when the Space Mushroom blew, but there won't be anything left of the alien ship but plasma.”
Capt. Curtis calculated in her head. “We are 500 km from the alien ship, we should be OK, even if the main store blows. Get the shuttles and the corvettes well away.” As the navigation officer called for the other ships of the task force to head away from the hulk the Captain issued commands to her crew. “Shields to maximum, Mr. Medina, and set all viewports to opaque...”
Marine Boarding Party, Alien Hulk
At the edge of the hole Washington lunged forward, grabbed Lt. Westfield by the leg and hauled him back from the opening. The two shuffled sideways, away from the hole and then stopped, their backs pressed against the inside of the alien hull.
As the timer ticked down, the dead captain's scuttling charge moved away from his ship at over 100 kph. The storage container held a bit less than a kilogram of antimatter. When it detonated 21 seconds later it was half a kilometer away from the ship's hull. As the freed antimatter annihilated material in the surrounding container it released the energy equivalent of a 20 megaton nuclear bomb.
About 50% of the energy of a matter/antimatter explosion is lost to neutrinos, which do no damage to normal matter and living things. The rest is released as pure energy—mostly photons energetic enough to be well beyond any light visible to humans. After mutual annihilation, any excess matter is irradiated by the torrent of gamma rays resulting in a bright visible flash. The flash, however, is a relatively feeble manifestation of the overall electromagnetic burst.
When a nuclear or AM explosion happens in the vacuum of space its effects are significantly different than such a blast in an atmosphere or in contact with a solid body. First, without material for a shockwave to propagate through, blast effect disappears completely.
Second, thermal radiation also disappears. There is no air for the blast wave to heat and the radiation emitted from the weapon itself is much higher in frequency. That radiation can be more intense without an atmosphere to attenuate it. In fact, the unprotected lethal radius of a multi-megaton blast can extend to hundreds of kilometers.
A shaft of radiation poured through the hull breach, causing everything in its path to flare brightly—aliens, girders and braces alike. A radiant circle was inscribed on the inside of the hull opposite the opening. Fortunately for the Marines they were not in the path of that awful wave of radiation. The combination of the alien ship's four meter thick metal and rock hull and their own armor's shielding protected them from the explosion's EM burst.
Slowly, Marines began reemerging from where they had taken cover before the explosion. Captain Rodriguez pulled up the status of everyone in the boarding party on her helmet's holographic display. By some miracle, it looked like everyone made it. A few readouts were showing a bit of reflected radiation but nothing life threatening. Rodriguez sounded the all clear and several of the Marines drifted down to the opening of the fuel bunker, including Westfield and Washington.
“Thank you for saving my life, Gunny,” Dirk said on suit-to-suit as they neared the front of the bunker.
“Just returning the favor, Lieutenant. If you hadn't chucked that bomb overboard we all would have bought the farm.”
Westfield had not had a chance to report to his CO in person before the bomb diverted their attention. This time he fervently hoped there would be no interruption.
“I believe we got the lot of them, Captain,” he said, floating up to Capt. Rodriguez. “We should probably make a second pass to make sure we didn't miss any hostiles but it looked like all those that didn't get caught when the inhabited spaces decompressed went with the captain on his suicide charge aft.”
“Yeah, I don't think any got past us either, but we need to double check before they send over any
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