Fundamentally, momentum conservation is linked to invariance under space translations. See Noether's theorem. If you want to find a system that does not conserve momentum you should look for situations where space is not uniform, e.g. balls rolling on the surface of a bowl, a planetary system (when the dynamics of the sun is neglected), etc.
Socorro is a city in Socorro County in the U.S. state of New Mexico. It is in the Rio Grande Valley at an elevation of 4,579 feet (1,396 m). In 2012 the population was 8,906.
It is the second-largest county in New Mexico by area, after Catron County, New Mexico. Socorro County ranges in elevation from approximately 4,528 ft (1,380 m) on the banks of the Rio Grande to 10,784 ft (3,287 m) at the top of South Baldy peak in the Magdalena Mountains. The southern portion of the Rocky Mountains extend into New Mexico and Socorro County.