The work flowed well and kept the reader engaged for the most part. I think, though, that you could have engaged more deeply with the theme and the way in which you chose to explore it. I'm not denying that military forces commit atrocities involving intentional or mostly-intentional attacks on civilian targets; I know full well that can and has happened. But the way in which you depict it happening here is, if you'll accept my being very frank, so cartoonishly evil that it ceases to be horrifying and becomes merely ludicrous.
I would suggest that Commander Y-'s motivation for ordering the attack should be something other than callous indifference to civilian lives. If you rework what Slippy can see of the human settlement so that it is not starkly and plainly obvious that the commander is ordering an orbital strike on a funfair, add some confusing and contradictory intelligence reports, and suggest what the military reason for the strike might be, you make the horror believable and even relatable, which adds to the power and poignancy of the story.
The other way you could take it is to make the attack part of a deliberate campaign of terror, in the manner of the Blitz or the firebombing of Japanese cities in WW2. Again, that gives the commander an understandable (if not, I hope, relatable) motivation he currently lacks: real militaries have attempted to win wars through demoralizing enemy populations with sustained mass slaughter, and starkly staring that horror in the face would, again, add believability without sacrificing the raw evil of the original.
In any case, I think that the intention to confront squarely and unflinchingly the worst atrocities of war is a powerful and necessary one, and a meaningful subject for art. I've offered my criticism in the hope that you can use it in future works to confront those atrocities in a more powerful and compelling manner.