You can edit your posts, you don't have to double-post.
You probably won't need to create different sprites, you'll just have to come up with colouring generic enough to work for all of them. You could, perhaps, apply some palette swaps or a colour overlay though, to help ground the character colour-wise in the various settings.
You're right that on a planet surface, there will be scattering and thus softer shadows. Even if the atmosphere is thin or otherwise nothing like Earth's, the dust, and just light reflecting from the surface of the planet will serve to soften the shadows. Interiors often aren't that different from exteriors, aside from colours. Both typically have a dominant light source direction (e.g. from above) and perhaps some secondary light sources (bounce light from the ground/floor, maybe some extra lights in the environment). It would not be difficult to create shadows that work for all of these, by e.g. having a sprite lit from above. Since it doesn't look like your character will be doing any space-walks, you probably don't need to worry about having a stark shadow version.
The hard part will likely be, as it often is, making sure the character's colours feel like the character is in the setting that's around them, when you have a lot of different locations. With a white-ish suit, which is likely to reflect environmental colours, this may be tough. You can simplify things by giving all your environments the same dominant light colour. With clever design, this need not result in samey environments, as you can use different accent colours and different shapes to create different visual identities for each location. Alternatively, you can use palette swaps or colour overlays to make the character match environments with very different colour schemes.