A lot more than what has gone wrong. Just getting there was an amazing feat.
After separation from Rosetta, the thrusters meant to direct the probe to the comet's surface didn't work.
Then, the two "harpoons" meant to anchor the probe to the comet's surface didn't deploy, resulting in the probe "bouncing" into its current position, resting in a hole or on the edge of a cliff.
So, what exactly went right with this mission?
So, what exactly went right with this mission?
...
The hype machine has worked perfectly.
The probe is on the comet, taking pictures, gathering solar energy, operating probes & analyzers, and communicating regularly with the orbiter & Earth. All less so than intended, but still way better than outright crashing or bouncing off & away.
For starters, a man made probe traveled approximately 4 billion miles and landed on a comet.
Roughly the equivalent of hitting a speck of dust with a BB gun from a distance of 10 miles.