Page 37 of Daikon

NINETEEN

THE JOB OF PREPARING THE Renzan bomber had continued around the clock since Keizo Kan’s and PO Yagi’s arrival at Tama Airfield.

Two of the four engines, eighteen-cylinder Nakajima Homares, were being overhauled, fuel pumps and compressors tested and replaced when found less than perfect.

Bearings had been repacked with grease, fuel lines and electrical systems inspected, along with all flight controls leading to the wings and the tail.

As darkness came on, tarpaulins were placed over the gaping holes in the roof of the hangar so that work could continue in blackout conditions.

A fresh team of mechanics came on duty. They worked on the plane all through the night and into the next day, testing and checking and then checking again.

It involved the four nubs that had been attached to the projectile assembly, at the rear end of the stack of uranium rings.

They were tiny, smaller than the end of his little finger.

But he knew from the moment he saw them that they were important.

This was confirmed when he removed them from the assembly and discovered with the Geiger-Müller counter that they were highly radioactive, much more so than the uranium to which they had been attached. What purpose did they serve?

The quest to understand them took him back to a more innocent time, to his studies under Dr. Robert Oppenheimer at UC Berkeley. Pure theory.

So you want to be a physicist.

Kan smiled at the memory. That had been Oppenheimer’s greeting when they first met in Room 219 in LeConte Hall, Kan invited to explain the research he had done in Japan.

Mostly childish, had been Oppenheimer’s devastating assessment. He turned away to light one of his ever-present cigarettes, not noting the shocked look on the face of his newest graduate student.

But this research you did on cosmic rays, he continued. A courageous piece of work. I think you might do well here.

Kan studied the nubs for a long time, turning them over in his hand.

All four were identical. They consisted of two pieces of gray metal, shades slightly different, separated by a thin layer of what appeared to be gold.

Could Oppenheimer’s mind be behind them?

Or perhaps his old classmate, Stanley J. Rothstein?

It was only after separating one of the nubs that Kan was able to deduce their purpose.

Although similar in appearance, the two metal halves were very different.

One half was light. A specific gravity test revealed it had a density of just 1.

85 grams per cubic centimeter. Apparently it was beryllium.

And the other half, a soft metal, yielding to Kan’s thumbnail—this was where the high levels of radioactivity came from. Its specific gravity was 9.2, in the vicinity of lead.

But lead wasn’t radioactive.

Polonium was.

Kan closed his eyes, visualizing the uranium-235 projectile fired into the U-235 target to form a critical mass.

A critical mass in the presence of beryllium and polonium, kept separate from each other by a thin layer of gold.

The beryllium and polonium would crush together when the projectile smashed into the target, creating a burst of neutrons that would accelerate the chain reaction at the critical moment, ensuring that more of the U-235 atoms fissioned before the mass blew apart.

That would greatly enhance the explosion.

“An initiator,” he murmured.

So then what was the silvery plating on the inside surface of the projectile rings, the plating that would come into contact with the identical plating on the exterior of the smaller rings in the nose? Kan’s initial conjecture that this was an initiator was wrong. But perhaps…

The final piece of the puzzle fell into place.

The plating was titanium, or cadmium, a neutron absorber.

It would rein in the chain reaction for a fraction of a second when the two uranium masses came together, allowing supercriticality to build.

Then the initiators on the trailing edge of the projectile would crush together as they smashed into the assembled uranium mass, beryllium and polonium melding to create a neutron burst.

Boom.

The process was elegant. And the discovery pleased him. The hint of a smile came into Kan’s face as he joined the beryllium and polonium pieces back together with a small daub of glue.

He was finding his right hand, red and swollen, increasingly painful to use.

The hangar was empty when Kan exited the workroom. The Renzan had been towed outside and was parked in the daylight. He had been so caught up in his thoughts that he had hardly heard the engines being tested.

He walked over to the plane, becoming aware that his legs felt weak. Mechanics were working on the outboard starboard engine. Another pair of men were atop a scaffold, brushing black paint onto the front of the plane. The bomb bay doors were open, sparks raining down.

Kan ducked underneath the aircraft and looked up into the bomb bay. Yagi and another man were perched inside, welding an iron cradle to the frame of the Renzan for the Daikon to rest on. Another shower of sparks.

“I think we’re ready to finish the assembly,” Kan said, shielding his eyes.

“Almost done,” said Yagi.

More sparks raining down. Kan stepped away.

One of the mechanics working on the engine was descending from his stepladder. Kan noted a look of frustration on his face.

“Is there a problem?” he asked.

The mechanic fetched his canteen. “The fuel is shit. We got barely fifteen hundred horsepower from this one.” He took a long drink. “Did you hear the news?”

Kan nodded glumly. “Now we have to fight the Soviets, too.”

“No, I mean Nagasaki. The Yankees used another new-type bomb.”

“Nagasaki?”

“It’s gone.” The mechanic took another drink and screwed the cap back on his canteen. “They wiped it out.”

Kan stood frozen, the vision of Hiroshima flooding back into his brain.

First Hiroshima and now Nagasaki. Counting the weapon in the hangar behind him, that meant the Americans had succeeded in building at least three atomic bombs.

And if they could build three, they could build more.

They possessed a destructive power that was almost without limit and were unleashing it against Japan.

He jumped at the touch of a hand on his shoulder.

It was Captain Onda. “Let’s go into the office,” he said.

“Yagi-heisō!” Onda called up into the bomb bay as they passed. “Come to the office! I have good news!”

“Yes, it’s true,” said Onda, closing the door. “The Americans attacked Nagasaki yesterday, just before noon. From what we’re learning, the effect was more or less the same as at Hiroshima.”

“Nagasaki,” murmured Yagi. “I knew guys from there.”

“Has this changed Colonel Sagara’s thinking?” Kan asked hopefully. “About the mission?”

Onda gave him a sharp look. “Changed his thinking? How?”

“It just seems…” Kan stopped to consider his words.

He tried again. “I was wrong about the Americans’ ability to build this type of weapon.

I advised Sagara-chūsa incorrectly, and for that I’m sorry.

I realize now that the Americans are far beyond what I ever imagined could be possible.

And so I wonder if the mission might be considered… futile.”

Onda’s eyes grew wide. “Futile! Our mission is even more critical now!”

He went to the map on the wall showing the Japanese empire in 1942.

“You asked about our target.” He stabbed his finger at the Mariana Island chain in the middle, almost directly south from Tokyo.

“It’s here. The B-29 that crashed outside Hikari, the one carrying the device Yagi-heisō recovered—it took off from here.

Tinian Island. So did the B-29 that attacked Hiroshima.

So did the plane that attacked Nagasaki.

If the Yankees have more of these weapons, then this is where they are.

Here.” He tapped the speck on the map. “Tinian Island. So that’s why our mission is even more critical.

If the Americans have more of these bombs, we have to stop them. Do you understand now?”

Kan lowered his head, abashed. “Yes. I see.”

Onda unfolded a second map he had been carrying and smoothed it out on the desk. It showed the island itself, twelve kilometers long by six kilometers wide, a large airfield situated at the north end.

He pointed out the airfield. “The bombers took off from here. V600 Special Task Planes. This is where they’re based, at Tinian’s North Airfield. Previously our airfield. It’s much larger now, covers the whole north end of the island. The Yankees expanded it for their B-29s.”

Kan looked up from the map. “What are V600 Special Task Planes?”

Onda explained. He then gestured toward the Renzan parked outside the hangar.

“With that, we’ll destroy them. The reports we’ve gotten from Hiroshima confirm your estimates, Sensei.

About thirty square kilometers of almost total destruction.

If our bomb is as powerful, it will easily destroy the entire airfield complex, the whole north end of the island. ”

Kan bent down to study the Tinian map more closely.

Onda was probably right. If the Americans possessed additional atomic weapons ready for immediate use, they were likely here.

The northern part of the island was approximately five kilometers by five, well within the limits of the devastation he had witnessed at Hiroshima.

Unlike Hiroshima, moreover, there were no surrounding hills to contain the blast. Judging from the minimal contour lines depicted on the map, Tinian’s north end was relatively flat. The Daikon would wipe it clean.

But wouldn’t the Americans just build more bombs? And use a different airfield?