During elevator trip, you should see another hangar's level and enemy's fighters. After reaching the top, your team leader will get new orders - clear the area of all enemies.
Clear Area of Enemies
After short walk, the lights will turn off. Choose machine gun, turn on the flashlight and wait until allied soldiers take their positions in a big hall. Hide behind the column and start exterminating the Stroggos, that will came in big numbers from the other side (destroy machine guns placed under the ceiling too - #25). To make things easier, shoot in the exploding barrels. If you get rid of all your opponents, than team leader will command you to get the explosive charge's expert.
Meet Rhodes/Protect Rhodes
Return to the elevator, which brought you on this level. Get some ammunition and with new buddy (#26) move to the room, where the fight has just finished. Use next door to walk inside the hangar (#27).
There're two rooms, placed on either side. Visit them (order doesn't matter), eliminate all enemies inside, and wait until Rhodes will set up the exploding charges (#28). Return to the main hall and get ready for another fight. You'll be out numbered for a while, so try to change it. Mind your new friend - if he'll die, than it's game over. After setting up the charges, Rhodes will tell you to run to run behind him, so do that. After jogging, you'll find yourself in command center and you'll see the explosion (#29).
Regroup with Voss
There's an elevator on the other side of command center (#30). Click on the panel to leave the hangar.