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Results for “CIRCULAR 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.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

A method for attitude control of a satellite in circular orbit by actively varying its inertia.

Equations are developed for a vehicle consisting of a system of particles which move in a generally prescribed fashion. These equations are then specialized to apply to a rigid vehicle with a constant amount of fluid contained in tanks and flowing through interconnecting lines. Various simplifications and specialized forms of the equations are derived, and relationships between mass and inertia that result from the fluid transfer logic and the physical constraints of the configuration are formulated. A tank arrangement and fluid transfer logic are devised which permit each vehicle product of inertia to be varied without varying the remaining elements of the inertia matrix or shifting the center of mass. Vehicle control is achieved by sensing angular rate and the local vertical and by transferring fluid as a function of these variables.

Clarke, W. D.↗
NASA NTRS1974

Nominal Profile Refinements Report: Target in 120 Nautical Mile Circular Orbit

The compability of the nominal rendezvous sequence with low target orbits is addressed. It was found that for targets in low earth orbits certain modifications of the nominal sequence are required to achieve a feasible anytime liftoff capability, notably the use of elliptical phasing orbits and the allowance of up to two days for rendezvous under certain phasing conditions.

Source record↗
NASA NTRS1991

Orientation and shape control of a weight optimum free-free beam in a circular orbit

In this study, the vibration and orientation control of large space structures using the linear quadratic regulator technique is investigated. Emphasis is placed on the control of both a class of optimally designed structures and uniform structures meeting the mission requirements using a long free-free beam in orbit as an example. The open loop and closed loop dynamics are compared and the transient responses are obtained to determine the effectiveness of the control system design.

Bainum, Peter M.↗
NASA NTRS1991

The origin of the systematic component of planetary rotation. I - Planet on a circular orbit

A computation is undertaken of the rotation rate of a planet that has accreted from small solid planetesimals, as a function of the eccentricities of the planetesimals' orbits at or near the plane of the planet's orbit. The spin angular momentum generated by a given collision can be either positive or negative; due to the tendency to approximately cancel out, this perturbation process must be pursued to the second order in the ratio of the planetary radius to the planetesimal radial excursions' amplitude. It is found that material accreted from the area of the planet feeding zone's outer edges furnishes the planet positive spin angular momentum.

Lissauer, Jack J.↗
NASA NTRS1993

Optimal cooperative power-limited rendezvous between neighboring circular orbits

A minimum-fuel rendezvous of two power-limited spacecraft is investigated. Both vehicles are active and provide thrust to complete the rendezvous. Total propellant consumption is minimized. Analytical solutions are obtained for cooperative rendezvous in the linearized Hill-Clohessy-Wiltshire gravity field. The optimal solutions depend in a complicated way on the power-to-mass ratios of the spacecraft, the initial orbits, and the specified transfer time. For comparison purposes, analytical solutions for active-passive rendezvous in the linearized gravity field are also determined. Cooperative rendezvous requires smaller total propellant consumption, resulting in greater payload capability.

Coverstone-Carroll, Victoria↗
NASA NTRS2013

Circular-Orbit Maintenance Strategies for Primitive Body Orbiters

For missions to smaller primitive bodies, solar radiation pressure (SRP) is a significant perturbation to Keplerian dynamics. For most orbits, SRP drives large oscillations in orbit eccentricity, which leads to large perturbations from the irregular gravity field at periapsis. Ultimately, chaotic motion results that often escapes or impacts that body. This paper presents an orbit maintenance strategy to keep the orbit eccentricity small, thus avoiding the destabilizing secondary interaction with the gravity field. An estimate of the frequency and magnitude of the required maneuvers as a function of the orbit and body parameters is derived from the analytic perturbation equations.

comet↗
NASA NTRS2020

TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P=3.6772±0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD’s radius R(b) = 1.34(+0.26, -0.15)R(J). We obtained high resolution spectroscopic observations with the FIES, Ondrejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be M(b)=53.7±1.2 M(J). The host star has a mass of M(*)=1.80±0.06M(ʘ), a radius of R(*)=1.70±0.05R(ʘ), an effective temperature of T(eff)=7650±160 K, and a relatively high metallicity of 0.61±0.07 dex. We used stellar isochrones to derive the age of the system to be ∼180 Myr, which places its age between that of RIK 72b (a ∼10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a ∼600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting main sequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert (35–55M(J) sin i) is reforesting.

Jan Subjak↗
NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the orbital maneuvering system

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbital Maneuvering System (OMS) hardware are documented. The OMS provides the thrust to perform orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS is housed in two independent pods located one on each side of the tail and consists of the following subsystems: Helium Pressurization; Propellant Storage and Distribution; Orbital Maneuvering Engine; and Electrical Power Distribution and Control. The IOA analysis process utilized available OMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluted and analyzed for possible failure modes and effects. Criticality was asigned based upon the severity of the effect for each failure mode.

Prust, C. D.↗
NASA NTRS1992

Production of recycled pulsars in globular clusters via two-body tidal capture

The numbers of binary systems containing a neutron star that are formed in the cores of globular clusters via two-body tidal capture are investigated. The subsequent evolution of the resulting binary systems is examined. Monte Carlo techniques are employed to trace the histories of many neutron stars in the core of a model globular cluster. Various scenarios for mass stripping during capture and orbital circularization, and the effects of magnetic braking on the circularized orbits are explored. Calculations are carried out for two model clusters: 47 Tuc and Omega Cen. Distributions of orbital periods for newly formed binaries containing a neutron star in orbit with either a main-sequence star or a giant are presented. Each binary is followed until contact between the captured star and the neutron star is established. It is argued that these systems should be regarded as potential progenitors of 'recycled' pulsars.

Di Stefano, R↗
NASA NTRS2014

Green Applications for Space Power Project

Spacecraft propulsion and power for many decades has relied on Hydrazine monopropellant technology for auxiliary power units (APU), orbital circularization, orbit raising/lowering and attitude control. However, Hydrazine is toxic and therefore requires special ground handling procedures to ensure launch crew safety. The Swedish Company ECAPS has developed a technology based upon the propellant Ammonium Dinitramide (ADN) that offers higher performance, higher density and reduced ground handling support than Hydrazine. This blended propellant is called LMP-103S. Currently, the United States Air Force (USAF) is pursuing a technology based on Hydroxyl Ammonium Nitrate (HAN, otherwise known as AF-M315E) with industry partners Aerojet and Moog. Based on the advantages offered by these propellants, MSFC should explore powering APU's with these propellants. Due to the availability of space hardware, the principal investigator has found a collection of USAF hardware, that will act as a surrogate, which operates on a Hydrazine derivative. The F-16 fighter jet uses H-70 or 30% diluted Hydrazine for an Emergency Power Unit (EPU) which supplies power to the plane. The PI has acquired two EPU's from planes slated for destruction at the Davis Monthan AFB. This CIF will include a partnership with 2 other NASA Centers who are individually seeking seed funds from their respective organizations: Kennedy Space Center (KSC) and Dryden Flight Research Center (DFRC). KSC is preparing for future flights from their launch pads that will utilize green propellants and desire a low-cost testbed in which to test and calibrate new leak detection sensors. DFRC has access to F-16's which can be used by MSFC & KSC to perform a ground test that demonstrates emergency power supplied to the jet. Neither of the green propellant alternatives have been considered nor evaluated for an APU application. Work has already been accomplished to characterize and obtain the properties of these 2 propellants. However, the spacecraft are using existing leak detection sensors that are typically used for Hydrazine. Using these green propellants for the APU application requires decrementing their TRL down to 3. This task would aim to establish a TRL of 4 at conclusion by showing a proof of concept with a KSC-instrumented EPU asset at the MSFC Component Development Area (CDA). The task to accomplish this is called Green Application for Space Power or GRASP.

Robinson, Joel↗
NASA NTRS2020

Charon: A Brief History of Tides

In 2015, the New Horizons spacecraft flew past Pluto and its moon Charon, providing the first clear look at Charon's surface. New Horizons images revealed an ancient surface, a large, intricate canyon system, and many fractures, among other geologic features. Here, we assess whether tidal stresses played a significant role in the formation of Charon's tensile fractures. Although presently in a circular orbit, most scenarios for Charon's orbital evolution include an eccentric orbit for some period of time and possibly an internal ocean. Past work has shown that these conditions could have generated stresses comparable in magnitude to other tidally fractured moons, such as Europa and Enceladus. However, we find no correlation between observed fracture orientations and those predicted to form due to eccentricity driven tidal stress. It, thus, seems more likely that Charon's orbit circularized before its ocean froze and that either tidal stresses alone were insufficient to fracture the surface or subsequent resurfacing removed these ancient fractures.

Alyssa Rose Rhoden↗