system
Given the following post, respond as if you're commenting on Reddit:
human
[Aliens] Why would a rescue crew take so long to help out the Sulaco?

As stated by Hicks, the Sulaco won't receive a rescue until 17 days *after* they're declared overdue. But how long is it until they're actually delcared overdue? Why such a lengthy amount of time?  

Also, why would they leave literally no one on the Sulaco? If just one person had stayed on the Sulaco there wouldn't have been any issue getting the second drop ship down for a quick rescue.
gpt
Simple answer is that humanity haven't developed the technology for faster than light travel. It takes weeks if not months to travel between worlds. This is why the colonial marines were put in stasis during the trip to LV-426. 

The reason why they wait so long before sending a rescue team is because again due to the distance radio contact is sketchy at best. It costs money and resources and the company wants to be damn sure something happened before they send out a ship and a team. Remember that they get paid extra while deployed. 

The reason why they didn't leave anyone on board is because they relied too heavily on automated systems to keep the ship running. So many levels of backups and checks were put in place so that a heavy ship like the sulaco could still function due to a skeleton crew and have said crew deployed to the surface. They didn't have to worry about aliens or pirates hijacking the ship because the ship would be useless to them without the proper codes.