The Theory

The hyperspace drive (HSD) is the only means of practical interstellar travel.  Put in layperson's terms the hyperspace field generator creates a bubble of normal space which conducts a phase transfer into a transdimensional state.  

This is known, colloquially,  but rather inaccurately, as 'entering hyperspace'.  Once in hyperspace, the drive alters the 'shape' of the normal space bubble containing the ship, so that it alters its dimensional parameters over time.  This is analogous to movement in normal space, but much faster.  Within the bubble, the physical laws of normal space continue - meaning that a ship can continue to accelerate or decelerate whilst in hyperspace, and can exit hyperspace in any orientation relative to the start position.  Whilst it's mass, subjective time and speed are retained, vector can be altered as required on exit.

The 'normal space bubble' in which the ship is encapsulated when in hyperspace is unbreachable.  If the HSD fails, the ship merely returns to normal space.  According to theoreticians, in order for a normal space object to move from the normal space bubble into the 'surrounding' hyperspace, that normal space object would have to take on the multidimensional properties of hyperspace.  In doing so it ceases to be  a normal space object, and to all practical purposes would cease to be part of our universe.  The mathematics suggests that this step, if it would possible to achieve (which it isn't) would be irreversible. It is believed that the interaction of a strong gravity field can cause the transition to a hyper-state - and this is one explanation of the M25 limit effect (see below).

WHen first developed, several centuries ago, hyperspece travel was slower, approximately 0.05 parsecs per day. The technology developed steadily over the ensuing two centuries, and by 3150 it had reached its maximum theoretical speed, which approximates to 1 parsec per day. See chart of rate of HSD speed development.

The M25 Limit

There is a limitation on the operation of the drives, that arises from part of the mathematical theory underpinning the operation of the drive.  The key physical constant is known, in the maths, as M25 - and the limitation imposed by this constant as the 'M25 Limit'.  This presents an operational minimum distance from a large mass that the drive will work safely.

Ship cannot operate their hyperspace drives within the M25 limit.  Ships that tried this in the past this generally vanished without a trace.  Put simply, for garvitational bodies of up to around 1000g, the M25 limit is directly proportional to the gravity (g) of the mass concerned.

The calculation M25 = g x 150,000,000 km (or the g in AU)

E.g.. Sol has an acceleration due to gravity of approx. 260 m/s/s (26g) so the M25 limit for the Solar system is 26 AU.

Any gravitational body, such as planets have an M25 limit (though much smaller) - so Earth would have an M25 of 1 AU (but since it is well within the Sun's M25, this hardly matters).  Even asteroids with micro-gravities have small M25 limits - an asteroid with 0.001g would have an M25 of 150,000 km.


When moving through a system - to avoid (or reduce) the chance of collision with debris or rocks, most transits into and out of hyperspace take place well outside the plane of the ecliptic (where most of the matter is to be found). Typically, the transits are at 90o to the plane of the ecliptic, either stellar 'north' or 'south'.

Once in system, movement is in normal space - see here for a useful interplanetary transit ready reckoner


Using the same technology, it is possible to modulate a micro-hyperspace packet, by using the hyperspace field generator that is part of every HSD.  Each HS field generator has a unique hyperlinium vibration frequency (HVF).  This means that messages can be sent 'to' a specific recipient, provided their HVF is known.  These packets can be sent at a speed of 2 parsecs a day, but can only be received by functioning HS field generators.  For this reason, all developed systems have one or more Hyperspace Transmission Stations (HSTS) situated just outside the M25 limit of the system.  They then receive microwave or laser comms from planets and ships within the M25, and relay them via hyperspace to their destination worlds.  The precise location of these small manned stations is often kept a secret, because of their vital strategic role.


Normally, the operation of an HSD is undetectable, and there is no way of finding out where a ship has gone, or in what direction, once it enters hyperspace.

Theoretically, you might detect the additional energy of an HSD field coming into being - but that would be utterly swamped by all the other, rather boring, thermal and other energy coming from a manned ship in any case (all the more so if it was accelerating at the time).

All these energies persist for very small periods of time (seconds) after the ship leaves normal space.

This means that if you *could* detect it, you would have to be there at virtually the same they entered hyperspace and therefore probably saw them go anyway.

There is also nothing about the creation of an HSD field that gives any indication of the likely final destination - so even if you actually saw them enter hyperspace, you wouldn't be able to tell where they were going.

For a very much more complete discussion of hyperspace technology, see 'Big Al' Jebbrah's more 'accessible' account here



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The Universe(of Starship Marine, Starship Strike and Plan A) is © Jim Wallman 1996-2011. You may freely use this material in other games, works, websites etc for your personal entertainment - with appropriate credits as to authorship and copyright. It may not be resold or distributed with any publication for sale without the express permission of the copyright holder.