Rescue On Fractalus

Released in 1984, the Atari 5200 game Rescue On Fractalus was one of LucasFilm's early attempts to break into the computer game market. Working closely alongside Atari to produce Ballblazer and Rescue On Fractalus, LucasFilm subsequently went on to produce more games under first this name and, later, the LucasArts label.

Rescue On Fractalus, as the name imples, made extensive and innovative use of fractal geometry to produce the mountainous ranges of the planet. Nowadays, it is by no means the only game to have done this - Captain Blood featured similarly generated alien canyons - but at the time, particularly considering the hardware limitations of the Atari 5200, its graphics were quite stunning.

Stunning... if a little jagged. Early prototypes were known as Behind Jaggi Lines, a reference to the jagged streaks of cockpit that the player was forced to peer through. The jaggy lines became personal enemies of the programmers, and thus the alien forces in the game became known as Jaggimonsters. Alas, despite the development of now-common anti-aliasing technologies, the 5200's colour palette wasn't large enough to allow for fancy graphical techniques. Low framerates and jaggy lines all round, then...

Though best remembered for its fractal graphics, which provided the right level of geek-appeal, the gameplay in Rescue On Fractalus was similarly engaging. Originally conceived purely as a straight-forward rescue mission, George Lucas enquired about the location of the fire button. Rescue On Fractalus rapidly evolved to include gun emplacements, jaggi monsters, suicidal flying saucers and alien impostors, who will leap up and bang on the front window in a most alarming fashion. All of which leads many to believe that Rescue On Fractalus, solely by design rather than luck, was one of the best Atari 5200 games to be produced.

Programmed by David Fox, Loren Carpenter, Charlie Kellner, Peter Langston, Gary Winnick and David Levine, Rescue On Fractalus was released for the Atari 5200 in 1984. Previously it had been named Star Mission, Rescue Mission and the doomed, pun-laden Behind Jaggi Lines.

Jeans Instability

Jeans Instability, despite its name, has nothing to do with the inherent tendencies of denim-based clothing to split, rend or fail during mission critical applications. This is almost a shame, as the notion of unstable trousers is, to the majority of mankind, far more comprehensible than the following.
Waves and instabilities are often related, and it is in relation to acoustic waves that Jeans Instability arises. When an area of gas is compressed, the pressure increases. This compression is smoothed out by the gas, and in the process acoustic waves are produced - futher areas of compression. Any more compressed areas of gas, however, possess enhanced gravity and thus more gas is pulled into the compressed region.

Normally, this isn't a problem. The minute fluctuations in gravity produced by typical sound waves in the air is negligible, as are the effect. Really - it might as well not have happened for all the effect it has. But transfer this theory to astronomical-sized bodies of gas floating about in deep space, Under such situations the changes in gravity are no longer negligible. More material is pulled to the compressed regions of gas, triggering an instability, and since the nature of this instability was first demonstrated by Jeans in 1902, the instability takes his name.

What form does this instability take? Well, under certain conditions the fluctuations will simply die out; the cloud of gas will disperse and return to its original state. Under other conditions the fluctuations will overpower the pressure of the gas, the perturbation will grow and the gas will continue to contract. It is believed that the stars and galaxies we see around us are the end results of perturbations which initially began as Jeans instabilities.

It should be noted that the instability only occurs for wavelengths greater than a certain size, known as the Jeans length. This length is dependent on density. The Jeans length may, in this case, be directly responsible for the size and distribution of galaxies and other matter in space.