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NASA NTRS1972

Properties of nearby interstellar hydrogen deduced from Lyman-alpha sky background measurements

For a sufficiently rapid relative motion of the solar system and the nearby interstellar gas, neutral atoms may be expected to penetrate the heliosphere before becoming ionized. Recent satellite measurements of the Lyman alpha emission above the geocorona indicate such an interstellar wind of neutral hydrogen emerging from the direction of Sagittarius and reaching to within a few astronomical units of the sun. A detailed model of the scattering of solar Lyman alpha from the spatial distribution of neutral hydrogen in interplanetary space is presented. This asymmetric distribution is established by solar wind and solar ultraviolet ionization processes along the trajectories of the incoming hydrogen atoms. The values of the interstellar density, the relative velocity, and the gas temperature are adjusted to agree with the Lyman alpha measurements. The results may be interpreted in terms of two models, the cold model and the hot model of the interstellar gas, depending on whether galactic Lyman alpha emission is present at its maximum allowable value or negligibly small.

Thomas, G. E.↗

NASA NTRS1973

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

An experimental sterilization facility was developed to simulate conditions that will be encountered during terminal sterilization of space vehicles. The system consists of a temperature controlled oven with a nitrogen gas stream containing a known concentration of water. Moisture analyzers are utilized to monitor the gas flowing over spore samples contained in the oven. In its original configuration, no provision was made for the control of water vapor during the sterilization cycle. Because moisture profoundly influences the thermal inactivation of bacterial spores, an upper limit for the moisture content in the gas used to sterilize the space vehicle was established (25% RH at 0 C STP). Accordingly, a controller was developed and installed to provide these conditions in the experimental sterilization facility.

Wimsatt, J. C.↗

NASA NTRS2003

The Sun to the Earth - and Beyond: A Decadal Research Strategy in Solar and Space Physics

The sun is the source of energy for life on earth and is the strongest modulator of the human physical environment. In fact, the Sun's influence extends throughout the solar system, both through photons, which provide heat, light, and ionization, and through the continuous outflow of a magnetized, supersonic ionized gas known as the solar wind. While the accomplishments of the past decade have answered important questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and other solar system bodies, they have also highlighted other questions, some of which are long-standing and fundamental. The Sun to the Earth--and Beyond organizes these questions in terms of five challenges that are expected to be the focus of scientific investigations in solar and space physics during the coming decade and beyond. While the accomplishments of the past decades have answered important questions about the physics of the Sun, the interplanetary medium, and the space environments of Earth and other solar system bodies, they have also highlighted other questions, some of which are long-standing and fundamental. This report organizes these questions in terms of five challenges that are expected to be the focus of scientific investigations in solar and space physics during the coming decade and beyond: Challenge 1: Understanding the structure and dynamics of the Sun's interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona. Challenge 2: Understanding heliospheric structure, the distribution of magnetic fields and matter throughout the solar system, and the interaction of the solar atmosphere with the local interstellar medium. Challenge 3: Understanding the space environments of Earth and other solar system bodies and their dynamical response to external and internal influences. Challenge 4: Understanding the basic physical principles manifest in processes observed in solar and space plasmas. Challenge 5: Developing a near-real-time predictive capability for understanding and quantifying the impact on human activities of dynamical processes at the Sun, in the interplanetary medium, and in Earth's magnetosphere and ionosphere. This report summarizes the state of knowledge about the total heliospheric system, poses key scientific questions for further research, and presents an integrated research strategy, with prioritized initiatives, for the next decade. The recommended strategy embraces both basic research programs and targeted basic research activities that will enhance knowledge and prediction of space weather effects on Earth. The report emphasizes the importance of understanding the Sun, the heliosphere, and planetary magnetospheres and ionospheres as astrophysical objects and as laboratories for the investigation of fundamental plasma physics phenomena.

Source record↗

NASA NTRS2018

ADEPT, A Mechanically Deployable Re-Entry Vehicle System, Enabling Interplanetary CubeSat and Small Satellite Missions

There is growing interest for utilizing Small Satellites beyond low Earth orbit. A number of secondary CubeSat payload missions are planned at Mars, cis-Lunar Space, near Earth objects, and moons of the Gas Giants. Use of smaller systems may enable utilization of otherwise unused capacity of larger "host" missions. Development of re-entry systems that leverage and accommodate Small Satellite technology will substantially expand the range of mission applications by offering the capability for high speed entry or aerocapture at destinations with atmospheres. Deployable entry vehicles (DEVs) offer benefits over traditional rigid aeroshells including volume, mass and payload form factor. The Adaptive Deployable Entry and Placement Technology (ADEPT) offers such a delivery capability for Small Sat or CubeSat orbiter(s), in-situ elements, or landers. The ADEPT system can package with off the shelf CubeSat deployment systems (1U-16U) to offer a delivery capability for a single CubeSat or constellations. Furthermore, ADEPT can deliver the same science payload to a destination with a stowed diameter a factor of 3-4 times smaller than an equivalent rigid aeroshell, alleviating volumetric constraints on the secondary payload accommodation or primary carrier spacecraft bus. This paper will describe ADEPT's current development status and define various interplanetary mission concepts in order to provide guidelines for potential Small Satellite payload developers and mission implementers.

Adaptive Deployable Entry and Placement Technology↗

NASA NTRSDate not supplied

Atmospheric Mining in the Outer Solar System: Interplanetary Transfer Vehicles, In-Situ Resource Utilization, and Moon Mining Issues

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. Analyses of orbital transfer vehicles (OTVs), landers, and in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. Aerospacecraft with closed cycle gas core propulsion are used to capture the 3He and deuterium from the outer planet atmospheres. Water ice on the outer planet moons has been identified as critical resources for refueling the moon landers and the nuclear electric OTVs. The numbers of interplanetary transfer vehicles (ITVs) and the launch vehicles will be presented. Preliminary design parameters for the ITVs and their payload limits will be assessed. The number of mining machines and their associated issues are addressed.

chemical propulsion↗

NASA NTRS1973

Observations of the He II 304-A radiation in the night sky.

The intensity and spatial variations of the He II 304-A radiation in the night sky were measured to an altitude of 264 km from a sounding rocket launched from Thumba, India, on Mar. 10, 1970. The data obtained are presented in the form of an all-sky map and are compared with theoretical predictions. The data are not consistent either with diffusive equilibrium models of exospheric helium or with plausible models of helium in the interplanetary medium. The data can be fit with a constant-density plasmasphere model bounded at the magnetic shell L = 4 in combination with a tenuous gas of helium ions in the plasma sheet. Numerical results obtained with this model are compared with in situ satellite observations.

Paresce, F.↗

NASA NTRS1992

Great magnetic storms

The five largest magnetic storms that occurred between 1971 to 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that: (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective.

Tsurutani, Bruce T.↗

NASA NTRS1992

Carbon petrology in cometary dust

Chondritic porous (CP) interplanetary dust particles (IDP's) are collected in the Earth's stratosphere. There exists an extensive database on major and minor element chemistry, stable isotopes, noble gas abundances and mineralogy of many CP IDP's, as well as infrared and Raman spectroscopic properties. For details on the mineralogy, chemistry and physical properties of IDP's, I refer to the reviews by Mackinnon and Rietmeijer (1987), Bradley et al. (1988) and Sandford (1987). Texture, mineralogy (Mackinnon and Rietmeijer, 1987) and chemistry (Schramm et al., 1989; Flynn and Sutton, 1991) support the notion that CP IDP's are a unique group of ultrafine-grained extraterrestiral materials that are distinct from any known meteorite class. Their fluffy, or porous, morphology suggests that CP IDP's probably endured minimal alteration by protoplanetary processes since their formation. It is generally accepted that CP IDP's are solid debris from short-period comets. The evidence is mostly circumstantial but this notion gained significant support based on the comet Halley dust data (Brownlee, 1990). In this paper, I will accept that CP IDP's are indeed cometary dust. The C/Si ratio in CP IDP's is 3.3 times higher than in CI carbonaceous chondrites (Schramm et al. 1989). The intraparticle carbon distribution is heteorogeneous (Rietmeijer and McKay, 1986). Carbon occurs both in oxidized and reduced forms. Analytical electron microscope (AEM) and Raman spectroscopic analyses have shown the presence of several carbon forms in CP IDP's but the data are scattered in the literature. Carbons in cometary CP IDP's are among the most pristine Solar System carbons available for laboratory study. Similar to a recently developed petrological model for the diversity of layer silicates in CP IDP's (Zolensky, 1991) that is useful to constrain in situ aqueous alteration in comets (Rietmeijer and Mackinnon, 1987a), I here present the first effort to develop a petrological concept of carbons in CP IDP's. This concept is useful to constrain comet evolution. I also present the philosophical constraint facing Earth Scientists in studies of protoplanets that require a new approach to cometary dust studies.

Rietmeijer, Frans J. M.↗

NASA NTRS1995

Terrestrial Response to Eruptive Solar Flares: Geomagnetic Storms

During the interval of August 1979 - December 1979, 56 unambiguous fast forward shocks were identified using magnetic field and plasma data collected by the ISEE-3 spacecraft. Because this interval is a solar maximum we assume the streams causing these shocks are associated with coronal mass ejections and eruptive solar flares. For these shocks we shall describe the shock-storm relationship for the level of intense storms (Dst < -100 nT). Then, we will discuss the interplanetary structures that are associated with the large-amplitude and long-duration negative Bz fields, which are found in the sheath field and/or driver gas regions of the shock and are thought to be the main cause of the intense storms.

Solar Flares↗

NASA NTRS1973

A satellite measurement of cosmic-ray abundances and spectra in the charge range 2 less than or equal to 7 less than or equal to 10

The composition of the nuclear component of the cosmic radiation was studied to yield information concerning the source, propagation, and confinement of cosmic rays within the galaxy. The first comprehensive satellite measurement is presented of cosmic-ray composition and spectra in the charge range 2 equal to or less than Z equal to or less than 10 using the geomagnetic field as a rigidity analyzer through the entire range of vertical cutoffs. The results indicate that the spectra of all the elements in the observed range are similar, and thus that various ratios of elemental abundances are nearly independent of rigidity over the range 2 equal to or less than P equal to or less than 15 GV. Calculations of the propagation of cosmic rays through the interstellar and interplanetary media predict that there should be a variation with rigidity of ratios of various elements, because of the charge-dependent effects of ionization of the interstellar gas by the cosmic rays. The absence of this variation can be explained by assuming a rigidity-dependent confinement of the cosmic rays in the galaxy.

Brown, J. W.↗

NASA NTRS1992

Terrestrial Response to Eruptive Solar Flares: Geomagnetic Storms

This paper describes the interplanetary structures that are associated with the large-amplitude and long-duration negative B subscript z fields that are found in the sheath field and/or driver gas regions of the shock and are thought to be the main cause of the intense storms.

solar flares geomagnetic storms magnetic field dat↗

NASA NTRS2010

Z-Pinch Pulsed Plasma Propulsion Technology Development

Fusion-based propulsion can enable fast interplanetary transportation. Magneto-inertial fusion (MIF) is an approach which has been shown to potentially lead to a low cost, small reactor for fusion break even. The Z-Pinch/dense plasma focus method is an MIF concept in which a column of gas is compressed to thermonuclear conditions by an axial current (I approximates 100 MA). Recent advancements in experiments and the theoretical understanding of this concept suggest favorable scaling of fusion power output yield as I(sup 4). This document presents a conceptual design of a Z-Pinch fusion propulsion system and a vehicle for human exploration. The purpose of this study is to apply Z-Pinch fusion principles to the design of a propulsion system for an interplanetary spacecraft. This study took four steps in service of that objective; these steps are identified below. 1. Z-Pinch Modeling and Analysis: There is a wealth of literature characterizing Z-Pinch physics and existing Z-Pinch physics models. In order to be useful in engineering analysis, simplified Z-Pinch fusion thermodynamic models are required to give propulsion engineers the quantity of plasma, plasma temperature, rate of expansion, etc. The study team developed these models in this study. 2. Propulsion Modeling and Analysis: While the Z-Pinch models characterize the fusion process itself, propulsion models calculate the parameters that characterize the propulsion system (thrust, specific impulse, etc.) The study team developed a Z-Pinch propulsion model and used it to determine the best values for pulse rate, amount of propellant per pulse, and mixture ratio of the D-T and liner materials as well as the resulting thrust and specific impulse of the system. 3. Mission Analysis: Several potential missions were studied. Trajectory analysis using data from the propulsion model was used to determine the duration of the propulsion burns, the amount of propellant expended to complete each mission considered. 4. Vehicle Design: To understand the applicability of Z-Pinch propulsion to interplanetary travel, it is necessary to design a concept vehicle that uses it -- the propulsion system significantly impacts the design of the electrical, thermal control, avionics and structural subsystems of a vehicle. The study team developed a conceptual design of an interplanetary vehicle that transports crew and cargo to Mars and back and can be reused for other missions. Several aspects of this vehicle are based on a previous crewed fusion vehicle study -- the Human Outer Planet Exploration (HOPE) Magnetized Target Fusion (MTF) vehicle. Portions of the vehicle design were used outright and others were modified from the MTF design in order to maintain comparability.

Polsgrove, Tara↗

NASA NTRS1989

Nuclear thermal rockets - Next step to space

The prospects for the use of nuclear thermal rockets in manned interplanetary exploration are examined. These rockets offer the possibility for trip times on the order of a year or less in the next two decades. Mission prospects for gas-core concepts are emphasized, showing how such concepts meet the mission requirements.

Borowski, Stanley K.↗

NASA NTRS1979

An empirical polytrope law for solar wind thermal electrons between 0.45 and 4.76 AU: Voyager 2 and Mariner 10

Empirical evidence is presented that solar wind thermal electrons obey a polytrope law with polytrope index gamma = 1.175 plus or minus 0.03. The Voyager 2 and Mariner 10 data used as evidence are compared and discussed. The theoretical predictions that solar wind thermal electrons in the asymptotic solar wind should obey a polytrope law with polytrope index gamma = 1.16 plus or minus. The widespread impressions in the literature that solar wind electrons behave more like an isothermal than adiabatic gas, and the arguments that Coulomb collisions are the dominant stochastic process shaping observed electron distribution functions in the solar wind are reexamined, reviewed and evaluated. The assignment of the interplanetary potential as equal to approximately seven times the temperature of the thermal electrons is discussed.

Sittler, E. C., Jr.↗

NASA NTRS1983

Prediction of a propellant tank pressure history using state space methods

An analysis of the time response of a propellant supply system operating in the blowdown mode is presented. The supply system is part of a pump-fed propulsion system intended for use on interplanetary spacecraft. As such, the supply system must provide the pump with propellant at sufficient pressure to avoid pump cavitation. The system, consisting of the tank, the liquid propellant, the pressurant gas and propellant vapor mixture, and a film layer separating the liquid and vapor phases, is analyzed using the principles of mass and energy conservation. The resulting set of ordinary, coupled, nonlinear differential equations for the thermodynamic state variables is integrated as an initial value problem. The resulting histories of total pressure, propellant vapor pressure, propellant liquid temperature, film layer temperature, propellant vapor/pressurant gas temperature, propellant vapor mass, and propellant liquid mass enable the calculation of the net positive suction head available at the pump which determines the viability of the pump-fed system concept when operated in the blowdown mode.

Estey, P. N.↗

NASA NTRS2015

Ultra-Compact Ka-Band Parabolic Deployable Antenna for RADAR and Interplanetary CubeSats

Over the past several years, technology and launch opportunities for CubeSats have exploded, enabling a wide variety of missions. However, as instruments become more complex and CubeSats travel deeper into space, data communication rates become an issue. To solve this challenge, JPL has initiated a research and technology development effort to design a 0.5 meter Ka-band parabolic deployable antenna (KaPDA) which would stow in 1.5U (10 x 10 x 15 cu cm) and provide 42dB of gain (50% efficiency). A folding rib architecture and dual reflector Cassegrainian design was selected as it best balances RF gain and stowed size. The design implements an innovative telescoping waveguide and gas powered deployment. RF simulations show that after losses, the antenna would have over 42 dB gain, supported by preliminary test results. KaPDA would create opportunities for a host of new CubeSat missions by allowing high data rate communication which would enable using high fidelity instruments or venturing further into deep space, including potential interplanetary missions. Additionally KaPDA would provide a solution for other small antenna needs and the opportunity to obtain Earth science data. This paper discusses the design challenges encountered, the architecture of the solution, and the antennas expected performance capabilities.

Sauder, Jonathan↗

NASA NTRS1990

Helium and neon isotopes in stratospheric particles

He and Ne isotope ratios were determined for 16 interplanetary dust particles (IDPs) collected in the stratosphere. The observed He concentration varied greatly from particle to particle, with the highest values approaching those found for lunar surface fines and some gas-rich meteorites. The average Ne-20/Ne-22 ratio was 12.0 + or - 0.5. The data suggest that the observed IDPs could have entered the atmosphere at relatively low velocities, and hence may be primarily of asteroidal rather than cometary origin.

Nier, A. O.↗

NASA NTRS2014

Astromaterials Research Office (KR) Overview

The fundamental goal of our research is to understand the origin and evolution of the solar system, particularly the terrestrial, "rocky" bodies. Our research involves analysis of, and experiments on, astromaterials in order to understand their nature, sources, and processes of formation. Our state-of-the-art analytical laboratories include four electron microbeam laboratories for mineral analysis, four spectroscopy laboratories for chemical and mineralogical analysis, and four mass spectrometry laboratories for isotopic analysis. Other facilities include the experimental impact laboratory and both 1-atm gas mixing and high-pressure experimental petrology laboratories. Recent research has emphasized a diverse range of topics, including: Study of the solar system's primitive materials, such as carbonaceous chondrites and interplanetary dust; Study of early solar system chronology using short-lived radioisotopes and early nebular processes through detailed geochemical and isotopic characterizations; Study of large-scale planetary differentiation and evolution via siderophile and incompatible trace element partitioning, magma ocean crystallization simulations, and isotopic systematics; Study of the petrogenesis of Martian meteorites through petrographic, isotopic, chemical, and experimental melting and crystallization studies; Interpretation of remote sensing data, especially from current robotic lunar and Mars missions, and study of terrestrial analog materials; Study of the role of organic geochemical processes in the evolution of astromaterials and the extent to which they constrain the potential for habitability and the origin of life.

Draper, David S.↗