MUOS-5 highlights a critical U.S. vulnerability in space

A strange thing happened in July when the U.S. Navy’s MUOS-5 satellite was on its way to geosynchronous orbit. The thruster it was using to raise its orbit stopped working unexpectedly. It’s never good when a part fails like this. It’s especially bad when this happens to a military satellite worth $475 million including launch costs, leaving it in the wrong orbit — at least temporarily. It turns out that the thruster in question — a BT-4 apogee engine made by IHI Aerospace of Japan — may have components in common with the engine on the Intelsat 33e satellite and NASA’s Juno probe, both of which recently experienced propulsion malfunctions.

If the problem for the military was limited to the MUOS-5 satellite…