1. Six months.
2. This is the fifth success, out of thirteen attempts, over sixty years.
3. There have been five successful landings.
4. No.
2. This is the fifth success, out of thirteen attempts, over sixty years.
3. There have been five successful landings.
4. No.
Failures include (going off of a list on Wikipedia) 2MV-3 (Soviet probe that never left Earth orbit; not sure if you want to count this or not since it didn’t fail during landing), Mars 2, Mars 3 (landed successfully but failed within minutes), Mars 6, Mars 7, Mars Polar Lander, Beagle 2 (landed but solar panels failed to deploy), and Schiaparelli.
So I think there have been eight successes and eight failures, if you only count probes intended to land. Notably, all eight successful landers so far have been launched by the United States.
Viking 1
Viking 2
Mars Pathfinder
Spirit
Opportunity
Phoenix
Curiosity
InSight
https://en.wikipedia.org/wiki/Mars_3#Entry,_descent,_landing...