[pavanky]

> 25th successive successful mission.

You added a word. What is more impressive is the current streak of 23 successful missions going back to 1999.

[walls]

> successive - following one another or following others

> successful - accomplishing an aim or purpose

What's the extra word here?

[pavanky]

There have been 25 total successful missions for PSLV. 23 of them have been successive / consecutive. Considering that "successive" is not a word used commonly and that the fact that the number of "successive" missions was wrong, I thought it was a typo.