This paper describes an analysis for the membrane dynamics and deformation of solar power sail demonstrator "IKAROS". After the successful deployment of membrane, some images of the whole sail membrane of IKAROS were taken by separation cameras. From these data, it has estimated that the membrane of IKAROS had a deformation different from the prediction considering the solar radiation pressure. In this paper, these observed deformations of membrane are reported and compared with the results of numerical simulation using multi-particle model. A membrane's deformation over time observed in the images taken by side monitor cameras is also reported and the cause of the changing is discussed. Nomenclature d = cross section diameter of tether E = Young's modulus of membrane E t = Young's modulus of tether h = thickness of membrane F = inter-particle force (Ixx, Iyy, Izz) = moments of inertia of main body K = spring constant of membrane L = distance between two particles L 0 = natural length of spring M = main body's mass (Ixy, Iyz, Izx) = products of inertia of main body (x g , y g , z g ) = center of mass of main body (x,y,z) = coordinate frame fixed to main body

No abstract

No abstract

The Medium Earth Orbit (MEO) offers a greater width of satellite view than the Low Earth Orbit, and a greater proximity to the Earth's surface than the Geostationary Earth Orbit. Global positioning systems and ionospheric sounding satellites have already operated in this orbit, and the MEO will appeal to satellite missions undertaking Earth observations, communications, positioning, and scientific explorations. The Sun-Synchronous Medium Earth Orbits (SS-MEOs) used in this study enable clear and daily observations of the Earth's surface. However, problems such as severe radiation from the Van Allen radiation belt, and the inefficiency to launch a satellite in a southwest direction, need to be resolved. This paper presents the results of early studies on SS-MEO utilization: orbital characteristics and environments, candidates for Earth observation missions, and the feasibility of the development and launch of a satellite for operation within this orbit.

A conceptual study was undertaken on earth observation missions for a satellite within the Sun-Synchronous and Medium Earth Orbit (SS-MEO). Our mission study of a MEO Satellite was performed as pioneering research into a newly utilized earth orbit that exists between the Low Earth Orbit (LEO) and the Geostationary Earth Orbit (GEO). One of the advantages of the MEO is that it delivers a wider field of view (FOV), which permits more frequent observations that are more easily obtained, in comparison with the LEO. Another advantage is that the performance demands for sensors are moderate, relative to those for the GEO. This conceptual study of earth observation missions is considered for the baseline (4184 km) orbits, focusing on optical sensors. We summarize the needs of each assumed user (products, observational frequency, and spatial resolution) related to four missions (agricultural, forest, ocean, and air pollution observations). Agricultural observation is expected to need a spatial resolution of 10 m and an observational frequency of a few times a week. As a result, required optical sensor is that with an aperture diameter of 30 cm, an f-number of 11, and a signal-to-noise ratio (S/N) of 20. It is thought that the optical sensor for the agricultural observation would be larger in comparison with the previous optical sensors used within the LEO, because the S/N and FOV are smaller. However, it was found there is a challenge to be met in terms of a compatibility with the f-number and FOV. This paper shows the results of this conceptual study and the issues raised relating to mission sensors for earth observation missions in the MEO.