[jakkals]

Am I the only one who got confused by the first sentence? "The Dragon spacecraft is on its way to the International Space Station this morning and is performing nominally...".

Is everything fine now, or is it not? "Nominally" in this sense to me means that something is amiss, but reading the rest of the article seems to imply that everything is on track.

[frabcus]

It seems to have a special space meaning:

"Aerospace & Engineering. According to plan or design: a nominal flight check."

http://www.thefreedictionary.com/nominally

[russell]

Having listened to 5 decades of rocket launches, I would say that nominal means that it is working within mission parameters. There may be glitches, but it is going to work, i.e. the payload is going into orbit. The engine failure wasnt planned, but there was enough redundancy in the system for it to succeed.

[jakkals]

Ah. That explains it. I did not know that meaning of the word, and the explanation I checked at: http://dictionary.reference.com/browse/nominal only showed the meanings that I was familiar with.

Live and learn, I guess. Thanks frabcus!

[saraid216]

I'm getting the sense that it's used because "numbers != reality", so it's a subtle reminder that they're basing their call on sensor data, rather than actually having their head inside the engine.

I find that to be a sufficient explanation, though I'm just guessing.

[thezilch]

Wikipedia has a better explanation than I or others' comments, so far, could provide: http://en.wikipedia.org/wiki/Real_versus_nominal_value, and it 's "secondary" meaning is not, at all, limited to aerospace linguistics.

[CUViper]

I'm not sure where you get that sense of the word. Nominal = according to plan.

[dtparr]

I see this confusion fairly often. Outside of the status of systems/missions etc., nominally often means something like 'in name only'. So to say it's proceeding 'nominally' to someone not familiar with its meaning in this domain sounds like "well, it's going according to 'plan', but ..."

[jakkals]

Hm. I have never heard that meaning of the word previously, and the link I previously provided (http://dictionary.reference.com/browse/nominal) also did not show that specific meaning (unless I am too blind to see it!). I do find it interesting though that you seem to think that it is commonly used in this sense, so I guess I am not moving in the right technical (aeronautics) circles :-) Thanks for the feedback.

[arrrg]

Here’s the Oxford English Dictionary (funny how words work – I know of all five those meanings of nominal, but when I hear it I first think of the fifth, while you first seem to think of the first three):

nominal |ˈnɒmɪn(ə)l|

adjective

1 (of a role or status) existing in name only: Thailand retained nominal independence under Japanese military occupation.

• relating to or consisting of names.

2 (of a price or charge) very small; far below the real value or cost: they charge a nominal fee for the service.

3 (of a quantity or dimension) stated or expressed but not necessarily corresponding exactly to the real value: EU legislation allowed variation around the nominal weight (that printed on each packet).

• Economics expressed in terms of current prices or figures, without making allowance for changes over time: the nominal exchange rate.

4 Grammar relating to or functioning as a noun: a nominal group.

5 informal (chiefly in the context of space travel) functioning normally or acceptably.

[waterlesscloud]

It's common enough for space launches that there was joking on twitter last night about playing a drinking game- take a drink every time someone said "nominal". But most people decided that might be a little too much alcohol even for a drinking game. :-)

[stcredzero]

Try the Bill and Ted's Excellent Adventure drinking game. There's only a few rules, like "Excellent" and air-guitar.

[CUViper]

Heh, no aerospace background for me, merely computer engineering. Maybe that's still close enough for the term to have crept around with that meaning. Now go forth and help spread this usage far and wide! ;)

[Sharlin]

"Nominal" is the favorite word of aerospace engineers. Both in the sense that they like to use it a lot, and in the sense that they very much like to hear that things are going according to the plan.

[bronson]

Unless reaching orbit with 8 engines was in the plan, I don't think your use of the term matches SpaceX's.

[CUViper]

It may not be following the optimal path, but it is absolutely within the planned contingencies: "Falcon 9 is designed to handle an engine out situation and still complete its mission."