I am very suspicious of software. It is too often a substitute for good design, by people who find it easier to monitor and supervise a process than to make a device robust and simple so it is less likely to fail.

You can't do space travel without software, Mars is too far away to use remote control, like a pilot flying a drone. The light-travel time alone makes it it impossible. But a half million lines of code that has never been tested all at once under real conditions is scary. Would you put your money in a bank with that philosophy?

Still, Nasa has done it before. Let's just hope they only use software where it is absolutely necessary, not just because it is cheaper or easier or because their engineers can't think of any other way to do it.