A Feasibility Study of An Ultra-light Large Antenna Reflector for Future Mobile Communications Satellites
- Paper number
IAC-05-C2.1.B.02
- Author
Dr. Akira Meguro, Japan Aerospace Exploration Agency (JAXA), Japan
- Coauthor
Mr. Satoshi Harada, NTT Access Network Service System Laboratories, Japan
- Coauthor
Dr. Masazumi Ueba, NTT Access Network Service System Laboratories, Japan
- Year
2005
- Abstract
To lower the costs and increase the performance of commercial satellite systems, larger and lighter antennas are needed. We have proposed an ultra-light reflector antenna whose aperture diameter is larger than 20m and whose areal density is less than 0.25 kg/m 2. Target total mass is 130 kg including the boom structure and holding structure. To realize this new reflector antenna, we proposed a geodesic cable network system supported by a tendon structure. Two requirements are fundamental to realizing a successful structural design. One is a cable network system that keeps its shape even if the supporting structures are strongly deformed by in-orbit thermal and vibration disturbances. The other is an extremely light weight support structure whose structural behavior is non-linear and whose deformation is very large. From research conducted over the last two years, we have reached the following conclusions. 1) Buckling modes in a support structure with spoke-like framing are effectively suppressed by tendons. The use of tendon cables increases the compression rigidity of long ribs 11 fold and their compression strength 4 fold. 2) Assuming that the thermal distortion of the supporting structure is 2 mm, the reflector structure has sufficient margin (surface accuracy) against in-orbit disturbances. 3) Large deployable mesh antenna reflectors, whose aperture is 20m and whose weight is less than 80 kg, appear feasible. In order to realize actual hardware, we considered three important issues. The first one is the estimation accuracy of non-structural mass such as hinge/driving mechanisms. The second is the margin of designed mass. The last one is manufacturing capability. To improve the feasibility of this design methodology, we undertook detailed design analyses of mechanisms, and further structural considerations. Detailed candidates for hinges, linkage mechanisms, drive mechanisms and stowed configurations of the basic structure were elucidated. The total mass of the entire structure was calculated. We examined the relationship between the total mass and strength of the support structure by changing structural metrics, cross-sectional areas, and material properties. We also examined the characteristics of the cable-mesh structure to achieve the design values needed considering current manufacturing capabilities. The following conclusions were reached. 1) Total weight and stowed size were estimated using detailed mechanical design drawings. Stowed height and non-structural mass for deployment control mechanism were found to be the most important issues in terms of system. 2) Assuming the acceptable load is 100N and the margin of safety (MS) is 0.5, a static load response analysis shows that the minimum total mass including non-structural mass, boom and holding structure would reach about 110 kg. 3) Partitioning of the entire cable-mesh structure, reduction in the number of facets, and arrangement of edge shape are effective design approaches to improving the stability of the structure and suppress the fluctuation of cable tension.
- Abstract document
- Manuscript document
IAC-05-C2.1.B.02.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.