@T-90 minuts for #Maxus9
If I'm not mistaken, this is the last castor 4 engine that will launch.
For the continuation of the Maxus sounding rockets, VS-43 and VS-50 are candidates. (GEM-40VN is also a possibility, as are new solids derived form POD-Y [Two (single solid) stage Sparrow], and Northstar Borealis)
More details about the mission: SSC Maxus 9