It costs 25 points to be a Jumpspace psi, plus 5 points per level. This is a very rare ability which allows the psi, when plugged into an appropriately incredible power source, to push his body (or, with sufficient energy, an entire ship) into Jumpspace.
Jumpspace itself is referred to as a "phase of existence" or "alternate dimension" which is extremely close to our own. Weaker psis can project their minds into the "near" Jumpspace, called Astral Space.
Although matter itself does not seem to exist in Jumpspace (a psi can travel through a planet), the gravity generated by that matter does - a Jspace psi can use those gravity wells to navigate.
The reason Jspace is important is that it is four-dimensional, and the distance between two gravity wells in Jspace is shorter than the distance in the physical plane. Further, the deeper one goes into the fourth dimension of Jspace, the shorter those distances get... and the more difficult to "percieve" the gravity wells. The more powerful the psi, the deeper she can safely go, and the faster the trip will be.
Level 0 (for 25 pts) shortens practical distances by 1000. Each additional level divides distance by x1/10. Thus, a level 5 psi shortens distance by 100,000,000 (allowing a ship travelling at 5 meters per second to exceed the speed of light). However, this costs an appalling amount of raw energy, fed straight to the psi: each kilogram of mass moved into Jspace costs 1 kilowatt x (psi level +1).
Once in Jspace, maintenance is roughly 1/1000th that amount, and getting back out of Jspace costs nothing (the psi stops holding the ship in Jspace, and it pops back out).
Jspace Entry - This is the psi's ability to pull the ship into Jspace. On a failed roll, 1/2 of the jump energy is expended but the ship doesn't go anywhere. On a critical failure, the psi takes 1d-2 damage per megawatt to the brain. Some psis get dampers built into their cybernetic energy plugs to protect themselves from this, but they subtract -1 from skill per +1 DR against the damage. On a success, the ship is now in Jspace.
Jspace Navigation - This is the psi's ability to direct the ship in Jspace. Although it is technically possible for a ship to be mechanically guided by measuring gravity levels and calculating approximate positions of the planets, the psi's "gravity sense" is realtime, and extends for millions of miles... making the psi a far better navigator than any computer. A psi can detect an Earth-sized mass at one thousand miles, modified normally for the level of Jspace the psi is in (thus, at level 0 Jspace, Earth can be detected at one million miles). Multiply other gravity masses by the square root of their difference from Earth. Thus, a planet one hundred times as large as Earth can be detected ten times as far away. Example - Marin has pushed her ship into Jspace 3; she can now detect the Earth from one billion miles away, and can detect the moon from 500 million miles away.
Jspace Movement - This is not actually a separate skill, but an application. A Jspace psi who is also psychokinetic can move objects normally in Jspace, except that effective speed is a lot faster!
As mentioned, Jspace requires an appalling amount of energy: 1 kW x (lvl +1), per kilogram. To shove a twenty ton craft into level 1 would cost 40 megawatts of power (40,000,000 watts). The ship must then generate 1/1000th that amount every second to remain in Jspace.
Note that most Jspace space craft do not have much in the way of reaction engines. Indeed, experiments in spacecraft with no reaction engine are underway - such craft would be fired from a mass driver, enter Jspace, exit at the exit point, and then be (hopefully) caught at that end by another mass driver or similar technology.
Most such small ships use a combination energy capacitor and TL 10 Fusion Reactor. The Fusion Reactor produces the maintenance cost plus some change (a Fusion plant which produces 45,000 watts per second weighs 5.5 tons.
A non-rechargeable, experimental TL 10 power cell capable of handling the entry cost and then one year (31,536,000 seconds) of maintenance costs would have 1,419,160,000,000 watts (1.4 terrawatts) and would weigh 18,062 kg. However, most small ships use the Fusion Reactor above, and then a smaller battery capable of supplying maintenance power for only a few days (250,000 seconds; 11,290,000,000 watts; 144 kg).
A larger ship can handle more, of course, A TL 10 Fusion Reactor producing 10,000,000 watts per second weighs 910,000 kg and provides enough power to maintain a 1,900,000 kg ship at level 4 Jspace. The battery required to push that ship into Jspace and maintain it for three days would have 2,500,095,000,000 watts (2.5 Terrawatts) and would weigh 31,819.4 kg.
It's not a well known fact except among fringe groups and those studying Jumpspace, but psis begin to hear voices in Jspace after long exposure to it. The length of time required is somewhat variable with the person, but is usually somewhere around 15,000 hours. Although it sounds like language, and sometimes a word is picked out of it, it mostly sounds (to the psi) like babble.
The scientific community has their own opinion on the matter, best expressed in this news article written by Howard Marris, PhD:
Generally, scientists discount theories of voices of god, ghosts or other such nonsense. The phenomena which our Jumpspace experts have been hearing is better explained (and more easily explained) by electronic noise. Yes, noise1.
Generally speaking, in order to accept that these are real voices, we would have to then presuppose that there were beings out there; that these beings are interested in communicating with us; that they can only communicate within Jumpspace (which all evidence suggests is *empty*); and that their voices sound remarkably like voices even though no other animal has a human voice2.
The tendency of the human mind to assign patterns to random data, however, is well documented. When presented with visual noise (such as the Rorschach tests, or clouds) we instinctively rehape our perception of it until it "looks" like something. This is particularly common when under stress - under duress, the first thing we attempt to do is make sense of what is happening to us.
Jumpspace is stressful. We knew that, or we wouldn't pay such high grade salaries! In addition, the psi, who is by definition a bit more sensitive mind, is plugged into something on the order of terrawatts of power flowing through a connection to the base of his brain. That he begins picking up a certain amount of electronic noise filtering through the non-conductors is not inexplicable - it is unavoidable.
The psi eventually learns to ignore the noise, until it becomes little more than a subconscious hum in the background. But recent evidence suggests that the noise is still there... and that there is enough of a chaos pattern for meaning to be associated with it3.
This also explains why the psis can not understand what the voices are saying - noise, even when voice-like patterns emerge, is still just noise. The best we can do is offer therapeutic courses designed to break back the ability of the psi to perceive the patterns.
[1] There is anecdotal evidence of this sort of thing in the past as well, when people would listen to radio static for long periods of time. SETI researchers, for example, began to hear human babble sounds in the radio static itself.
[2] It should be noted that while there are animals who can mimic a few sounds of the human larynx, the ability to consistently mimic the sound and "feel" of human talking patterns is not possible.
[3] A few of my colleagues have also suggested that we might hear voices even if there wasn't enough patterning - the ability of the human mind to create faulty patterns *just to have them* is amazing. There is not quite enough evidence to support this as a full assertion, however - just a possible line of research that others might wish to pursue.
Also, the oldest Jumpspace psis have been at the game for a while. Some people say that it's inevitable they start to crack a bit. And "hearing voices" is one of the fundamental mental illnesses known.
But a number of people disagree with this assessment. For one thing, it has never actually been proven that the voices some people hear are, in fact, not there - it has only been proven that the person in question is the only one hearing them. Like a one-eyed man in a crowd of the blind, the crowd has named his condition "seeing things" and called him delusional.
That this attitude should persist in light of proven psi phenomena is more evidence of the need for Jumpspace than scientific inquiry.