Realistic Space Travel

When speaking of space travel, it is important to distinguish interplanetary travel from interstellar travel. Travel between planets is within the grasp of modern technology and is likely to become easier as science develops new fuel sources or new ways to maximize existing fuel sources. Travel between stars, on the other hand, calls for some truly radical leaps in a number of different fields. Realistically, the starships presented in the Starships section are capable only of interplanetary travel, not interstellar travel.


[h=2]Hazards of Space TravelL[/h] Space travel is nowhere near as easy as books and movies make it seem. Foreign objects are a constant danger; even a micrometeoroid traveling at a high enough velocity can punch a hole through a starship’s hull and expose the entire crew to the vacuum of space. Ionizing radiation also poses a serious threat. Finally, characters must adapt to the weightlessness of space or suffer the effects of space adaptation syndrome (SAS), referred to colloquially as “space sickness.”
[h=4]Meteoroids[/h] Meteoroids are small rocks that travel through space at a speed of 7 miles per second. They can be as small as a grain of sand or as big as a mountain. Although they generally burn up in a planet’s atmosphere before reaching the ground, meteoroids in space aren’t likely to suffer such a fate. Instead, they slam into other objects, including starships and space stations, like volleys of rifle or artillery fire.

Unarmored starships and space stations can easily survive impacts from the smaller meteoroids, but larger ones can punch lethal holes in such fragile vessels. Fortunately, large meteoroids are rare and easier to detect before they can get too close to cause any real damage.

Roll on Table: Meteoroid Encounters to determine whether a meteoroid threatens a given starship or space station. Each roll represents one 24-hour period.

Meteoroid Size: The size of the meteoroid.
Collision Damage: When a meteoroid collides with a starship, space station, or other object, both the meteoroid and the object it strikes take damage.
Computer Use Check DC: A starship or space station equipped with a sensor system can detect an incoming meteoroid; doing so requires a successful Computer Use check. A starship or space station cannot attempt to avoid or destroy a meteoroid it fails to detect.
Pilot Check DC: Avoiding a meteoroid requires a successful Pilot check. Only starships or space stations that move are capable of avoiding meteoroids.
Defense: The meteoroid’s Defense.
Hardness: The meteoroid’s hardness.
Hit Points: The meteoroid’s total hit points.

[bar]Table: Meteoroid Encounters[/bar]
[h=4]Vacuum Exposure[/h] Beings exposed to the airless cold of space are not immediately doomed. Contrary to popular belief, characters exposed to vacuum do not immediately freeze or explode, and their blood does not boil in their veins. While space is very cold, heat does not transfer away from a body that quickly. The real danger comes from suffocation and ionizing radiation.

For rules on vacuum exposure and the effects of weightlessness, see Atmospheric Conditions and Gravity in the Environments section.
[h=4]Radiation[/h] Ionizing radiation is common in space. For the effects, see Radiation Sickness in the Environments section.
[h=4]Rentry[/h] Anything that travels too fast in an atmosphere generates an enormous amount of friction, which produces tremendous heat. (Temperatures of 2,280 degrees Fahrenheit have been recorded.) Objects trying to enter a planetary atmosphere safely must shed velocity. However, decelerating consumes large amounts of fuel, and many ships (especially at Progress Level 5) simply don’t have enough. As an alternative, scientists have developed ways to slow ships in reentry by using the atmospheric friction itself. Ablative shielding or ceramic tiles take care of any excess heat. Even so, entering a planet’s atmosphere is a tricky business; the angle of entry is precise, and deviation either way causes the heat to build up too quickly for the heat shields to reflect away from the ship. Worse yet, during the most intense heating, the ship is surrounded by a thin layer of plasma that blocks radio signals, and the crew have no contact with ground control.

Entering planetary atmosphere safely requires a Pilot check (DC 20) each round for the 1d10+20 rounds it takes to slow the ship using friction alone. Success means that the ship takes only 3d6 points of fire damage each round. Failure means that the ship’s angle is too low, and that it is not shedding velocity fast enough; the ship takes 6d6 points of fire damage each round until the pilot succeeds at the Pilot check to correct the angle of descent. If the check fails by 5 or more, the angle is too steep, and the ship takes 10d6 points of fire damage each round until the pilot succeeds at the Pilot check to correct the angle. Each round spent at too low an angle does not count toward the number of rounds required to land the ship; the ship isn’t making any downward progress. Conversely, each round spent at too steep an angle counts as 2 rounds, indicating that the ship is descending much faster than it should.
[h=2]Interplanetary Travel[/h] In Progress Level 5, humanity has the technology to send unmanned probes to the edge of the solar system. However, human sojourns into space are limited to orbital missions and trips to the Moon, as longer journeys would take decades and consume ridiculous amounts of fuel and oxygen.

Interplanetary travel becomes possible at Progress Level 6. Ships fitted with magnetic ram scoops allow the crew to manufacture fuel from particles of hydrogen gas floating loose in space (though at only a few atoms per cubic inch). Such a ship could even incorporate a particle accelerator that converts matter into antimatter—with far more efficient thrust-to-payload ratios than solid fuel. With a sufficient supply of food, water, and oxygen, a ship so equipped could travel to the edges of the solar system and perhaps to another solar system entirely.
[h=2]Interstellar Travel[/h] Realistically, the starships presented in the Starships section are capable only of interplanetary travel, not interstellar travel. The reason for this is simple: Even the best engine can’t accelerate a ship to light speed, and without light speed, interstellar journeys take tens of thousands of years. The speed of light is 186,000 miles per second. That’s 1,116,000 miles per round, or 66,960,000 miles per hour. Maneuvering a ship at this speed is a tricky proposition; by the time you notice an object in your path, it’s probably too late to avoid it. One must also consider relativity: The closer the ship’s velocity comes to the speed of light, the greater its mass. A starship cannot achieve light speed via simple acceleration, no matter how powerful the ship’s engine, as increasing the power only increases the mass.

The greatest impediment to traveling between the stars is time: What would be the point of sending astronauts to Alpha Centauri, for example, if, by the time they arrived, no one on Earth could remember why they’d gone in the first place? Time dilation—the slowing of the passage of time in relation to an object traveling at close to the speed of light—becomes a factor. A few years might pass on board the ship, while a few hundred years might have passed both at the ship’s point of origin and its point of arrival.
[h=2]Realistic Travel Times[/h] Table: Realistic Travel Times provides various “realistic” interplanetary and interstellar travel times. These times assume that starships cannot achieve velocities anywhere near the speed of light, for reasons discussed under Interstellar Travel (see above). Using the table, a starship equipped with a PL 6 ion engine would take 67.2 days to travel from Earth to Mars, while the same ship equipped with a PL 7 induction engine would take 16.8 days.

The travel times listed are based on average distance. Planets move closer together and farther apart based on their relative orbits around the sun, and the travel time between worlds may increase or decrease accordingly.

[bar]Table: Realistic Travel Times[/bar]
[h=5]Time Dilation[/h] When a ship approaches to within 90% of the speed of light, time slows down. Characters on board the ship would not notice, but if they were to make hourly reports back to their point of origin, those reports might arrive only once every hundred hours.
This creates an interesting paradox, in that if a character managed to travel at the speed of light to another star and back again, a newborn child he left behind would now be older than him—if the child hadn’t died of old age some time ago.

The actual amount of time dilation observed aboard a ship traveling near light speed increases in proportion to just how close it is to light speed. Technically, time dilation occurs at any speed, but it only becomes noticeable at relativistic speeds. The dilation is a ratio that determines how much time passes aboard the ship; it is a multiplier when determining how much time passes outside the ship.

For example, a ship moving at 70% the speed of light has a time dilation of 1.4. Ten hours of travel aboard the ship at this speed means that 14 hours (10 × 1.4) have passed outside the ship. However, if ten hours pass for those left behind, only 7.1 hours have passed aboard the ship (10 divided by 1.4).

[bar]Table: Time Dilation[/bar]

Starship Speed: The vessel’s speed in miles per second.
AU per Hour: How many Astronomical Units (AU) a vessel traveling at this speed can cross in 1 hour. One AU equals 93,000,000 miles (the distance between the Sun and the Earth).
% Speed of Light: The percentage of the speed of light (186,000 miles per second).
Time Dilation: Divide the time traveled by this number to arrive at the amount of time that passes on board the starship.
[h=2]Jump Gate Technology[/h] If a starship cannot reach the speed of light through sheer thrust, perhaps the answer lies in bending the laws of time and space so that the distance itself is shorter. A ship could then get around the need to travel at relativistic speeds, leaving behind the problem of increased mass and negating—if not actually reversing— the effects of time dilation. In other words, if one could find a shortcut through the galaxy, it might be possible for spacecraft to travel quickly between star systems, and perhaps even travel backward in time.

Shortcuts through space and time are called wormholes. Wormholes are created naturally when black holes collapse, though they tend to close so rapidly that a ship attempting to pass through would instead encounter a singularity—a point with infinite density and a radius of zero—and be instantly crushed. But, if the technology were developed to enable a wormhole to remain open, it might become possible for spaceships to enter wormholes, travel for a few million miles, and emerge several light years away—perhaps at the point of a white hole.
White holes are theoretical objects that spew energy into the universe from unknown sources. One theory suggests that quasistellar objects (also known as quasars) are actually white holes, at the far end of which might be wormholes. Thus, it is theoretically possible to enter a wormhole in one location in the universe, and emerge from a white hole in another. Such a stable conduit could be called a jump gate.

At Progress Level 5, the technology does not exist to stabilize wormholes in order to create jump gates, though by PL 6 scientists might have developed the technology to map the exit points of wormholes. With a theoretical advance in astrophysics, humanity might be ready to make the first safe jump by Progress Level 7.
[h=4]Jump Holes[/h] In theory, a collapsing wormhole in a strong enough gravitational field could remain open of its own accord, creating a kind of natural jump gate, or “jump hole.” The jump hole would function the same way as a jump gate but could close while travelers are en route to the exit point.

A jump hole might collapse while there are ships still traveling through its jump space. Roll d% each hour; on a result of 100, the hole collapses. If this happens, any ships in its jump space immediately drop back into “real” space—most likely in the middle of nowhere. Determine what percentage of the journey the ship had completed, then compare that percentage to the real distance; this is how far from its destination the ship is.
[h=4]Jump gate (PL 7)[/h] Jump gates consist of gigantic rings in space that use fusion reactors to generate a magnetic field capable of holding open a collapsing wormhole. This allows starships to enter the wormhole, engage their engines, and reduce the effective travel distance to the wormhole’s exit point by a factor of 1,000. For example, the 48,360,000-mile trip from the Earth to Mars would be reduced to 48,360 miles via a jump gate (assuming a wormhole had appeared near the Earth and that its exit point was near Mars). Thus, a starship with PL 6 ion engines traveling through “jump space” could reach Mars in approximately 1.6 hours (instead of 67.2 days) and completely avoid the effects of time dilation.

Jump gates have a few limitations:

• Jump gates have only one exit point. Therefore, a jump gate from Pluto to Alpha Centauri is useless to characters who don’t want to go to Alpha Centauri.
• Jump gates are one-way. The journey to the exit point might be comparatively short, but the journey back could take just as long as it always did—or require a circuitous route from jump gate to jump gate, some of which could be dozens of light years out of the way.
• Jump gates are rarely located near one another. A starship might have to cross an entire system to get from one exit point to the next jump gate.
• Maneuvering a jump gate into position requires a successful Navigate check (DC 35). If this check fails by 5 or more, the jump gate collides with the closing wormhole and is crushed against the forming singularity.

In PL 7, jump gates are most likely owned by megacorporations that charge for their use. The toll varies according to the real distance between the jump gate and the exit point: Divide the real distance by 1,000,000 miles to determine the purchase DC for passage through the jump gate.
Purchase DC: 75 (per jump gate)
Restriction: Licensed (+1)
[h=4]Jump Network (PL 8)[/h] As science develops ways to harness the power of singularities, astrophysicists apply the technology to wormholes. A jump network is a series of jump gates that can each serve as an entry or exit point. Thus, jump gates are no longer one-way: A jump gate can take a ship from the Earth to Mars and back. Further, the network could also include jump gates leading to and from Jupiter, Saturn, and Pluto.

Jump gates in the network are still expensive, but the risk of placing one has completely vanished; the jump gate merely has to be moved into the desired position—usually a Lagrange point—and switched on.

Many gates in the jump network are owned by megacorporations, who charge for their use. Some gates are operated by the military and have restricted access. However, the gates between common locations like planets and stars are government owned and designated for public use.
Purchase DC: 75 (per jump gate)
Restriction: Licensed (+1)
[h=4]Jump Drive (PL 9)[/h] The jump drive is a portable version of a jump gate. Ships carrying a jump drive can create a stable, though temporary, wormhole. The artificial wormhole lasts until the ship that created it emerges from the exit point.

The jump drive suffers from one major limitation. Once a ship has entered jump space, it has only two real options: continue to the exit point or deactivate the jump drive. The ship cannot change course while in jump space; it must drop out of jump space, set a new course, and re-engage the jump drive. The drawback to this is that jump drives require a lot of energy; recharging the drive takes hours, as shown on Table: Jump Drive Recharge Time.

[bar]Table: Jump Drive Recharge Time[/bar

Purchase DC: 25 + one-half the base purchase DC of the starship.