Death From Above

 is a Fallout 3 quest and achievement that is added to the game in the Broken Steel downloadable content pack.

Walkthrough
The player is sent to assist a Brotherhood assault on an Enclave outpost at the southwest corner of the map (west of the Dunwich Building), reached via the Rockland Car Tunnel. The Satellite Relay Station is in a new area altogether and is heavily defended by Enclave Soldiers.

Talk to Scribe Rothchild
After you wake up in the Citadel's clinic, you are greeted by Elder Lyons who gives a short overview of what happened during the two weeks you have been passed out and sends you to Scribe Rothchild for a more detailed briefing. Rothchild explains how the Brotherhood systematically attacked Enclave camps with the help of Liberty Prime which has proven to be far more effective than expected. The objective of your mission is to learn how the Enclave are still able to communicate and coordinate their scattered forces, even though their main base has been destroyed. It is believed that the Enclave-controlled Satellite Relay Station might be able to provide answers and you are sent there to assist the assault.

Meet Paladin Tristan and support him during the assault
When you arrive at Rockland Car Tunnel, you are briefed by Paladin Tristan. As in Take It Back!, Liberty Prime will take point, with you and other Knights providing support. The first phase of the assault proceeds much like that mission, as the giant robot stomps implacably down a canyon, swatting Vertibirds out of the sky and crushing all "Communist" opposition in its path.

When the Brotherhood force arrives at the relay station, Liberty Prime analyzes it for weaknesses and then punches a hole in its wall, allowing entrance. Soon afterward, however, he warns that an uplink transmission has been detected and that an orbital strike is imminent. If you do not stay back or immediately retreat to a safe distance from the robot, you will be killed.

Liberty Prime is wrecked by the missile strike, managing to drag himself only a few yards with his remaining arm before shutting down. In the process, his head comes off; like Deputy Weld's when Megaton is destroyed, it can be activated to hear some of his anti-Communist phrases, now slurred and garbled.

Gather data from the Relay Station
The surviving Brothers regroup, and Tristan orders you to enter the base and find out what just happened. Assisted by a squad of Paladins and Operations Officer Edwards, you must fight through many Enclave soldiers before finally reaching a computer room. Encrypted codes can be downloaded from the mainframe terminal.

Return the data to Scribe Rothchild
You are told to return to the Citadel and give the codes to Scribe Rothchild for further investigation. After lamenting the robot's fate, Rothchild takes the data and directs the player to Elder Lyons. Talking to him finishes Death From Above and starts the next quest, Shock Value.

Trivia

 * Liberty Prime's death sequence is a reference to the Overseer in Fallout 1; or of a wounded super mutant in a cut scene if the PC sides with the Master at the end of the same.
 * The final moments of Prime also bear a striking resemblance to the finale of The Terminator, in which the Terminator has lost its legs and pursues Sarah Connor by dragging itself with its remaining hand. Liberty is similarly crippled and moves just the same way.

Bugs

 * At the end of Broken Steel Liberty Prime's head can still be found at the Satellite Relay Station despite being in the Citadel at the same time.
 * After completing the quest, you don't get the 30 gamer score or the achievement added to your list of unlocked achievements. On the PC, you can fix this by typing into the console "player.setstage XX000802 200", where XX is the load position for Broken Steel.esm.