One Earth Space Defense engineers were ready to test a prototype planetary-wide forcefield.

"How will we know it's effective?" asked Space Commander Erika Jones.

"We’ll know immediately when the Martian Republic launches another strike," answered the chief engineer.

"I certainly hope so. They're developing an EMP bomb capable of crippling an entire continent."

"It'll work, ma'am."

"Fire when ready."

Sure enough, the Martians launched a barrage of interplanetary missiles exploding within their own terraformed atmosphere.

"Chief, did you miscalculate something? The forcefield isn't surrounding Earth."

"Correct, ma'am. Mars can now be designated a prison planet."

"Even better!" clapped Commander Jones.