The Rolling Stones (11 page)

“
Silence!
” When he got it he went on as if to himself, “It says right here in the book to give orders, not explanations, and never to let them be argued. So help me, I’m going to run a taut ship if I have to put my own mother in irons.” He raised his voice. “All hands! Prepare for maneuvering. Departure for Mars, gravity-well procedure.”

Edith Stone said softly to Hazel, “The baby is all right, Mother. I’m sure.” Then she turned to her sons. “Castor, Pollux—come here, dears.”

“But Dad said—”

“I know. Come here first.” She kissed each of them and said, “Now man your stations.”

Meade appeared at the hatch, towing Lowell behind her like a toy balloon. He seemed cheerful and his face was cheerfully smeared with chocolate. “What’s all the racket about?” she demanded. “You not only woke us; you must be disturbing people three ships behind.”

IN THE GRAVITY WELL

A
GRAVITY-WELL MANEUVER

involves what appears to be a contradiction in the law of conservation of energy. A ship leaving the Moon or a space station for some distant planet can go faster on less fuel by dropping first toward Earth, then performing her principal acceleration while as close to Earth as possible. To be sure, a ship gains kinetic energy (speed) in falling toward Earth, but one would expect that she would lose exactly the same amount of kinetic energy as she coasted away from Earth.

The trick lies in the fact that the reactive mass or “fuel” is itself
mass
and as such has potential energy of position when the ship leaves the Moon. The reactive mass used in accelerating near Earth (that is to say, at the bottom of the gravity well) has lost its energy of position by falling down the gravity well. That energy has to go somewhere, and so it does—into the ship, as kinetic energy. The ship ends up going faster for the same force and duration of thrust than she possibly could by departing directly from the Moon or from a space station. The mathematics of this is somewhat baffling—but it works.

Captain Stone put both the boys in the power room for this maneuver and placed Hazel as second pilot. Castor’s feelings were hurt but he did not argue, as the last discussion of ship’s discipline was still echoing. The pilot has his hands full in this maneuver, leaving it up to the co-pilot to guard the auto-pilot, to be ready to fire manually if need be, and to watch for
brennschluss.
It is the pilot’s duty to juggle his ship on her gyros and flywheel with his eyes glued to a measuring telescope, a “coelostat,” to be utterly sure to the extreme limit of the accuracy of his instruments that his ship is aimed exactly right when the jet fires.

In the passage from Earth to Mars a mistake in angle of one minute of arc, one sixtieth of a degree, will amount to—at the far end—about fifteen thousand miles. Such mistakes must be paid for in reactive mass by maneuvering to correct, or, if the mistake is large enough, it will be paid for tragically and inexorably with the lives of captain and crew while the ship plunges endlessly on into the empty depths of space.

Roger Stone had a high opinion of the abilities of his twins, but, on this touchy occasion, he wanted the co-pilot backing him up to have the steadiness of age and experience. With Hazel riding the other couch he could give his whole mind to his delicate task.

To establish a frame of reference against which to aim his ship he had three stars, Spica, Deneb, and Fomolhaut, lined up in his scope, their images brought together by prisms. Mars was still out of sight beyond the bulging breast of Earth, nor would it have helped to aim for Mars; the road to Mars is a long curve, not a straight line. One of the images seemed to drift a trifle away from the others; sweating, he unclutched his gyros and nudged the ship by flywheel. The errant image crept back into position. “Doppler?” he demanded.

“In the groove.”

“Time?”

“About a minute. Son, keep your mind on your duck shooting and don’t fret.”

He wiped his hands on his shirt and did not answer. For some seconds silence obtained, then Hazel said quietly, “Unidentified radar-beacon blip on the screen, sir. Robot response and a string of numbers.”

“Does it concern us?”

“Closing north and starboard. Possible collision course.”

Roger Stone steeled himself not to look at his own screen; a quick glance would tell him nothing that Hazel had not reported. He kept his face glued to the eyeshade of the coelostat. “Evasive maneuver indicated?”

“Son, you’re as likely to dodge into it as duck away from it. Too late to figure a ballistic.”

He forced himself to watch the star images and thought about it. Hazel was right, one did not drive a spaceship by the seat of the pants. At the high speeds and tight curves at the bottom of a gravity well, close up to a planet, an uncalculated maneuver might bring on a collision. Or it might throw them into an untenable orbit, one which would never allow them to reach Mars.

But what could it be? Not a spaceship, it was unmanned. Not a meteor, it carried a beacon. Not a bomb rocket, it was too high. He noted that the images were steady and stole a glance, first at his own screen, which told him nothing, and then through the starboard port.

Good heavens! he could
see
it!

A great gleaming star against the black of space…growing—growing!

“Mind your scope, son,” said Hazel. “Nineteen seconds.”

He put his eye back to the scope; the images were steady. Hazel continued, “It seems to be drawing ahead slightly.”

He had to look. As he did so something flashed up and obscured the starboard port and at once was visible in the portside port—visible but shrinking rapidly. Stone had a momentary impression of a winged torpedo shape.

“
Whew!
” Hazel sighed. “They went that-a-way, podnuh!” She added briskly, “All hands, brace for acceleration—five seconds!”

He had his eye on the star images, steady and perfectly matched, as the jet slammed him into his pads. The force was four gravities, much more than the boost from Luna, but they held it for only slightly more than one minute. Captain Stone kept watching the star images, ready to check her if she started to swing, but the extreme care with which he had balanced his ship in loading was rewarded; she held her attitude.

He heard Hazel shout, “
Brennschluss!
” just as the noise and pressure dropped off and died. He took a deep breath and said to the mike, “You all right, Edith?”

“Yes, dear,” she answered faintly. “We’re all right.”

“Power room?”

“Okay!” Pollux answered.

“Secure and lock.” There was no need to have the power room stand by, any corrections to course and speed on this leg would be made days or weeks later, after much calculation.

“Aye aye, sir. Say, Dad, what was the chatter about a blip?”

“Pipe down,” Hazel interrupted. “I’ve got a call coming in.” She added, “
Rolling Stone,
Luna, to Traffic—come in, Traffic.”

There was a whir and a click and a female voice chanted: “Traffic Control to
Rolling Stone,
Luna—routine traffic precautionary: your plan as filed will bring you moderately close to experimental rocket satellite of Harvard Radiation Laboratory. Hold to flight plan; you will fail contact by ample safe margin. End of message; repeat—” The transcription ran itself through once more and shut off.

“
Now
they tell us!” Hazel exploded. “Oh, those cushion warmers! Those bureaucrats! I’ll bet that M-S-G has been holding in the tank for the past hour waiting for some idiot to finish discussing his missing laundry.”

She went on fuming: “‘Moderately close!’ ‘Ample safe margin!’ Why, Roger, the consarned thing singed my eyebrows!”

“‘A miss is as good as a mile.’”

“A mile isn’t nearly enough, as you know darn well. It took ten years off my life—and at my age I can’t afford that.”

Roger Stone shrugged. After the strain and excitement he was feeling let down and terribly weary; since blast-off he had been running on stimulants instead of sleep. “I’m going to cork off for the next twelve hours. Get a preliminary check on our vector; if there’s nothing seriously wrong, don’t wake me. I’ll look at it when I turn out.”

“Aye aye, Captain Bligh.”

First check showed nothing wrong with their orbit; Hazel followed him to bed—“bed” in a figurative sense, for Hazel never strapped herself to her bunk in free fall, preferring to float loosely wherever air currents wafted her. She shared a stateroom with Meade. The three boys were assigned to the bunkroom and the twins attempted to turn in—but Lowell was not sleepy. He felt fine and was investigating the wonderful possibilities of free fall. He wanted to play tag. The twins did not want to play tag; Lowell played tag anyhow.

Pollux snagged him by an ankle. “Listen, you! Weren’t you enough trouble by being sick?”

“I was not sick!”

“So? Who was it we had to clean up after? Santa Claus?”

“There ain’t any Santa Claus. I was not sick. You’re a fibber, you’re a fibber, you’re a fibber!”

“Don’t argue with him,” Castor advised. “Just choke him and stuff him out the lock. We can explain and correct the ship’s mass factor tomorrow.”

“I was not sick!”

Pollux said, “Meade had quite a bit of sack time on the leg down. Maybe you can talk her into taking him off our hands?”

“I’ll try.”

Meade was awake; she considered it. “Cash?”

“Sis, don’t be that way!”

“Well…three days’ dishwashing?”

“Skinflint! It’s a deal; come take charge of the body.”

Meade had to use the bunkroom as a nursery; the boys went forward and slept in the control room, each strapping himself loosely to a control couch as required by ship’s regulations to avoid the chance of jostling instruments during sleep.

THE MIGHTY ROOM

C
APTAIN
S
TONE HAD ALL HANDS

with the exception of Dr. Stone and Lowell compute their new orbit. They all worked from the same data, using readings supplied by Traffic Control and checked against their own instruments. Roger Stone waited until all had finished before comparing results.

“What do you get, Hazel?”

“As I figure, Captain, you won’t miss Mars by more than a million miles or so.”

“I figure it right on.”

“Well, now that you mention it, so do I.”

“Cas? Pol? Meade?”

The twins were right together to six decimal places and checked with their father and grandmother to five, but Meade’s answer bore no resemblance to any of the others. Her father looked it over curiously. “Baby girl, I can’t figure out how you got this out of the computer. As near as I can tell you have us headed for Proxima Centauri.”

Meade looked at it with interest. “Is that so? Tell you what: let’s use mine and see what happens. It ought to be interesting.”

“But not practical. You have us going faster than light.”

“I
thought
the figures were a bit large.”

Hazel stuck out a bony forefinger. “That ought to be a minus sign, hon.”

“That’s not all that’s wrong,” announced Pollux. “Look at this—” He held out Meade’s programming sheet.

“That will do, Pol,” his father interrupted. “You are not called on to criticize Meade’s astrogation.”

“But—”

“Stow it.”

“I don’t mind, Daddy,” Meade put in. “I knew I was wrong.” She shrugged. “It’s the first one I’ve ever worked outside of school. Somehow it makes a difference when it’s real.”

“It certainly does—as every astrogator learns. Never mind, Hazel has the median figures. We’ll log hers.”

Hazel shook hands with herself. “The winnah and still champeen!”

Castor said, “Dad, that’s final? No more maneuvers until you calculate your approach to Mars?”

“Of course not. No changes for six months at least. Why?”

“Then Pol and I respectfully request the Captain’s permission to decompress the hold and go outside. We want to get to work on our bikes.”

“Never mind the fake military-vessel phraseology. But I have news for you.” He took a sheet of paper out of his belt pouch. “Just a moment while I make a couple of changes.” He wrote on it, then fastened it to the control room bulletin board. It read:

Hazel looked it over. “Where are we headed, Rog? Botany Bay? You forgot to set a time to flog the peasants.”

“It seems very reasonable to me.”

“Possibly. Six gets you ten it won’t last a week.”

“Done. Let’s see your money.”

The twins had read it with dismay. Pollux blurted out, “But Dad! You haven’t left us any time to repair our bikes—do you want us to lose our investment?”

“I’ve assigned thirty hours of study a week. That leaves one hundred and thirty-eight other hours. How you use them is your business as long as you keep our agreement about studying.”

Castor said, “Suppose we want to start math at eight-thirty and again right after lunch? Can we get out of school that much earlier?”

“I see no objection.”

“And suppose we study evenings sometimes? Can we work up some velvet?”