Book/Software Reviews

MARS NAVIGATOR

Version 1.0 June 1996, CD-ROM
Georgia Tech Aerospace Engineering Multimedia Lab
Jet Propulsion Laboratory

This software runs under Windows 3.11 and Windows 95. To run it under Windows 95 you must follow the instructions on the disk and install the 16-bit version of QuickTime which is supplied on the CD. If you don't, the installation will crash with a fatal error message. After installing QuickTime you have to return to the CD and click on MARSNAV.EXE. You can then select one of two missions, namely the Mars Pathfinder Mission or the Mars Global Surveyor. Operation is pretty straightforward from then on, with several options to proceed further: INFO, LECTURE, MISSION, HELP.

The Mars Pathfinder Mission covers the subject quite well, giving an overview of the mission and its objectives as well as covering other related topics such as space manoeuvers, data transmission, event sequences, rover characteristics, budget and a comparison of the Pathfinder and Viking missions.

One is introduced to four people involved in the project and each one gives a brief speech - some of these people feature further into the CD-ROM. One can also attend a lecture on the Project. There are also several animated sequences with appropriate music - I enjoyed the bit where the rover is deployed accompanied by music of the ``Charge of the Light Brigade.''

The graphics are not fancy, but are adequate to hold the attention of any audience, and the technical content is fairly basic, so most users should be able to grasp the information. I found that the program crashes when one selects the option ``Was Mars' climate like earth?'' even though I tried two different computers. The sound quality of Golombek's introductory speech is also rather poor.

When you have completed your tour of the Mars PathFinder Mission you must select ``Return'' to get back to the start up screen so you can progress onto the Mars Global Surveyor Mission. Pressing ``Quit'' means exactly that and you will be returned to your Windows start-up screen. The Mars Global Surveyor Mission covers the following topics: The Solar System; Beyond the Solar System; The Destination Planet; The Home Planet; The Journey; The Spacecraft.

The Solar System section has information on the planets as well a laboratory exercise on planetary orbits, which is interesting. The Destination Planet, Mars, is discussed in terms of its meteorology, geology and topography, with illustrations where appropriate. The animation of the rotation of Mars as seen by the Hubble telescope is quite impressive. Find out about the infamous ``face on Mars" under Unanswered Questions ( we now know what this is - see Sky and Telescope, June 1998). You can also conduct a virtual tour of six interesting areas on Mars.

The Home Planet section deals with Earth. The different types of co-ordinate systems used are briefly dealt with and then the user progresses to Planning a Space Mission, which covers various aspects of planning and launching a space mission. This is then followed by a section on telecommunications. In the laboratory exercise you can drive the rover across the surface of Mars - I was not very successful at doing this!

Having crashed the rover several times you can then move onto the Journey to Mars where you will discover gravity and Newton's Laws as well as two-body motion and the different kinds of orbits. Orbital manouvers are dealt with including plane orbit changes, followed by navigation and how Doppler is used. The cruise phase is then discussed and finally in a laboratory exercise you have to fly a mission to Mars with different launch dates. By selecting different speeds you can try to intercept Mars - I enjoyed this exercise, although my crew died long before my spacecraft arrived anywhere near Mars!

Finally, the spacecraft is discussed. Aspects covered include spacecraft components, subsystems, command and data handling, instruments and experiments, the planet encounter and Mars orbit insertion. A laboratory exercise then allows you to prepare a mission (select your launch vehicle, trajectory, equipment, etc.) and then evaluates your proposal - quite simple if you have gone through all the previous sections.

All in all, I enjoyed going through this CD-ROM, discovering new material every time I used it. I found the second part of the CD, the Mars Global Surveyor Mission, more interesting than the first part. The technical knowledge required is not high (making it ideal for young people) and anyone slightly interested in the subject should find it quite fascinating.
Greg Roberts