Derek M. Tournear, the head of the Space Development Agency that spearheaded the trailblazing push to buy and launch small satellites at a speed and scale unseen in military space circles, is departing the organization for a job in academia just before a momentous launch. 
The long-term future of one of the Space Development Agency’s two satellite constellations is on hold as officials study the options for replacing a planned “data transport layer” with one or more commercial solutions. President Trump’s proposed 2026 defense budget...