Hades XVII

Hades XVII was a spaceship destined to land on the moon. Its goal was to collect knowledge of the different minelars and how they could be used to fulfill certain needs on earth. However, Hades didn't make it to the moon, as communications were suddenly lost and it disappeared. Days passed and Nasa scoured the region, but Hades was nwhere to be found, not even a trace of it. Nasa even suspected it was destroyed by Russia or Chuna, a claim that didn't make it to the public as there weren't enough elements to support something like this.
In truth, the aliens had captured the spaceship and examined the astronauts on their spaceships, called ziggurats. The crew of the spaceship provided very important information about the human body and structure, knowledge that was important to the aliens in order to attack.
Moreover, a member of the crew ( Scott Matthews ) of Hades XVII joined the aliens and served as their emissary to the humans. He was the one to address to the humans all over the world and instruct them to surrender. He was killed when the humans al over the globe refused to surrender, forcing the aliens to attack and leech the majority of the population by force.