Across Time by David Grinnell

High in their mountain watchtower, testing a new device for tracking aircraft, Carl Halleck and his wife, Sylvia, saw blips on their radar screen that signaled the approach of unidentified flying objects. They signaled Captain Zachary Halleck, back at the farmhouse, to turn off all power immediately! Zack recognized those blips, quickly turning into green dots, drawing closer to the isolated secret Air Force research station. They were exactly the same objects Zack had encountered earlier while test piloting the latest jets for the U.S. Air Force. His skirmish with the UFO on that occasion had hospitalized him, resulting in his being sent here to assist the brother he hated and the sister-in-law who should have been his wife. “Turn off the power now, goddamit - it’s attracting them!” came the cry from the tower. Captain Halleck’s hand closed on the switch, but he didn’t finalize his move. He waited, his eyes fixed on the screen, anticipating the flare of light; then silence.

Attracted by power radiating from the isolated secret Air Force research station, unidentified flying objects are closing in fast. With his hand on the switch to turn off all power, Captain Halleck doesn’t finalize his move. Instead he waits, his eyes fixed on the screen, anticipating the flare of light; then silence.

Mission to a Star by Frank Belknap Long

It began with the sighting of the Scorpion ships in the new 400-inch reflecting telescope on Mount Palomar. The ships landed on Earth to disgorge aliens quite indistinguishable from human beings, except that they were all apparently equal to the genius level of human beings. And, all were in perfect physical condition. They came in peace, they said. Their leader spoke to a plenary session of the United Nations — nations truly united now in the face of what might be a threat to all the peoples of Earth — and he talked as if he were talking to old and trusted friends. He said, "You have asked for proof that we are a responsible and enlightened race. There can be no wisdom without strength, no true enlightenment unless the power to work immense harm exists and is deliberately renounced. We have come to Earth on a scientific mission only, just as someday you will travel to the stars. We ask only complete freedom, your friendship, trust, and understanding as long as we choose to remain."

The Scorpion ships landed on Earth and disgorged aliens quite indistinguishable from human beings. They said they came in peace. Speaking to the United Nations the leader said, “…We have come to Earth on a scientific mission only, just as someday you will travel to the stars. We ask only complete freedom, your friendship, trust, and understanding as long as we choose to remain."

The Rim of Space by A. Bertram Chandler

(This is volume one on the Rim World series)

Derek Calver touches down on Lorn and is determined to join the Rim Runners to explore desolate planets. He joins the crew of Lorn Lady and sets forth for Mellise, which is inhabited by intelligent amphibians; for Groller, where the natives have just qualified as humanoids; for Stree, with its tea-loving lizards; and for Tharn, home of a pre-industrial civilization.