The mysterious 4th astronaut

In the year 3021 three astronauts were sent in the safest and most luxurious space craft to the destination of mars to collect and sell some mars minerals.
They had to train for years and get the highest quality space suits to get to this point and perfect teamwork.
The suits were made out of gold and silver and was extremely thin with a dome like mask and added jet packs, and the space ship contained a bathroom, a living room, a dining area, a kitchen and 3 beds for the team. 
the take off was simple and smooth as it had ufo like properties as it defied gravity and its speed was of the light, the astronauts thought that this technology was stolen from alien spacecraft but they remained silent in fear that they would be punished for saying such things.
as the others were eating the driver noticed that there was more weight then the result of 3 astronauts that confused and surprised him so he asked the others to search the entire ship.
However they could not find another passenger, they went to the speed of light and stopped directly over mars and landed safely.
then they were ordered to dig up the rocky ground of mars so they grabbed their drills and began to dig and took pictures to show NASA near the spacecraft NASA noticed a fourth astronaut from one of the pictures but he was larger then the average human its size reached 14 feet tall.
They deleted the picture to prevent the public from investigating it and they kept ordering the tired astronauts to keep digging.
As they got several different ores they decided to get back to the surface and fly back to earth, but as they were in the mines of mars that they fabricated they heard footsteps as if a fourth member was following them.
the radio did not respond to them anymore as it was cut off and they just kept walking without looking back.
they arrived on the surface and one of them fell on the ground which resulted in a broken helmet but unfortunately nobody heard him scream and he died without notice as his body was dragged into the mines.
the second astronaut took a picture for himself and saw two more astronauts in the picture which frightened him so he ran to the ship and warned the other to join him.
The last astronauts entered the space craft but somehow they were locked in and this was when they tried to fix the communication system but nothing seemed to work so one of them decided to rest on his bed and as he was drifting to sleep, a large thin white alien with grey and black reptilian eyes appeared before him its tail seemed sharp and its fingers and toes were long.
the astronaut screamed and then silence followed both the alien and the body vanished without a trace the first astronaut was now alone thinking about his next move, three of the white aliens jumped around the astronaut and the communications were fixed Nasa recorded these messages.
Astronaut 1: WHAT DO YOU WANT FROM US!
Largest Alien: we need the human soul to create children as we are going extinct 
Astronaut 1: No please there must be another way?
Largest Alien: I am afraid not, but I will promise this you will be the last killed
Then a loud slashing sound is heard until the audio gets cut off again.
This audio was leaked online from alien enthusiasts and the astronauts were reported dead until they were seen again parading through new york as if nothing happened but these fools never looked what lied under these astronaut suits so they are among us.