You must visit every sector within each block. So for Sirius sector block, you must visit Vulcan, Orion and Risa sectors. Once you clear all the sector blocks for a specific area (all Federation blocks for example) you will receive an amount of EC and some trade and exploration CXP. When returning to the mission giver you get nothing as the rewards are given as the mission progresses. He just finishes the mission and allows you to pick it up again.
and another tip: you can do this MORE than once as long the timer is going (1 hour) with the right ship and transwarp, you can do this upto x4 times (I only pull x2 and almost x3, but I have been told it can be done upto 4)
Growing old is inevitable. Growing up is optional.