Relationship between “State-Space View” and Simulation view:
The following diagrams come in pairs each showing the same “flight” or trajectory. The left diagram of each is the “state-space view”, and the right one is a long-exposure shot of the spacecraft actually moving in the Simulation tab-page. State-space shows height on the y-axis and velocity on the x-axis. This means the further left the blue line goes in state-space (that is negative velocity), the faster it will be falling at the corresponding instant in the Simulation view.
In the following two diagrams the spacecraft is simply falling without thrusting at all. In both diagrams the spacecraft is just getting faster and faster. Note that in the state-space view, it is only the blue curve we are looking at here, and it starts at the blue square and end on the horizontal axis. Also note that the velocity is always negative, which means it is falling all the time.
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In the next two diagrams the spacecraft free-falls for a while and the switches its engines on and starts thrusting. This is seen in the left diagram by the kink in the curve, which shows the velocity becoming less negative (I.e. slowing down). In the right diagram you can see the thrust trail, and also just notice that the lowest few spacecraft images are getting closer together again.
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To investigate the state-space view further, using the demo program you can move the mouse pointer over the grey-scale image and for each mouse pointer position, you can see the corresponding height and velocity (and other variables) displayed in a text window below the graphics, as illustrated in the following image:
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As a final example, here are two trajectories that start with the spacecraft moving upwards and then eventually fall to the ground without thrusting at all.
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