Free Camouflage by Joe Haldeman

the mask.
    Outside, twenty men were sprawled around in various attitudes of misery, coughing and retching. There were spatters and pools of vomit everywhere. The changeling ordered his stomach to eject its contents.
    A friend, Hugh, came over to where he was kneeling and pounded him on the back. "Geez Louise, Jimmy. You musta held your breath three minutes."
    The changeling coughed in what it hoped was an appropriate way. "Swim a lot underwater," it said breathlessly. "God, don't that stuff smell awful?"
    But the memory of nostalgia was strong. Where on Earth could it have lived, where chlorine was so concentrated in the air? Nowhere on the surface. That would be a good research project, after the war.
    A lot of their training had a quality of improvisation, since much of the material of war had already left for the Pacific. So they learned how to work with tanks by advancing in formation behind a dumptruck carrying tank signs wired to its front and rear. They carried World War I Springfield rifles and practiced with them on the range.
    Hand-to-hand combat training was a ballet of restraint for the changeling, who had been a remorseless predator for most of its life. It allowed the other trainees to throw it around and simulate dangerous blows. When it was its turn to be aggressive, it spared everyone's lives, knowing it could rip off one person's leg and beat everybody else to death with it.
    It was properly respectful to the sergeants, and studied their individual ways with the men. Those techniques were more interesting than the coercive strategies of college professors, who presumably had intellectualized the process. The sergeants instinctively reached back into primate behavior, becoming the dominant male by shoving and punching and screaming. Anyone who resisted them was punished— immediately and then again later, with assignments, "shit details," that were degrading and exhausting.
    The changeling did its share of those—cleaning toilets with a toothbrush and pulling twenty-four-hour kitchen police—not, of course, because it had actually lost its temper or misread the sergeants' desires. Too much self-control would make it conspicuous. It had to play the game.

    -16-

    Apia, Samoa, 2020

    Russ and Jack, especially, agonized over the contract, distrusting the government on principle, but unable to deny either the financial argument or the scientific one. They faxed it to their Chinese and stateside lawyers, and they agreed that it was what it claimed to be.
    They signed it on Friday, and on Saturday morning their work crew was suddenly tripled, cargo helicopters thrumming in hourly with the prefabricated materials for their laboratory's exoskeleton.
    The carpenters and painters who were putting the finishing touches on the lab were nonplussed, to say the least. The elegant heat exchange system was carved away and replaced with heavy-duty machinery. The carefully glazed windows that looked out on the ocean now had a view of plain steel plate.
    The moat was filled with fast-setting plastic concrete that supported the footers for the new metal walls and roof. NASA dug a new moat, wider and deeper and open to the sea: the lab became an artificial island fortress.
    The twelve scientists, seven women and five men, were sensitive to turf. They never approached the artifact unaccompanied by the original team; they spent hours every day comparing notes with them, planning out approaches. It was a congenial, collegial mix, everyone linked by passionate curiosity.
    None of the NASA scientists knew that the SNAP-30 reactor had been modified so that it could function as a bomb. Some of the mass that they thought was shielding was actually extra plutonium. Nesbitt had known, but his first allegiance was to the NSA, "No Such Agency," not NASA.
    And he was no longer in the picture.
    The NASA team was "all chiefs, no Indians," officially, but their nominal leader was Jan Dagmar, a white-haired exobiologist old enough to remember