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I've read in the biology book the following sentence:

In the 1970s,Viking space probes may have picked up some microbes that emitted CO2."

I'm not sure if this sentence is grammatically correct because the word probes should be in the past simple tense rather than in present simple tense. Am I right or it's grammatically correct?

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When I read the question title, I thought it would be about how the Vikings could have had space probes. – Mr Lister Feb 28 at 9:52
And you had to ask a question before spending 1 second googling define:probe. SO: Space probes are the opposite of anal probes which are used by aliens and not vikings. – CodeAngry Feb 28 at 15:00
Seriously now, your question should read "Am I right or is it grammatically correct?" – Mr Lister Feb 28 at 16:37
It makes me think of another word, scout, that is used for both "what he is" and "what he does". A probe (noun) is something that probes (verb). The plural noun looks like the present-tense verb. And the singular noun looks like the infinitive verb. Personally, I think the opposite use of -s helps disambiguate, helping to take apart complex sentences more quickly. – JDługosz Feb 29 at 3:52

Your example is using probes as a noun.

A probe is a scientific instrument for analysis and measurement, e.g. a surgical probe.

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To clarify: probes can also be a verb, but it is not in this case. – RBarryYoung Feb 29 at 0:51
Should your "i.e." be an "e.g."? :) – Martin Ender Feb 29 at 10:32
@MartinBüttner Yes, it should - "surgical probe" is an example, it's not another way of saying "A probe is a scientific instrument for analysis and measurement". – Anthony Grist Feb 29 at 11:18
I think "probe" is not only an instrument, but also a sample you get for some examination (e.g. "tissue probe") – Alissa Feb 29 at 13:55
I think it's generally thought that a probe is the instrument that gets you a sample, specimen, or observation – Peter Feb 29 at 14:08
up vote 5 down vote accepted

I found the answer on Wikipedia -here

There is a scientific instrument which called space probe - is a robotic spacecraft that leaves Earth orbit and explores space". (wiki)

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