Where does it say that venerable Moggallana got lost in space? I've heard a story about venerable Moggallana (after he became enlightened). Moggallana, the left chief disciple of the Buddha, got lost in space when he tried to find the limits of the universe. Then when he was about to give up on life, the Buddha sent his aura(a beam of light) to show venerable Moggallana the way back to earth. Anyone has a reference to this story?
It is just a fable. It is not come from the ancient theravada pali cannon, both tipitaka and commentary. Because in Thailand we have many translated pali cannons, included those both, but no one found this fable in any cannon.

However, it maybe derived from SN Sagāthavagga, rohitassasutta, and KN Jātaka, javanahaṅsajātaka's commentary, which bodhisatta had helped the past life of moggallana.