There are 6 Scientist you can find in Blast Corps. The scientist have to be collected after finishing the mission once. After that, start the mission again and take your time without the ticking clock. After finding a scientist, you have to finish the mission to get credit for it and collect the achievement at the end.
TEMPEST CITY (00:14
The first scientist in Tempest City can be found near your spawn point. Turn right and drive to the end of the street. A little bit further to your left are 3 rocket crates. Pick them up and shoot the big block that is hiding a runway that is leading to the upper platform. Drive up there and shoot the stone squares to get to the scientist. Don't forget to finish the mission after this, or the scientist won't count ;).
EBONY COAST (01:22
Turn around and push the TNT into the rock that is blocking the tunnel. Now park your vehicle on the train and enter the train. Go all the way to the end of the tracks and jump back into your vehicle. Crash into the building on the right side (The building has to be hit from the angle in the video or it's almost impossible to bring it down). Push the TNT onto the train platform and take the train back to the beginning and through the open tunnel. Stop the train so that the TNT is next to the statue. This will unlock the mech. Take control of it and use the jetpack to get to the platform directly behind the mech. Walk a bit to the left and follow the edge to the end until you reach a wall. Turn left twice now to find the scientist.
IRONSTONE MINE (04:35
Follow the train tracks until you find the train and take it all the way back. Exit and take the small bridge and walk past the crane. There is a small walkway on the right that takes you to the RamDozer. Drive it down, and park it on the crane platform. Lift the RamDozer over the gap where the TNT is placed. Push the explosives into the structure next to it to open up a secret road that leads you underground. The scientist is located in the back of this little maze.
ARGENT TOWER (07:34
Near your spawn point on the left, you can find a grey block. Push it aside and walk down to the RamDozer. Push the TNT into the little door and enter the train. Drive it to the next exit and get out. Go back to the blown up door and enter it again. Now that the train is gone you can run into the tunnel. Stay left and push against the wall while you walk forward. There is an opening that leads you to a new vehicle and a maze. Follow the video to find the scientist.
GLORY CROSSING (09:45
Follow the red light on the ground to the yellow truck and turn left. Drive through the little underground passage and pick up the next scientist.
OYSTER HARBOR (10:27
Get to the RamDozer and follow the map straight until you get to the boats. Get onto the third one and position it on the right side. Get out, take the bridge and position the second boat as well. Now get onto the first boat and ride it all the way to the left to get the TNT. Use the RamDozer to get it in the boat and head back to the right side. You now want to get the TNT to the Stone that is blocking the third boat. Blow the blockade up and take the boat to the far right side. The last scientist will be waiting for you there.
If you are having trouble with finishing Oyster Harbor, here is the mission walkthrough