Final answer:
NASA ensures predictable spacecraft motion using thorough planning, understanding of physics, and precision technology. The Space Shuttle must reach a high velocity, which is achieved by longer acceleration compared to an ICBM, and in interplanetary missions, craft follow carefully plotted trajectories, making use of gravity-assists.
Step-by-step explanation:
NASA ensures that the motion of spacecraft, like the Space Shuttle, is predictable through meticulous planning and understanding of orbital mechanics and the laws of physics. Spacecraft use powerful engines to achieve the required velocity to enter orbit, which for the Space Shuttle is approximately 17,500 miles per hour. To reach orbit, the Shuttle undergoes a significant acceleration period, longer than that of an intercontinental ballistic missile (ICBM), but with a greater final velocity to sustain orbit. This is governed by Newton's laws of motion and precise calculations of necessary speed, thrust, and trajectory.
The predictability is further enhanced by using technologies like small thruster rockets that allow for minor trajectory adjustments. In interplanetary flight, as with robotic spacecraft sent to outer planets, the craft must achieve an escape velocity that allows them to exit Earth's gravitational influence and then coast to their destination following carefully plotted trajectories that sometimes leverage gravity-assisted flybys. All of this precise control of spacecraft movement is essential to ensure safe and successful missions, whether in Earth orbit or on journeys to other planets.