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Photon Sailor aims to create a realistic photon-sailing experience in KSP. A photonsail, also known as solar sail or laser sail, allows a spacecraft to propel itself using radiation pressure from the sun or laser transmitters, removing the need to carry any reaction mass and simply using the deflection of photon energy to provide thrust. The acceleration gained from solar radiation is extremely small but can be applied over a long period of time to reach extremely high speeds, given a large enough sail and a payload of low mass. Besides being propelled by the photons emitted by the sun, it can also be propelled by photons emitted by KSC beamed power station or by (KSPIE) beamed power transmitters, allow ejecting solar sail to be launched at much higher speeds than with using only solar energy. Photon sails function both under real time as and non-physical timewarp, allowing for them to be useful for interplanetary travel. Photonsails must operate mainly outside the proximity of atmospheres (> 400 km) which due to their large sail surface area are much subject to the effects of drag which are accurately simulated. The sail can also use drag as an effective means of orbital capture Download Photon Sailor Version 1.7.3 for Kerbal Space Program 1.8.1 - 1.12 Older versions can be found here source code: GitHub If you want to chat about Photon sailing you can do it at our KSP Interstellar Discord Server Supported Mods CKAN Recommended mods which improve play experience: License: Credits SasquatchMarmalade for creating the Solar Sail part @Fractal_UK For for initial creation of solar sail code @mrsolarsail For improving the solar sail code Photon Sail Control To help you with altitude control, the part interface contains several useful indicators like Periapsis, Apapsis and Orbital Diameter Change Understanding Solar Sails Changing orbits with a solar sail is counter-intuitive, since the forces at work are significantly different to both rockets, and sailing ships. The simplest way to understand and experiment with this is to leave Kerbin's sphere of influence, and put the sail in a solar orbit with conventional rockets. It is possible to use sails in low planetary orbits, but there are several complexities here - it becomes more difficult to align the sail, and the planet tends to get in the way. In a solar orbit, there will be two vectors acting on the craft. One vector will push the sail directly away from the sun, and the other will be controlled by the deflection of the sail - most efficiently at an angle of 45 degrees to the radial vector. Travelling away from the sun: (45 degrees retrograde) Travelling towards the sun: (45 degrees prograde) (Images from SolarSailWiki, by Ben Diedrich, under a Creative Commons Licence) Since this will take a long time to take effect, the sail may complete several solar orbits before reaching it's destination. Therefore, this will require holding a heading, time warping, re-adjusting the heading, and time warping again. It's possible to consider the above in terms of "reflecting the light in the intended direction of thrust", since lowering an orbit would require thrusting with a rocket oriented to the retrograde vector, or equally the exhaust oriented towards the prograde vector. Configuration/Modding Change Log Research Sources