Spacecraft design

The design of spacecraft covers a broad area, including the design of both robotic spacecraft (satellites and planetary probes), and spacecraft for human spaceflight (spaceships and space stations). The design of spacecraft is somewhat related to the design of rockets and missiles.

Spacecraft design brings together aspects of various disciplines, namely:

• Astronautics for mission design and derivation of the design requirements,
• Systems engineering for maintaining the design baseline and derivation of subsystem requirements, said subsystems listed below:
• Communications engineering for the design of the Telemetry, Tracking, and Command (TTC) subsystem, which uses technologies and techniques of terrestrial radio and digital communications to communicate with the ground, and to perform Ranging.
• Computer engineering for the design of the On-Board Data Handling (OBDH) subsystem, which includes on-board computers and computer buses. This subsystem is mainly based on terrestrial technologies, but unlike most terrestrial applications, it must cope with space environment, be highly autonomous and provide higher fault-tolerance:
  • It may incorporate space qualified radiation-hardened components.
  • It may use techniques to further improve fault-tolerance, such as use of watchdog timers.
• Software engineering for the on-board software which runs all the on-board applications, as well as low-level control software. This subsystem is very similar to terrestrial real-time and embedded software designs,
• Electrical engineering for the design of the power subsystem, which generates, stores and distributes the electrical power to all the on-board equipments,
• Control theory for the design of the Attitude and Orbit Control (AOCS) subsystem, which points the spacecraft correctly, and maintains or changes the orbit according to the mission profile; Although the techniques in AOCS design are common with terrestrial methods, the hardware used for actuation and sensing in space is usually very specific to spacecraft,
• Thermal engineering for the design of the thermal control subsystem, which maintains environmental conditions compatible with operations of the spacecraft equipments; This subsystem has very space-specific technologies, since in space, radiation and conduction usually dominate as thermal effects, by opposition with Earth where convection is typically the main one,
• Propulsion engineering for the design of the propulsion subsystem, which provides means of transporting the spacecraft from one orbit to another. This is the only technology which is really specific to spacecraft design. Popular culture has made a cliché of spacecraft propulsion engineers, as embodied by the term rocket science,
• Mechanical engineering for the design of the spacecraft structures and mechanisms. These include beams, panels, and deployable appendages or separation devices (to separate from the launch vehicle).

Origin

Spacecraft design was born as a discipline in the 50s and 60s with the advent of American and Russian space exploration programs. Since then it has progressed, although typically less than comparable terrestrial technologies. This is for a large part due to the challenging space environment, but also to the lack of basic R&D, and to other cultural factors within the design community. On the other hand, another reason for slow space travel application design is the high energy cost, and low efficiency, for achieving orbit. This cost might be seen as too high a "start-up-cost."

Indeed the shallow view is that we have been to the Moon, we have space stations, we have workable planetary orbital space craft, and we can get to Mars if someone put up the funding. What seems to be needed next is an efficient way to achieve orbit.

References

• Wertz, James R. (1999). Space Mission Analysis and Design (3rd Ed. ed.). Kluwer Academic Publishers. ISBN 1-881883-10-8. {{cite book}}: |edition= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)