MONTREAL (Reuters) - Canada’s NorthStar Earth & Space and Thales Alenia Space said on Tuesday they will begin work on a commercial satellite system to combat the threat of collisions in space. NorthStar, an information service company, said it has contracted Thales Alenia Space, a joint venture between France’s Thales and Italy’s Leonardo, to build the first three satellites of its “Skylark” constellation. Montreal-based NorthStar said the constellation would be the first commercial service to monitor objects like satellites in space from space, where they can be tracked more precisely than from Earth.