Last night, Hilkka and I attended a presentation by the Royal Astronomical Society of Canada Vancouver Centre . Eric Dunn, a well-known popularizer of Astronomy and long-time member, gave us a talk about the latest developments in Solar System exploration. Much of our present knowledge comes from the technical marvels called "orbiters" - vehicles sent from Earth to "circle" or pass by other planets, their "moons", or to probe comets, asteroids, etc., all part of our solar system.
Because the difficulty of reaching some of the planets, we have varying amounts of knowledge about them. Also, several of them (i.e. the "gas giants" Jupiter, Saturn, Uranus, Neptune) have no solid surfaces that we know of, or are too inhospitable likely ever to support a human presence (Venus, or Jupiter's moon Io, for example). Therefore, more detailed exploration efforts are currently directed to those places where human beings could survive. The most likely of these is the planet Mars.
Now, getting there is not accomplished without some better technology than is currently available. As a first step, plans are being made to land people on our Moon again. From 1969 to 1972 the USA landed people on the Moon and returned them to Earth, but, incredibly, there is no "hardware" on hand right now to do this again - for instance, no spaceworthy "Saturn" rockets (the biggest rockets ever built) exist. There are a lot of extras that need to go along, most importantly a "return vehicle". All these require prodigious amounts of energy (fuel, meaning really big rockets) to lift out of Earth's "gravity well". At the moment, this kind of spacecraft is not available.
This means, of course, that we also cannot get to, and return from Mars right now. None-the-less, to land people on Mars, you need to know as much as possible about it beforehand. To this end, there have been many "robot" explorers sent there. Some of these orbit Mars, probing it with a variety of cameras and sensors; a couple are actually on Mars' surface - the spectacularly successful "rovers", Spirit and Opportunity. You can see pictures and related information here: http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20070503a.html
The talk by Eric mentioned other worlds as well. Perhaps the most successful planetary explorer ever is the Cassini orbiter which has taken a multitude of pictures and transmitted to Earth a huge amount of information about Saturn, many of its moons (we know of about 60 at last count) and the environment out there. For instance, I showed a picture of a "backlit" Saturn on an earlier post, which Cassini sent.
There are many other images at: http://www.nasa.gov/mission_pages/cassini/multimedia/index.html
Every now and then, one needs to get away from one's problems and concerns. I find my "getaway" in the fields of Astronomy and space exploration. If you're interested in some of this, link to http://www.nasa.gov/, or http://www.jpl.nasa.gov/, and do some "link-hopping".