Shiva Purana
दूरश्रवण विज्ञानमदृश्यं बहुरूपधृक् ॥ सतताभ्यासयोगेन खेचरत्वं प्रजायते ॥ २२ ॥
He is farsighted, knowledgeable, invisible and assumes many forms. By the combination of constant practice one becomes an astronaut.
english translation
dUrazravaNa vijJAnamadRzyaM bahurUpadhRk ॥ satatAbhyAsayogena khecaratvaM prajAyate ॥ 22 ॥
hk transliteration by Sanscript