The p42 glider shuttle is a period-42shuttleoscillator discovered by Noam Elkies in 1994. It was the first non-trivial period 42 oscillator to be discovered[note 1] and is based on a period 66 oscillator discovered by Robert Wainwright in September 1984. It consists of two copies of eater 3 and four copies of unix to shuttle two gliders back and forth. By increasing the distance between the two reflectors, oscillators of periods 42 + 24n can be created. Dean Hickerson found that the distance between the reflectors could be decreased using a custom period 6 oscillator to create a period 18 glider shuttle. In April 1992 Hickerson created another related oscillator by crossing two pairs of gliders using rephasers, which allowed the construction of oscillators of periods 246 + 24n.
↑A nontrivial period-42 oscillator, such as unix on 44P7.2, could have been constructed from two oscillators of lower period (such as p6 and p7), both of which were known by an earlier date. However, no such LCM oscillators were attested prior to the discovery of this oscillator in 1994.