Browse Topic: Solar rocket engines
Inflatable and deployable beams and masts such as solar sail supports used in space missions are often made of polymer composites and may be stored for one to two years in space before deployment. While stored, these polymer composites degrade on a molecular level, which can limit the ability of the beams to unfurl properly, reducing performance or even failing to unfurl. Researchers at NASA’s Langley Research Center developed a fiber-reinforced polymer composite to reduce the effect of viscoelastic creep and prolong the molecular integrity of polymer-based beams over time
NASA’s Marshall Space Flight Center is building a small CubeSat that uses an 85-m2 solar sail deployed from a central location to capture the push of photons from the Sun as its propulsion source. To integrate this sail into the CubeSat, NASA inventors have developed a new method for folding and packaging the thin membrane
Sunlight can be reflected into permanently shadowed regions (PSRs) using S/C solar sails in order to detect and confirm the presence and distribution of water ice cold-trapped in PSRs in lunar polar craters. This reflected light is then viewed with an optical spectrometer
This work describes a discontinuous or segmented mirror whose overall flatness is less dependent on the limited tension that can be supplied by the booms. A solar sail is a large, nominally flat sheet of extremely thin reflectorized film rigidly attached to a spacecraft, enabling propulsion via solar radiation pressure. Rip-stop fibers embedded in the backside of the film — with diameters ≈100× the thickness of the film — are commonly used to arrest tear propagation, which can easily occur in the handling and/or deployment of these gossamer-thin structures. Typically, the thin film or membrane that is the sail is systematically folded to enable both volumetrically compact transportation to space and mechanized deployment. It is the aggressive folding and creasing of the thin film that limits the ultimate flatness that can be achieved
A new method has been developed to create coherent laser light efficiently with direct optical coupling of the Sun’s energy into the gain medium for multiple uses. New advances in solar cell photovoltaic (PV) technologies have greatly improved their efficiencies, mostly by improving their ability to convert many wavelengths or wider bands of the solar spectrum to electricity. New advances in actively doped fibers and optical glasses have been shown to produce very broad, multi-line absorption bands as well as stimulated emission lines, or laser lines. By designing the optical cavity system to feed back all emission bands into the gain media for amplification, a multi-wavelength source can be generated requiring no electronics
A report describes upgraded CubeSat satellite elements for the interplanetary environment, with solar sail propulsion and the interplanetary superhighway for navigation and maneuvering. They can host small, capable instruments and optical telecommunications on a mission to map the composition of a sequence of near-Earth asteroids and planetary bodies
The Sunjammer Mission team — including NASA, lead contractor L’Garde, Space Services Holdings (SSHI), and Micro Aerospace Solutions — is preparing to launch Sunjammer, the largest solar sail ever deployed, named in honor of legendary science fiction author Sir Arthur C. Clarke. In a 1963 novella, Clarke christened a solar sailing ship “Sunjammer,” powered only by the pressure created by photons from the Sun
UltraSail is a next-generation, high-risk, high-payoff sail system for the launch, deployment, stabilization, and control of very large (km2 class) solar sails enabling high payload mass fractions for interplanetary and deep space spacecraft. UltraSail is a non-traditional approach to propulsion technology achieved by combining propulsion and control systems developed for formation- flying microsatellites with an innovative solar sail architecture to achieve controllable sail areas approaching 1 km2, sail subsystem area densities approaching 1 g/m2, and thrust levels many times those of ion thrusters used for comparable deep space missions. UltraSail can achieve outer planetary rendezvous, a deep-space capability now reserved for high-mass nuclear and chemical systems
A report discusses the ability to control the attitude and translation degrees-of-freedom of a solar sail vehicle by changing its center of gravity. A movement of the spacecraft's center of mass causes solar- pressure force to apply a torque to the vehicle. At the compact core of the solar-sail vehicle lies the spacecraft bus which is a large fraction of the total vehicle mass. In this concept, the bus is attached to the spacecraft by two single degree-of-freedom linear tracks. This allows relative movement of the bus in the sail plane. At the null position, the resulting solar pressure applies no torque to the vehicle. But any deviation of the bus from the null creates an offset between the spacecraft center of mass and center of solar radiation pressure, resulting in a solar-pressure torque on the vehicle which changes the vehicle attitude. Two of the three vehicle degrees of freedom can be actively controlled in this manner. The third, the roll about the sun-line, requires a low
A document presents computational simulation studies of a concept for stabilizing the attitude of a spacecraft during deployment of such structures as a solar sail or other structures supported by inflatable booms. Specifically, the solar sail considered in this paper is a square sail with inflatable booms and attitude control vanes at the corners. The sail inflates from its stowed configuration into a square sail with four segments and four vanes at the tips. Basically, the concept is one of controlling the rates of inflation of the booms to utilize in mass distribution properties to effect changes in the system's angular momentum
A document discusses a proposal to incorporate holographic optical elements into solar photon thrusters (SPTs). First suggested in 1990, SPTs would be systems of multiple reflective, emissive, and absorptive surfaces (solar sails) that would be attached to spacecraft orbiting the Earth to derive small propulsive forces from radiation pressures. An SPT according to the proposal would include, among other things, a main sail. One side of the sail would be highly emissive and would normally face away from the Earth. The other side would be reflective and would be covered by white-light holographic images that would alternately become reflective, transmissive, and absorptive with small changes in the viewing angle. When the spacecraft was at a favorable orbital position, the main sail would be oriented to reflect sunlight in a direction to maximize the solar thrust; when not in a favorable position, the main sail would be oriented to present a substantially absorptive/emissive aspect to
Polymers having low color and a favorable combination of other properties, including high glass-transition temperature (Tg) and high mechanical properties (strength, tensile modulus, and toughness) will find use in a variety of terrestrial and space applications. Some of the space applications will be in thin films used as membranes on antennas, solar concentrators, coatings on second-surface mirrors, solar sails, sunshades, thermal and optical coatings, and multi-layer thermal insulation blankets. Depending upon the application, the film will be required to exhibit a unique combination of such properties as resistance to degradation by ultraviolet light, visible light, and electrons; low color and/or low solar absorptivity; resistance to tearing and/or wrinkling during packaging and deployment; and high mechanical properties (e.g. high strength, stiffness, and toughness). Recently developed polyimides having several of these desired properties are described below
A report describes the personal radiation protection system (PRPS), which has been invented for use on the International Space Station and other spacecraft. The PRPS comprises walls that can be erected inside spacecraft, where and when needed, to reduce the amount of radiation to which personnel are exposed. The basic structural modules of the PRPS are pairs of 1-in. (2.54-cm)-thick plates of high-density polyethylene equipped with fasteners. The plates of each module are assembled with a lap joint. The modules are denoted bricks. A report discusses the attitude-control system of a proposed spacecraft that would derive at least part of its propulsion from a solar sail. The spacecraft would include a bus module containing three or more reaction wheels, a boom attached at one end to the bus module and attached at its other end to a two-degree-of-freedom (DOF) gimbal at the nominal center of mass of a sail module. Each DOF of the gimbal could be independently locked against rotation or
A report proposes a high-temperature- resistant solar sail with an areal mass density less than 1 g/m2, for a spacecraft that would approach the Sun to within a distance of 0.2 astronomical unit (≈3 × 107 km). The sail would be made in multiple segments of a carbon microtruss fabric held in a network of tensioned lines. The segments and network would be designed to minimize tension in the fabric. The porosity of the fabric would be tailored so that to photons, the fabric would behave as though it were solid. Reflective metal surface films could be attached to the fabric. In advanced versions, the fabric could be directly coated with metal, or, alternatively, the fabric surface would be the sail surface and there would be no metal layer. The sail fabric would be wrapped around a sail cylinder and deployed by use of centrifugal force. A separate structure next to the sail cylinder would contain most of the deployment hardware and would be ejected after deployment of the sail to reduce
A report proposes that solar sails for spacecraft be constructed in segments in such a way as to minimize stresses. The segments could be made of metallized fabric or film and could be connected by short, strong tethers. Alternatively, the segments could be like islands, held loosely in pockets bounded by fibers. For stowage during transport to outer space, the sails could be folded along the gaps between segments, so as to minimize folding stresses in the sail material. Because tensile and other stresses in the sail material would be minimal, the sail material could be made in a thickness of the order of a micron and could thus be very lightweight. In cases in which there are requirements for sails to sustain tensile stresses, carbon-fiber nets like those described in the preceding article could be used
A report proposes that solar sails for spacecraft be made from nets of carbon fibers. The reason for choosing carbon nets over thin polymeric films is that nets offer greater capability for carrying tensile loads. The sails could be made from carbon-fiber nets of various thicknesses: nets used for high emissivity could be made from nanotube carbon fibers; nets for holding aluminum reflectors could be made from micron-thickness fibers; nets to carry tensile loads in sails could be made from fibers with thicknesses between 10 and 100 µm; and nets to carry large bulk loads and loads in high-stress areas could be made from fibers with thicknesses from 100 to 1,000 µm
A report discusses a proposed nesting-hoop solar sail that would be used to propel a spacecraft on a deep-space mission. The nesting-hoop design concept was chosen as one that would afford a desired combination of small mass and compact stowage during launch. The sail would include multiple disks, each comprising a thin fabric stretched over a hoop of wire or thin tubing (e.g., hypodermic-needle tubing). The adjacent hoops would be bonded together by springy extensions that would be fabricated in their sail-deployed positions. The sail would be stowed by folding at the springy extensions. Successive hoops would be progressively slightly smaller so that when stowed, the hoops would nest and therefore the thickness of the stowed sail would be approximately proportional to the thickness of the fabric (instead of the much greater thickness of the hoops). The fabric would not be folded for stowage; consequently, the spring tension (and thus the required thickness of the hoops) needed to
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