The Voyager Interstellar Mission sounds like something out of Star Trek, but it is in fact the extended mission of the doughty spacecraft that taught us so much about the outer Solar System. An extended mission can be just as valuable, and sometimes more so, than the original -- think about the continuing adventures of our Mars rovers, working well beyond their projected timelines. In Voyager's case, we're learning much about how the Solar System behaves as it moves through the interstellar medium, and about the heliopause, where the Sun's solar winds effectively lose their dominance over the winds from other stars. Now the Deep Impact spacecraft, which provided such spectacular scenes of Comet Tempel 1, will acquire an extended mission of its own, and in two parts. The one that catches my eye is called Extrasolar Planet Observation and Characterization (EPOCh), which will turn the spacecraft loose on the study of several nearby bright stars already known to have gas giant planets...

The challenge of working with a small sample of exoplanetary systems -- and one tilted toward those detectible through radial-velocity methods -- is that building up solid models of planet formation is tricky. I'm thinking about this in terms of the recent planetary conference at Santorini, and also recalling work performed at the University of Texas, where Michael Endl and team have looked into the relationship between planets around red dwarfs and the metallicity of their stars. It's an intriguing question and one that only continuing observations can nail down. Metallicity refers to the presence of elements higher than hydrogen and helium in a star's composition, something we can determine through spectroscopic analysis. Endl and co-author Fritz Benedict, as originally noted in this post, worked with graduate student Jacob bean on a study of three dwarfs known to have planets: Gliese 876, Gliese 436 and Gliese 581, noting their lower values of metallicity compared to stars of...

In another decade or so, we should have space-based telescopes actively looking for life around other stars by studying the atmospheres of exoplanets. In the beginning, it will make sense to look for bio-chemistries similar to our own. This isn't some kind of species chauvinism but simple realism. We know more about how life works on Earth than it might in far more extreme environments, so we'll turn first to Earth analogues, seeking the bio-signatures of carbon-based metabolisms on worlds with liquid water. But as we explore our own Solar System, the situation will continue to evolve. If life exists on Enceladus, or Ceres, or in some bizarre Kuiper Belt ecosystem, it's not going to be operating on the same principles as life here on Earth. These aren't Earth analogues, and moreover, they are places for which we have the possibility of lander and rover exploration within the forseeable future. We'll want to widen our range so we don't overlook a form of life that isn't immediately...