The main goal of this study was to find feasible methods and strategies for the deflection of large asteroids in the diameter range of 5 to 200 km. For the deflection of asteroids in the 50-200 km range only one feasible way was found, which is an indirect but extremely powerful technique ! (see Deflection-Strategy_3). A first assessment of our ability to deflect an asteroid of a certain diameter was carried out. It was considered that only existing and proven technology and a powerful direct deflection method (a nuclear explosion on or close to the surface of the asteroid) would be used for this task. The result of this assessment is presented in the form of a table. This table shows the minimum amount of NED's (Nuclear Explosive Devices) which is required for the deflection of an asteroid with a given diameter, so that it just misses our planet Earth. Here it was considered that either the maximum explosive yield (Deflection-Strategy_1) or only a small defined fraction of the explosive yield (Deflection-Strategy_2) of the used NED's is transformed in work (kinetic energy) which is usable for a direct change of the trajectory of the asteroid at a given distance to Earth (of either 250 or 500 million km). For the deflection of asteroids in the 50-200 km range only one feasible way was found, which is an indirect but extremely powerful technique ! see Deflection-Strategy_3. This indirect Deflection-Strategy_3 makes use of the Deflection Strategies 1 or 2. There is clear statistical evidence for a 62-million-year-cycle in bio-diversity (fossil diversity) on Earth. Currently we live at the end of the declining phase of such a 62-Myr cycle. The declining phase of this cycle must be called an extinction period ! If we look at the diagram which shows the bio-(fossil)-diversity on Earth (Diagram-1), it is evident that there are abrupt and deep cuts into the bio-diversity within each marked extinction period ! Possible cause of this bio-(fossil)-diversity cycle (or extinction cycle) could be a 20 Myr long Big-Impact-Period every 62 +/- 3 Myr, which may be caused either by a periodic crossing of the galactic plane all 66+/-6 Myr, by our Solar System, or by a periodic behavior of our sun (e.g. sharp rises and drops in the Solar-Wind-Flow and Flare Activity), which may disturb the asteroid- and comet orbits in our solar-system.