There had to be hundreds or thousands of planets to chose from. What was the cover story behind colonizing LV 426? We know the Weyland-Yutani Corporation was interested in the Xenomorph on LV 426, but the colonists didn't. The colonists went there for a different reason. Do they ever state in any part of the franchise what made LV 426 a prime candidate for terraforming?
It was Weyland Yutani that set up the colony not a group of independent colonists. This is quite obvious in the 'special edition' of Aliens where additional scenes are added showing the colony and it's Weyland Yutani branding.
Take note of this event during the Alien movie:
Accessing the ship's computer, Ripley discovers that Ash has been ordered to return the Alien to the Nostromo's corporate employers even at the expense of the crew's lives.
Weyland Yutani is shown to be a pretty evil corporation which was a common movie theme back in the late seventies and eighties therefore we can only assume that an unnamed someone at Weyland Yutani chose LV426 after the Nostromo dissapeared there in order to find out what happened.
Note: I have not seen Prometheus yet, in which some of these questions may be addressed.
It would make some sense that the extraterrestrial spacecraft with the space jockey (the chestbursted pilot) and the xenomorphs, which is shown at the beginning of Alien and Aliens, crashed on LV 426 not by coincidence but because at some point in the past, there existed life on this planet (all obvious traces of which are gone by now), e.g.:
- The Space Jockeys had a base on LV 426 and the spacecraft was on its way there when being infected by aliens and thus crashed.
- The Space Jockeys were in war with the inhabitants of LV 426 and the spacecraft was damaged during an attack and crashlanded. (I faintly remember to have read about crashed spacecraft being a bomber with the alien eggs being the bombs.)
Either way, this would explain that LV 426 to has somewhat life-friendly conditions and thus why it is a preferred candidate for colonisation without requiring a coincidence or Weyland–Yutani’s interest in the xenomorphs.
The Company was unaware of the events that took place during Alien. The existence of the colony on the LV-426 was entirely a coincidence. Going from the theatrical release of Alien and the Special Edition of Aliens, we may determine the following:
No Communication between the Nostromo and Earth
None of the events of Alien require any communication with anyone outside the ship. The characters explain to each other in the beginning that the computer has standing orders to wake the crew "should certain conditions arise"- in this case, the detection of a transmission indicating possible intelligent origin. The ship's order to sacrifice the crew in the name of specimen collection could have been installed at the same time the Company programmed it to wake up the crew to investigate.
Additionally, there are no signs of FTL communication existing on the Nostromo, even when it would be logical to use it. The crew attempts to contact Antarctica traffic control when they wake up but they immediately give up once they realize they're 39 light years from Earth (Zeta 2 Reticuli). No one attempts to directly contact Earth at this point, nor again later when the alien is brought on board, nor when they are attempting to kill it and not even when they learn that the ship's computer has been conspiring with Ash to get everyone killed.
The Aliens Remain Undiscovered and Unknown 57 Years Later
In Aliens, after the inquest, Ripley confronts Van Leuwen and asks him to go check out LV-426.... and he responds "I don't have to. There have been colonists there for over 20 years and they never complained about any hostile organism."
If the Company was aware of the alien organism on LV-426, why didn't they go gather a specimen 57 years earlier, after the events of Alien? Why spend trillions? quadrillions? and decades terraforming the planet and filling it with witnesses when you could just go gather some eggs in the first place? If they built the colony near the alien spaceship to facilitate discovery, why didn't discovery happen until after Ripley returns and tells everyone about the ship?
Their Discovery is Directly Caused By Things Ripley Says and Does
There is direct causation between Ripley's return and the colonists being exposed to the aliens. Ripley tells Carter Burke about the events that took place during the Alien film. Burke sends a memo instructing company employees to go investigate the grid reference with the alien ship after Ripley's inquest. Immediately after the inquest scene, two company employees discuss how a "mom and pop survey team was sent out there on company orders." Immediately after, we see the survey team discover the alien ship and become infected. Later, there is a scene where Ripley discovers Burke's orders to investigate the alien ship. Burke found out about the Aliens from Ripley and told the colonists to go find them. If not for that, the colonists could have continued for some time without encountering the aliens.
- the events of Alien were known only to Ripley until she shared that information with other people 57 years later
- the aliens remain undiscovered until Ripley tells people about them
- the Company behaves in a way that is inconsistent with it being aware of the events of Alien until Ripley returns
- the colony was founded decades after the events of Alien but decades before the events of Aliens
- the colonists surveyed the planet for over 20 years without finding the giant alien ship full of eggs... until someone told them where to find it
Which means the Company did NOT select LV-426 because the alien ship was there. They just selected it because they're in the terraforming business.