Alan E. Nourse 
The Link [EPUB ebook] 

It was nearly sundown when Ravdin eased the ship down into the last slow arc toward the Earth’s surface. Stretching his arms and legs, he tried to relax and ease the tension in his tired muscles. Carefully, he tightened the seat belt for landing; below him he could see the vast, tangled expanse of Jungle-land spreading out to the horizon. Miles ahead was the bright circle of the landing field and the sparkling glow of the city beyond. Ravdin peered to the north of the city, hoping to catch a glimpse of the concert before his ship was swallowed by the brilliant landing lights.