The pirates are also humans. This is set like, way in the future where like, mars and some moons and asteroids have been colonized, but they are already filling up and are horribly ineffective and expensive, because they just can't sustain human life. So, the government ship's task is to go to the alien world, get it ready for human habitation by transplanting earth plants there for oxygen(since they don't know that there is ANY life there, they think it's just as barren as mars but with a better atmosphere and oceans). And so what the government did was send out a probe ot the planet to see if it could sustain human life, found it could, and sent a huge ship filled with people to start colonizing. But the pirates followed the first probe, thinking that they could strip it for parts and sell it, and found the planet.

And yeah, she wouldn't have to be a scientist. Maybe like the daughter of a scientist and a powerful politician who sends the daughter on board the ship so she can be one of the first landing and thus have the opportunity to get a big stake of land for their future.

And yeah, eventually, the aliens will join together with the humans to kill the pirates.

The human ship should have somewhere from 300-500 people on it, initially, but in the crash landing, half that number perishes, and more die both from run-ins with the pirates, alien animals, and the Eiasians.