Titan

CHAPTER TWO

INFORMATIONAL DISPATCH #0931

(REPLY TO HOUSTON TRANSMISSION #5455,5-20-25) 5-21-25

DSV RINGMASTER (NASA 447D, L5/1, HOUSTON-COPER- NICUS GCR BASELINE)

JONFS, CIROCCO, MISCOM

SECURITY INTERLOCK *ON* CODE PREFIX DELTADELTA BEGINS.

1. Concur your analysis of Themis as interstellar space vehicle of the generation type. Don't forget we suggested it first.

2. Latest photo follows. Note increased resolution of bright areas. Still no luck finding docking facilities at hub; will keep looking.

3. Concur your mid-course scheduled 5122.

4. Request updated tracking as new orbital insertion is approached, begi

5. Turnaround 5122,0400 UT, after the mid-course bum. 22

WORMA'EONALENDS PERSONAL (CIRCULATION LIMITED TO RINGMASTER MISSION CONTROL COMMN-TEE) BEGINS:

Re the Contact Committee which has been bending my car: 'buzz off!' I don't care WHO'S on the damn thing. I've been get- ting contradictory instructions that sound like they have the

force of direct orders. Maybe you don't like my ideas of how to handle this, maybe you do. The fact is it's going to have to be my show. Time-lag alone is enough to make that necessary. You gave me the ship and the responsibility, so 'GET OFF MY BACK!'*

ENDS

Cirocco hit the ENCODE button, then TRANSMIT, and leaned back in her chair. She rubbed her eyes. A few days ago there had been too little to do. Now she was snowed under with the status cheek to ready Ringmaster for orbital insertion.

Everything was changed, and all by those six tiny points of light in Gaby's telescope. There seemed little sense in exploring the other Saturnian moons now. They were committed to an early rendezvous with Themis.

She called up the schedule of things still to be done, then the duty roster, saw it had been rearranged again. She was to join April and Calvin outside. She hurried to the lock.

Her suit was bulky and tight. it murmured at her while the radio hissed quietly. it smelled comfortably like herself, and like hospital plastic and fresh oxygen.

Ringmaster was an elongated structure consisting of two main sections joined by a hollow tube three meters in diameter and a hundred meters long. Structural strength for the tube was provided by three composite girders on the outside, each of which transmitted the thrust of one engine to the life system balanced on top of the tube.

At the far end were the engines and a cluster of detachable fuel tanks, hidden from sight by the broad plate of the radiation shield which ringed the central tube like the rat guard on the mooring line of an ocean-going freighter. The other side of that shield was an unhealthy place to be.

On the other end of the tube was the life system, consisting of the science module, the control module, and the carousel.

Control was at the extreme front end, a cone-shaped protuberance rising from the big coffee can that was SCIMOD. It had the only windows on the ship, more for tradition than practicality.

The Science Module was almost hidden behind a thicket of instrumentation. The high-gain ante

Just behind it was the carousel: a fat, white flywheel. It rotated slowly around the rest of the ship, with four spokes leading up from the rim.

Strapped to the central stem were other items, including the hydroponics cylinders and the several components of the lander: life system, tug engine, two descent stages and the ascent engine.

The lander had been intended for exploring the Saturn moons, in particular Iapetus and Rhea. After Titan-which had an atmosphere and was therefore unsuited for exploration this trip-Iapetus was the most interesting body in the neighborhood. Until the 1980's, it had been significantly brighter in one hemisphere, but it had changed over a twenty-year period until its albedo was nearly uniform. Two troughs in the graph of luminosity now occurred at opposite points on its orbit. The lander had been designed to discover what caused it.

Now that trip had been scrapped in the face of the much more compelling object called Themis.

Ringmaster resembled another spaceship: the fictional Discovery, the Jupiter probe from the classic movie 2001.. A Space Odyssey. It was not surprising that it should. Both ships had been designed from similar parameters, though one sailed only on celluloid. Cirocco was EVA to remove the last of the solar reflection panels which wrapped the life system of Ringmaster. The problem in a space vehicle is usually one of disposing of excess heat, but they were now far enough from the sun that it paid to soak up what they could get.

She hooked a safety line around a pipe that went from the carousel hub to the airlock, and faced one of the last panels. It was

silver, a meter square, made of two sheets of thin foil sandwiched together. She touched the screwdriver to one corner and the device clucked as it found the slot. The counterweight rotated. It gulped the loose screw before it could drift away.

Three more times and the panel floated away from the layer of anti-meteorite foam beneath. Cirocco held it and turned to face the sun, conducting her own informal puncture survey. Three tiny, bright lights marked where the sheet had been hit by grains of meteoritic dust.

The panel was held rigid by wires along the edges. She bent two of these in the middle. After the fifth fold it was small enough to fit in the thigh pocket of her suit. She fastened the flap, then moved to the next panel.

Time was at a premium. Whenever possible they combined two chores, so the end of the ship's day found Cirocco reclining on her bunk while Calvin gave her a weekly physical and Gaby showed her the latest picture of Themis. The room was crowded.

"It's not a photo.," Gaby was saying. "It's, a computer- enhanced theoretical image. And it's in infra-red, which seems to be the best spectrum."

Cirocco raised herself on one elbow, careful not to dislodge any of Calvin's electrodes. She chewed on the end of the thermometer until he frowned at her.

The print showed a fat wagon wheel surrounded by broad- based, bright red triangular areas. There were six red areas on the inside of the wheel, but they were smaller, and square.

"The big triangles on the outside are the hottest parts," Gaby said. "I figure they're part of the temperature control system. They soak up heat from the sun or bleed off the excess."

"Houston already decided that," Cirocco pointed out. She glanced at the television camera near the ceiling. Ground control was monitoring them. If they thought of something Cirocco would hear of it in a few hours, asleep or not.

The wheel analogy was almost literally true, except for the heating or cooling fins Gaby had indicated. There was a hub in the center, and it had a hole which could have taken an axle if

Themis had actually been a wagon wheel. Radiating from the hub were six thick spokes which flared gradually just before joining the outer portion of the wheel. Between each pair of spokes was one of the bright, square areas.

"This is what's new," Gaby said. "Those squares are angled. They're what 1 originally saw; the six points of light. They're flat, or they'd scatter a lot more light. As it is they only reflect light to Earth if they're at just the right angle, and that's rare."

'What kind of angle?" Cirocco - lisped. Calvin took the thermometer out of her mouth.

"Okay. Light comes in parallel to the axis, from this angle." She moved an extended finger toward the print. "The mirrors are set to deflect the light ninety degrees, into the wheel roof." She touched the paper with her finger, turned the finger, and indicated an area between two spokes.

"This part of the wheel is hotter than the rest, but not so hot that it could be soaking up all the heat it gets. It's not reflecting it or absorbing it, so it's transmitting it. It's transparent or trans- lucent. it lets most of the light go through to whatever's underneath. Does that suggest anything to you?"

Cirocco looked up from her careful examination. "What do you mean?"

"Okay. We know the wheel is hollow. Maybe the spokes are, too. Anyway, picture the wheel. It's like a car tire, big and fat and flat on the bottom to give more living space. Centrifugal force pushes you away from the hub."

"I've got all that," Cirocco said, slightly amused. Gaby could he so intense when explaining something.

"Right. So when you're standing on the inside of the wheel, you're either under a spoke, or under a reflector, right?"

"Yeah? Oh, yeah. So-" "So it's always either daytime or nighttime at any particular spot. The spokes are rigidly attached, the reflectors don't move, and neither can the skylights. So it has to be that way. Permanent day or permanent night. Why do you think they'd build it that way?"

"To answer that, we'd need to meet them. Their needs must he different from ours." She looked back at the picture. She had to keep reminding herself of the size of the thing. Thirteen hundred meters in diameter, 4000 around the outer rim. The prospect of meeting the beings who built such a thing was worrying her more each day.

"All right. 1 can wait." Gaby was not that interested in Them- is as a spacecraft. To her it was a fascinating problem in observation.

Cirocco again looked at the picture.

"The hub," she began, then bit her lip. That camera was still ru

"What about it?"

"Well, it's the only place you could dock with the thing. The only part that's motionless."

"Not the way it is now. That hole in the middle is pretty big. The first time you reach anything solid, it's moving at a pretty good clip. 1 can calculate-"

"Never mind. It's not important right now. The point is, only at the very dead center of rotation could you dock with Themis without a great deal of trouble. 1 sure wouldn't want to try it."

"So? "

"So there must be a compelling reason why there's no docking facilities visible there. Something important enough to sacrifice that location, some reason for leaving a big hole in the center."