Ok so the first chest I found was at the jumping puzzle with the hive tombships. So once your fireteam gets close to the end of it the chest is close. It is at the part where you have two people stand on the two pads that deactivate the portal shield in the middle. You can see the door you need to get to if you look straight across where you are supposed to go and look to the left about halfway over and halfway up. That is the door you need to go through. So all you need to do is have two people stand back and wait around. The other four fireteam members run and jump on the hive tombship that goes straight across. Once you are getting close to the wall you are going to jump to the left and make it all the way to the wall. There is a tiny ledge that you will land on and you are gonna take that up until you reach the door. Then the two remaining guardians will step on the pads and that will open the door to get the chest. Make sure they stay off the pads until then bc if you stay on it too long with them on the pads you will go through the door and the ship disappears and you will land on the finishing side. If that happens you will not be able to get the chest. We had it happen to one of our fireteam members. He had to go to orbit and come back to get it and it spawns you at the very beginning of the jumping puzzle so you don't want that to happen so have them stay off the pads until you four are at the door. Once in you will see the chest directly ahead. I don't think this is the exotic chest. We got smoldering shards and antiquated runes (the tier 3 for court of oryx I'm not sure if I spelled that right). So then the 4 guardians that got the chest will jump down to the finishing side and you will activate the pads on the finishing side so the two remaining team members may get the chest. I don't think it's on a timer so you are fine to take your time if need be.