For a terraforming campaign I would really recommend what @penpenpen suggests: A pre-existing device of extreme complexity (a McGuffin Brand Terraformer!). When discovered, it may even be partially functional, creating a small bubble of environment that is perfectly calibrated to raise the weird spice spiders, or something similarly valuable. The device needs more energy and [arbitrary common resource (water?)] to function on a larger scale. The challenges the PCs face would include securing generators, water imports, valuables export, repairing pieces of the device, if the device is force-powered (like the Star Forge) they have to deal with random Inquisitors, etc. Before the device is functional you can easily add [arbitrary space-wolves (not Tony)] or other creatures to force the players to deal with them.
On a side note, if you decided to run this as a Play-by-Post somewhere, I would be down to play the Explorer or Doctor.
Maybe something like a scaled down opposite version of these things: