Belters

Following up on last week's posting, that concentrated on the inner planets, we now move outward in our solar system and visit three current or pending missions.

First up is the Dawn Mission, designed to explore the Asteroid Belt. This could almost be called the Phoenix Mission (except that name is already taken!) as the mission has gone from being active, to almost being canceled, and then back to a go again.

So what's the big deal? Several big deals, actually. First up, following up on the successful use of ion engines in missions such as Deep Space 1 and SMART-1, Dawn will use an ion engine. These will be improved models and are expected to run longer and carry a much heavier payload that any previous ion-propelled mission. The second big deal is where Dawn is going. The Asteroid Belt appears to be the remnants of a planet that never finished forming (possibly stopped by the nearby presence of Jupiter and its massive gravity field). So we have a chance of seeing what the protoplanets that eventually became places like our home started out like. Third, we have a big deal in the route we are taking. Our deep space efforts to date have either been flybys (sometimes of more than one planet) or missions that end in orbit. For Dawn, thanks in part to the use of continuous thrust ion engines, we will travel to one asteroid, orbit it for several months, then travel to a second asteroid and orbit it.

Finally, when it comes to our future in space, we're visiting a very interesting place and two very interesting objects. If we are to extend our presence into the solar system, we'll need resources. You can launch them from Earth or another planet, but even from Mars (with the potential of water there, for example), you're fighting gravity. The asteroids (and, by extension, the comets) offer the potential of plenty of resources, with much smaller gravity wells.

What kinds of resources can these smaller bodies provide? Long the setting in science fiction as a kind of "Wild West", there is the potential of some serious resource gathering out there. There are basically three kinds of asteroids, rocky (or "silicaceous"), metallic and carbonaceous. Carbonaceous asteroids are the most numerous, and are made up of various carbon compounds. With a little money and know-how, such compounds could be turned into building materials...fertilizer...food and more. Metallic asteroids (the smallest part of the population) could potentially yield resources for building habitats, ships, or for use back in the "inner system". And then there's water. Comets are icy bodies, and many asteroids are expected to yield water as well. For example, one of Dawn's targets is the asteroid (or "dwarf planet") known as 1 Ceres, the other is 4 Vesta. What makes 1 Ceres so interesting, for resources, that it might contain water. How much water? One theory puts the amount of water at 200 million cubic kilometers, or more water than that is found on Earth!

With past missions, plus Dawn, we've barely scratched the asteroid belt. About 5,000 of these bodies are discovered each month; the catalog numbers in the hundreds of thousands (for a nice graphical view click here). The potential for resources is vast.

Metal shortages? Water shortages? Pollution? Energy problems? Our planet may be a "closed system", but we may come to have the means of "opening" it up to the point where scarcity of resources is a thing of the past.

Addendum: You too can participate in the Dawn Mission! NASA is encouraging amateur astronomers to observe Ceres and Vesta. Why? Larger telescopes are in constant use, there are more targets than telescopes. On the other hand, there is a large community of amateur astronomers. If enough observe a particular target, a baseline of information can be built up. Amateurs are often on the forefront, for example, in spotting comets, events in the atmosphere of Jupiter or storms on Mars.

No telescope, you say? Well, how are your model-making skills? Give a paper model of Dawn a try!