Buster Machine III

Buster Machine III (バスターマシン三号）, also known as the Black Hole Bomb（ブラックホール爆弾）, is a superweapon of megastructure scale that appears in the science fiction anime OVA Aim for the Top! Gunbuster.

Description
Meant to be Earth's trump card against the space monsters, Buster Machine III (BMIII) is a giant prolate spheroid that is jet-black in color. Measuring 896 kilometers along its longest axis and 415 kilometers in diameter, BMIII easily dwarfs the 70 kilometer-long Eltreum-class warship.

BMIII is so numbered as it is the third in a series of Buster Machines, powerful anti-space monster weapons in the Gunbuster universe. Buster Machines 1 and 2 were large spacecraft that combined to form the title mecha of the OVA, Gunbuster.

BMIII is, as its nickname suggests, a single-use artificial black hole generator. Most of its mass is actually taken up by the planet Jupiter, which was collapsed to 1/30000 of its original size using gravity manipulation and inserted as the weapon's core.

BMIII is capable of long-range warp travel (from the Solar System to the center of the Milky Way). Although it is unarmed, BMIII is protected by a tremendously strong energy barrier that was able to weather a continuous space monster kamikaze attack for several minutes before collapsing. (Many space monsters in Gunbuster are thousands of meters in length and can travel close to the speed of light, so surviving such a barrage can indeed be considered an outstanding feat.)

BM III is manned during transit by a crew of one pilot. However, as it prepares to detonate, the Black Hole Bomb is completely remote-controlled from the bridge of the battleship Eltreum.

Operation Carneades
The inhabitants of earth were originally planning to abandon Earth and the Solar System altogether as the space monsters pushed the battles closer and closer. However, after seeing the effectiveness of generating an artificial black hole on a swarm of space monsters, authorities decided to scrap the evacuation plan and began drawing up Operation Carneades instead. (Named after the philosopher Carneades, who is said to have postulated that if two shipwrecked men will endanger both their lives by clinging onto the same plank of wood, one of them cannot be blamed if he murdered the other in order to ensure his own survival). The ultimate goal of Operation Carneades was the extermination of the space monsters, for the sake of humanity's survival.

Operation Carneades involved the creation of BMIII and the conversion of the Eltreum into a heavily armed dreadnought that would serve as the flagship of the Galactic Core Attack Fleet. (Eltreum was originally intended to be a colony ship to be used for the evacuation of Earth)

The plan was to launch a massive fleet of warships into the center of the galaxy to lure the space monsters (which were biologically capable of warp travel) away from Earth. BMIII, slowly completing its detonation process, would then warp into the galactic center where the fleet would protect it until it detonated. The fleet would only warp out of the area once the core reached its explosive compression stage. If everything went as planned, the simultaneous detonation of BMIII and 3000 internally mounted slave units would create a giant black hole that would consume all of the space monsters and their nesting areas within a radius of 10,000 light-years--including a large portion of the galactic core.

Detonation Process
''Disclaimer: Since BMIII appears in a fictional anime work, the actual science involved in the following explanation is not to be taken seriously. However, the creators of Gunbuster did their best to maintain a sense of scientific verisimilitude, even including "science lessons" at the end of each episode to explain the various scientific phenomena featured in the OVA. Thus, an explanation for the BMIII detonation process would not be so far-fetched.''

While the actual science was never explained in the anime, it can be inferred that BMIII was meant to transform Jupiter into a black hole by compressing it until its Schwarzschild radius was larger than its actual radius. (Operators on the bridge of the Eltreum were observing how far Jupiter was from collapsing to its Schwarzschild radius) An object that is smaller than its Schwarzschild radius is considered a black hole.

An object with Jupiter's mass (1.899 x1027kg) has a Schwarzschild radius of 2.82 meters. In order to transform Jupiter into a black hole, it needed to be compressed into a sphere that measured less than 5.64 meters from its original equatorial diameter of 142984km. While the actual process is not described, it can be said that the process requires all of the slave generators to fire. A failure of as few as 2% of the slave generators would result in a complete dud.

Explosive Compression
Operation Carneades was successful for the most part---BMIII made it safely to the galactic center and miraculously survived a vicious battle that claimed a large portion of the Earth fleet. Even after its barrier failed, BMIII was still operational. However, only 98% of the slave generators fired,(subsequent scenes showed some slave generators severely damaged) causing the mightiest weapon in human history to fail.

However, the heroine of the series, Noriko Takaya, volunteered to use her own spacecraft's collapser reactor to jumpstart the failed reaction and achieve explosive compression. Although Admiral Tashiro Tatsumi refused at first, he eventually allowed Takaya and her partner, Kazumi Amano, to enter BMIII. Noriko tore out Gunbuster's first collapser reactor and shoved it into the slave generator as it exploded. The explosion resumed the collapsing chain and detonated the Black Hole Bomb. The result was a titanic black hole that consumed the entire galactic center. Towards the end of the anime, images of the Milky Way with a massive hole punched through its center were shown.