Search NASA⌕ Search

SEARCH · Search NASA

Results for “solar orbit”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Space platforms - A cost effective evolution of Spacelab operation

The capabilities added to the Shuttle/Spacelab configuration by the addition of the Power Extension Package (PEP), the Power System (PS), and the Science and Applications Space Platforms (SASP) are reviewed with an emphasis on SASP. SASP are intended for placement in orbit by the Shuttle to test new instruments and systems, for clustering of instrumentation, and for servicing, refurbishment, repair, or augmentation by the Shuttle. The PEP permits extended stays in orbit (30 days), and the PS is an orbital solar array and energy storage system acting as a free flying spacecraft. The Shuttle can deliver payloads to the PS or attach to it for extension of the Spacelab operations. Applications of SASP for long term space-based biological experiments are outlined, and the fact that SASP do not increase the required Shuttle in-orbit time is stressed.

Stofan, A. J.↗
NASA NTRS1990

Orbital debris removal and salvage system

Four Texas A&M University projects are discussed. The first project is a design to eliminate a majority of orbital debris. The Orbital Debris and Salvage System will push the smaller particles into lower orbits where their orbits will decay at a higher rate. This will be done by momentum transfer via laser. The salvageable satellites will be delivered to the Space Station by an Orbital Transfer Vehicle. The rest of the debris will be collected by Salvage I. The second project is the design of a space based satellite system to prevent the depletion of atmospheric ozone. The focus is on ozone depletion in the Antarctic. The plan is to use an orbiting solar array system designed to transmit microwaves at a frequency of 22 GHz over the region in order to dissipate polar stratospheric clouds that form during the months beginning in August and ending in October. The third project, Project Poseidon, involves a conceptual design of a space based hurricane control system consisting of a network of 21 low-orbiting laser platforms arranged in three rings designed to heat the upper atmosphere of a developing tropical depression. Fusion power plants are proposed to provide power for the lasers. The fourth project, Project Donatello, involves a proposed Mars exploration initiative for the year 2050. The project is a conceptual design for a futuristic superfreighter that will transport large numbers of people and supplies to Mars for the construction of a full scale scientific and manufacturing complex.

Source record↗
NASA NTRS2008

Conceptual Design Methods and the Application of a Tradespace Modeling Tool for Deep Space Missions

Concept studies for deep space missions are typically time-consuming and costly, given the variety of missions and uniqueness of each design. Yet, in an increasingly cost-constrained environment, it is critical to identify the most scientifically valuable and cost-effective designs early in the design process. Modeling is an integral part in helping to identify the most desirable design option. While some spacecraft design models currently exist for Earth-orbiting spacecraft, there has been less success with deep space missions. Instead, these missions require a modified design and modeling approach to enable the same construction of a comprehensive, yet credible, mission tradespace. This paper presents an approach for efficiently constructing such a mission tradespace. In addition to a proposed design and modeling approach, three case study missions are presented including a solar orbiter, a Europa orbiter, and a near-Earth asteroid (NEA) sample return mission.

space vehicles↗
NASA NTRS2006

Solar CIV Vacuum-Ultraviolet Fabry-Perot Interferometers

Aims: A tunable, high spectral resolution, high effective finesse, vacuum ultraviolet (VUV) Fabry-Perot interferometer (PPI) is designed for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155 nm). Methods: The integral part of the CIV narrow passband filter package (with a 2-10 pm FWHM) consists of a multiple etalon system composed of a tunable interferometer that provides high-spectral resolution and a static low-spectral resolution interferometer that allows a large effective free spectral range. The prefilter for the interferometers is provided by a set of four mirrors with dielectric high-reflective coatings. A tunable interferometer, a VUV piezoelectric-control etalon, has undergone testing using the surrogate F2 eximer laser line at 157 nm for the CIV line. We present the results of the tests with a description of the overall concept for a complete narrow-band CIV spectral filter. The static interferometer of the filter is envisioned as being hudt using a set of fixed MgF2 plates. The four-mirror prefilter is designed to have dielectric multilayer n-stacks employing the design concept used in the Ultraviolet Imager of NASA's Polar Spacecraft. A dual etalon system allows the effective free spectral range to be commensurate with the prefilter profile. With an additional etalon, a triple etalon system would allow a spectrographic resolution of 2 pm. The basic strategy has been to combine the expertise of spaceflight etalon manufacturing with VUV coating technology to build a VUV FPI which combines the best attributes of imagers and spectrographs into a single compact instrument. Results. Spectro-polarimetry observations of the transition region CIV emission can be performed to increase the understanding of the magnetic forces, mass motion, evolution, and energy release within the solar atmosphere at the base of the corona where most of the magnetic field is approximately force-free. The 2D imaging of the full vector magnetic field at the height of maximum magnetic influence (minimum plasma beta) can be accomplished, albeit difficult, by measuring the Zeeman splitting of the CIV resonance pair. Designs of multiple VUV FPIs can be developed for integration into future orbiting solar observatories to obtain rapid cadence, spectral imaging of the transition region.

Gary, G. Allen↗
NASA NTRS1979

In-orbit evaluation of the control system/structural mode interactions of the OSO-8 spacecraft

The Orbiting Solar Observatory-8 experienced severe structural mode/control loop interaction problems during the spacecraft development. Extensive analytical studies, using the hybrid coordinate modeling approach, and comprehensive ground testing were carried out in order to achieve the system's precision pointing performance requirements. A recent series of flight tests were conducted with the spacecraft in which a wide bandwidth, high resolution telemetry system was utilized to evaluate the on-orbit flexible dynamics characteristics of the vehicle along with the control system performance. The paper describes the results of these tests, reviewing the basic design problem, analytical approach taken, ground test philosophy, and on-orbit testing. Data from the tests was used to determine the primary mode frequency, damping, and servo coupling dynamics for the on-orbit condition. Additionally, the test results have verified analytically predicted differences between the on-orbit and ground test environments, and have led to a validation of both the analytical modeling and servo design techniques used during the development of the control system.

Slafer, L. I.↗
NASA NTRS1980

On-orbit evaluation of the control system/structural mode interactions on OSO-8

The Orbiting Solar Observatory-8 experienced severe structural mode/control loop interaction problems during the spacecraft development. Extensive analytical studies, using the hybrid coordinate modeling approach, and comprehensive ground testing were carried out in order to achieve the system's precision pointing performance requirements. A recent series of flight tests were conducted with the spacecraft in which a wide bandwidth, high resolution telemetry system was utilized to evaluate the on-orbit flexible dynamics characteristics of the vehicle along with the control system performance. This paper describes the results of these tests, reviewing the basic design problem, analytical approach taken, ground test philosophy, and on-orbit testing. Data from the tests was used to determine the primary mode frequency, damping, and servo coupling dynamics for the on-orbit condition. Additionally, the test results have verified analytically predicted differences between the on-orbit and ground test environments. The test results have led to a validation of both the analytical modeling and servo design techniques used during the development of the control system, and also verified the approach taken to vehicle and servo ground testing.

Slafer, L. I.↗
NASA NTRS2023

Prospects of Detecting Nonthermal Protons in Solar Flares via Lyman Line Spectroscopy: Revisiting the Orrall-Zirker Effect

Solar flares are efficient particle accelerators, with a substantial fraction of the energy released manifesting as nonthermal particles. While the role that nonthermal electrons play in transporting flare energy is well studied, the properties and importance of nonthermal protons are rather less well understood. This is in large part due to the paucity of diagnostics, particularly at the lower-energy (deka-keV) range of nonthermal proton distributions in flares. One means to identify the presence of deka-keV protons is by an effect originally described by Orrall & Zirker. In the Orrall–Zirker effect, nonthermal protons interact with ambient neutral hydrogen, and via charge exchange produce a population of energetic neutral atoms (ENAs) in the chromosphere. These ENAs subsequently produce an extremely redshifted photon in the red wings of hydrogen spectral lines. We revisit predictions of the strength of this effect using modern interaction cross sections, and numerical models capable of self-consistently simulating the flaring nonequilibrium ionization stratification, and the nonthermal proton distribution (and, crucially, their feedback on each other). We synthesize both the thermal and nonthermal emission from Ly α and Ly β, the most promising lines that may exhibit a detectable signal. These new predictions are weaker and more transient than prior estimates, but the effects should be detectable in fortuitous circumstances. We degrade the Ly β emission to the resolution of the Spectral Imaging of the Coronal Environment (SPICE) instrument on board Solar Orbiter, demonstrating that though likely difficult, it should be possible to detect the presence of nonthermal protons in flares observed by SPICE.

Solar flares↗
NASA NTRS2022

Influence of Large-Scale Interplanetary Structures on the Propagation of Solar Energetic Particles: the Multi-Spacecraft Event on 2021 October 9

An intense solar energetic particle (SEP) event was observed on 2021 October 9 by multiple spacecraft distributed near the ecliptic plane at heliocentric radial distances R ≲ 1 au and within a narrow range of heliolongitudes. A stream interaction region (SIR), sequentially observed by Parker Solar Probe (PSP) at R = 0.76 au and 48° east from Earth (ϕ = E48°), STEREO-A (at R = 0.96 au, ϕ = E39°), Solar Orbiter (SolO; at R = 0.68 au, ϕ = E15°), BepiColombo (at R = 0.33 au, ϕ = W02°), and near-Earth spacecraft, regulated the observed intensity-time profiles and the anisotropic character of the SEP event. PSP, STEREO-A, and SolO detected strong anisotropies at the onset of the SEP event, which resulted from the fact that PSP and STEREO-A were in the declining-speed region of the solar wind stream responsible for the SIR and from the passage of a steady magnetic field structure by SolO during the onset of the event. By contrast, the intensity-time profiles observed near Earth displayed a delayed onset at proton energies ≳13 MeV and an accumulation of ≲5 MeV protons between the SIR and the shock driven by the parent coronal mass ejection (CME). Even though BepiColombo, STEREO-A, and SolO were nominally connected to the same region of the Sun, the intensity-time profiles at BepiColombo resemble those observed near Earth, with the bulk of low-energy ions also confined between the SIR and the CME-driven shock. This event exemplifies the impact that intervening large-scale interplanetary structures, such as corotating SIRs, have in shaping the properties of SEP events.

D. Lario↗
NASA NTRS2024

Improved Modelling of SEP Event Onset Within the WSA–Enlil–SEPMOD Framework

Multi-spacecraft observations of solar energetic particle (SEP) events not only enable a deeper understanding and development of particle acceleration and transport theories but also provide important constraints for model validation efforts. However, because of computational limitations, a given physics-based SEP model is usually best suited to capture a particular phase of an SEP event, rather than its whole development from onset through decay. For example, magnetohydrodynamic (MHD) models of the heliosphere often incorporate solar transients only at the outer boundary of their so-called coronal domain – usually set at a heliocentric distance of 20–30 R⊙. This means that particle acceleration at coronal mass ejection (CME)-driven shocks is also computed from this boundary onwards, leading to simulated SEP event onsets that can be many hours later than observed, since shock waves can form much lower in the solar corona. In this work, we aim to improve the modelled onset of SEP events by inserting a “fixed source” of particle injection at the outer boundary of the coronal domain of the coupled WSA–Enlil 3D MHD model of the heliosphere. The SEP model that we employ for this effort is Solar Energetic Particle MODel (SEPMOD), a physics-based test-particle code based on a field line tracer and adiabatic invariant conservation. We apply our initial tests and results of SEPMOD’s fixed-source option to the 2021 October 9 SEP event, which was detected at five well-separated locations in the inner heliosphere – Parker Solar Probe, STEREO-A, Solar Orbiter, BepiColombo, and near-Earth spacecraft.

Solar eruptions↗
NASA NTRS2001

Origin of Martian Moons from Binary Asteroid Dissociation

The origin of the Martian moons Deimos and Phobos is controversial. A common hypothesis for their origin is that they are captured asteroids, but the moons show no signs of having been heated by passage through a (hypothetical) thick martian atmosphere, and the mechanism by which an asteroid in solar orbit could shed sufficient orbital energy to be captured into Mars orbit has not been previously elucidated. Since the discovery by the space probe Galileo that the asteroid Ida has a moon 'Dactyl', a significant number of asteroids have been discovered to have smaller asteroids in orbit about them. The existence of asteroid moons provides a mechanism for the capture of the Martian moons (and the small moons of the outer planets). When a binary asteroid makes a close approach to a planet, tidal forces can strip the moon from the asteroid. Depending on the phasing, either or both can then be captured. Clearly, the same process can be used to explain the origin of any of the small moons in the solar system.

Landis, Geoffrey A.↗
NASA NTRS1978

Planning for large construction projects in space

The paper discusses briefly some broad plans for developing the technology needed for large construction projects in space ranging from orbiting solar power stations to large communications antennas. Space construction classes include assembly of modules, deployment of compacted structures, assembly of passive preformed pieces, and fabrication of structures from sheet stock. Technological areas related to structural concepts include (1) analyses for prediction of structural behavior, structural/control interaction, electromagnetic and control performance, and integrated design development; (2) electronics for signal conditioning and data acquisition, power distribution, and signal channel interference and multipaction; (3) concepts for shape control, attitude/pointing control, and orbital transfer and station keeping; and (4) materials and techniques for 30-year dimensional stable composites, thermal control, thin-lightweight structural alloys, and material joining in space. The concept of a power module for the construction operations is discussed along with a concept for a habitability module.

Disher, J. H.↗
NASA NTRS2023

Multi-Spacecraft Observations of Shocklets at an Interplanetary Shock

Interplanetary (IP) shocks are fundamental building blocks of the heliosphere, and the possibility to observe them in situ is crucial to address important aspects of energy conversion for a variety of astrophysical systems. Steepened waves known as shocklets are known to be important structures of planetary bow shocks, but they are very rarely observed related to IP shocks. We present here the first multi-spacecraft observations of shocklets observed by upstream of an unusually strong IP shock observed on 3 No v ember 2021 by several spacecraft at L1 and near-Earth solar wind. The same shock was detected also by radially aligned Solar Orbiter at 0.8 AU from the Sun, but no shocklets were identified from its data, introducing the possibility to study the environment in which shocklets developed. The Wind spacecraft has been used to characterize the shocklets, associated with pre-conditioning of the shock upstream by decelerating incoming plasma in the shock normal direction. Finally, using the Wind observations together with ACE and DSCOVR spacecraft at L1, as well as THEMIS B and THEMIS C in the near-Earth solar wind, the portion of interplanetary space filled with shocklets is addressed, and a lower limit for its extent is estimated to be of about 110 R E in the shock normal direction and 25 R E in the directions transverse to the shock normal. Using multiple spacecraft also reveals that for this strong IP shock, shocklets are observed for a large range of local obliquity estimates (9° –64°).

plasmas↗
NASA NTRS1980

Dual-spin spacecraft nutation control using articulated payloads

A technique is presented for achieving active control of nutation on a dual-spin spacecraft with an articulated payload through use of the payload's control system. Using the Orbiting Solar Observatory (OSO)-8 as an illustration, the closed-form solution to the nutation/control system dynamic interaction is presented. Control system design criteria are developed which establish the basic stability of the interaction. Design procedures are described to achieve the most effective nutation damping. Limitations on the amount of damping which can be achieved are characterized as functions of spacecraft and payload mass properties and servo-design parameters. The design techniques presented are verified through a series of on-orbit tests recently conducted on the OSO-8 spacecraft.

Slafer, L. I.↗
NASA NTRS1990

The Advanced Solar Observatory

A conceptual plan for the development of a comprehensive long duration solar space observatory, The Advanced Solar Observatory (ASO) is described. The ASO is intended to provide solar astronomers with the observational power necessary to address fundamental problems relating to the solar convection zone and activity cycle; the thermal and nonthermal processes that control the transport of energy, mass, and magnetic flux in the solar atmosphere; the generation of the solar wind; and the dynamics of the inner heliosphere. The ASO concept encompasses three proposed Space Station-based instrument ensembles: (1) the High Resolution Telescope Cluster, which includes far ultraviolet, extreme ultraviolet, and X-ray telescopes; (2) the Pinhole/Occulter Facility, which includes Fourier transform and coded aperture hard X-ray and gamma ray telescopes and occulted ultraviolet and visible light coronagraphs; and (3) the High Energy Facility, which contains neutron, gamma ray, and low frequency radio spectrometers. Two other facilities, the Orbiting Solar Laboratory, and a package of Global Dynamics Instrumentation, will, with the Space Station ensembles, form a comprehensive capability for solar physics. The scientific program of the ASO, current instrument concepts for the Space Station based ASO instrument ensembles, and plans for their accommodation on the Space Station are described.

Walker, Arthur B. C., Jr.↗
NASA NTRS1995

(T2L2) Time Transfer by Laser Link

T2L2 (Time Transfer by Laser Link) is a new generation time transfer experiment based on the principles of LASSO (Laser Synchronization from Synchronous Orbit) and used with an operational procedure developed at OCA (Observatoire de la Cote d'Azur) during the active intercontinental phase of LASSO. The hardware improvements could lead to a precision better than 10 ps for time transfer (flying clock monitoring or ground based clock comparison). Such a package could fly on any spacecraft with a stable clock. It has been developed in France in the frame of the PHARAO project (cooled atom clock in orbit) involving CNES and different laboratories. But T2L2 could fly on any spacecraft carrying a stable oscillator. A GPS satellite would be a good candidate, as T2L2 could allow to link the flying clock directly to ground clocks using light, aiming to important accuracy checks, both for time and for geodesy. Radioastron (a flying VLBI antenna with a H-maser) is also envisioned, waiting for a PHARAO flight. The ultimate goal of T2L2 is to be part of more ambitious missions, as SORT (Solar Orbit Relativity Test), aiming to examine aspects of the gravitation in the vicinity of the Sun.

Veillet, Christian↗
NASA NTRS2024

Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity

We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available multispacecraft data. The first method utilizes intensity fitting with a circular Gaussian distribution, while the second method is based on the time arrival of radio bursts. We demonstrate the effectiveness of these methods through the analysis of a single type III burst event and compare their results with the traditional radio triangulation technique. Furthermore, we conduct a statistical study of 17 type III bursts associated with M- and X-class solar flares in years 2020–2022. Our findings suggest a possible correlation between solar flare intensities and longitudes, with east limb flares tending to be weaker than west limb flares. We also observe a systematic drift of radio burst longitudes toward the east, potentially explained by a poleward component of the local density gradient. Our results suggest a strong correlation between solar flare intensities and radio burst properties, enhancing our understanding of the relationship between solar flares and type III radio bursts.

Radio astronomy↗
NASA NTRS1980

Analysis of GaAs and Si solar cell arrays for earth orbital and orbit transfer missions

Solar array systems have been studied and compared for earth orbital and orbit transfer missions with the principal objective of quantifying the cost tradeoffs between gallium arsenide and silicon array for specific classes of missions and system characteristics. For the missions considered, it is found that the purchase cost advantage of Si arrays is not overcome by the greater radiation resistance of GaAs arrays. The use of reflectors for concentration may significantly reduce the power system cost. However, GaAs arrays benefit considerably more from solar concentration than Si arrays in terms of mission cost because of their higher allowable temperature. In the case of orbit transfer missions, a cover glass thickness of at least 0.05 cm is recommended to reduce total mission cost.

Jefferies, K. S.↗
NASA NTRS2024

Acceleration and Release of Solar Energetic Particles Associated with a Coronal Shock on 2021 September 28 Observed by Four Spacecraft

The main driver of the acceleration of solar energetic particles (SEPs) is believed to be shocks driven by coronal mass ejections. Extreme-ultraviolet (EUV) waves are thought to be the propagating footprint of the shock on the solar surface. One of the key questions in SEP research is the timing of the SEP release with respect to the time when the EUV wave magnetically connects with an observer. Taking advantage of close-to-the-Sun measurements by Parker Solar Probe (PSP) and Solar Orbiter (SolO), we investigate an SEP event that occurred on 2021 September 28 and was observed at different locations by SolO, PSP, STEREO-A, and near-Earth spacecraft. During this time, SolO, PSP, and STEREO-A shared similar nominal magnetic footpoints relative to the SEP source region but were at different heliocentric distances. We find that the SEP release times estimated at these four locations were delayed compared to the times when the EUV wave intercepted the footpoints of the nominal magnetic fields connecting to each spacecraft by around 30–60 minutes. Combining observations in multiple wavelengths of radio, white light, and EUV with a geometrical shock model, we analyze the associated shock properties and discuss the acceleration and delayed release processes of SEPs in this event as well as the accuracy and limitations of using EUV waves to determine the SEP acceleration and release times.

Solar coronal mass ejections↗