WITH CONTINUING INTEREST in space travel, increasing technological and economic prowess, and the fact that many of the space-faring nations soon will be largely Catholic, we can imagine that the Mass will be celebrated in outer space. And so, it is not too speculative to consider how the Mass ought to be celebrated there.
We take so many things for granted here on Earth, like constant gravity, a breathable atmosphere, a 24 hour day, a 365 day year, a definite 'up', and so forth, which would not be necessarily found in the heavens. Future space-liturgists could perhaps take two paths of dealing with the special conditions found in the Great Void: either enculturating the Mass to local conditions to such a degree that it becomes unrecognizable, or a moderate approach that makes minor, prudent changes to the rubrics as needed. The latter way, I think, is best, and fits in with the Catholic tradition.
Imagine, if you will, a Benedictine monastery in low-Earth orbit. An obvious problem is that the sun rises every ninety minutes or so, which kind of messes up the daily cycle of the Divine Office, because Matins ought to be in the dark of early morning, Lauds before dawn, and Vespers at dusk. Clearly, a regular conventional time would have to be kept, perhaps tied to Greenwich Mean Time. Keeping a regular 24-hour schedule for times of sleeping, prayer, and work would allow the monks to keep to the Rule, despite the actual position of the sun. It would be prudent, or even psychologically necessary, to continuously vary the lighting in the monk's cells and chapel according to the hours in the liturgical 'day', simulating an Earth day.
Zero gravity is much more of a problem. As a child, I was led to believe that in the future everyone would wear silver spandex jumpsuits, which are hardly appropriate for religious or clerical wear, but certainly Earth-clothing won't work either, since they often rely on gravity to keep them on. Skirts, for example, would be completely immodest in zero gravity. Vestments would not stay on in zero gravity: copes, stoles, mitres, pectoral crosses, and birettas would not stay put and just fly away. A simple solution, however, that would keep the tradition, would be discrete use of tie cords and velcro at strategic places to keep everything in place.
I would not think that zero gravity would affect much the praying of the Divine Office; keeping the monks in reasonable order would probably require seat-belts in the choir stalls, as well as tying down the prayer-books so they won't get loose and fly around the chapel, which could be both dangerous and distracting.
Far more problematic is the celebration of the Mass in zero gravity.
Not only is it nearly impossible to constantly order an orbiting oratory towards the orient, there is no 'up' in orbit either, gravitationally speaking. So when the priest raises the host for veneration after consecration, in which direction will he raise it? Imagine the chaos of clergy and congregation floating around the chapel, drifting in whichever direction, constantly bouncing off of each other! Pardon me, Father, I didn't mean to put my foot in your face. A solution to this problem would be defining a liturgical 'up' in the chapel as well as a liturgical 'east'. Since pews are completely unneeded in space, perhaps the priest and congregation could be kept 'vertical' with velcro or magnets in their shoes, attaching them to the 'floor', keeping everyone more or less pointed in the same direction. More problematical would be kneeling for the consecration, since weight no longer keeps people in that prayer posture; perhaps parishioners could hold onto a kind of space prie-dieu fixed to the 'floor'. They could hold onto the communion rail similarly.
A traditional chalice and paten will not work at all in zero gravity. Not only would it be a sacrilege to have the Body and Blood of our Lord floating around in a space ship, the species would probably not stay in place long enough to even consecrate them. First, the chalice and paten would need to be velcroed to the corporal, which in turn must be securely tied to the altar. Second, the Bread and Wine would need to be definitely confined to their sacred vessels, with some kind of lids for each. I would think that it would difficult to drink from an enclosed space chalice in any way except through a straw, which would pretty much rule out general communion for the laity with both species. Communion in the hand would not be practical either, since a 'dropped' Host could float off in any direction.
A minor problem is that candles and thuribles won't work at all without gravity; since the flames and smoke can't go up, the fires would be quickly snuffed out. A simple solution would be the installation of blowers, which would direct a small jet of air over the wick or incense, allowing the flames to keep going. Space thuribles would need to be redesigned, since Earth thuribles are suspended from chains, which need gravity: perhaps having the thurible on a rod would work just as well, allowing the use of existing rubrics.
Science fiction films nearly always show space ships with artificial gravity, even though there is no theoretical way to provide for this. Older fiction was more aware of this problem, and often portrayed space stations of circular shape, creating a normal gravity environment on the outside edge of the station due to centrifugal force, just like those amusement park rides that make your stomach turn inside out. There, the Mass could be celebrated quite normally.
On the Moon, an indoor Mass would pose no particular problems, although gravity is much less and the priest would have to be more careful, since the Eucharistic species are not held strongly in their vessels. When drinking from the chalice, the priest would have to raise the vessel very slowly, because spillage would be much more possible.
An outdoor Mass on the Moon would be more difficult. Priest and congregation would have to wear bulky space suits, and so vestments would have to be oversized. Since there is no air on the Moon to propagate sound, the priest, congregation, and choir all must be fitted with radio transmitters. Candles would have to be completely enclosed, as well as have their own oxygen supply. I'm not too sure how well those cheap pulp-paper missalettes would hold up under the extreme temperature conditions found on the lunar surface. Normal Earth liturgical vessels could be used, since there is some gravity, but wine exposed to the vacuum would immediately start boiling and evaporate into the nonexistent lunar atmosphere. How the congregation (or even the priest!) would receive Communion is quite problematic, unless there is some sort of small air-lock on their helmet visors. Communion, in this situation, could not be directly on the tongue.
Outdoor Masses on other planets would have their own problems, such as crushing atmospheric pressures, poisonous vapors, and extreme heat or cold which would either freeze the wine solid or burn the host and liturgical books and melt the vessels.
Some planets have excessive gravity. Getting up from a genuflection on Jupiter (yes, I know Jupiter does not have a solid surface!) would be difficult, and rising from a prostration would be a highly penitential exercise.
Other planets have day and year lengths different from Earth. There would be a temptation, I think, to enculturate the calendar to fit the conditions on the new planet, but this is a mistake. Certainly the major feasts, especially Easter, ought to be celebrated at the same time everywhere in the universe.
Liturgical bread and wine may be hard to come by in the cosmos, and some liturgists may want to substitute Spacebread and Synthwine made out of Martian rocks and alien space fungus. This should not be compromised: besides, grapes grow very well in lunar dust.