The Earth Saver — Catherine Wells

Tana Winthrop had finally managed to transport herself aboard the long-lost ship Homeward Bound, with the aid of a new technology. But when she found the ship, its surviving members living on Earth, an idyllic life on a beautiful, healthy planet, Tana's arrival had reopened the door to the stars, and once, again, and Earth was at risk of destruction. She faced the most important battle of her life, as word of the new technology and the newly vibrant Earth began to spread. Time was running out, and Tana was forced to face the prospect of defeat, unless she found help from an impossible source--a legendary hero who had been dead for over two hundred years....