One can, however, reach heavenly planets by virtuous activities, but one can never expect to go beyond Svarga or Janaloka by such mechanical or materialistic activities, either gross or subtle
SB Canto 2
The transcendentalists are concerned with the spiritual body. As such, by the strength of their devotional service, austerities, mystic power and transcendental knowledge, their movements are unrestricted, within and beyond the material worlds. The fruitive workers, or the gross materialists, can never move in such an unrestricted manner.
The materialistic scientist's endeavor to reach other planets by mechanical vehicles is only a futile attempt. One can, however, reach heavenly planets by virtuous activities, but one can never expect to go beyond Svarga or Janaloka by such mechanical or materialistic activities, either gross or subtle. The transcendentalists who have nothing to do with the gross material body can move anywhere within or beyond the material worlds. Within the material worlds they move in the planetary systems of the Mahar-, Janas-, Tapas- and Satya-loka, and beyond the material worlds they can move in the Vaikuṇṭhas as unrestricted spacemen. Nārada Muni is one of the examples of such spacemen, and Durvāsā Muni is one of such mystics. By the strength of devotional service, austerities, mystic powers and transcendental knowledge, everyone can move like Nārada Muni or Durvāsā Muni. It is said that Durvāsā Muni traveled throughout the entirety of material space and part of spiritual space within one year only. The speed of the transcendentalists can never be attained by the gross or subtle materialists.