...And We Will Have Snow

Chapter 8-7: Altitude

Once inside the apartment ring, Andy explained more of the Sky Dome's special features. Sedna was interested in the modifications to the Farm that made the Sky Dome almost completely independent of land based food sources. Newt said it was a lot like what they were planning for the Space Pod. He said Andy had often helped them with that phase of development.

Among the other things Andy mentioned, he explained in more detail how the cable suspension allowed the cylinder to be drawn up inside the dome balloon for protection or lowered below it for better visibility and drone access.

"In transparent mode the balloon works well to capture solar heat energy, but it distorts the view, and that's one of our best features."

"So solar heat keeps you aloft?" Sedna asked.

"Not completely. We get constant upward thrust from the DDM engines, and there's always some waste heat from the electrical converters. The three give us enough lift to keep it aloft. Then the DDM thrusters also provide steerage way. In fact, we do most of our cruising at night, so we can use the extra lift when we don't have solar heat."

Andy's tour took them to the top of the farm cylinder, and from there onto the roof where a transparent dome covered both the Farm and the apartment ring. Looking up they could see where the thrusters were mounted, around the inside perimeter. They could also see several drone fliers hovering in the space, not projecting any avatar images.

"That's a service crew, probably doing a routine inspection. We have very little trouble with the equipment, but it's good to have that kind of access."

Sedna knew that even with the apartment structure raised up inside there would still be five hundred meters of space overhead to the top of the balloon. It was so big it was hard to make out any structural details. With the balloon transparent she might as well have been looking at the open sky. She wondered aloud what it would look like at night.

"The lensing effect of the hot air does create some interesting distortions," Andy told her. He led them out an air lock and they soared up into the middle of the balloon, then out to the perimeter to inspect the sheath and the thruster mounts up close. "It's really handy for servicing to have the thrusters mounted inside the dome, and since DDM is unimpeded by the balloon we can do that." Sedna knew this of course, but remembered that early domes had fan thrusters mounted outside. She asked Andy, "How high have you flown it?"

"A balloon is no good beyond about ninety thousand feet," he said. "The air gets too thin. I think the highest we've gone is about seventy thousand."

"To go into space they would have to rely completely on thrusters," Newt added.

They all flew back down to the deck, and there the visitors said goodbye to Andy and headed back to Houston for dinner. On the way Sedna asked Newt what it would take to put a balloon in low Earth orbit, like they had been the night before.

"That's actually not a good plan for a balloon," he said.

"How come?"

"Well, it's not that it's really a problem. It's just the ballistics thing again. Aiming for a low Earth orbit would mean achieving near orbital velocity before completely leaving the atmosphere. As thin as the air is, it's too much to ask a balloon to withstand the wind and friction."

"If the balloon makes things difficult, couldn't we just leave it behind? "

Newt liked the way Sedna talked as if she was planning to make the trip. But he kept his answer technical. "Better to go straight up with just enough curve to keep the air speed zero, and plan on a higher, slower orbit. Besides, having the bag of air is good. Instead of venting it to equalize the pressure, we redesign the balloon to hold an atmosphere. Fifteen psi. Keep it sealed and carry the air with us. Recycle it slowly through the Farm to scrub out the CO2. Solves the water supply problem too."

"Sounds perfect."

"Almost. One more problem. Gravity. In orbit we'll be weightless. Messes with the Farm."

"So what do we do? Keep accelerating?"

"That's one way. Just enough to counter Earth's pull at whatever distance we choose. But of course that means anything that is in orbit at that altitude would go whizzing by like a bullet. Or hit us like one."

"Not so good then. Any better ideas?"

"Two balloons could pair up and use a long tether to spin around each other, like bolas."

"And you have this all figured out?"

"Yup. Show you tomorrow."