Doomsday machine - Memory Alpha
From Memory Alpha, the free Star Trek reference.
The doomsday machine, also referred to as the planet killer, was an automated, self-propelled weapon capable of destroying entire class-M planets. It was encountered in 2267 by the Federation starships USS Enterprise and USS Constellation. Its origins are unknown, but based on its apparent trajectory, it was believed to have come from outside the Milky Way Galaxy.
Around stardate 4202.1, the Constellation, under the command of Commodore Matthew Decker, encountered massive destruction in system L-370 — all seven planets had been destroyed. Proceeding to system L-374 (stardate 1313.1), the ship found three intact planets, and a fourth in the process of breaking up. Orbiting the fourth planet was the doomsday machine, firing a beam of pure antiprotons at the planet and consuming the planet's rubble as fuel.
As the Constellation approached, it was quickly attacked by the planet killer. The ship's deflector shields were quickly overwhelmed by the onslaught, and the machine proved completely invulnerable to counterattack, because its hull was composed of pure neutronium. The Constellation sustained heavy damage — the main bridge was destroyed, the phaser banks were exhausted, and the warp drive was damaged. In addition, the machine projected a powerful dampening field, cutting off all communications with Starfleet, and somehow deactivating the Constellation's antimatter fuel and leaving the ship nearly powerless.
Unable to continue the attack or escape, Decker ordered the crew to evacuate to the third planet in the system. Decker himself remained aboard as the last man. However, after finishing consuming the fourth planet, the machine then turned towards the third planet. Decker tried to beam his crew back up, but the machine attacked again, damaging the transporter. He could only watch, helpless, as the machine consumed the planet below, and his entire crew of 400 men and women killed.
A short time later, the Enterprise, under the command of Captain James T. Kirk, received a faint and garbled distress signal. Unable to make out any words aside from Constellation, she entered system L-374 and found her sister ship drifting and abandoned, with Commodore Decker the sole survivor aboard. Assessing the situation using the Constellation's sensor records taken by science officer Masada, Spock projected the weapon's origin. He also determined, based on its present course, that it would enter the most densely populated regions of the Alpha Quadrant, including the nearby Rigel system.
As the Enterprise held alongside the Constellation, it was suddenly and swiftly attacked by the Planet Killer. Although the Enterprise was more maneuverable, the weapon was extremely fast and gaining on its target. In the first volley, the Enterprise took heavy damage, with shields almost consumed and transporters and communications damaged. While Captain Kirk was trapped with the boarding party aboard the Constellation, Spock ordered evasive action. Commodore Decker, taken aboard the Enterprise for medical treatment, exercised his authority to assume command under Starfleet General Order 104 and countermanded Spock's orders to avoid the machine and seek a clear space to warn Starfleet. With a combination of seeking retribution for the loss of his ship and crew, and the presumption that the nearby Rigel colonies would be the next target of the machine, Decker ordered an immediate attack on the weapon. However, the Enterprise was overwhelmed as quickly as the Constellation had been, and soon trapped by a tractor beam which was pulling the ship towards the doomsday machine's maw.
Meanwhile, on the Constellation, Chief Engineer Montgomery Scott managed to effect partial repairs to the impulse engines and a single phaser bank. Kirk launched a diversionary attack on the Planet Killer that allowed both ships to escape. The doomsday machine apparently had a relatively simple and straightforward defensive computer program that only allowed it to engage single targets within a specific range. The immediate danger past, Captain Kirk ordered Decker relieved of command of the Enterprise.
As the two Starfleet ships withdrew, the Planet Killer returned to L-374 and resumed consuming the planetary debris, taking in additional fuel. When Decker gave indications he was going to continue to press the attack despite narrowly avoiding disaster in the previous engagement, he was relieved of command by Spock under direct orders from Kirk on the basis that to continue to press the futile attacks would be indication he was suicidal, and was ordered to report to sickbay for a psychological examination.
Suffering from insanity brought on by the extreme stress and the loss of his ship, crew and command, Commodore Decker escaped custody and stole a shuttlecraft from the Enterprise, piloting it on a suicide course directly into the weapon's maw, where it was quickly destroyed. However, the Enterprise sensors detected a small drop in the power output of the Planet Killer — the shuttlecraft's explosion, however small, had in fact caused some minor damage to the weapon from the inside. Based on this data, Captain Kirk proposed detonating the Constellation 's main impulse engines inside the Planet Killer, creating a much bigger explosion and hopefully causing major damage to the weapon, if not destroying it outright.
As the Enterprise held position near the Planet Killer, outside of weapons range, Kirk piloted the Constellation on a direct course toward the weapon. Beaming out at the last second, the Constellation 's engines detonated directly inside the weapon's maw, bypassing the neutronium hull. The Planet Killer was completely deactivated by the explosion — although it was left intact, power levels dropped to zero.
The Doomsday Machine was featured a in a few non-canon productions.
The Wildstorm Star Trek comics included a Star Trek: Voyager miniseries with another Doomsday Machine. In this encounter, it was revealed that the machine was the creation of an extinct species designated by the Borg as Species 4672; the Borg had attempted and failed to assimilate the Doomsday Machine technology, and had as yet been unable to discover a defence against it. As the Machine began to advance on an inhabitated planet in the nearby system, Voyager tried to find some way to destroy it. An attempt to duplicate Kirk's stunt for stopping the original Machine (Using a damaged spaceship belonging to an alien they had rescued) failed, but the crew came up with the idea of infecting the machine with a nanoprobe-based virus.
Initial attempts to infect the machine with the virus by launching probes filled with the nanobots into the machine failed, but they eventually had the idea of using Voyager to draw the Machine's fire while Tom Paris and the Doctor took the Delta Flyer up close. As Voyager distracted the Machine, Paris transported the Doctor in so he could inject the nanoprobes into the machine, his mobile emitter coated with neutronium so it couldn't detect him as it was made of that very mineral. (According to the crew, the original Machine was used by the natives of Rigel as a monument to its victims, and they speculated the same would be true of this one).
Peter David's novel "Vendetta" featured another (and is the source of the above speculation as to its Borg-based origin). In this novel, it was hypothesized that the Planet Killer was an ancient race's (perhaps the Preservers) last resort weapon against the Borg. Its basic design - destroy planets already assimilated by the Borg for use as fuel - coupled with an indestructible neutronium hull and antiproton beam (against which there is little or no defense), make it an ideal weapon against the Borg.
In Kevin Lauderdale's short story "Devices and Desires" (in Constellations), the Doomsday Machine was taken to The Yard, a top secret facility where the alien technology Starfleet has acquired is stored and studied. One of its researchers is Dr. Pad – a reference to Peter (Allen) David, above.
The fan series Star Trek: New Voyages also featured the Doomsday Machine in the episode, "In Harm's Way".