Space exploration, although it has spawned amazing engineering achievements, I think is a total waste of resources. Nothing it has done has bettered the human race in any tangible way.
Exploring the moons of Jupiter, searching for life on Mars, etc. is of no interest or solace to 99 percent of the human race. And living on Mars or journeying to another Earth-like planet is total fantasy. Living on Mars; if at all possible, would be like living in the middle of the Gobi desert only 100 times worse. As for searching for life elsewhere I think it can be positively assumed that, if it exists on a tiny piece of dust (the Earth) located on the edge of a non-descript galaxy, it must be widespread throughout a universe of billions of galaxies. Of course, the satellites put into near Earth orbit are of great benefit to us Earthlings but they are only 200 miles above us which cannot be deemed “deep space.”
No, let’s use our brain power to solve critical Earthly problems. If the “fertilize Mars” people want something to do let them try fertilizing the Mojave desert; that should be easy in comparison. All the science and engineering involved in space exploration is old hat and not a patch on the science involved and evolving in medicine, biology and other disciplines which are a benefit to human kind.