Basically, a few years ago, I was working on an as-of-yet-unpublished novel set on Mars. A consortium of four countries -- Israel, Canada, Germany, and Japan -- have established a research base on Mars. I decided that two of the Israeli characters would be Orthodox Jewish, so I could have fun playing with the very questions of applying Jewish law in a science fictional setting.
(By the way, this is a game a lot of us like to play. Nomi was even on a panel about such things at last year's Worldcon, called "Jewish Time-Based Mitzvoth in a Lunar Colony." Nomi mentions the panel in her con report here, but you can find more detail in Lis Riba's report here and in Evelyn Leeper's report here.)
Now, when I need a halakhic ruling on a science fiction or fantasy question, I go to one particular rabbi I know. I won't mention his name here, but I will note that he is always careful when giving me a ruling to confirm that I need it for a work of science fiction. I imagine that if I were really moving to Mars, he'd want to consult more sources and make sure his ruling was completely accurate.
The nice thing about SF halakha is that we already have precedent to argue from. Time travel question? We've dealt with the question of how to observe a fast day if you find yourself flying over the International Date Line on that day; must you skip it entirely or observe it for 48 hours? (The first answer someone usually gets is, "Don't fly over the International Date Line on a fast day." They're encouraged to alter their travel plans if possible. But if one must cross the Date Line, one simply observes a regular fast day period.)
So here's three of the questions I had to research and a little background to help you understand each one.
I should make clear before going on that I am neither a rabbi nor a halakhic authority. Everything I am about to relate is simply based on what I've heard from others. Should you really be planning to go into Low Earth Orbit or Mars, please consult your local rabbi for an official ruling.
1. When does one observe shabbat in orbit?
As I noted above, this question has already been answered by a responsum from the Conservative movement, on behalf of Col. Ilan Ramon, I'm not going to repeat everything that David Golinkin says, but I will note that since the ruling came from the Schechter Institute, it technically means that we don't yet have an Orthodox ruling on these issues. However, most SF-oriented Orthodox Jews I've spoken to tend to agree that when the Orthodox movement finally is called upon to make a ruling, the results will probably be the same.
The answer according to the responsum is that one who is on the space shuttle orbiting the Earth observes shabbat according to Houston time, since the shuttle mission follows Houston time, as that is where Mission Control is located. However, it is interesting to note that one might argue for the shuttle to follow Cape Canaveral times, since that is the location from where the shuttle launches. That argument is based on the older concept of how one observes shabbat on a ship. Essentially, one marks off the hours as if you were still in the port from which you left. You only start marking the hours for the new location once you've arrived.
Relevant side note: When Nomi's father was working for Mitre, he had to travel to Alaska a few times. And during the time of year he would be in Alaska, the Sun was not going to set where he was living. Shabbat starting time is always determined by local sundown, so this would seem to imply that he would not need to observe shabbat when he was there, but he doubted that would actually be the case. So he consulted his rabbi on when to keep shabbat, and this was the ruling he got:
If you're traveling to a place like Alaska not to live permanently but merely to stay for a short time, you observe shabbat times by following the times in your home community and then translating those times to where you are now. So a Boston Jew in Alaska for shabbat would see what time shabbat starts in Boston, and then start shabbat at that same time in Alaska according to Alaska local time.
However, things change if you're visiting a place with an established Jewish community. In that case, you follow the precepts of the community. And how does an Alaskan Jewish community figure out when shabbat starts, given half a way with no sunset and half a year with no sunrise? They draw a line down the line of longitude from their location to the first city that has a) an established Jewish community and b) actual sundown. And then they follow that community's time.
Rulings such as these allow us to answer questions such as:
2. How does one determine a Jewish calendar on Mars?
This was the big question I needed an answer for. According to the rabbi I consulted, the Jews on the ship would follow the Jewish calendar according to either mission control or from where they launched. (Another opinion suggests that they should follow Jerusalem time.) However, since Mars has its own day and year cycle, once they landed on Mars they would start counting a new Jewish calendar from when they landed.
For example, let's say that they land on Mars on the 23rd of Elul according to the calendar they've been keeping. The next Martian day will be the 24th of Elul for them, and so on, even though that puts them out of sync with everyone on Earth. (The Martian day is about 24 hours 40 minutes.)
By the way, a few years ago I got unofficial confirmation that there's a Chabad on Babylon 5. Presumably they follow Earth standard time (based on Geneva in the TV series, I believe) when it comes to determining shabbat starting times.
3. How does one build a mikvah on Mars?
Finally, this was a real problem. A mikvah, or ritual bath, requires a certain amount of natural water in the bath . The natural water must come directly from a natural source, such as rainwater. This presents a problem on Mars, where there is no rain or natural flowing water. The only solution the rabbi and I came up with was to build a network of pipes from the polar ice cap and use heating lamps to melt the ice as required. At first glance, this might seem to be a lot to do simply to provide a ritual bath used by only one member of the base once a month. But I could justify it by having the base use the network of pipes for all their water, and then the extra pipe for a mikvah is an easy addition.