The German scientist looked at me with disdain. “As I told the general, I’m not one who likes surprises. Your presence on this training mission wasn’t announced until yesterday.”

ABE prompted me with a prepared comeback. “GOLEM wanted a backup to go through the training, just in case. There’d probably be three more of me onboard if the habitat had the room.”

“How fortunate we don’t.” Bruemmer clicked a palm control, causing a holographic image of Oceanus to bloom into view above the table’s center hole. “This is Oceanus I. It’s identical to the habitat we’ll be transporting to Europa, except that its cryogenic chamber will be located aboard the shuttle, affording Oceanus II more living space. As you can see, the design is spherical, allowing for optimal compressive strength required to maintain structural integrity at great depths. Oceanus is contained within a three-foot-thick outer casing composed of aero gel, the lightest, lowest density solid material ever produced. Aero gels are made by removing all of the liquid from silica gel while leaving its molecular density intact.”

To demonstrate his point, Bruemmer removed an ice cube–size piece of clear aero gel from his lab coat pocket. “If you examined aero gel under a microscope, you’d see trillions of nanometer-size particles of silicon dioxide interconnected in a porous labyrinth made up mostly of air. The material is incredibly dense. If you flattened this cube out, it would span an entire football field. And yet as dense as Oceanus’s three-story, hundred-fifty-foot-in-diameter sphere appears, the entire structure weighs less than fifty thousand pounds. The substance was used by NASA as thermo-insulation, making it perfect for the supercold temperatures of both space and Europa’s ocean.

“To locate, mine, and segregate helium-3 from Europa’s hydrothermal vents, GOLEM devised a porous aero gel vacuum tube composed of He-3 sensitive fluorophores. The tube will be used to cap a vent, then redirect steam generated by the superheated waters to churn a turbine, which will power Oceanus while the fluorophores break down and separate the helium-3 from the rest of the discharge. It’s really quite ingenious.”

“The volcanic vents are located on the seafloor. How does GOLEM expect to get this giant beach ball through eight miles of ice?”

Bruemmer pointed to the sphere’s four anchor arms. “Besides serving as a base, each of these support arms contains twin rockets, one exhaust pointing down, the other up. Each engine holds enough fuel to melt through thirty miles of ice. Fire up all four rockets and you have an instant elevator shaft melted within the ice sheet.”

The scientist changed the image to an internal layout of the sphere. “As you can see, Oceanus has three main decks. The lower level is dedicated to gathering and storing helium-3 as well as the habitat’s power station—a small nuclear reactor.”

“I thought you said Oceanus runs on steam generated by the vents?”