Prayer: Praying When the Qibla is Unknown
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 771
If someone does not have any means to find the direction of qibla, or despite his efforts, he cannot arrive at a supposition as to its direction, it is sufficient for him to perform prayers facing a direction that he thinks could be qibla. Furthermore, the recommended precaution is that if there is enough time, he should perform prayers four times, each time facing one of the four compass directions [i.e. what he supposes to be north, east, south, and west].