Exceedingly Unlikely Plot Arc by SpinelStride
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"Lero, you don't have to do this!" Rainbow Dash begged. "There has to be some other way. Something!"
Lero bent down to hug her, but pried her forelegs off of his waist when he was done. "We both know I'm the only one who can do it, Rainbow." He sighed, looking up. A purple star beamed in the sky.
"She got up there, she can get down!" Rainbow Dash insisted. "Lero, this is me we're talking about here, and I'M telling you this is insanely way too crazy dangerous!"
Lero kept trying to pry himself free. "Rainbow, Princess Luna explained all this. Unicorn-style magic doesn't extend above the atmosphere, and astral magic doesn't do any good when your body's physically up there. That's why Luna didn't just teleport back to Equestria when Celestia bound Nightmare Moon there in the first place; Luna's physical body was stuck until that thousand-year conjunction let her access Equestria's unicorn magic. Twilight teleported herself up there, but she can't teleport back down. And there's no air for her to flap her wings against, so she can't fly either."
Rainbow Dash let go, reluctantly, but pointed at the massive metal edifice Lero was about to enter. "But Lero! You can't seriously tell me you think that thing is going to get you safely up there and back! At least let me fly it! Nopony can fly like I can and you know it!"
Lero kissed her firmly. "Outside of magic. Twilight's an alicorn and that lets her stay aware. You aren't. You'd be drooling on the control panels and floating around the cabin."
Rainbow Dash outright whimpered. "But... Lero, how the hay did Applebloom even make that thing?"
Lero smiled at his mare. "Apparently she got her cutie mark in rocket science. Who knew? The first apple-powered spacecraft ever." He pulled his helmet on and started climbing the gantry. "Hold on, Twilight! I'm coming for you!"
Up in orbit, Twilight sighed into the vacuum and swore once again to never answer an "Is it possible for an alicorn?" question with "Let's find out."