Insignificantly small; a matter of form. "For a nominal fee." Except when it comes to NASA which, being engineers, they made up their own meaning for the word, which seems to be "normal", but they don't want to say a flight is normal because then they'd have to say "not normal" when some fudge didn't work, for which they have some other terms to obfuscate their boo-boos. My guess, YMMV.

Nominal means one thing to most dictionaries. However, if you're a space nut, it may mean something completely different to you. The Webster 1913 definition of 'in name only' to mean 'small' may be the root of this; then again, it may not. Generally, if you listen to NASA personnel (from controllers to commentators to astronauts) describe the status of something, you'll hear 'nominal' used to mean 'everything is OK.'

There are a few theories of why this is so. One theory holds that the word 'normal' has several meanings, including 'perpendicular to' - and that this would be confusing to use. "Flight is normal" could then mean "Uh, we're traveling 90 degrees off course." Another theory, one subscribed to by members of the Spaceflight Now forums, is that 'nominal' just...sounds cooler than 'normal.' I mean, 'normal' is what you do every day, right? And launching spacecraft is just too darn cool to use words which mean 'everyday.'

Of course, the root definition may be to blame here. Another hypothesis (one I subscribe to) is that it's shorthand for 'nominal variation from expected parameters' or some similar phrase. After all, many of the activities being described - launches, especially - were experiments, or first uses of systems, so calling anything 'normal' is misleading as those things had never been done before. There was no 'normal.' There was, however, 'expected values' or 'expected behavior' - so a 'nominal' status as shorthand for 'not varying much from expected range' would thus be a good thing.

How long has it been in use? It's hard to say, but user Ed Kyle from the NASA Spaceflight forums dug up a NASA Launch Vehicle Handbook from 1961 which uses the term liberally, and a 1954 report from NACA (NASA's predecessor) which used it. The first line of the first page of the former with real text, page 5, states when describing the Scout launch vehicle: "For nominal flights, the pitch gyro of the Scout will be torqued at rates which will produce a zero lift..." Interestingly, that same page uses the word in the Webster fashion when it states that '...although such maneuvers do seem feasible with only nominal changes to the guidance system."

Perhaps the only thing that really matters is the dictionary - and in dictionaries from the past ten or fifteen years, the NASA usage can be found in the definition for 'nominal' even if it's the fourth or fifth use in the entry. Even Russian translators for spaceflight broadcasts tend to translate Russian 'normal' and equivalent Russian terms as 'nominal' for English listeners.

So I guess it's official.

Nom"i*nal (?), a. [L. nominalis, fr. nomen, nominis, name. See Name.]


Of or pertaining to a name or names; having to do with the literal meaning of a word; verbal; as, a nominal definition.

Bp. Pearson.


Existing in name only; not real; as, a nominal difference.

"Nominal attendance on lectures."



© Webster 1913.

Nom"i*nal, n.


A nominalist.



2. Gram.

A verb formed from a noun.


A name; an appellation.

A is the nominal of the sixth note in the natural diatonic scale. Moore (Encyc. of Music. )


© Webster 1913.

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