http://en.wikipedia.org/wiki/Religion_in_space

Muslims aboard the International Space Station (ISS) have struggled with fulfilling their religious obligations including kneeling and facing Mecca to pray in microgravity traveling at thousands of miles per hour. The issue first came up when Sultan bin Salman bin Abdulaziz Al Saud a Saudi Prince flew aboard STS-51-G and again when Anousheh Ansari flew as a tourist to the international space station. [3] In preparation for Malaysia's Sheikh Muszaphar Shukor trip to the ISS in 2007, the National Fatwa Council created "Muslim Obligations in the International Space Station" outlining permissible modifications to rituals such as kneeling when praying (not required in space), facing Mecca when praying (left to the astronaut's best abilities at the start of prayer), and washing (a wet towel will suffice).

http://www.csmonitor.com/2007/1010/p16s02-stss.html

And so the Malaysian National Space Agency (MNSA) and its Department of Islamic Development held a two-day conference in April last year. They invited 150 scholars, scientists, and astronauts to discuss "Islam and Life in Space." The result is a recently published booklet of guidelines for the faithful Muslim astronaut.
Five times a day (before sunrise, at midday, in late afternoon, after sunset, and at night), earth-bound muezzins call Muslims to prayer. A spaceship traveling 17,400 miles per hour orbits the earth 16 times in a day. Does that mean praying 80 times in 24 hours?
The guidelines are much more reasonable: Daily prayer in space is not linked to sunrises and sunsets, but to a 24-hour cycle based on the "home" time zone of Baikonur, the Russian-leased launch site in Kazakhstan. Five meditations every 24 hours will suffice.
If interrupting work to pray is not possible, the astronaut may practice a shorter version of the prayer or combine midday and afternoon prayer times, or the evening and night ones.
The next problem: Where is Mecca?
Muslims on Earth face Mecca, in central Saudi Arabia, when they pray. The MNSA suggests that the astronaut pray toward Mecca as much as possible, or at the Earth in general. But if it becomes necessary, the astronaut may simply face any direction.
The attitude while at prayer is also an issue. In zero gravity, the sequence of the praying postures – standing, bowing, kneeling, and prostrating oneself – is difficult at best. Malaysian Islamic authorities say the astronaut should stand, preferably. If he can't stand, he should sit. If he can't sit, he should lie down. And if he can't do any of those, he's allowed to symbolically indicate the postures "with his eyelids" or to simply imagine them, according to the MNSA booklet.
Before worship, a Muslim must perform ritual washing – cleaning face, hands, arms, feet, and hair. The problem: Water on the ISS is so precious that even sweat and urine are recycled. And so the Muslim astronaut is permitted "dry ablution." In desert areas on earth, Muslims use dirt and sand to clean the hands. The astronaut will strike his palms on a wall or mirror – though this is not likely to raise any dust.

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