Hyperthin solar sails deployed as close to the Sun as possible are the only currently feasible approach to extrasolar solar exploration and interstellar travel. This paper quantifies and investigates ...the effects of timing errors in the unfurlment (or inflation) of solar sails at the perihelion of parabolic solar orbits upon the spacecraft's trajectory direction. Methods of correcting such aim errors include on-board solar-, radioisotope-, or nuclear-electric thrusters, electromagnetic thrustless turning, application of electric or magnetic sails, and a new application of toroidal magnetic ion scoops.
The Sun's gravity focus at >550AU is of interest to astrophysicists including SETI scientists, researchers seeking to image extra-solar planets and others. One method for an extra-solar probe to ...reach the Sun's inner gravity focus within a human working lifetime (less than 50 years) is to combine solar and nuclear propulsion techniques. Here, we present a non-optimized probe concept including state-of-the-art solar-sail, radioisotope-electric propulsion and giant-planet gravity assists. Application of radioisotope propulsion allows some cross range capability during and after the powered and cruise phases of the flight to >600AU. Such a capability is likely necessary to fully utilize the solar gravitational lens effect for SETI and astrophysical observations.
Hyper-thin, high-speed solar-photon sail space probes exploring the Sun׳s Oort comet cloud could also be used to set an upper bound to the concentration of WIMPS (weakly interacting massive ...particles), one of the suggested (but unconfirmed) forms of dark matter within the vicinity of the solar system. Newton׳s Shell Theorem would be applied to determine variations in apparent solar mass as the probe moves further out from the Sun. Application of this technique to the trajectories of Pioneer 10/11 reveals that the upper limit to WIMP concentration within ~60AU of the Sun is ~0.2 Earth masses, as revealed in studies of the Pioneer Anomaly. If the published accuracy of the Pioneer acceleration measurements can be increased by an order of magnitude, probe trajectory measurements out to ~10,000AU may confirm or falsify the hypothesis that WIMP mass within the solar vicinity is ~3X star mass. It is shown that a space-manufactured ~40-nm thick beryllium hollow-body solar sail deployed from a ~0.07AU perihelion is a candidate spacecraft for such a mission. Possible science-team organization strategy for a ~100-year mission to ~10,000AU is discussed.
•Discusses rival explanations for anomalous stellar motions.•Reviews concepts of WIMPS and MACHOS.•Discusses and applies Newton׳s Shell Theory for local WIMP search.•Reviews solar sail theory and potential.•Proposes sail mission to hunt for WIMPS.
Human interplanetary missions are constrained by the problem of astronaut exposure to galactic cosmic radiation. This paper surveys the existing on-line near-Earth object (NEO) data base in an effort ...to identify NEOs that cross both Earth's ad Mars’ orbits and could be used as cosmic ray shields by interplanetary voyagers. The search concentrated on low-inclination Mars-crossing NEOs that approach Earth, Mars, and main-belt asteroids in the 2020–2100 time frame. Both outbound and return transfers were searched for. Several candidates for Earth–Mars, Mars–Earth, and Earth–Vesta transfers have been found from the very incomplete August 2008 data base. Other aspects of this interplanetary transfer option are considered.
Near-sun space-environment effects on metallic thin films solar sails as well as hollow-body sails with inflation fill gas are considered. Analysis of the interaction of the solar radiation with the ...solar-sail materials is presented. This analysis evaluates worst-case solar radiation effects during solar-radiation-pressure acceleration. The dependence of the thickness of solar sail on temperature and on wavelength of the electromagnetic spectrum of solar radiation is investigated. Physical processes of the interactions of photons, electrons, protons and α-particles with sail material atoms and nuclei, and inflation fill gas molecules are analyzed. Calculations utilized conservative assumptions with the highest values for the available cross sections for interactions of solar photons, electrons and protons with atoms, nuclei and hydrogen molecules. It is shown that for high-energy photons, electrons and protons the beryllium sail is mostly transparent. Sail material will be partially ionized by solar UV and low-energy solar electrons. For a hollow-body photon sail effects including hydrogen diffusion through the solar-sail walls, and electrostatic pressure is considered. Electrostatic pressure caused by the electrically charged sail’s electric field may require mitigation since sail material tensile strength decreases with elevated temperature. It also can substitute inflation-gas pressure loss due to gas diffusion and perforation by micrometeoroids impact to keep the sail inflated.
: Geosynchronous satellites are invisible at high latitudes. A pole‐sitting spacecraft would have communication, climate‐studies, and near‐polar Earth observation applications. We present a ...pole‐sitter based on the solar photon thruster (SPT), a two‐sail variant of the solar sail using a large curved collector sail (always normal to the Sun) to direct sunlight against a much smaller thruster. Thrust decreases slower for an SPT than for a conventional sail arrangement as the angle between sunlight and the collector normal increases. An SPT pole‐sitter is offset from the terrestrial pole so that a component of Earth gravity balances the solar radiation‐pressure component pushing the SPT off station. The component of gravitational attraction of the Earth pulling the spacecraft towards Earth is also balanced by a solar radiation‐pressure component. Results are presented for 80‐100% collector/thruster reflectivities. For a spacecraft areal mass thickness of 0.002 kg/m2, collector and thruster reflectivities of 0.9, the SPT can be situated above latitude 45° at a distance of approximately 60 Earth radii. An SPT pole sitter would be affected by lunar perturbation, which can be compensated for by an on‐board rocket thruster producing 2 × 10−6g acceleration, a second SPT thruster sail thrusting against the influence of the Moon, or by directing a microwave beam against the spacecraft. Since an SPT pole sitter is in a position rather than an orbit, the effect of terrestrial gravitation limits the size and design of the payload package, which limits terrestrial target resolution.
The solar collector (SC), a two-sail solar-photon thruster utilized to concentrate solar energy, is a possible method to deflect Earth-threatening near-Earth objects (NEOs). This paper expands an ...existing SC model to categorize SC performance as a function of parameters including NEO composition, solar distance and rotation.
Phobos/Deimos Sample Return via Solar Sail MATLOFF, GREGORY L.; TAYLOR, TRAVIS; POWELL, CONLEY ...
Annals of the New York Academy of Sciences,
December 2005, Letnik:
1065, Številka:
1
Journal Article
Recenzirano
Odprti dostop
: A sample‐return mission to the Martian satellites using a con‐temporary solar sail for all post‐Earth‐escape propulsion is proposed. The 0.015 kg/m2 areal mass‐thickness sail unfurls after launch ...and injection onto a Mars‐bound Hohmann‐transfer ellipse. Structure and payload increase spacecraft areal mass thickness to 0.028 kg/m2. During the Mars encounter, the sail functions as a parachute in the outer atmosphere of Mars to accomplish aerocapture. On‐board thrusters or the sail maneuver the spacecraft into an orbit with periapsis near Mars and apoapsis near Phobos. The orbit is circularized for Phobos‐rendezvous; surface samples are collected. The sail then raises the orbit for Deimos‐rendezvous and sample collection. The sail next places the spacecraft on an Earth‐bound Hohmann‐transfer ellipse. During Earth encounter, the sail accomplishes Earth‐aerocapture or partially decelerates the sample container for entry into the Earth's atmosphere. Mission mass budget is about 218 grams and mission duration is less than five years.
On-orbit deployment tests and operational missions for first-generation solar-photon sails may require a method of monitoring post-deployment sail health. A low-technology device capable of ...performing this function is the pinhole camera, combined with an inflatable hydrostatic beam mounted at the sail's center of mass.
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