At 70 years old, I know that there are several things I will not see again, like Halley's Comet. And the next time Mars comes close to Earth, I will miss that also. But as the light pollution on earth gets worse every year, some things like dim comets will be harder to see than ever. I do not think it will effect the next time Mars come close, planets are not effected that much by light pollution. So I am hoping for an unknown very bright comet appearing in the near future, maybe that will give some of us older ones a thing to remember in our later years. But as time passes by, I am thankful for being able to view the heavens as much as I have ( which is not as much as lots of you ) but enough to keep my interest.