Emergency air lock open!'The tall, broad-shouldered officer, wearing the magnificent black-and-gold uniform of the Solar Guard, spoke into a small microphone and waited for an acknowledgment. It came almost immediately.'Cadet Corbett ready for testing,' a voice crackled thinly over the loud-speaker.'Very well. Proceed.'Seated in front of the scanner screen on the control deck of the rocket cruiser Polaris, Captain Steve Strong replaced the microphone in its slot and watched a bulky figure in a