Ground controllers are analyzing a fault aboard Europe’s Rosetta spacecraft after an encounter with comet dust confused the probe’s navigation system, leaving the robot explorer in a temporary safe mode and halting regular science operations.

A potential problem with a rocket thruster designed to keep the Philae lander from bouncing off comet 67P/Churyumov-Gerasimenko after touchdown Wednesday will make the probe’s daring descent even more challenging, officials said.

Amateur astronomers around the globe have a ringside seat as Comet 2013 A1 (Siding Spring) hurtles through space en route to an incredibly close encounter with the planet Mars on Sunday, 19 October.