The chance of any live microbes from earth arriving on Mars from this launch are so small they're effectively negligible.
Even if one of the pieces manages to hit Mars ( a very big If, given that there'll be no course corrections for the debris, and a different momentum for each piece..) , there is the cold, the radiation, and the heat of re-entry without a heat shield or parachute.
But the odds are easy to demonstrate.. Take a bit of steel, and drop it on the floor of your average pub loo at closing time ( or a healthy compost heap if you're squeamish ) . This guarantees Contamination. Then drop it in liquid nitrogen, and place it near a convenient gamma source for 7 months. After that , take the piece and put it in an induction ring at full power until orange-yellow. Let it cool until safe enough to swab, and inoculate some agar plates, see what grows.
It's pretty safe to say that piece of steel will be more sterile than anything classified as such here on Earth.