Up where? Do you know what "Raki'a" refers to? You seem to agree it is not the stratosphere (which rockets reach in seconds) - so what is it? Interplanetary space? Or intergalactic space? Or a spiritual concept altogether - measured in something spiritual called "years"?

Even if it refers to plain years, why should you assume it refers to years of rocket travel, rather than years of travel by foot or chariot (or light years)?

I think the Gemara is too vague and we can't ask this type of question on it.

Be well,

Mordecai Kornfeld