Commercial Towing Vessel

Commercial Towing Vessel 'Nostromo', an M-Class starfreighter property of the Weyland-Yutani Corporation, is a tug, a towing vessel, hauling an enormous (some 1.5 miles length) ore refinery and 20 million tons of raw ore, weighing many times the mass of the Nostromo. The ship itself is still substantial, over 60,000 metric tons and almost 245 metres (800 feet) long, including three decks, four holds, stores, engines, and lots of pipes and ducts; its escape ship is called Narcissus. The ship is fitted with a self-destruct system.

Nostromo Info[aliens.wikia.com]