They can detect cache (chests) around you in a 30m range on specific planets, increase your glimmer gain, or generate gunsmith telemetry data (reputation items you can turn in to the gunsmith) (dulfy.net)
We'll need the maximum chance for success before committing resources to specific planets once we get into the business of trying to identify biomarkers on possibly habitable worlds. (centauri-dreams.org)
Once you have unlocked the Milestone, it'll give you an additional high level reward for completing a number of Public Events on a specific planet for that week. (eurogamer.net)