Engineering is historically divided into a number of specialties because of the large amount of knowledge it contains in total, and the different areas of application of that knowledge. Many of those specialties are still relevant when you change the location from Earth to space. One in particular, Aerospace Engineering, is concerned with vehicles and hardware that travel to and operate in space, but a typical design for a space project will require support of the other specialties. Although there are specialties, they rest on a common foundation of the sciences and mathematics, therefore there is overlap between them. For example, both aerospace vehicle structures and building structures analyze stress loads in the same way, but differ in the materials used and where the loads come from.
We will not go into great detail in the following list of specialty areas, but a space systems designer, whether generalist or specialist, should at least know what areas exist besides their own. They can then find detailed information on a topic or specialists as needed, when it is beyond their own area of knowledge. For those who want to learn more about a particular area, one place to start is the MIT Open Courseware website, which has an increasingly large collection of college level open source course material available (2100 so far). Additional information can be found through the links here or in the References Section at the end of this book.
This is the field concerned with the design of systems which operate in the atmosphere and space. It is further divided into Aeronautical Engineering and Space Systems Engineering, the latter being the primary subject of this book. Astrophysical or Planetary Engineering involves manipulating entire natural bodies, such as Terraforming, making a body more Earthlike, changing the orbit of an asteroid, or the unplanned 120 parts per million increase in CO2 in the Earth's atmosphere. Astrophysical Engineering is as yet mostly theoretical and not organized as a distinct specialty. Among the areas of interest in aerospace engineering are the following:
In physics and engineering, this is the evolution of physical processes with time. Within aerospace engineering these particular areas of dynamics are important:
- Aerodynamics - This uses knowledge of fluid and gas dynamics as applied to the interactions of atmospheres with primarily solid objects such as vehicles.
- Astrodynamics - Also known as Orbital Mechanics, this is the application of ballistics and celestial mechanics to practical problems.
Structures and MechanismsEdit
This topic is how the load bearing and mechanical parts of an aerospace system are designed.
- Materials Science - This is the relationship between the structure of materials at atomic scale and their larger scale properties, and the selection of materials for particular applications
- Solid Mechanics - This is the behavior of continuous solid matter under external actions such as forces, temperature changes, or applied movements.
Power and Electrical SystemsEdit
This area is concerned with the supply of power and electrical systems such as heaters and motors with respect to aerospace systems in particular. It overlaps with Electrical Engineering, which is the more general subject.
This is the area involving devices for moving artificial carriers of people or goods over any distance. With respect to air and space vehicles these tend to be self-contained. In this book the various types of propulsion are generalized to include non-device methods such as gravity assist maneuvers, under the heading Transport Methods.
Thermal Control SystemsEdit
The air and space environment, and the operation of internal systems, can generate wide variations of temperature. Thermal control systems have the function of keeping all parts of an operating system within acceptable temperature ranges. This includes passive methods such as insulation, and active methods such as radiator panels.
When an air or space system is operating, these are the parts which make it behave in desired ways. It includes sensors and instruments to detect the current status, devices to transmit, store, and process the data thus generated, methods to generate the appropriate response, and to transmit commands to other parts of the system to change their operation. Typically control systems operate in a Closed Loop fashion. This is where a cycle of detecting status, processing data, issuing commands, and then detecting the new status repeats multiple times. Human in the Loop control systems include humans as part of their operation. For example, airplane pilots use their eyes, brains, and hands as part of the control loop. Control systems can include the following elements:
- Ground Software
- Data and Communications Hardware
- Flight Software
- Sensors and Instruments
- Artificial Intelligence and Autonomous Operation
- Trained Operators
With respect to space systems in particular, the environment has significantly different conditions than found on Earth. The space environment includes all external factors that can affect a system - such as lack of atmosphere, gravity, and wide temperature fluctuations, among others. The following are particular hazards to humans and space hardware:
- Meteoroid and Debris - Natural and artificial objects that, due to their high relative velocity, can cause damage on impact.
- Radiation - Particles of high enough energy to damage people and equipment. On the Earth's surface we are sheltered by the magnetic field and atmosphere from the naturally high radiation levels that exist most other places in the Universe.
Life Support SystemsEdit
This is the area involving meeting the needs of humans and other living things when they are present in an aerospace system.
Life support keeps humans alive. Human factors considers people as a functioning element of a system. That includes how to design control inputs and information displays, maintaining crew training on a long mission.
Simulation and TestEdit
Aerospace systems are often complex, and the conditions in which they operate are different than those normally found on the Earth's surface. Thus one distinct area has developed to simulate the conditions, and how the system will function within them, electronically before building hardware. Another distinct area is to test physical components, models, and materials in the proper conditions, and Flight Test, which is testing the entire system to see if it operates properly. For very large and complex systems, such as the International Space Station, there was no way to test it as a whole. Therefore testing it's parts on the ground, extensive analysis, and the ability to repair or update ones that needed improvement has to suffice.
Other Engineering SpecialtiesEdit
The following are the major conventional divisions of the engineering field into specialties. Knowledge in general does not have such divisions, they are made by humans for historical and teaching purposes. A given engineer may have knowledge and work that spans across multiple specialties or is concentrated in a narrow area within only one.
Bioengineering applies knowledge from the biological sciences towards satisfying human needs. This includes producing food, materials, and energy, and maintaining human health and the natural environment.
This is the subset of bioengineering concerned primarily with food and material products produced on land. As a human activity it extends back to the origin of civilization. As one based on scientific knowledge that is a relatively recent development.