With the potential for long-term missions around the Earth's orbit, the Moon and Mars, some health issues such as the physiological effects of microgravity and radiation become a major concern for space crews. Long periods of microgravity are known to reduce bone density, muscle strength and cardiovascular fitness. The calcium which is lost from bones can end up in kidneys, form kidney stones (KS) and eventually put astronauts at risk. For instance, 14 American astronauts suffered from urolithiasis (formation of KS) in the period between 2001-2006 [1]. These mineral deposits can travel through the urinary tract, causing intense pain. One of the most common types of KS is caused by the buildup of calcium oxalate, although calcium phosphate is also common [2]. This topic is in the agenda of different space agencies, although the experiments which are performed nowadays are normally based on clinical tests where microgravity conditions are simulated putting the astronauts at rest on a tilted bed [2]. In order to address the problematics of urolithiasis and its treatment for space crews, this work will focus on a physico-chemical study of this phenomenon. Specifically, the effectiveness of different drugs [3] and natural products on the dissolution of kidney stones will be analyzed. Clinical follow-ups or surgery are not feasible options during a long mission, and hence the interest to study remediation through reduction and/or elimination of the stones with a pharmaceutical treatment. The idea of this project is to study the nanoscale mechanisms of early stages of dissolution/precipitation of the phases present in KS under different conditions of pH and solution chemistry. This approach aims to develop an experimental basis to better understand the kinetics of drug-KS interaction and extrapolate the evolution in time in order to provide an assessment on potential health risks. Experimental techniques used in this work will include scanning electron microscopy (SEM), to carry out a preliminary characterization of KS surface and identify calcifying nanobacteria [4], as well as the atomic force microscope (AFM), to perform quantitative nanometrology studies on KS dissolution kinetics under controlled physico-chemical conditions. References cited: [1] Djojonegoro B., Jones J. (2006) Kidney Stones. In: The Longitudinal Study of Astronaut Health Newsletter , Vol. 14, Issue 2. From: lsda.jsc.nasa.gov/refs/LSAH/Vol_14_Issue_2_Dec_06.pdf [2] Monga M., Macias B., Groppo E., Kostelec M., Hargens A. (2006) Renal stone risk in a simulated microgravity environment: impact of treadmill exercise with lower body negative pressure. The Journal of Urology 176, Issue 1, pp. 127-131. [3] Whitson P.A. (2001) Renal stone risk during space flight: assessment and countermeasure validation. NASA, Marshall Space Flight Center From: www.nasa.gov/centers/marshall/news/background/facts/renal.html [4] Ciftcioglu N., Björklund M., Kuorikoski K., Bergström K., Olavi Kajander E. (1999) Nanobacteria: an infectious case for kidney stone formation, Kidney International, Vol 56, pp. 1893-1898