sentences:  In 1928 the pair—adopting the Latin motto "per aspera ad astra" ("through hardship to the stars")—began engaging in homemade gunpowder-based rocket experiments in the nearby Arroyo Seco canyon, as well as the Parsons family's back garden, which left it pockmarked with craters from explosive test failures.They incorporated commonly available fireworks such as cherry bombs into their rockets, and Parsons suggested using glue as a binding agent to increase the rocket fuel's stability.This research became more complex when they began using materials such as aluminium foil to make the gunpowder easier to cast.