Really interesting technical note on how Orbital ATK’s Mission Extension Vehicles stack with other satellites in an article by Caleb Henry of SpaceNews:
Intelsat is not the first satellite operator to agree to launch an Orbital ATK-built satellite stacked with the company’s Mission Extension Vehicle. Late this year, the Eutelsat 5 West B satellite will be stacked with MEV-1 for launch aboard an International Launch Services Proton rocket. Both Galaxy-30 and Eutelsat 5 West B are based on Orbital ATK’s GEOStar spacecraft platform.
The ability to directly stack MEVs with GEOStar satellites gives Orbital ATK a new selling point. Because one side of the MEV is devoid of crushable instruments, a satellite can be stacked on top of it without using the protective barrier Ariane 5 normally places between dual-launched satellites. Stacking MEV with a GEOStar satellite enables dual launch on rockets that have no divider, like Proton, or, in the case of MEV-2, enable a third passenger to share the cost of a launch.