In the film's [official novelisation][1], the plateau (where the Space Jockey ship was found) was also discussed. Ripley's plan was to 'glass' the colony *and* the ship.

> *I say we take off and nuke the entire site from orbit **and the whole
> high plateau where we originally found the ship that brought them
> here.** It’s the only way to be sure.*

> <sub><sup>[Aliens: Official Novelisation][1]</sub></sup>

In the film, this bit of the conversation appears to have happened off-screen. 


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That being said, I think we can assume that the catastrophic destruction of Hadley's Hope was also enough to take out the ship **since the Company had to rely on harvesting Ripley's DNA (from the Fury facility) in order to get a viable sample of xenomorph DNA.** 


  [1]: https://avp.fandom.com/wiki/Aliens_(novel)