The following is taken from “The Holy Quran in Today’s English” by Yahiya Emerick under the commentary of the above verse (note 165):
(You may) eat and drink until the white thread of dawn appears distinct from its black thread. Then fast until the night approaches again,
Commentary (Note 165):
People who live in the extreme north or south of the globe, where there are prolonged periods of dark and light, must observe the fast according to a regular timetable that reflects the rhythms of normal life elsewhere on the globe. Once a man asked the Prophet what people would do if they lived in a place where there was shortened day or night, and he responded, “Then go by normal days.” i.e., fix a schedule regardless of the movement of the sun. This principle can be applied to prayer during space travel, as well.
Emerick, Yahiya. The Meaning of the Holy Qur’an in Today’s English (p. 827). Unknown. Kindle Edition.