Borrowed Time by Jack Campbell

-.”
    “No! The rock will still reenter and we’ll have no idea where it’d impact.” Pam stared at me. “Trust me.”
    “But -. Okay.” It sounded like Pam was going to try to make the object enter earlier than planned. It’d come from the east, Pam had told me, so that meant the new trajectory would bring it down somewhere east of England. What was east of London in 1908? Europe. Heavily populated even then. Then Russia. Or the Russian Empire, rather, in 1908 CE.
    Pam seemed to be sweating as her assistant worked silently to alter the space object’s destination. Jeannie and I waited. I watched Pam’s face for any sign of how her attempt to alter the asteroid’s path was working, but couldn’t see any clues there. I found myself looking outward, wondering if I’d see the incandescent path of the space object heading for London.
    A light blinked off on the device. Then another. Pam drew a long, deep breath. “It’s coming down early.”
    “Where?”
    “Somewhere in a region called Siberia.” She shot me an aggrieved look even though I hadn’t said anything. “I couldn’t stop it and I can’t achieve a precise target area without a homing device like this there, so I aimed it for emptiest place I could. Siberia seems the best chance we have to minimize the death and destruction this intervention will cause.”
    I nodded, realized it’d been a while since I’d breathed, and inhaled deeply. “Siberia is one of the least populated regions on Earth right Now.”
    “Yes.” Pam sagged with reaction as the tension fell out of her. “When we get back to our own Here and Now’s, there’ll no doubt be mention of a big explosion in Siberia on,” she paused to check the date, “30 June, 1908 CE. Hopefully in the middle of nowhere.”
    I grinned. “I wonder to what they’ll attribute the good fortune of it hitting in the middle of nowhere?”
    “The usual, I’m sure. Accident or chance or luck. The standard way of explaining something when they don’t really know the answer.”
    “If they didn’t explain things away like that, your and my jobs would be a lot harder.”
    “True.” We heard a strangled sound, and both looked toward where we’d left psycho-blond. The killer was snarling soundlessly at us, having recovered from the tranq with amazing speed. “What should we do with her?” Pam wondered.
    “If they don’t manage another counter-intervention, she should loop out any time now when the future that created her ceases to exist.”
    “Yeah, but how long will that take?” Metal clanked on the heels of Pam’s question, and as we watched the loops of chain which had been wrapped about psycho-blond collapsed into the vacant space she’d once occupied. “I think the fat lady just sang. How’s it feel to know you’ve saved London?”
    “Right now it still hurts. Too bad the bruises that woman inflicted didn’t vanish along with her.” I stared at the pile of chain. “I wonder what kind of person she’ll be with a different history? Maybe not too bad.”
    “Are you planning on looking her up?”
    “No way. I think I’m going to be a little wary of blonds for a while.” I suddenly noticed shouting outside. “I think all the gunplay has attracted too much attention.” I went to what must have been the same point where psycho-blond had been firing from and looked downward. People who’d had cause to be about in the very early hours of the morning were gathering around the bodies of the dead soldiers, examining them and speaking in indistinct but clearly excited voices. “We’d better get out of here.”
    “Not without this.” Pam indicated the now-silent device. Unlike psycho-blond, it’d been put here by a history that still existed. “I hope it’s not too heavy.” She tried to raise it, then grinned with relief as it came up easily. “Not bad at all. I can handle it alone. Let’s go before anyone realizes the shots came from here.”
    “Wait.” I checked to make