Changes

===Retirement===

Over the past few decades, with ever-increasing orbital launches, “space debris” has become a critical issue. We may choose to either retire before its mission life in case of onboard malfunction or extend the mission life based on the system performance towards the end of its stipulated mission life. It may either be automatic or telecommand based. There are various international regulations in place in order to manage and reduce the space debris. Many satellites have dedicated infrastructure onboard for deorbiting.

==Vee - Model==

All of the major phases of the life cycle model are often visualized with a graphical ‘Vee’ (or V) model representation of the processes and stages of a program development (See figure). Although there might be overlapping stages & processes within the different phases of the system life cycle model, the sequence of processes depicted in the graphical ‘Vee’ model are designed to provide a structured framework for completing the design and verification of a system.

As depicted, the phases begin from the upper left section, and subsequently are worked downward to the center, and then upward again onto the upper right side. <br/>

The initial phases of the life cycle model, as mentioned earlier, capture the system-wide requirements, various elements of the system, as well as concepts for realising the system.<br/>