Low Earth Orbit

Once the thrusters are finally switched off, your virtual self will experience weightlessness for the first time. You are freely falling around the Earth - following a path dictated by a combination of gravity and your now considerable speed. Free fall isn't difficult to achieve on Earth - just jump, and you will experience it. Normally the experience ends rather quickly when your orbital path hits the Earth's surface. But now, virtually, you're moving quickly enough to stop that from happening.

It's not a bad idea at this point to emulate NASA Astronauts and have a good look at the Earth out of the window before our next course adjustment.



Aligning orbits

Every orbit around a planet fits entirely into a plane (a flat surface). This surface also passes through the centre of the planet. Different orbits fit into different planes. One of the most frequent manoevres we need to perform is to change the plane of our orbit.

In this case, I want to align the plane of our current orbit with the plane of Mars' orbit. We've already gone some way towards this by taking off at the right moment - now is the time to finish the job, and also to iron out any errors introduced during takeoff. The correct tool for this is the alignment MFD.

As you can see, my relative inclination to Mars has got worse since I took off owing to the faults in my takeoff technique. Now is the time to put things right.

In this case, I'm not doing much more than following the instructions the alignment MFD gives me. As I approach the descending node, I turn to thrust in the ascending (+) direction. I then fire the main engine when the MFD tells me to - which is always when Tn = 0.5 * Tth

You can use a bit of time acceleration (up to 100x is probably fine) in low earth orbit.

After the required thrusting is done, our orbit around Earth is parallel to Mars' orbit around the Sun.



We've done this alignment because our next task is to finalise our plans to leave the Earth behind. We're off to Mars on our next orbit.

Leaving for Mars