Lockheed Martin [LMT], Rocket Lab USA [RKLB], Northrop Grumman [NOC], and L3Harris Technologies [LHX] are to build 72 satellites for Tranche 3 of the U.S. Space Force's Space Development Agency's (SDA) Tracking Layer under more than $3.5 billion in Other Transaction Authority (OTA) rapid prototyping contracts, SDA said on Friday. For the Tracking Layer of Tranche 3, each of the four companies is to build 18 satellites under the firm fixed price OTA awards. Lockheed Martin received $1.1 billion, L3Harris…