Satellite Configuration Design - Finite Element Analysis for Satellite Structures - page 26

to package components, select suitable structural architecture, and define main
structural load paths. This will be done generally by following the steps in
Table 2.1 , which describes a general process for configuring a satellite. Products of
this phase will be layouts of stowed and deployed configuration. The calculation of
mass properties will be discussed in Sect. 2.8 . Normally, the conceptual design
phase results in several configurations, but only one will be presented to limit work
efforts.
From Table 2.2 , there are no outstanding requirements that will dictate a rev-
olutionary design or new technology. From Table 2.3 , the total predicted mass of
Small Sat is 225 kg, including launch vehicle adapter, which is within the
allowable mass band (200-300 kg) and leaves a high margin, based on the Dnepr's
payload capability of 800 kg for Small Sat selected orbit. The initial equipment list
indicates that there are some assumptions already made regarding the satellite's
deployed configuration. The 3.2 m 2 of solar-array area is based on the assumption
of deployable-fixed solar arrays. Thus, rotation mechanisms are needed to deploy
and fix solar arrays in space.
2.7.1 A Quick Look at On-Orbit Configuration
Using this information and the payload requirements, a ''quick-look'' can be
sketched for on-orbit configuration, as shown in Fig 2.5 . Because the MBEI is
heavy and bulky, it is located at the middle of the satellite and directed to the earth
''Nadir'', which provides a clear field of view. This location makes the mass
distribution as symmetric as possible. Moreover, it enables mounting the payload
directly along the primary load path, which reduces the shock effect and distributes
structural loads uniformly during launch.
Since the high gain antenna (X-band antenna) communicates through a ground
station, it needs to be fixed at the forward end and directed to the earth ''Nadir''. A
dipole antenna of the S-band equipment and one of the GPS receiver antennae are
mounted at the aft end to be directed to ''Zenith'', which is the opposite direction
of ''Nadir''. The other GPS receiver antenna and two conical antennae of the S-
band equipment are mounted at the forward end to be directed to ''Nadir''. Using
symmetric solar arrays about the satellite's center of mass minimizes environ-
mental disturbances. They will be most efficient if they protrude from the satellite
near the aft end along the axis perpendicular to the orbit plane. Determination of
how many solar array panels should be used depends on the configuration shape,
method and location of stowed panels, and mass properties of the final configu-
ration. Four solar arrays with 3.2 m 2 total area are assumed to be mounted on the
initial configuration. To provide symmetrical shape, each two solar arrays located
at opposite sides are identical.
The star sensor requires a narrow field of view to identify the relative location
of certain stars, so it is located at the aft end and directed toward the horizon. The
star sensor mounting is turned by 49 o from Zenith direction in the positive Y-axis