Pre-pulsar spaceship (or PPS for short) is any of three different period 30 c/5 orthogonal spaceships in which a pre-pulsar is pushed by a pair of spiders. The back sparks of these spaceships can be used to perturb gliders in many different ways, allowing the easy construction of c/5 puffers.
The first pre-pulsar spaceship, the symmetric pre-pulsar spaceship (or SPPS for short, shown to the right) was found by David Bell in May 1998 and was based on the P15 pre-pulsar spaceship found by Noam Elkies in December 1997.
The asymmetric pre-pulsar spaceship (or APPS for short, shown below) was found by Alan Hensel, also in May 1998, based on a skewed version of the pre-pulsar.
The third period 30 pre-pulsar spaceship, shown below, is similar to the symmetric pre-pulsar spaceship but contains an extra T-tetromino between the spiders and is glide symmetric.
- 128P30H6V0.1 at Heinrich Koenig's Game of Life Object Catalogs