The solar photon sail (SPS) allows space missions without propellant that would otherwise not be feasible. Thrust models frequently used in the literature for the calculation of trajectories often underestimate the effect that the surface roughness has on SPS dynamics. A small variation of the thrust vector can induce a large modification of sail flight. In this work, the variation of the photon momentum vector (PMV) is computed as resulting from the incident Sun radiation, taking into account the absorbed and reflected photons. The momentum resulting from diffuse light has been modeled by using vectorial scattering theories in the limit of a quasi-smooth sail where the first-order of Rayleigh-Rice can be applied. In particular, the momentum change resulting from diffuse radiation causes a PMV reduction as well as a deviation of its direction from what is foreseen in the case of an ideally smooth sail.

We examine the theoretical implications of incorporating metasurfaces on solar sails, and the effect they can have on the forces applied to the sail. This would enable a significant enhancement over state-of-the- art attitude control by demonstrating a novel, propellant-free and low-mass approach to induce a roll torque on the sail, which is a current limitation in present state-of-the-art technology. We do so by utilizing anomalous optical reflections from the metasurfaces to generate a net in-plane lateral force, which can lead to a net torque along the roll axis of the sail, in addition to the other spatial movements exhibited by the sail from solar radiation pressure. We characterize this net lateral force as a function of incidence angle. In addition, the influence of the phase gradients and anomalous conversion efficiencies characteristics of the metasurfaces are independently considered. The optimum incidence angle that corresponded with the maximum net lateral-to-normal force ratio was found to be -30° for a metasurface exhibiting 75% anomalous conversion efficiency with a phase gradient of 0:71k₀.

Atmospheric drag limits most solar sails to altitudes>1000 km. A two-sail variant, the Solar-Photon Thruster (SPT) , could be used in Low-Earth Orbit (LEO). An SPT has a fixed-orientation collector sail that focuses light against a smaller, adjustable thruster sail. Maintaining the collector surface parallel to the Earth minimizes SPT drag in LEO. To minimize solar-radiation back pressure towards Earth, the upper collector surface is non-reflective. The reflective lower collector surface directs light reflected and reradiated from the Earth against the thruster. Thruster orientation is adjusted in LEO to increase the orbital energy by the net radiation-pressure. Experiments reveal that holograms are tolerant to solar-wind radiation. SPTs with white-light holographic thrusters are useful in LEO because small thruster rotations produce greatly altered reflectivity. It may be possible to holographically combine SPT collector and thruster.

This paper discusses a space debris removal mission in low Earth orbit in which, for a preliminary design, a solar sail is used as a chaser satellite to reach, capture and de-orbit a debris object. The sail, which exploits the solar radiation pressure as its main source of thrust, is subject to the effects of aerodynamic forces, Earth's oblateness and eclipse occurrence. Locally-optimal laws are used to control the transfer with the aim of maximizing (or minimizing) the rate of change of a specific orbital element or a suitable combination of them, depending on the transfer phase. When blended control laws are used to target the debris, the optimal weighting factors are calculated with a genetic algorithm to assess the relative importance of each orbital element. Numerical simulations show the effectiveness of locally-optimal laws in driving the sail towards the target even in the presence of the above-mentioned orbital perturbations. In a test-case scenario, a solar sail with a characteristic acceleration of 0.1 mm/s2, departing from 550 km of altitude, is able to reach the debris orbit at 1200 km of height in less than 200 days with a good accuracy level. The same analysis has been repeated for a solar sail with performance characteristics similar to those of NASA's planned Advanced Composite Solar Sail System (ACS3) mission.

Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The two spacecraft to successfully use the technology for propulsion were IKAROS, launched in 2010, and LightSail-2, la S… In… The… IKAROS, launched in 2010, was the first practical solar sail vehicle. As of 2015, it was still under thrust, proving the practicality of a solar sail for long-duration… On 21 May 2010, Japan Aerospace Exploration Agency (JAXA) launched the world's first interplanetary solar sail spacecraft "IKAROS" (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) to Venus. Using a new solar-photon propulsion method, it was the first true solar sail spacecraft fully propelled by sunlight, and was the first spacecraft to succeed in solar sail flight. JAXA successfully tested IKAROS in 2010. The goal was to deploy and control the sail and, for the first time, to determine the minute orbit perturbations caused by light pressure. Orbit determination was done by the nearby AKATSUKI probe from which IKAROS detached after both had been brought into a transfer orbit to Venus. The total effect over the six month flight was 100 m/s. Until 2010, no solar sails had been successfully used in space as primary propulsion systems. On 21 May 2010, the Japan Aerospace Exploration Agency (JAXA) launched the IKAROS spacecraft, which deployed a 200 m2 polyimide experimental solar sail on June 10. In July, the next phase for the demonstration of acceleration by radiation began. On 9 July 2010, it was verified that IKAROS collected radiation from the Sun and began photon acceleration by the orbit determination of IKAROS by range-and-range-rate (RARR) that is newly calculated in addition to the data of the relativization accelerating speed of IKAROS between IKAROS and the Earth that has been taken since before the Doppler effect was utilized. The data showed that IKAROS appears to have been solar-sailing since 3 June when it deployed the sail. IKAROS has a diagonal spinning square sail 14×14 m (196 m2) made of a 7.5-micrometre (0.0075 mm) thick sheet of polyimide. The polyimide sheet had a mass of about 10 grams per square metre. A thin-film solar array is embedded in the sail. Eight LCD panels are embedded in the sail, whose reflectance can be adjusted for attitude control. IKAROS spent six months traveling to Venus, and then began a three-year journey to the far side of the Sun.

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/m(2), collector and thruster reflectivities of 0.9, the SPT can be situated above latitude 45 degrees 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 x 10(-6) g 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.