We cannot prevent storms now, but think about it, just because our technology now is preventing us from doing unimaginable things doesn't mean that future discovery / inventions will hinder this. What did people say to the Wright brothers in the 1900's? The Wright brothers discovered flight, but they still couldn't even [FONT="]dream of jet engines, [/FONT]yet here we are 100 years later with jet engines, scramjets turbojets, and rockets.
Not to play Devil's Advocate (because I look nothing like Keanu Reeves), but the Wright brothers did not discover flight. Human flight was already feasible thanks to lighter-than-air airships and gliders, and we already knew the laws of aerodynamics. As for jet engines, the principle of jet propulsion was known since Hero's aeolipile.
In order to colonize our own solar system we'd have to invent stuff we don't have yet. The most "friendly" planet out there is Mars, and Mars is even less hospitable than Antarctica. How many big cities do you see on Antarctica? And that's a pretty place compared to Mars. The rest of the Solar System is even worse. We could
survive in some places, but surviving is not living and in order to form a viable colony with a chance to expand, you need to
live. I'd like to point out we've had many example of failed colonies here on Earth, in places where there was water, food - and especially OXYGEN - aplenty.
Beyond the Solar System, without FTL, better to forget it. We don't have the foggiest idea how to go beyond the speed of light for real. There are some exotic theories, but they're theories and theories are good in a classroom or in a lab, they do not build anything.
Multigenerational spaceship? Oh yeah. Find me enough people who are masochist enough to be willing to spend their whole lives, and the lives of their kids and grandkids, cooped up inside a spaceship. Even if you could find them, the travel time is so darned long to go beyond the MTBF of any vital component. Unless you can build a ship without breakable parts (like the ship from Heinlein's
Orphans of the Sky) it would still take a very little accident to turn your advanced spaceship into a floating mass grave. Yeah. Keep in mind there aren't any pit stops between Sol and your destination.
So, unless we find a way to bypass the speed of light, we're pretty much confined here.
That said, I'm all for manned space exploration, which is a different thing than colonization. As for "necessary"... Well, nothing is strictly necessary but for food, water and air. Is modern medicine necessary? No, the human race could easily survive without it, but it's good we have it. Are computers necessary? No, but they're useful. Space exploration can bring us a lot of useful knowledge we could apply on Earth, until we find a way to crack the light barrier.