Every ship has a 'Discovery Scanner' by default. To use it first make sure it's mapped to a Fire group and you'll also need to go into your controls and map a button for your new HUD mode.
Go to: Options - Controls - Mode Switches - down to 'Switch HUD Mode' - there's probably no button that isn't already mapped for you, but I just swapped it for
+
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Now when you enter a system you can switch to 'Analysis Mode' and hit the Discovery Scanner like normal. Although the scanner has infinite range it will only fully scan stars, you'll require the further use of a 'Full Spectrum System Scanner' for planets, moons, belts and rings, however you don't need that for this achievement- just find a system that only contains stars scan it and the achievement will unlock.