During the mid-20th Century, we were faced with the existential threats of Soviet dominance of outer space & nuclear weaponry, so we & our parents marshalled the scientific & technological & economic resources of this great nation & met the challenge. We & our parents did good.
Today in the 21st Century, we & our children are faced with similar existential dangers of anthropogenic global warming & climate change. So once again, this great nation must marshall its scientific & technological & economic resources to meet those challenges. We & our children will do good.
And NASA certainly has a very vital role & a multitude of preeminent missions to gather the data & analyze the effects of AGW, including warming rising seas, melting ice caps & glaciers, extreme weather events, acidification of oceans, expanding desertification, & accelerating migration & extinction of species.
NASA's World of Change
NASA's Earth Observatory
NASA's Earth Observing System
Mastery of other worlds may just have to wait while we secure spaceship earth and its priceless payload...
re: "So why do you need to collect more data, launch more satellites"