Although it was not strong enough to harm spacecraft, the microwave probes were no match for its power.

"I'll bet it can be used to open the spacecraft.

In front of them was a huge panel that could open to permit spacecraft to pass through the airlock, and on either side of it were sets of doors to allow men through.

"We already concluded that the ability to sheath spacecraft and even asteroids comes from an alien intelligence more advanced than our own race.