Abstract.We have undertaken a thorough dynamical investigation of five extrasolar planetary systems using extensive numerical experiments. The systems Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208 were examined concerning the question of whether they could host terrestrial-like planets in their habitable zones (HZ). First we investigated the mean motion resonances between fictitious terrestrial planets and the existing gas giants in these five extrasolar systems. Then a fine grid of initial conditions for a potential terrestrial planet within the HZ was chosen for each system, from which the stability of orbits was then assessed by direct integrations over a time interval of 1 million years. For each of the five systems the 2-dimensional grid of initial conditions contained 80 eccentricity points for the Jovian planet and up to 160 semimajor axis points for the fictitious planet. The computations were carried out using a Lie-series integration method with an adaptive step size control. This integration method achieves machine precision accuracy in a highly efficient and robust way, requiring no special adjustments when the orbits have large eccentricities. The stability of orbits was examined with a determination of the Rényi entropy, estimated from recurrence plots, and with a more straightforward method based on the maximum eccentricity achieved by the planet over the 1 million year integration. Additionally, the eccentricity is an indication of the habitability of a terrestrial planet in the HZ; any value of e > 0.2 produces a significant temperature difference on a planet's surface between apoapse and periapse. The results for possible stable orbits for terrestrial planets in habitable zones for the five systems are: for Gl 777 A nearly the entire HZ is stable, for 47 Uma, HD 72659 and HD 4208 terrestrial planets can survive for a sufficiently long time, while for Gl 614 our results exclude terrestrial planets moving in stable orbits within the HZ. Studies such as this one are of primary interest to future space missions dedicated to finding habitable terrestrial planets in other stellar systems. Assessing the likelihood of other habitable planets, and more generally the possibility of other life, is the central question of astrobiology today. Our investigation indicates that, from the dynamical point of view, habitable terrestrial planets seem to be compatible with many of the currently discovered extrasolar systems. they could host additional terrestrial-like planets in their habitable zones (=HZ).Since the discovery of the first extrasolar planetary system about 10 years ago (Mayor & Queloz 1995), a major point of dynamical investigations has been the determination of stable regions in extrasolar planetary systems, where additional planets on stable orbits could exist. Today we know about 105 planetary systems with 120 planets, where 13 systems have more than one planet (both confirmed and unconfirmed cases).Article published by EDP Sciences and available at

Celestial Mechanics and Dynamical Astronomy, 102, pp. 13-27, http://dx.doi.org./10.1007/s10569-008-9152-7International audienc

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Space manifolds act as the boundaries of dynamical channels enabling fast transportation into the inner- and outermost reaches of the Solar System. Besides being an important element in spacecraft navigation and mission design, these manifolds can also explain the apparent erratic nature of comets and their eventual demise. Here, we reveal a notable and hitherto undetected ornamental structure of manifolds, connected in a series of arches that spread from the asteroid belt to Uranus and beyond. The strongest manifolds are found to be linked to Jupiter and have a profound control on small bodies over a wide and previously unconsidered range of three-body energies. Orbits on these manifolds encounter Jupiter on rapid time scales, where they can be transformed into collisional or escaping trajectories, reaching Neptune’s distance in a mere decade. All planets generate similar manifolds that permeate the Solar System, allowing fast transport throughout, a true celestial autobahn.

This work reexamines the dynamics of the 5:2 mean motion resonance with Jupiter located in the Outer Belt at a ∼ 2.82 AU. First, we compute dynamical maps revealing the precise structure of chaos inside the resonance. Being interested to verify the chaotic structures as sources of natural transportation routes, we additionally integrate 1000 massless particles initially placed along them and follow their orbital histories up to 5 Myr. As many as 99.5% of our test particles became Near-Earth Objects, 23.4% migrated to semi-major axis below 1 AU and more than 57% entered the Hill sphere of Earth. We have also observed a borderline defined by the q 2.6 AU perihelion distance along which particles escape from the Solar System.