"For dinner tonight, fossil soup," Bob said, and Kyoichi replied without missing a beat: "Great idea! Lots of calcium."

I was with Bob McNally and Kyoichi Sasazawa on MDRS Crew 24's eighth EVA, or extra-vehicular activity, and we had found the mother lode of all fossils. These fossilized mollusks, Gryphaea, from the late Jurassic period, are about 130 million years old. A previous EVA team had discovered them under Kyoichi's direction, and today we found even more of them. Kyoichi even thinks he can find some microfossils inside the larger fossil shells. (For more details about the fossils, see Kyoichi's Geology Report today.)

The fossil find isn't the only exciting thing that happened today. Even more important was getting the sump pump in the Greenhab fixed. When people actually start living on Mars, as excited as they will be about the scientific discoveries they make, most of their time will be spent in survival tasks.

That's why the GreenHab is so important. It is planned to be not just a greenhouse, but also part of a very ambitious experiment in recycling waste-water. When the system is working properly, used "gray water" from the Hab will cycle through a series of filters and water tanks in the GreenHab. Plants will grow in these tanks, which will overflow from one to another until the water is returned to the Hab for use in the toilet. (Right, no flushing toilets on Mars, but this is the best compromise for now between the ideal future and the practical present.)

More good news: The plants have arrived, and some students from Brigham Young University will be driving down this weekend to help plant them in the Greenhab, check out the telescope in the Musk Mars Desert Observatory, and do a little geology.

All this work, and to what purpose? I have been asked more times than I can count why I care about going to Mars. Why does anybody care? Shouldn't we be staying here and taking care of our own green Earth? Isn't the cost of space exploration too great considering the social problems we could be fixing at home?

I'm guessing that anyone reading this has heard these questions, and considered the answers, before now, including all the facts about the advances in earthly science and medicine that have resulted from space exploration.

So here's my two bits anyway (short version): This is what we humans do. We explore, we look to the future, we imagine other places and times, we go outside of ourselves and our immediate experiences just to see where we'll get. We step out of the circle of light and comfort where we are now, and then we shine our light ahead to the next unknown.

Mars is a destination, but not, I think, our final destination.