Join our newsletter to get the latest military space news every Tuesday by veteran defense journalist Sandra Erwin. ARLINGTON, Va. — Defense giant Lockheed Martin announced Nov. 19 that its new mid-size satellite platform will make its orbital debut next year aboard a Firefly Aerospace rocket. The LM 400 satellite bus — roughly the size of a household refrigerator — represents Lockheed’s bid to capture a sweet spot in the satellite market: missions requiring more power and payload capacity than small satellites can provide, but not demanding the complexity of…