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that we're aware of and would need to work on probably right away. 

I guess the bottom line of this really is that it's only from Earth orbit that we believe we can get the proper perspective to do this global study of the Earth and the global study of the interactions of the components. We know what to observe and we know how to observe it, and this is the first time in our history that we've been at that point, which makes this a very timely initiative. 

The second-would you like me to just go straight through these?

Mr. NELSON. Yes, give us all four, and then I'm going to turn to the members for their comments and their questions. 

Dr. RIDE. Okay. 

The second initiative that I'll describe is also a science-oriented initiative. This exploration of the solar system, and we're talking here about robotic exploration of the solar system. This initiative builds on a very long standing NASA tradition of solar system exploration, and it would continue those efforts to understand the planetary system, the origin of the planetary system, and the evolution of the planetary system and our place in it.
 
Now, the solar system is divided up into three basic classes of bodies-the inner or terrestrial planets, which is sort of from Mars in, the outer gas giant planets, which are Jupiter on out, and then the primitive bodies, which are the comets and the asteroids. This initiative would have one mission directed towards each of those, to really get a broad understanding of the solar system. 

The first mission in this would be the comet rendezvous asteroid flyby craft, which I suspect this subcommittee is very, very familiar with. That's a mission that would, in the vision of this initiative, launch in 1993, go past an asteroid to do a good characterization of that asteroid, compositional studies, that sort of thing, then continue its journey on to rendezvous with a comet-in this case, Temple II-and fly formation with the comet, and then as the comet became more active and approached the Sun, it would back off and do a good study of the coma and the tail. 

That's something that we believe will give us some insight and some clues into the origin of the solar system, just because comets really are the most primitive bodies in the solar system that we have to study. 

A second mission in this initiative is Cassini, a mission to Saturn. This kind of reflects that ambitious nature of the initiatives because the Cassini mission that was recommended by the Solar System Exploration Committee, the task force of the NASA Advisory Council, and was fairly well defined by that group. In this initiative, we have enhanced that considerably. We have assumed that there will be a heavy lift launch vehicle available, or this initiative would require a heavy lift launch vehicle, which greatly enhances the science that can be done on the Cassini mission. It allows you to carry three probes instead of one, and it really makes it a much more viable scientific mission. 

I think, as one of the scientists said, it's a very long way to Saturn, so if you're going to go, you should probably do it right, and having a heavy lift launch vehicle allows you do it right.