ABANDONED. Sci-fi big spaceship sent to hunt dangerous aliens about 5 years after first contact

[Toby]

I saw it in a bookshop today in Sydney and read the back. Red cover with a picture of an astronaut in liquid. The letters of the title and author name also floating in the liquid. Title is a single word with an O in it (not the first letter)

Humans encounter aliens for the first time but discover they are threatening, so they build a big spaceship to hunt them down. It's 4 or perhaps 7 years after first contact that the ship is launched. At some point the ship loses contact with earth.

[Mary]

Do you think it's an Australian publication? Or some other country?

[Kris]

No response, moving to Abandoned folder.

Toby (OP) was last active on the site in September 2020.