Space exploration and technology development present great potential to humanity through the expansion of useful infrastructure such as satellites, space stations, launch facilities and space agencies. In addition, access to scientific opportunities such as understanding the origin of our solar system may prove valuable, and resources ranging from ice to metals and rare earth elements may be utilised to great benefit. The presence of these resources has been demonstrated on the Moon, Mars, comets, and asteroids, while the concentrations remain less certain. The risk of asteroid and comet impacts poses a great threat to life on Earth. To date, little to nothing is known about the interior of most planetary bodies. Seismic techniques are used with great success to understand the subsurface of Earth and have been proposed for expanded use in off-Earth environments, such as on the Moon, Mars, and asteroids to advance the knowledge of their interiors. The goal of this thesis is to examine the potential use of seismic techniques to explore and understand the subsurface of off-Earth environments for the purposes of resource prospecting, mining, and asteroid/comet deflection. This thesis presents a novel and innovative methodology for measuring the seismic properties of regolith and uses it to develop an understanding of the effect of the space environment on seismic data collection, such as the differing atmospheric pressure and regolith properties. The potential use of other remote sensing and geophysical techniques to assist with seismic exploration is also reviewed in addition to mission proposals. A novel testing system was designed for measuring the seismic properties of fine-grain, low compaction regolith, called the Seismic Apparatus for Fine-Grained Sediment (SAFGS). Seismic experiments were performed at UNSW Sydney, Australia and the Jet Propulsion Laboratory (JPL), Pasadena, the USA on two available off-Earth regolith simulants designed based on known off-Earth regolith properties; the Australian lunar Regolith Simulant (ALRS-1) and the Mojave Mars Simulant (MMS). ALRS-1 had a measured P-wave velocity of 98.6 m/s, comparable to the measured in-situ¬ velocity of lunar regolith (104 m/s and 114 m/s). The P-wave velocity of the MMS regolith was measured with a possible relationship between increasing grain size and velocity being found. The MMS dust had a mean velocity of 61.3 m/s, small-grain MMS had 244.5 m/s, and medium-grain MMS had 271.2 m/s. Computational and analytical modelling methods are explored to validate and expand upon the experimental work.