ESA Science & Technology - Publication Archive
This document describes the proposed model payload of MarcoPolo-R, a sample return mission to a near-Earth asteroid (NEA), which is currently under assessment as a candidate mission in ESA's Cosmic Vision 2015-2025 Plan.
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Made available online 25 August 2011
To date, ozone has only been identified in the atmospheres of Earth and Mars. This study reports the first detection of ozone in the atmosphere of Venus by the SPICAV ultraviolet instrument onboard the Venus Express spacecraft. Venusian ozone is characterized by a vertically confined and horizontally variable layer residing in the thermosphere at a mean altitude of 100 km, with local concentrations of the order of 107-108 molecules cm-3. The observed ozone concentrations are consistent with values expected for a chlorine-catalyzed destruction scheme, indicating that the key chemical reactions operating in Earth's upper stratosphere may also operate on Venus.
Published online on 5 October 2011.
For decades, the source of Earth's volatiles, especially water with a deuterium-to-hydrogen ratio (D/H) of (1.558±0.001)×
Summary of the study performed at ESA's Concurrent Design Facility (CDF) into the M-class mission Large Observatory for X-ray Timing (LOFT).
Contents of the presentation:
- Study logic
Baseline design for a launch with Vega
- Main trade-offs
- System and subsystem overview
- System budgets
- Risk, cost, and programmatics
- Design assessment for a launch with Soyuz
- Payload aspects
- Open issues
Two main modes of star formation are know to control the growth of galaxies: a relatively steady one in disk-like galaxies, defining a tight star formation rate (SFR)-stellar mass sequence, and a starburst mode in outliers to such a sequence which is generally interpreted as driven by merging. Such starburst galaxies are rare but have much higher SFRs, and it is of interest to establish the relative importance of these two modes. PACS/Herschel observations over the whole COSMOS and GOODS-South fields, in conjunction with previous optical/near-IR data, have allowed us to accurately quantify for the first time the relative contribution of the two modes to the global SFR density in the redshift interval 1.5 < z < 2.5, i.e., at the cosmic peak of the star formation activity. The logarithmic distributions of galaxy SFRs at fixed stellar mass are well described by Gaussians, with starburst galaxies representing only a relatively minor deviation that becomes apparent for SFRs more than 4 times higher than on the main sequence. Such starburst galaxies represent only 2% of mass-selected star forming galaxies and account for only 10% of the cosmic SFR density at z~2. Only when limited to SFR> 1000MSun/yr, off-sequence sources significantly contribute to the SFR density (46±20%). We conclude that merger-driven starbursts play a relatively minor role for the formation of stars in galaxies, whereas they may represent a critical phase towards the quenching of star formation and morphological transformation in galaxies.
Astro-ph preprint submitted on 30 September 2011.
The Hipparcos satellite was launched in 1989. It was the first, and remains to date the only, attempt at performing large-scale astrometric measurements from space. Hipparcos marked a fundamentally new approach to the field of astrometry, revolutionising our knowledge of the positions, distances, and space motions of the stars in the solar neighbourhood. In this retrospective, I look back at the processes which led to the mission's acceptance, provide a short summary of the underlying measurement principles and the experiment's scientific achievements, and a conclude with a brief summary of its principal legacy - the Gaia mission.
Published as: "EAS Tycho Brahe prize lecture 2011", The Astronomy and Astrophysics Review, Volume 19, Issue 1, December 2011, Article 45. http://dx.doi.org/10.1007/s00159-011-0045-5