The Gangstas in Space DLC comes with 3 new missions, and several new achievements, some of which can be 'missed'. If you do miss one, you can simply complete the 3 missions, save/reload your game, and re-select the first mission from your Cell Phone.
In order to be efficient, you should aim for the following achievements within each mission. Check the Gangstas In Space Walkthrough
for a more detailed walkthrough.Faster, More Intense! Hangar 18 1/2 That's Not in the Script! Please either comment below or send me a Personal Message if you have any comments or improvements.