The next maximum of solar activity is expected on May 2013. During this period the far ultraviolet portion of the solar spectrum intensifies, reaching Earths’ ionosphere making it thicker and denser. Space weather is significantly influenced. The definition of space weather in U.S. National Space Weather Program Strategic plan is following: “conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health”. The space weather is one of the main sources of errors experienced by GNSS systems and their users. It is one of the major sources of errors for single-frequency GNSS receivers, as well as for differential GNSS applications. The development of space technology has reached an application level, where the ability to predict space weather becomes significant. NASA has developed a Solar Dynamics Observatory satellite to study processes on the Sun, especially during the period of solar activity. Mission will be managed by NASA Goddard Space Flight Centre, Greenbelt, Md. SDO mission is scheduled for 5 years, however as a result of satellite apparatus thorough tests, usually it can operate considerably longer. SDO will perform extended and complex studies of the Sun, which for the first time would allow to understand yet uncertain processes, to make the space weather forecasts.