Low Reynolds Number liquid jet break-up in a gravitational field occurs in one of threemodes; periodic dripping, chaotic dripping and jetting. These break-up modes have beenstudied extensively with a variety of theoretical, numerical and experimental techniques.The break-up modes of a liquid jet not influenced by a gravitational field has not previouslybeen investigated thoroughly. This dissertation looks at a low Reynolds Number liquid jetin reduced gravity and documents the break-up modes it undergoes.Liquid jets were created by a smoothed peristaltic pump system, pumping mixtures ofglycerol and water into an air filled chamber. Experiments were conducted in a 2.0s droptower providing gravity levels of ' 1x10−4g. The liquid jet was back lit and filmed duringthe experiments and parameters associated with the jet break-up recorded. 121 tests wereconducted in reduced gravity with 101 used to investigate a variety of flow conditions. Eachtest conducted in the drop tower took approximately 0.5-2.0 hours to run, with analysisof the data taking on average a further five hours. Three break-up modes were observedin the reduced gravity experiments, jetting, chaotic dripping and a stable region where nodrops were formed. The break-up modes were mapped onto the Reynolds-Weber Numberplane, with the domain of each mode described. Transitions between modes were determinedthrough a combined analysis of the drop size, jet length and instability wavelengths.Contemporary methods of numerical and theoretical simulation developed for liquid jetswere reviewed. Several methods; a 1-D Navier-Stokes free surface solution, two Mass-Spring-Damper chaotic models for dripping and a linear stability analysis of cylindrical liquid jetswere used for comparison with the experimental results. The Navier-Stokes code appearedto simulate the liquid jet in reduced gravity for the jetting break-up mode. The Mass-Spring-Damper models adequately simulated characteristics of the chaotic drop generationobserved in the dripping mode. The linear stability analysis generated the transition betweentwo dominating forms of surface tension induced instability, convective and absolute. Thedomain of the jetting break-up mode and the transition between jetting and chaotic drippingagreed well with this theory. Despite the fact that the stability theory was developed forsemi-infinite cylinders and the geometry of the dripping jet is different, conclusions drawnfrom this analysis gave an important insight into the instability driving the chaotic drippingliquid jet break-up.Development of the drop tower facility used to conduct the experiments has been embeddedin this dissertation. This facility represents one of a handful in the world with thecapabilities to conduct the proposed investigation. The aim of this part of the project wasto take a drop tower facility in its infancy and improve its operational performance. Thiswas a necessary requirement for generating the experimental data, increasing the qualityand duration of the reduced gravity environment to useable levels. Work presented in thisproject focusses on improving the release characteristics, reducing the drag of the fallingexperiment and improving the performance of the deceleration of the drop package. Theresulting improvement was an increase in gravity quality from 1x10−2g to ' 1x10−4g and anincrease of test time from 1.11 seconds to 1.95 seconds.In summary, this dissertation provides experimental data on three break-up modes ofliquid jets in a reduced gravity environment. The existence of a dripping mode in reducedgravity has been previously conjectured, but this investigation provides the first experimentalevidence of one. Experimentally determined domains and transitions of the break-upmodes are presented. Experimental results are compared to several numerical and theoreticalmodels, with areas of agreement and disagreement discussed. The driving mechanismsfor each break-up mode are also discussed.