Head to the Cryo Bay and talk to a man named Nigel McCoy, who has patiently been waiting for you since damn near the beginning of the game. His brother was an early colonist of Eos, and based on what you saw down there, it’s no surprise he didn’t make it. Obviously there’s nothing you can do to bring his brother back, but you can bring him some solace by reuniting a family heirloom on Eos. This starts the quest "Task - Lost Brother".
Travel back to Eos, and once on land, fast travel to Site 1’s Forward Station. From there drive the Nomad west, then south out of the failed settlement, past the water treatment rings, and up a steep slope to the northwest. Once atop the slope walk or drive to the northeast, then east, following the edge of the cliffs that surround Site 1 until you find the indicated site where you can place the pendant. This will earn you a bit of XP and end the quest. Easy-peasy.