Airlocks!
The first team was made up of three grenadiers and two Squad members, and when the door opened again, they had the exact same number of people. “There’s power and air, sir, but no people manning the gate,” the Squaddie told Tobias. “No communications network up on the other side, either. My suit couldn’t even find anything to handshake with.”
Reithner had been listening to one of the grenadiers, presumably telling her the same thing. “Nothing from our suits, either. The atmosphere is breathable, but the temperature is at thirty seven degrees.”
“Well, at least there’s no ice — no, wait.” Tobias frowned. “I forgot: your people still use Celsius. You’re saying it’s hot in there?”
“Yes. Blood temperature, in fact.” She sounded incredulous, which was fair, because so was Tobias. Most of Heinlein Base had been shut down and sealed off in order to conserve heat; the other human-occupied outposts had the exact same problem. If this place was that well heated, they probably had power, and to spare. Yet one more reason to investigate, he thought. Not to mention, handle gently.