This interdependence between satellite bus and PL subsystems has historically resulted in many nonstandard interfaces developed and implemented by the incumbent spacecraft builders. The PL operational requirements sometimes impose specific requirements on the satellite bus that must be satisfied for the PL to accomplish its mission. Traditionally, the PL is considered a subsystem of the satellite bus that is designed to generally satisfy the corresponding mission requirements. Since PLs and their missions vary widely, so is this satellite bus supporting role. The PL is often a unique and one-of-a-kind design tailored to meet specific mission requirements, frequently relying heavily on newer technology, while the satellite bus has the supporting function, and as such relies largely on existing or modified hardware such as batteries, inertial devices, and star trackers. The PL design includes dimensions, interfaces, weight, physical characteristics, and basic utility needs (e.g., power consumption), which usually influences spacecraft (SC) bus design. In general, the space mission dictates the type of orbit 2, satellite design and its expected life cycle, and its operational scenarios. The user segment consisting of all the individuals and groups who use and benefit from the data and services provided by the payloads of the satellite and the equipment that allows this use. Practically, the control segment is also referred to as satellite ground segment because it is usually located on the ground. The satellite control (or control) segment consisting of all the personnel, facilities, and equipment that are used to monitor and control all the assets in space. The space segment consisting of all satellites and associated equipment required for the mission applications and the launch vehicles used to deliver those satellites to orbit.

There are three specific segments shown in Figure 2 below that must work together for the larger overall system to provide communication, navigation, or any other type of missions: This chapter focuses on architecture and functionalities of the communications subsystem that usually resides on the satellite. Regardless of the mission type 1 and the payload that a spacecraft carries, a subsystem that must exist in all satellites is the communication subsystem that enables the spacecraft to communicate with the ground stations that control the satellite and to deliver the data that the mission requires. Note the clear separation between the spacecraft bus that provides solar power and maneuvering capability via thruster, while the payload consisting of the camera and supporting communication devices such as antennas and guidance devices such as star trackers.Ī typical satellite with bus and payload separation.

Shown below in Figure 1 is a typical imaging satellite used for the remote sensing mission. A satellite may have one type of PL or a combination of payload types to accomplish its mission such as navigation, remote sensing, and communications. Examples of mission payloads (or payloads or PLs) are: scientific instruments, remote sensing instruments, navigation service transmitters, or communications equipment. The spacecraft bus provides control of the satellite and support services to the mission payload, while the mission payload provides the mission part of the satellite including payload control, mission data processing, and mission data downlink dissemination. In addition, the space environment (thermal, radiation, atomic oxygen, space debris, micrometeoroids, etc.) imposes constraints on the design such as parts and material selection.Ī spacecraft is consisted of two parts: the spacecraft bus and the payload (PL).

Secondly, the mass and volume limits affect the size of the power system on the spacecraft therefore, the amount of power available to the satellite is also limited. First, satellite designs are limited in their mass and volume to fit on the launch vehicle that places them into orbit. A spacecraft has several design constraints placed upon it before it can be placed in an orbit around the intended celestial body. In the context of this chapter, a satellite is a spacecraft (SC) that orbits around a celestial body such as the earth.

Omniweb spacecraft data