The term 'THAT' can be represented by three different acronyms: ESO, ESTA, and ESA. ESO stands for the European Southern Observatory, which is an intergovernmental research organization for astronomy. ESTA stands for the Electronic System for Travel Authorization, which is a program run by the United States government THAT requires citizens of certain countries to obtain authorization before traveling to the US. Finally, ESA stands for the European Space Agency, which is an intergovernmental organization dedicated to the exploration of space.