An astromech droid, sometimes shortened to just an astromech and also referred to as an astro droid, was a type of droid that served as an automated mechanic, performing a variety of repair duties and often serving as an adjunct or substitute for a nav computer on smaller starships. Astromech droids could also use the mainframes of larger ships to their advantage. Many starfighters relied on astromech copilots.
- "You stupid little astro droid!"
- ―A super battle droid to R2-D2, moments before being incinerated
An astromech droid's primary purpose on a smaller ship such as a starfighter was as a backup or replacement for a nav computer; however, due to the limitations of each unit's astrogation buffer, an astromech could only hold a set number of hyperspace coordinates. The droid also provided in-flight maintenance and repair, and performed a number of routine functions so the pilot could focus on flying the ship.
Larger starships usually carried a large complement of these droids in case of malfunctions or combat damage, while some snubfighters (notably the T-65 X-wing starfighter and Naboo N-1 starfighter) carried a droid in a special port for in-flight field repairs. Astromech droids had, in some cases, also been known to carry out light janitorial duties, and several instances of slicing carried out by these droids have been known, though this often required the installation of special programming.
Most astromechs were only able to communicate in writing, conveyed via another computer system, or through binary, a special code of clicks, bleeps, and similar sounds. Some craft that used astromechs could be equipped with astromech translators to facilitate communication.
The term "astromech droid" had been used informally by spacers since around the time of the Jedi Civil War at least, to refer to the Utility droids that performed similar tasks during that era. It was not until some decades before the beginning of the Clone Wars, when the company Industrial Automaton started launching its highly successful lines of astromech droids, that the term caught on and started to become synonymous with its models, most notably the R-series of astromech droids, ranging from the R1-series to the R9-series.
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