Mathilde has an extremely long rotation peroid of 415 hours. Only two other asteroids (1220 Clocus and 288 Glauke) are known to have longer rotation peroids. Mathilde is also one of the blackest objects in the solar system, reflecting only 3% of the light that strikes it. As one scientist said, “It is blacker than coal” or two times the darkness of a chunk of charcoal. The density is lower than a typical C-class asteroid, and its geography is marked by several extremely large craters.
Mathilde was discovered by Johanna Palisa on November 12, 1885 in Vienna, Austria. In 1997 NASA's Near-Earth Asteroid Rendezvous (NEAR) spacecraft flew past and returned more than 500 images, providing the first close-up assessment of Mathilde.
During the pre-war asteroid mining boom, Mathilde's low density and very low rotation rate made it an attractive site for colonization. Although it contained little in the way of metal resources, it was a good base for processing ores brought in from other asteroid mines. The colony was developed using belter recoms, and became the largest and best-known belter population center. The name of the colony is New Philadelphia, and the asteroid is now commonly referred to by that name, probably more often than as Mathilde.
New Philadelphia has always been a center of industry. The belter culture has a strong heritage in engineering, and great skill at assembling large structures in microgravity. As a result, the New Philadelphia Shipyard has become the most sophisticated and reputable in known space, exceeding those of Luna and Oceania.
The shipyard at New Philadelphia spaceport can build and modify ships up to size class 5, including ships that are unable to enter atmosphere or land on any planetary surface. Skilled belter workers, with free-floating access to all parts of the ship, are able to make ship repairs more quickly than at any other shipyard. However… They do not sell weapons or ammunition, nor will they service ships matching known configurations of ships reported missing/stolen, as this is against the colony's policies.
The Port Authority is the primary law enforcement and self-defense force for New Philadelphia and 253 Mathilde. While functioning under the governance of the belter population, a large contingent of the Port Authority police are comprised of off-world “technical assistance”, largely from the Space Defense Force and Annyrion Colonist - Eisshari Coalition, using smaller gunships and backed up by defensive systems emplaced on the asteroid itself. This agreement allows the largely peace-loving belter population to defend itself and its shipyards from aggressive outsiders (think “pirates”). The Coalition Shogun-class space dominance vehicle Dallenhome bases its operations from a secure facility in the shipyard.