Something About Environment

TO discuss how spacecraft are designed, we need to know a little bit about the environment in which they operate. The design of just about every machine built by engineers is influenced by its operating environment. For example, the design of an automobile is influenced by a number of factors, such as vehicle robustness, reliability, safety, the minimization of fuel consumption, reducing aerodynamic drag, and so on. These requirements are governed by the environment in which the vehicle will operate, that is, the conditions it will encounter on urban roads and highways. So, as you drive to work you can see the outcome of this environment-driven design process. Given that the design requirements for each vehicle are similar in terms of the encountered conditions, the computerized design process used by auto manufacturers these days results in all the cars (of the same vintage) looking similar to one another, apart from minor cosmetic tweaks!

As the environmental aspects become more dominant, such as in the case of an airplane, it becomes even more difficult to distinguish manufacturers, with only the connoisseurs being able to tell an Airbus from a Boeing.

In spacecraft, we have already seen in Chapter 5 how the flight environment of the launcher influences the spacecraft's design. In this case, the launch environment, which entails high levels of acceleration, vibration, and noise, governs how the spacecraft structure is designed. The designer has to ensure that the spacecraft survives the few minutes' ride from launch pad to orbit (we will return to this issue again in Chapter 9).

From the above discussion, it is easy to see that once the spacecraft has reached orbit, the natural space environment it finds there will also influence the spacecraft's design, and the designers need to know about this environment and take it into account as the design evolves. The characteristics of the space environment have been investigated by space scientists over many decades, and this information has been grasped enthusiastically by the engineers, thus enhancing the performance of spacecraft in the space environment. This environment has many different aspects, but the ones most influential in spacecraft design are microgravity

G. Swinerd, How Spacecraft Fly: Spaceflight Without Formulae, DOI: 10.1007/978-0-387-76572-3_6, © Praxis Publishing, Ltd. 2008

(or weightlessness), vacuum, radiation, and space debris. This chapter briefly discusses each of these from the point of view of both the scientist and the engineer. The former is driven by curiosity to know the nature of what's out there, whereas the latter is interested in understanding the impact the environment has on the design of the spacecraft.

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