Launching matter into space is environmentally odious owing to the energy requirements.
My preferred option for dealing with halogenated organic species, of which DDT is member of a subset, relatively minor now in comparison to fluorinated species, far more troubling that DDT at this point, is radiolysis, given my appreciation of the value of radioactive things, a subset of free radical decomposition. Since gamma and x-ray radiation are highly energetic, they can break the problematic carbon-fluorine bond which has energy roughly comparable to the far UV range, to which x-rays and gamma rays can easily be down-converted, although down conversion is not necessary. (This would be an excellent way to utilize so called "nuclear waste." ) Other free radical generation approaches are well known, and often industrially applied, in particular ozonolysis, and chlorination, although the later often generates chlorinated by products which are themselves problematic.
Interestingly, the current issue of Environmental Science and Technology, Volume 57, Issue 47, which I am currently exploring, is all about the issue of purifying water of contaminants, and there is much discussion of free radical reactions therein.
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