generation filter system.

ISS↗
NASA NTRSDate not supplied

Influence of sediment resuspension on deep-ocean Pa-231 and Th-230 cycling: A PROGRESS REPORT

The naturally-occurring particle-reactive radionuclides protactinium-231 (231Pa) and thorium-230 (230Th) are used as tracers of a variety of oceanic processes, both at present and in the past. Most notably, the sediment 231Pa/230Th ratio has been used to infer changes in the Atlantic Meridional Overturning Circulation over the last (de)glaciation. However, recent measurements along the U.S. GEOTRACES North Atlantic transect (GA03) revealed two features which are at odds with current understanding about 231Pa and 230Th behaviour in the ocean: (i) a sharp decrease in dissolved 231Pa and 230Th activities with depth below 2000-4000 m and (ii) very large particulate 231Pa and 230Th activities near the bottom, at a number of stations between the New England continental shelf and Bermuda. Concomitant measurements of particulate matter concentration and potential temperature showed that both features are associated with the benthic nepheloid layer (BNL) and the bottom mixed layer (BML) that are present at these stations. Here we develop and apply a simplified model of the exchange of particles, 231Pa, and 230Th between the BNL and the upper sediment, to explore the extent to which the radionuclide anomalies observed near the bottom at a number of GA03 stations can be explained by local sediment resuspension. We find that the model can broadly reproduce the observed anomalies at two stations where samples for radionuclide analyses were collected near the seafloor. Sensitivity tests with the model show that the 231Pa/230Th ratio of particles in the BML and the sediment varies by a factor of 3 as the sediment resuspension rate fluctuates within a range consistent with observational estimates. The modelled variability is comparable to the spatial variability of 231Pa/230Th of suspended particles in the modern North Atlantic and to the variability of Atlantic sediment 231Pa/230Th records across the last (de)glacial period. Two factors are found to contribute to the modelled sensitivity of the sediment 231Pa/230Th to sediment resuspension rate: the vertical turbulent mixing in the BML and the differential scavenging intensity of Pa and Th due to variation in particle concentration. Overall, our study indicates that the exchange of material between the BNL and the upper sediment can affect the particulate 231Pa/230Th ratio in the bottom water and the sediment, which may complicate the use of sediment 231Pa/230Th as a palaeoceanographic tracer.

particle-reactive radionuclides↗
NASA NTRS1972

Small scale analogs of the Cayley Formation and Descarts Mountains in impact associated deposits, part C

The exploration of the Cayley Formation and material of the Descartes Mountains and an understanding of the origin and evolution of these units were primary objectives of the Apollo 16 lunar mission. This section examines several areas associated with impact crater deposits that show small-scale features similar in morphology to the regional characteristics of the Cayley and Descartes units shown in the Apollo 16 photography.

Head, J. W.↗
NASA NTRS1973

Structural lineaments of Gaspe from ERTS imagery

A test study was conducted to assess the value of ERTS images for mapping geologic features of the Gaspe Peninsula, Quebec. The specific objectives of the study were: 1) to ascertain the best procedure to follow in order to obtain valuable geologic data as a result of interpretation; and 2) to indicate in which way these data could relate to mineral exploration. Of the four spectral bands of the Multispectral scanner, the band from 700 to 800 nanometers, which seems to possess the best informational content for geologic study, was selected for analysis. The original ERTS image at a scale of 1:3,700,000 was enlarged about 15 times and reproduced on film. Geologically meaningful lines, called structural lineaments, were outlined and classified according to five categories: morpho-lithologic boundaries, morpho-lithologic lineaments, fault traces, fracture zones and undefined lineaments. Comparison with the geologic map of Gaspe shows that morpho-lithologic boundaries correspond to contacts between regional stratigraphic units. Morpholithologic lineaments follow bedding trends, whereas fracture traces appear as sets of parallel lineaments, intersecting at high angles the previous category of lineaments. Fault traces mark more precisely the location of faults already mapped and spot the presence of presumable faults, not indicated on the geologic map.

Steffensen, R.↗
NASA NTRS1973

Landmark navigation and topographical mapping.

Proposed new navigational and mapping techniques could be of interest when using unmanned vehicles in the exploration of planets within the solar system. Recently developed techniques make use of landmarks whose coordinates are unknown but within sight of the surface vehicle. The techniques described in the present paper still make use of landmarks whose positions are unknown; however, they offer the added features of (1) travel and mapping beyond the original landmarks by discarding them and choosing new ones, (2) the determination of ranges relative to a selected range at the original starting point, (3) the determination of the direction back to the original starting point or any other previously travelled point, and (4) travel and mapping regardless of whether an angle reference is available.

Bennett, J. E.↗
NASA NTRS1984

Growth/reflectance model interface for wheat and corresponding model

The use of modeling to explore the possibility of discovering new and useful crop condition indicators which might be available from the Thematic Mapper and to connect these symptoms to the biological causes in the crop is discussed. A crop growth model was used to predict the day to day growth features of the crop as it responds biologically to the various environmental factors. A reflectance model was used to predict the character of the interaction of daylight with the predicted growth features. An atmospheric path radiance was added to the reflected daylight to simulate the radiance appearing at the sensor. Finally, the digitized data sent to a ground station were calculated. The crop under investigation is wheat.

Suits, G. H.↗
NASA NTRS1988

Ultraviolet Spectra of Two Magnetic White Dwarfs and Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey and Ultraviolet Absorptions in the Spectra of DA White Dwarfds

Research under NASA Grant NAG5-287 has carried out a number of projects in conjunction with the International Ultraviolet Explorer (IUE) satellite. These include: (1) studies of the UV spectra of DA white dwarfs which show quasi-molecular bands of H2 and H2(+); (2) the peculiar star HR6560; (3) the UV spectra of two magnetic white dwarfs that also show the quasi-molecular features; (4) investigations of the UV spectra of subluminous stars, primarily identified from visual wavelength spectroscopy in the Kiso survey of UV excess stars, some of which show interesting metal lines in their UV spectra; and (5) completion of studies of UV spectra of DB stars. The main result of this research has been to further knowledge of the structure and compositions of subluminous stars which helps cast light on their formation and evolution.

Wegner, Gary A.↗
NASA NTRS1991

Thermal Synthesizer System - An integrated approach to spacecraft thermal analysis

The Thermal Synthesizer System (TSS), which is being developed to meet the thermal analysis needs of Space Station Freedom and of the proposed Space Exploration Initiative missions, is examined. The key requirements and design goals to be met by TSS are summarized, and the software engineering and user interface design philosophy are reviewed. The basic architecture for all applications within TSS is described. An overview is given of the main features of each of the applications of TSS.

Panczak, Tim↗
NASA NTRS1993

Software Coherence in Multiprocessor Memory Systems

Processors are becoming faster and multiprocessor memory interconnection systems are not keeping up. Therefore, it is necessary to have threads and the memory they access as near one another as possible. Typically, this involves putting memory or caches with the processors, which gives rise to the problem of coherence: if one processor writes an address, any other processor reading that address must see the new value. This coherence can be maintained by the hardware or with software intervention. Systems of both types have been built in the past; the hardware-based systems tended to outperform the software ones. However, the ratio of processor to interconnect speed is now so high that the extra overhead of the software systems may no longer be significant. This issue is explored both by implementing a software maintained system and by introducing and using the technique of offline optimal analysis of memory reference traces. It finds that in properly built systems, software maintained coherence can perform comparably to or even better than hardware maintained coherence. The architectural features necessary for efficient software coherence to be profitable include a small page size, a fast trap mechanism, and the ability to execute instructions while remote memory references are outstanding.

Bolosky, William Joseph↗
NASA NTRS1994

Radiative acceleration in outflows from broad absorption line quasi-stellar objects. 2: Wind models

We investigate the dynamics of radiatively driven broad absorption-line (BAL) outflows in quasi-stellar objects (QSOs) by developing radial and time-independent numerical models. Two limits are explored. The first assumes that the absorbing matter is not forced to comove with the substrate, which provides pressure confinement. This assumption allows us to explore in detail a case in which the acceleration is entirely due to radiation pressure. Using the parameters inferred from observations, we find that under these conditions radiative acceleration (mainly due to resonance line scattering) can readily accelerate the flow to the observed velocities. An important feature of the noncoupled flow is that the line profiles tend to stay relatively flat throughout the velocity interval covered by the line. We discuss how relaxing the assumptions of radial symmetry and time independent may help to explain the structures observed in BALs. In the second class of models, the absorbing flow is assumed to be completely coupled to the substrate in which it is embedded. Aside from being more plausible physically, these models produce line profiles that trail off at higher velocities, a behavior observed in some BALs. We show that, even if the substrate is massless, we have to assume a starting radius very close to the inferred radius of the broad emission-line region (approximately 0.1 pc) in order to obtain a significant contribution from radiative acceleration, given a typical active galactic nucleus (AGN) spectrum. The reason is that the energy input needed to pressurize the substrate, allowing the flow to become supersonic and to retain a reasonable ionization equilibrium, at the same time contributes appreciably to the acceleration. A way to relax the small starting radius constraint is to use a softer ionizing spectrum.

Arav, Nahum↗