Rocket launches may change schedule due to a few different factors. These include target and goals, its trajectory, type of rocket, and expected weather in the area. Some of the most important aspects scientist must consider is the mission and payload. When the mission is Earth focused, then trajectory must consider the Earth’s rotate and axis. When the mission is exceeding Earth’s orbit then the calculations change drastically; For example, to send a rocket to Mars, there is only opportunity every 26 months making this very time sensitive. Launch conditions must be perfect to continue and changes in weather can cancelled even the most carefully planned launches. Changes in schedule can cause alterations in trajectory which may affect the mission, for example, how much fuel the rocket will need to reach orbit.