FORT LEE, N.J. ,May. 7, 2008--ORBCOMM Inc. (Nasdaq: ORBC)  announced that it has signed a next generation satellite constellation contract with Sierra Nevada Corporation (SNC) to build 18 new ORBCOMM Generation 2 (OG2) satellites with an option to purchase up to 30 additional OG2 satellites to augment and upgrade ORBCOMM's existing satellite constellation.