**1. Background and introduction**

Typical commercial and civilian satellite systems take about 2–3years to build and launch [1–4], while military systems take between 7 and 10 years [5, 6]. A typical production flow for assembling and launching of a space vehicle is presented in Ref. [6] and redrawn in **Figure 1** as introduction steps for better understanding of the design, build and launch of a satellite system. This chapter focuses on practical design issues for satellite Bus' and mission PL's system/subsystem components builds, and corresponding interface-design's challenges associated with satellite Bus integration, mission PL integration, and satellite system integration. A survey of existing commercial, civilian and military satellite systems revealed that a typical satellite Bus includes the following modular components [7–16]:


**Figure 1.**

*A typical satellite system production flow (redrawn from [6]).*

Frequency (IF) conversion, and Analog-to-Digital/Digital-to-Analog conversion functions—Note that typical HPAs are Traveling Wave Tube Amplifier (TWTA) and Solid State Power Amplifier (SSPA), and some advanced satellite transponders use Linearized TWTA (L-TWTA) or L-SSPA in the RF Back-End Subsystem;


Similarly, our survey also revealed that a typical mission PL consists of the following modular components [7–16]:

*Future Satellite System Architectures and Practical Design Issues: An Overview DOI: http://dx.doi.org/10.5772/intechopen.92308*


In practice, the above satellite Bus modular components can be found in the following typical satellite Busses [7, 11, 14]:


For achieving optimum weight and power, existing satellite Bus and mission PL are tightly coupled together with customized interface design. The industry trends for the design and build of future satellite systems are moving toward OSA using MOSA principles, in which the satellite Bus is loosely coupled with the mission PL

using "Open" and widely accepted interface standards. The key communication linkage between a satellite Bus and a mission PL is the communication data Bus. Currently, majority of satellite Busses employ the standard 1553 data Bus for data communications among Bus components, and between the satellite Bus and mission PL components. The communications over 1553 data Bus is limited to 1 Mega bit per second (Mbps). Recently, there was an advanced development effort that was funded by the U.S DOD to develop new 1553 standards called 1553 Enhanced Bit Rate (EBR–1553) increasing the speed to 10 MB/s [17]. The EBR-1553 requires a star/hub topology to provide the higher data rate and additional components to implement the architecture. For data rates larger than 10 Mbps, space industry trend is moving toward SpaceWire data Bus that was recently developed in Europe for use in commercial satellites and scientific spacecraft [18].

The objective of this chapter is three-fold: (1) Provides an overview of existing modular satellite Bus, mission PL architectures and related communication data Busses, (2) Discusses future trends on the modular and open design and build of satellite Bus and mission payload using MOSA principles, and (3) Addresses the practical design challenges associated with "Modular" and "Open" design for future satellite Bus and mission PL. The chapter is organized as follow: (i) Section 2 describes existing modular satellite Bus and mission PL architectures and related communication data Busses; (ii) Section 3 presents industry view on "Open" and "Close" interfaces for connecting satellite system components and existing popular standards; (iii) Section 4 discusses the interface design challenges and provides an overview of MOSA and related DOD Guidance and assessment tools for MOSA implementation; (iv) Section 5 provides examples how to transition modular satellite Bus and mission PL architectures to modular-and-open architectures using MOSA implementation approach and tools in Section 4; and (v) Section 6 concludes the chapter with remarks on the benefits associated with the proposed approach.
