Discussing the state of space mission planning recently with Centauri Dreams contributor Ashley Baldwin, I mentioned my concerns about follow-up missions to the outer planets once New Horizons has done its job at Pluto/Charon. No one is as plugged into mission concepts as Dr. Baldwin, and as he discussed what's coming up both in exoplanet research as well as future planetary missions, I realized we needed to pull it all together in a single place. What follows is Ashley's look at what's coming down the road in exoplanetary research as well as planetary investigation in our own Solar System, an overview I hope you'll find as useful as I have. Dr. Baldwin is a consultant psychiatrist at the 5 Boroughs Partnership NHS Trust (Warrington, UK) and a former lecturer at Liverpool and Manchester Universities. He is also, as his latest essay makes clear, a man with a passion for what we can do in space. by Ashley Baldwin We've come a long way since the discovery of the first "conventional"...

Before I get into some NASA-funded exoplanet work that grew out of a study of the binary nature of Pluto and Charon, I want to mention that NASA TV will air an event of exoplanet interest on Tuesday the 7th, from 1700 to 1800 UTC. A panel of experts will be discussing the search for water and habitable planets, presenting recent discoveries of water and organics in our own system and relating them to the search for Earth-like worlds around other stars. NASA streaming video, along with schedules and other information, can be found here. As to that Pluto/Charon work, it actually took Ben Bromley (University of Utah) and Scott Kenyon (Smithsonian Astrophysical Observatory) much deeper into space when they began relating it to the formation of planets in circumbinary orbits around binary stars. These are planets that orbit both stars rather than one of the two. In other words, the work, funded by NASA’s Outer Planets Program, has examined the familiar ‘Tatooine’ scenario from Star Wars,...

Alpha Centauri continues to be a maddening and elusive subject for study. Two decades of radial velocity work on Centauri A and B have been able to constrain the possibilities -- we've learned that there are no gas giants larger than Jupiter in orbits within 2 AU of either of the stars. But lower mass planets remain a possibility, and in 2012 we had the announcement of a planet slightly more massive than Earth in a tight orbit around Centauri B. It was an occasion for celebration (see Lee Billings' essay Alpha Centauri and the New Astronomy for a glimpse of how that moment felt and how it fit into the larger world of exoplanet research). But the candidate world, Centauri Bb, remains controversial, and for good reason. The work involved radial velocity methods at a level of precision that pushed our instruments to the limit. Andrew LePage explored the issues in Happy Anniversary α Centauri Bb?, where the question-mark tells the tale. Here he discusses the instrumentation...

The search for sub-planetary scale features in other solar systems continues, with encouraging news from the Hunt for Exomoons with Kepler project. A moon around a distant exoplanet is a prize catch, but as we’ve also seen recently, scientists are weighing the possibilities in detecting exoplanetary ring systems (see Searching for Exoplanet Rings). Confirming either would be a major observational step, but exomoons carry the cachet of astrobiology. After all, a large moon around a gas giant in the habitable zone might well be a living world. David Kipping (Harvard University) and colleagues at HEK have released a new study that tackles the question of how detectable exomoons really are. Published online today by the Astrophysical Journal, the paper examines 41 Kepler Objects of Interest, bringing the total number of KOIs surveyed by HEK thus far up to 57. The paper demonstrates that the process is beginning to move out of the realm of computer simulations and assumption-laden theory...

The Titius-Bode law has always been a curiosity, one often attributed to little more than happenstance. But recently this numerological curiosity, which predicts that planets in a solar system appear with a certain ratio between their orbital periods, has been the subject of renewed investigation. Francois Graner (Ecole Normale Superieure, Paris) and Berengere Dubrulle (Observatoire Midi Pyrenees, Toulouse) revisited Titius-Bode in the 1990s, asking whether it actually flagged symmetry properties that most solar systems should exhibit. And now continuing work out of Australian National University and the University of Copenhagen has made predictions using a modified version of the law that can be tested against observation of known exoplanetary systems. So we need to refresh our memory on the formulation, which shows us a relationship that predicts planetary orbits. Take a sequence where each number is double the number that preceded it. Thus 0, 3, 6, 12 and so on. Add 4 to each of...

One of these days we'll have the instruments in place to examine light from a terrestrial-class world around another star. This opens up the possibility of identifying atmospheric gases like oxygen, ozone, carbon dioxide and methane. All of these can occur in an atmosphere in the absence of life, but if we find them existing simultaneously in great enough quantities, we will have detected a possible biosignature, for without life's activity to replenish them, these gases would recombine and leave us with a much less tantalizing atmospheric mix. But tackling planetary atmospheres for biosignatures is only one way to proceed. An interdisciplinary team led by Cornell University's Lisa Kaltenegger and Siddharth Hegde (Max Planck Institute for Astronomy), is examining life detection based on the characteristic tint of lifeforms. An alien organism covering large parts of the planet -- think forests, for example, on Earth -- would reflect light at particular wavelengths, light that could be...