Perseverance Lander minutes away from Mars.

[BrianSoddingBoru4]

Spacecraft can make course corrections.  Even if the math is perfect, the various engine burns aren't.  The last correction would've been two days ago, and an orbital insertion burn was likely done hours before touchdown.

Calculating spacecraft trajectories is fairly easy math for computers to solve.  It is a minimization problem.  The mechanics are largely Newtonian, and with a minimum of fuel, determine a trajectory.  Now, doing it before computers -- that would be tough!

Gravity assist on more complex missions makes these calculations really fun.  The spacecraft gains most of the angular momentum of the planet is slingshots around, plus the spacecraft gains extra speed for burns done within the gravity well (compared to outside the well).

Computers certainly have replaced human labor with things like this, but it took a buildup of all sorts of sciences that humans figured out to be able to write the code and programs and build the rockets and rovers to make this moment possible.

100 years ago computers were literally a system of on off switches with light bulbs taking up gym sized rooms. It is amazing to me that we have gone from that to a laptop replacing that. 

And, it would not surprise me one bit if we find the building blocks of life on Mars.

Actually, the vast majority of computers in the 1920s looked like this:

---

---

Boru