Space missions award a non-trivial amount of experience as well. When you unlock each "tier" (first should be available when you get your ship, and consists of three missions. Second opens at level 20), you'll get a set of quests from the ship computer, one for each mission in that tier. These award 8-10k each, plus the experience for the mission itself.
Once you've completed the single missions, you'll get the repeatable "campaign" missions, which usually encompass the whole "tier" (exception for the first tier, which is broken in two, a single one for the escort, then a double one for the other two). These are dailies that award 8-10k.
Completing the first "tier" of missions, as well as the campaigns for the first time, has consistently gained my characters just over a level. That's doing them as soon as the ship becomes available, usually around level 15-16.
In the space missions themselves, there are optional objectives to complete, which also award experience.
There are hidden objectives as well. For example, in the first-tier "Cartel Listening Post", there's a heavily-shielded attackable point on the bottom of the space station. Destroying this (use missiles every chance you have, it takes quite a few, at least at level 1 upgrades) will gain you an additional 2.5k xp/credits. This appears to be a daily as well. Destroying it in subsequent runs gains you 500xp flat out, no bonus.
For the first tier, running that particular mission (without the associated quest) awards ~330 credits and ~1900xp each time, in addition to what's acquired in the mission itself. You can easily reach ~4k per run.
These don't appear to take Rested into account, however.