Approaching Mars

After most of the ten million seconds have gone by, it's time to start checking on how things are going. Let's check on what the instruments say now..

This is the sync orbit MFD after the cruise. In many ways it looks quite similar to the way it looked before the cruise. But some things have changed. Mars is now only 0.01 AU away - about 1.5 million kilometres. The error in our arrvival times has increased, but doesn't look too bad - the worst the error can be is 1500 kilometres, and Mars is larger than that.

Sometimes on a flight you may find your flight path is wandering off. If you're not happy, keep stopping and correcting as you go. Ideally, you want as near a perfect flight path as possible.

At around this time, we can start to look at how our orbit appears relative to Mars. Selecting the orbit window, and specifying Mars as the reference gives this. It's not a good idea to select this window too far from the planet, as in extreme cases you can crash Orbiter by trying to look at an orbit around a distant body.

Notice that your direction of movement relative to Mars is completely different from your movement relative to the Sun - the two are over 90' apart.

All the navigation modes - prograde, retrograde, orbital normal(+) and (-) refer to your orbit around the most gravitationally dominant object, and you can't change this selection. At this point in your journey, the dominant object is the Sun. Mars provides only 2% of the gravity.

All the same, from around this point in, you should start adjusting your orbit so that your approach to Mars is as you want it. The best way is to aim to skim pretty close to the surface. At first the Sun's gravity will mean that the orbit keeps wandering off again, but keep regularly adjusting it - it doesn't take much fuel and the final payoff is pretty good.

Once Rad passes about 400M, you should keep checking the view out of the window. Mars will soon be in sight, and will soon start to grow enormous in the screen.

Keep regularly adjusting your orbit so that you will skim just above the surface. These are successive orbit MFD's as seen on this final approach.

On the last screen, the spacecraft is only three minutes from its closest approach to Mars. At closest approach, or just before, select retrograde autopilot, and engage full forward thrust. Your speed will be reduced, and you will finally drop into Mars orbit, which will then reduce to become a low Mars orbit. 

You have arrived.

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