1. Start with the Mission to Mars.
- First, read the Background information and
then use that information to figure out the proper semimajor axis (a) and
eccentricity (e) for the spacecraft orbit.
- Then work out Mars' position
at launch (the angle theta) and enter all these quantities into the applet.
- Hit "Launch" and see if your mission is successful.
Note: you can also do this by trial-and-error, just by typing in different
values and launching a bunch of probes until one makes it to Mars. This
is a very inefficient and costly way of exploring Mars, and not at all
the way NASA does it! You should first calculate the orbit, and then launch
your probe. If you're careful, you should be able to hit it on the first shot!
2. With a successful Mars mission under your belt, now it's time to explore
the outer planets.
3. Now, examine the time and energy required for your Grand Tour.
- Once you have the mission running, note how long it takes to make it
all the way to Neptune. Also note how much energy it takes for this mission.
- Now run the Voyager 2 mission by clicking the "Voyager" checkbox, and note
the time taken and energy used.
- Voyager was able to complete the mission
faster because it used more energy -- energy which typically came from the
use of gravity assist boosts during the flybys of each planet. Your mission
involved the minimum energy orbit, and so took much longer to unfold.
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