I invite people to read this delightful Rand study. It does not rule out
far fetched possibilities but simply takes alot of observed facts and
infers things which are not immediately obvious.
For example, ALL life has cells, all cells are based on water and water can
only exist between 32 and 212 farenheight. Therefore it is "suggested"
that if life existed on other planets it would be in the 32-100 degree
range. We actually reach a conclusion.
In a similar vein I am claiming that all Judaic theorists believe that the
soul during life must coexist with a body. The mystics all teach that G-d
wanted "residence" in the lower worlds and created man for that purpose.
What is man? Simply an animal who can recognize G-d.
Once we grant this we can start deducing universal mitzvoth. All bodies
need food, water, shelter ,ownership,procreation and all who recognize G-d
need "dialog" with Him. Thus any planet that can support life would invite
a desire by G-d to be present: one species would get a soul, and then this
animal-soul species would require the same laws we have: Laws governing
diet, ownership, modesty, learning, prayer, places for prayer(Temples etc).
Let me ask a specific halachic question: Can a Jew marry a person on
another planet if that person has a Torah like ours, believes in prophecy,
Russell Jay Hendel; Ph.d.;ASA; rhendel @ mcs . drexel . edu