At least, that was as far as could be told. It's thin atmosphere was mostly carbon dioxide and methane, but those could easily be converted to oxygen and water. This enabled them to establish a small research station on the surface for observing, close up, the idiosyncracies of the stars and planets in the system.
Over the years, occasional sightings of large bugs were noted, but they were assumed to be non-sapient. The sightings became more frequent and closer to the station.
In addition, seismic activity was noted. Nothing severe, and the station was not there to do seismic research.
Then came the day of doom. Ground breaches occurred all around the station, and within the compound itself. Bugs poured out, attacking and killing any living thing that they encountered.
The staff retreated to the main barracks, but not before half of their inhabitants had been torn limb from limb. The objective of the bugs was clear -- annihilation.
They had managed to get out a distress call, before the communications hut was overrun. Now the bugs were searching every inch of the outside of the barracks to seek entry.
The rescue ship arrived and had to fire blast a landing spot as close to the barracks as they could. Troopers emerges and slowly opened a corridor to the barracks.
There were heavy losses of both troopers and remaining researchers, as the bugs just kept coming. They finally managed to get a handful of the researchers into the ship, which took off, abandoning the troopers who remained.
Stargazer was among the handful. He nearly suffered a cardiac arrest from loss of blood on the way out, but the medics were able to save him with artificial blood and adrenalin.
But what he saw in those few hours, watching friends and co-workers being torn limb from limb, he never wants to see again. It haunts his sleep.