Desert Perimeter

"Escorting merchant convoys and evacuating citizens."

That pretext held for seven days.

May 11, C.E. 71. North Africa, 160 kilometers beyond the Tunisia-Libya border.

Han Zheng looked out from the cockpit of the modified Black Iron unit. The panoramic display showed an endless brownish-yellow gravel plain, with a surface temperature of fifty-three degrees Celsius. Cold air blew against his back from the cooling vents in the seat, but everything below the collar of his pilot suit was already soaked through.

Tian Mu's voice came through the comm channel, muffled as though he were speaking inside a steamer.

"Brother Han, Unit Two's right knee joint has triggered a temperature warning. Eighty-seven degrees. What should the normal upper limit be?"

"Sixty-five."

"Then I'm twenty-two degrees over."

"Try shortening your stride by twenty percent. Reduce the frequency of joint flexion."

Tian Mu fell silent for a few seconds. Then came the sound of sand crunching beneath his feet as he adjusted his gait.

"Seventy-nine now. It dropped a little. But walking like this feels like wading through water. Speed's down by a third."

Liu An from Unit Three cut in, his throat obviously parched.

"Captain Han, Unit Three's Bombard Gun ammunition belt preheat indicator has turned yellow. We need to confirm the thermal stability of the propellant in this high-temperature environment."

Han Zheng brought his unit to a stop and opened Jiachen's diagnostic interface. The ammunition belt was at forty-one degrees, still nine degrees below the propellant's sensitive range, but the trend line had been steadily climbing.

"Deputy Officer Sheng, did you receive the joint and ammunition belt data?"

Sheng Lan's voice came from the communications vehicle in the rear escort convoy, accompanied by the droning background noise of a generator.

"Received. The joint cooling issue is more severe than expected. The desert's radiant heat wasn't sufficiently sampled in the SEED Framework's climate simulations. Where's Professor Xu?"

From a communications terminal at the 811 Institute eight thousand kilometers away, Xu Yanqiu's voice burst through.

"Tell them to remove the auxiliary cooling plate on the outside of the right knee joint."

Tian Mu's eyes widened in the cockpit.

"Remove it? Professor Xu, that plate is part of the bulletproof structure."

"Bulletproof my ass. Is anyone shooting at you right now? There's an insulating gasket between the auxiliary cooling plate and the main joint housing. In high temperatures, that gasket turns into insulation instead. Remove the auxiliary plate so air can blow directly onto the joint housing, and the temperature can drop by fifteen to twenty degrees."

Han Zheng glanced at the desert outside.

"Professor Xu, is this a temporary solution or a design flaw?"

The comm channel went silent for three seconds. Xu Yanqiu's voice dropped half a beat.

"A design flaw. The joint cooling module was originally designed for temperate climate conditions. We never considered extreme environments above fifty degrees. We'll fix it after you return."

Sheng Lan added a note to the memorandum in the communications vehicle, the handwriting slanting at one corner from the vehicle's bumps.

"Professor Xu, what about the ammunition belt temperature?"

"The ammunition propellant's heat-sensitive range begins at fifty degrees. You're at forty-one now, so you still have a nine-degree window. But after two in the afternoon, that window will shrink to less than five degrees. Have the pilots finish any live-fire testing before noon. In the afternoon, rely on the ammunition sunshades to get through it. Once night falls, the temperature will naturally drop."

Sheng Lan tucked her pen into her pocket.

"Han Zheng, adjust today's route plan. The escort convoy will stop where it is. The three Black Iron units will advance to the coordinates for cooling tests and high-temperature firing data collection with the Bombard Guns, then return before two in the afternoon."

"Received. Tian Mu, Liu An, remove the auxiliary cooling plates first. The tool kits are in the external storage compartments on your left legs."

Viewed from the observation camera atop the communications vehicle, the three Black Iron units crouched in the sand and removed armor plates like three gray giants squatting on the Gobi to repair tractors.

Han Zheng took seven minutes to remove his own plate. Just as he was about to stand, a line of text suddenly appeared on Jiachen's tactical display.

Bearing 217 degrees. Distance 4,600 meters. Four moving heat sources detected. Speed: 35 kilometers per hour. Carrying metallic objects.

Han Zheng pulled his hand back from the tool kit and gripped the control stick.

"Deputy Officer Sheng, we've got a situation here. Jiachen detected four moving heat sources to the southwest."

Sheng Lan's voice immediately tightened.

"ZAFT?"

"Not sure. Too slow for MS units. Possibly armed vehicles."

Ye Qingluan's voice came from the communications vehicle. She had only arrived with the convoy through an intelligence channel twenty minutes earlier.

"Han Zheng, don't open fire."

"Why?"

"Desert Tiger's ZAFT frontline troops are sixty kilometers east of us. They wouldn't appear in this direction using armed vehicles. Those four moving heat sources are most likely scout vehicles from a local resistance group."

Tian Mu's voice came from Unit Two, his tone tightening.

"Resistance groups have anti-armor rockets too, Team Leader Ye."

The moment he finished speaking, an object trailing white smoke flew out from behind a sand dune and struck the sand fifteen meters ahead of Black Iron Unit One's right side. An orange-red explosion threw up a wall of sand, while stone fragments clattered against the Ceramic Steel leg armor.

Tian Mu's comms exploded.

"Fuck, they opened fire!"

"Do not return fire!" Han Zheng pushed the control stick forward. Black Iron Unit One took a step, its nineteen-meter-tall dark-gray body positioning itself in front of the escort convoy.

A second rocket followed immediately, striking the Ceramic Steel external plate on Unit One's left arm. The warhead detonated, its flames spreading into a circle of black scorch marks across the gray armor, but the plate did not budge.

On Jiachen's tactical display, the positions of the four heat sources had already been locked. Trajectory backtracking marked the coordinates of the launch point.

Han Zheng lowered the Bombard Gun's barrel, aimed at the air thirty meters above the launch point, and pulled the trigger.

A drill round left the barrel. Its rocket booster erupted into a dazzling orange fireball in midair. The blast wave rolled over the dunes with sand and dust, shaking every grain of loose sand off the hoods of the armed vehicles opposite them.

The comm channel fell silent.

Han Zheng raised the gun back to its standby position and remained motionless in the desert.

Thirty seconds later, Ye Qingluan's comms rang. The transmission came from a contact frequency reserved by the East Asian Intelligence Bureau.

A hoarse male voice on the other end spoke a sentence in Arabic. The translation software lagged half a beat before catching up.

"You aren't United Army?"

Ye Qingluan's voice was flat, without a trace of warmth.

"No. East Asian Republic escort convoy, for citizen evacuation."

The channel was silent for five seconds.

"East Asia?"

Another five seconds passed.

"That iron coffin belongs to you?"

Hearing the term in the cockpit, Han Zheng's lips twitched.

Ye Qingluan did not respond to that description. She only said one thing.

"Put away the rockets. We can talk."

Several low voices discussing something came from the other end, mixed with the sputtering idle of engines.

The hoarse voice returned.

"We can talk. But there's a large United Army ship eighteen kilometers behind you in that direction. If you're with them, there's nothing to discuss."

Sheng Lan's hand paused over her memorandum in the communications vehicle.

In the lower-right corner of Han Zheng's panoramic display, Jiachen silently refreshed a line of data.

Bearing 039 degrees. Distance 17.6 kilometers. Large metallic structural heat source detected. Ninety-two percent match with known vessel signature database.

Match result: Archangel.