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Up, Away, and Beyond

If the /Princess Ark/ can fly into space, so can your D&D(R) game PCs!
Space travel in the D&D(R) game
by Bruce Heard

The Known World on which D&D(R) adventures are set is slightly smaller than our Earth, with about the same shape and with a similar atmosphere. Outer space is a vast, airless void, with planets, moons, and other celestial bodies. However, there are certain major laws of physics (Unalterable & Universal Principles) that affect the universe of that world:

/UUP #1:/ Magic is omnipresent in the D&D game, which allows DMs to alter "reality" as they like to fit their fiendish schemes and any general game needs of the moment.

/UUP #2:/ The D&D game is first and foremost a game that puts the emphasis on role-playing and simplicity rather than on hard science (the D&D game hardly qualifies as realistic!).

/UUP #3:/ There are no such things as hard rules or preconceptions of any type, including the UUPs themselves, except for Principle #4 (also referred to as the Golden Principle).

/UUP #4:/ This is a game meant solely for your enjoyment. Have fun, folks! It's /your/ game and /your/ world.

Those of you who use the AD&D(R) game's SPELLJAMMER(TM) accessory may find it simpler to use that set to handle space travel in the D&D game. The SPELLJAMMER set is generic and straightforward enough to be used much as it stands with the D&D game. But for those looking for a different feel, here's an optional approach.

*Gravity in D&D(R) game space*

Planets, moons, and asteroids exert gravity in proportion to their mass. Any object with a mass equal to or greater than 20,000 cn exerts an attraction; smaller objects do not.

In the D&D game universe, the direction of gravitational attraction depends on the shape of the object, specifically on /curvature/. Gravity on a roughly spherical body is directed toward the centre of the body. If the object has no curved surfaces, a /gravity plane/ comes into effect, and you run the risk of falling off the world if you walk too far. To understand how this works, imagine the way that an object would float if it was tossed into a gigantic pool of water. The surface of the water would then show the exact location of the gravity plane in relation to the object. What lies above the surface of the water is within the /positive gravity field/. What lies below the surface of the water is in the /negative gravity field/. The positive field pulls things toward the surface of the gravity plane. The negative field pushes things away from the gravity plane. In other words, everything goes /down/ (see diagram 1). Things that fall off a world, falling "down," continue falling through space until they strike something, which could take eons (living beings would have long since died of air loss). Because space is three-dimensional, the gravity planes of different world could be oriented in different directions and might even be mobile, changing as the worlds themselves rotate or revolve.

There is a second important gravitational effect called /neutral gravity/. The body of a very large object, such as a planet, generates a cohesive force that holds the object together (friction does the same for smaller objects, such as for ships that are nailed or pegged together). Neutral gravity does not affect anything on an object's surfaces, either outside or inside (in tunnels, on the lower decks of a ship, etc). Neutral gravity has no equivalent with common laws of physics affecting other game worlds. Think of it as "cosmic glue."

*Odd examples of gravity*

*Disk-shaped world:* A disk-world would "float" flat on one side, with the gravity plane right across its thickness. This allows the existence of exotic flat worlds, but they need to be slightly concave or have walls or mountains around their edges in order to retain atmospheres. Air currents and atmospheric pressure keep the bulk of air circulating from the edges down toward the centre, then up from the centre and back toward the edges (see diagram 2). Some disk worlds rotate as they revolve around their suns, giving them day and night cycles, but some face always toward or away from their suns. Some also spin like records, producing spiral cloud patterns and winds of up to hurricane strength. Flat worlds are loved by cartographers because they are so easy to map.

*Planetoid shard:* A shard is a roughly conical section that broke away from a spherical planet during a collision between worlds or other planetary disaster. These strange planetoids are often found among asteroid clusters containing debris from the original world.

The sharp edge of a shard's cone points downward. A section of the original planet's surface remains on the round edge on top of the shard. The sharp point of the cone must be made of a material (usually an iron or nickel alloy) dense enough to stabilise that world in an up-down position (see diagram 3).

The shard's gravity field is unusual. Having once been a part of a spherical planet, it retains its former gravitational field so that gravity is directed from its rounded top down toward the pointed end of the cone, once at the core of the shard's world. This arrangement allows life to exist on the shard's top surface if there are mountains or walls ringing the edges of the top surface to prevent the loss of its atmosphere, or if there is a deep valley or crater on top in which an atmosphere can be kept. The lower part of the shard remains in the negative gravity field and is therefore devoid of any atmosphere.

*Cylinders:* These worlds are partially round, so gravity on the rounded surface of such a world is directed down towards the long axis of the cylinder. Gravity along the flat "top" and "bottom" sides is directed straight down through the cylinder. Like spheres, cylinder worlds can retain their own atmospheres, though walking from the rounded side to a flat side is very disorienting. Cylinders can spin along their long axes, producing day and night if oriented properly. Cylinder worlds, like disk worlds, are easy to map.

*Ships:* A space going skyship has to be very carefully balanced, just like a normal seafaring vessel, or else it will list so badly that its hapless crew would have to walk on bulkheads to remain upright! Then, too, the gravity plane on a poorly balanced ship could suddenly shift, causing the crew and atmosphere to fall off into space (see diagram 4).

Air can easily be trapped in a ship's hull, provided the hull is airtight. Unfortunately, the air on the deck slowly flows downward off the deck and into space. One way of retaining a viable environment on the ship's deck--other than making the ship look like an ungainly tub--involves having each crewmember on deck wear an item permanently enchanted with a third-level /create air/ spell (see Book Three, page 22, in the /Dawn of the Emperors/ boxed set) to provide supplies of both oxygen and air pressure. A good example is the /airmask/ presented in this issue's "The Voyage of the /Princess Ark/."

The ship itself could be enchanted to create and maintain its own air supply, but a modified /create air/ spell is needed to prevent air loss into space. This new spell is a fourth-level enchantment spell called /create atmosphere/. This spell is virtually the same as the /create air/ spell, except that it holds the air within an 8,000 cubic-foot space. The spell-caster conveniently determines the exact shape of the breathable area. For example, thanks to the spell, an 80'x10'x10' area on the deck could become breathable. Just as conveniently, entire areas could be left in vacuum for security reasons. Of course, the addition of /climate/ enchantments would not be a bad idea, either (see Book Three, page 22, in the /Dawn of the Emperors/ boxed set). Keep in mind that a hold in the ship's hull would be a catastrophe, since the air on the ship would then escape down through the hold and into space.

Planets and other celestial bodies are most often found in one of the previously mentioned forms, most commonly as spheres, disks, and cylinders. Artificially created objects can be of any shape, but care is required to ensure that gravitation on them performs as expected. Experience with the principles of voodoo astrophysics can be helpful. What is gravity like on a cone-shaped world that is not a shard? As you see, space travel in the D&D game world can be far more bizarre than sea navigation.

*Where are the AD&D(R) game worlds?*

Before tackling the connection with AD&D 2nd Edition game, it would be useful to clarify the existence of the D&D game world in relation to the AD&D game universe. The various AD&D game worlds occupy physical positions in space. These worlds can be reached by spelljammer ships. The D&D world and its universe /do not exist at all/ in the AD&D world, which explains why they were not mentioned in the SPELLJAMMER(TM) boxed set. The two universes cannot be connected by normal space navigation. This leaves three alternatives:

1. Keeping all D&D and AD&D campaigns separate.

2. Adapting a campaign world from one game system to another game system's rules (e.g., the Known World to the AD&D game, or Oerth to the D&D game).

3. Having existing characters from one game system travel to another game system's world and be converted to the latter game's rules.

The first alternative is by far the quickest--provided that everyone is interested in rolling up new characters and possibly learning a completely new set of rules!

The second alternative is probably the best, but it requires a lot of preparation on the part of the DM.

Finally, moving existing characters from one universe into another by altering those characters to fit the latter system is the trickiest option. Beware: You may not like this! This will involve the alteration of the characters' physical attributes and personal memories to fit the new world. The problem lies in the fact these characters may have certain attributes that do not work with the other set of rules, especially when converting AD&D game characters to the D&D game. For example an elven thief would become either a thief or an elf in the D&D game, and he would forget all past knowledge of the "lost" class!

To travel from one game universe to another, the characters must invoke a /reality shift/. This is different from opening a magical /gate/ or casting a /wish/. The /reality shift/ causes the character to travel not only across space and parallel dimensions, but also across the very fabric of reality, which causes the characters' transformation. The characters would not actually be aware of this alteration. Incompatible aspects of the character's cultural background, personal history, and memory are instantly and painlessly modified to fit the new world.

Characters returning from a trip across a /reality shift/ would instantly revert to their former selves. No experience is lost in the process, since the party would be "persuaded" that all of their adventures took place in whatever world they occupy! They simply cannot suspect or even grasp the concept that there are effectively two or more different realities.

For simplicity's sake, we'll establish that time flows in the same direction on both sides of the /reality shift/. A character spending 10 years in one reality before returning to his previous reality would reappear 10 years later and 10 years older as well.

/Reality shifts/ may be effected only by greater gods in the AD&D game or the most powerful Immortals of the D&D game. These deities would first have to discover the another universe /that logically does not exist/--something difficult to achieve even for them. Some of those divine beings crossed over and were subjected to the unavoidable transformation. Although unaware of their personal metamorphosis, divine beings retain their memories about their previous worlds, unlike mortals.

When a deity leaves for another reality, an alter ego of the deity is created. The alter ego is a metaphysical force whose usefulness lies in its ability to grant spells to worthy clerics in the deity's absence. When the deity returns, the alter ego dissipates (or reappears in the other reality, if the deity gained worshippers there).

Unless they are being worshiped in several realities, divine beings tend to remain in their home realities. They experience discomfort caused by the strange alteration of their senses when crossing realities, and they dislike the vague, unexplainable discrepancies between the two universes' realities. Even deities fear the unknown.

*Spelljammers in space*

Thanks to /reality shifts/, a spelljammer ship from the AD&D game could end up on the Known World, and a skyship could appear over Krynn or Toril. Fortunately, the /reality shift/ allows the transformation of any ship to match its alternate setting.

The main difference between the SPELLJAMMER set's background and the D&D setting suggested here is the way in which gravity functions. Spelljammer ships have a gravity plane, but both sides of a spelljammer's gravity field pull toward that plane. This means that people can actually walk on the underside of their ship's hull. This also means that the crew must walk on the ceilings of the decks located on the other side of their ship's gravity plane.

D&D ships are propelled by /fly/, /levitation/, or similar spells, or through the use of very fine sails that trap particles of energy travelling across open space (also called /solar winds;/ see M1 /Into the Maelstrom/). These huge currents of energy could be mapped out like rivers, and great speeds could be progressively attained with those "winds." Since small boats do not generate their own gravity, passengers must use seat belts to stay aboard them!

Of course, some spelljammer ships would not be suitable in D&D game space, such as the illithids' nautiloid, which would end up with its gravity plane sideways. Outriggers would be a must for that kind of ship to survive.

*Cast-off & re-entry*

Building flying ships is very difficult, even by Alphatian standards. Huge amounts of time, manpower, and gold are required. Building vessels capable of reaching space is a different (and even more difficult) matter. As a general rule, this requires the careful use of /reverse gravity/ enchantments in several areas of the ship's structure. These spells should be triggered when the ship reaches the maximum altitude allowed by her weight and the planet's attraction.

There is a persistent rumour that very large monsters, such as dragons, are physically capable of reaching space. Hooking a vessel to one or more of these creatures might just do the trick. Once in space, the creatures are freed, since the ship can manoeuvre on her own.

In the case of the Known World, there is a curious phenomenon routinely described in Alphatian schools of air navigation as /tubular breaches/. These dangerous turbulences are caused by an anomaly to the Known World's gravity field due to the inner structure of the planet itself. (More on the origins of this phenomenon will be revealed in later issues of DRAGON Magazine.) A tubular breach is an area where gravity reverses itself. The phenomenon is temporary, varies greatly in strength, and occurs only at very high altitudes. A tubular breach was observed once at the peak of a very high mountain in Glantri. The breach was a weak one, but strong enough to pick up rocks and gravel with which to shower a nearby monastery when the breach ended.

A tubular breach can be used to enter space. First a breach must be located, usually by observing the upper layers of clouds (tubular breaches cause a billowing funnel of clouds to rise toward space). Then the ship must enter the breach while performing a barrel roll--a perilous manoeuvre requiring crack airmen. If the breach is long enough, the ship reaches space safely. If not, the ship goes into a dive and immediately regains a normal flight configuration. Needless to say that: a) heavy warships and cargo ships cannot perform this manoeuvre; b) all sailors and equipment must be appropriately secured.

Re-entry is normally not a problem for relatively slow-moving vessels such as those described in the D&D game. The ship descends rapidly to its maximum air altitude, then slows down as desired.

It is possible to build a simpler vessel made solely for space travel. It would have no limits on its size, but it would have to be either transported to or built in space. This type of vessel would not be able to navigate within a planet's atmosphere. If it somehow re-entered an atmosphere, it would tumble, break apart, and crash to the ground at terminal velocity--with no survivors.

By now you should have the basics required for space travel in D&D games. Just remember never to re-enter an atmosphere upside down, right? Farewell.

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