Mission to Mars - Navigation Hints

The spacecraft cannot take enough fuel to operate its engines continuously all the way to Mars. Instead, the engines are used in brief bursts called "burns" which point the spacecraft in the right direction. It then coasts into position for the next burn. This mission to Mars is accomplished with 8 burns, listed below. You will need to memorize this list.

1. Earth Ascent (EA) - from the launch pad into Earth orbit
2. Trans-Mars Insertion (TMI) - from Earth orbit towards Mars
3. Mars Orbit Insertion (MOI) - into Mars orbit
4. Mars Descent (MD) - down to the surface of Mars
5. Mars Ascent (MA) - from the surface of Mars to Mars orbit
6. Trans-Earth Insertion (TEI) - from Mars orbit towards Earth
7. Earth Orbit Insertion (EOI) - into Earth Orbit
8. Earth Descent (ED) - down to the surface of the Earth

The navigation computer executes these burns automatically. However, the astronauts must start each burn at the proper time with the GO button. Make sure the navigation computer is set on the correct burn before pressing the GO button. If not, the computer will execute the wrong maneuver and the spacecraft will be lost.

For best fuel economy, the burns should be executed at precisely the point of overlap of the old and new orbits, as shown in the figures below. A burn executed within 20 seconds of the ideal time will still work, but it will require more fuel. A burn executed more that 20 seconds off will fail and the spacecraft will be lost.

© Copyright 2000 by Bill Lovegrove. All rights reserved.

Last Updated 04/01/2000