The main contribution of ozone is to absorb harmful ultraviolet light from the sun so that it does not reach the Earth in potentially harmful amounts. In fact, the ground level concentration of ozone rarely exceeds 0.04 parts-per-million (ppm) where it reaches approximately 8ppm at a height of approximately 24 km. This higher concentration prevents dangerous sunlight radiation from reaching the lower atmosphere by absorbing wavelengths of light below 320 nm. The students can detect the ozone layer, its thickness and altitude during the mission by observing the changes in UVA and UVB data collected by the light sensor, SL01. For additional data collection, the SG10 sensor can be attached to measure ozone gas levels within the range 0 to 20ppm. The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains high concentrations of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer is one of the layers in the earth's atmosphere, contained mostly within in the stratosphere's layer, at a distance of between 15 and 30 km from the surface of the earth. Ozone is a molecule, with a strong smell and it is blue in color. In 10 million air molecules, only 3 are ozone, making it much less common than other molecules such as oxygen, which make up about 2 million of every 10 million air molecules. Despite the relatively small percentage of ozone molecules in the earth's atmosphere, it is extremely important for life on earth. Ozone molecules absorb the UVB ultraviolet light that does so much damage on the planet. The ozone layer is able to absorb up to 98% of the sun's ultraviolet light, and 90% of the ozone is located in the stratosphere layer of the atmosphere.