27
Nov 10

Hylas-1 in orbit brings Europe broadband from space

Source: ESA PR27-2010


Ariane 5 launcher lifted off from Europe’s Spaceport in French Guiana on its
mission to place two telecommunications satellites, Hylas-1 and Intelsat 17.
Image credits: ESA/CNES/ARIANESPACE - Optique Video CSG - S. Martin, 2010

A flawless launch has delivered Hylas-1, ESA's first public-private partnership in a full satellite system, into space. The satellite was released today into its transfer orbit after a textbook launch by an Ariane 5 vehicle from Europe's Spaceport in French Guiana.

Owned and operated by Avanti Communications plc of the UK, and with its key payload constituents developed by EADS Astrium in the framework of ESA's Advanced Research in Telecommunication Systems (ARTES) programme, through funding essentially from the UK Space Agency, the Hylas-1 communication satellite will demonstrate advanced high-speed technologies and provide innovative broadband services across Europe.

The 53rd Ariane 5 (V198) lifted off from Kourou, French Guiana, at 15:39 local time (18:39 GMT, 19:39 CET) and released its two payloads, Hylas-1 and Intelsat-17, into their planned transfer orbits.

ESA has devoted years to developing satellite broadband technologies through its Advanced Research in Telecommunication Systems (ARTES) programme. Now several of these innovations are being put to work on Hylas-1.

ESA's involvement focuses on the mission's most inventive element - its highly adaptable payload. The satellite's flexible technology means that it can modify its data throughput across the European regions it serves, keeping pace with market demand.

"ESA's cooperation with Avanti Communications on Hylas-1 is a prime example of a public-private partnership, a creative fast-track for demonstrating and reaping the benefits of satellite high technology as part of an operational mission," commented Magali Vaissiere, ESA Director of Telecommunications and Integrated Applications

This is a new way of working that ESA will pursue in telecoms. Within the next 24 months, two similar initiatives in partnership with satellite operators Inmarsat and Hispasat will foster the development of state-of-the-art technologies to serve the new needs of the worldwide market and Europe's citizens. (read more)

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27
Nov 10

Were wandering globular clusters the first dwarf galaxies in the universe?

Source: arXiv

In the last decade the advent of new types of dwarf stellar systems became a reality.

The new dwarf stellar systems include ultra-compact dwarfs, ultra-faint dwarf spheroidals, and exotic globular clusters, breaking the old simple paradigm for dwarf galaxies and globular clusters. These objects become more intriguing, and understanding of these new findings becomes more challenging. Recently we discovered a new type of large scale structure in the Virgo cluster of galaxies: it is composed of globular clusters. Globular clusters in Virgo are found wandering between galaxies (intraclus- ter globular clusters) as well as in galaxies.


The Virgo Galaxy Cluster. Source:DSS.

These intracluster globular clusters fill a significant fraction in the area of the Virgo cluster and they are dominated by blue globular clusters. These intracluster globular clusters may be closely related with the first dwarf galaxies in the universe. (read the full pdf article from arXiv)

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27
Nov 10

Galaxies pin down dark energy

Source: Physics World
Hubble Space Telescope image of a pair of spiral galaxies with swirling arms.
The galactic system is located in the constellation of Draco, about 350 million light-years away.
Image credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration
and A Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

A new way of measuring the geometry of the universe confirms that dark energy dominates the cosmos and bolsters the idea that this unusual form of energy is described by Einstein's cosmological constant. The technique, developed by physicists in France, involves a relatively easy measurement of the orientation of distant pairs of galaxies.

Over the past decade or so, several kinds of observation, such as measurements of the distances of remote supernovae, have provided strong evidence that the expansion of the universe is accelerating. Cosmologists believe that this expansion is being driven by what is known as dark energy – a substance with negative pressure that opposes the pull of gravity. Unfortunately, however, they have little idea of what dark energy actually is, having been unable to measure its properties well enough to distinguish between rival hypotheses.(read more)

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27
Nov 10

Space Ministers emphasise priority to deliver Galileo and GMES

Source: ESA PR26-2010


Credit&Copyright: ESA/A. Le Floc'h.

Ministers in charge of space activities representing the Member States of the European Space Agency and the European Union met in Brussels today for the Seventh Space Council. Today's Council was jointly chaired by Sabine Laruelle, the Belgian Minister of Small and Medium Enterprises, the Self-employed, Agriculture and Science Policy, on behalf of the EU Competitive-ness Council, and Giuseppe Pizza, Italian State Secretary in the Ministry of Education, University and Research, on behalf of the ESA Council at Ministerial Level. Antonio Tajani, Vice-President of the European Commission and Commissioner for Enterprise & Industry, and Jean-Jacques Dordain, ESA Director General, also took part. The Space Council unanimously endorsed a resolution that called for the necessary actions to deliver a space strategy that would enable economic growth, respond to public policy objectives and develop the vocations of science and technology in Europe. Ministers emphasised that the flagship programmes Galileo and GMES (Global Monitoring for Environment and Security) remain the priorities for the EU in space and identified the key decisions to be taken in these areas over the coming months. In the areas of Global Climate Change and Security, the ministers asked the European Commission and the Director General of ESA to collaborate with the Member States and other relevant actors in Europe to identify how to fill gaps in existing space capabilities. Ministers also recognised the need to move towards establishing a Space Situational Awareness capability for the protection of Europe's space assets. They stressed the need for Europe to voice a single European position in international discussions on space exploration. Following on from the 16 September conference 'Space for the African Citizen' and taking account of the expected inclusion of space in the communication for the EU-Africa Summit, to be held in Libya on 29 and 30 November, the Space Council called for expanded partnerships with the African Union, the Regional Economic Groupings and African nations to build capacities for acquiring and exploiting space systems. Aware that the EU-ESA Framework Agreement, under which the Space Council was established, has been extended until May 2012, ministers of the EU and ESA invited the European Commission and the Director General of ESA respectively to conduct an evaluation by May 2011 of the experience gained under that agreement. ESA Director General Jean-Jacques Dordain emphasised the progress that had been achieved in space missions since the previous Space Council meeting in May 2009, adding: "The entry into force of the Treaty on the Functioning of the European Union, with a specific space competence, is good news for space, good news for Europe and good news for ESA. It allows us not to do the same thing differently but to do more, together."

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27
Nov 10

Cassini Finds an Oxygen–Carbon Dioxide Atmosphere at Saturn’s Icy Moon Rhea

Source: Science Express

The flyby measurements of the Cassini spacecraft at Saturn’s moon Rhea reveal a tenuous oxygen–carbon dioxide atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn’s magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies such as Jupiter’s moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O2 locked within Rhea’s ice. The presence of CO2 suggests radiolysis reactions between surface oxidants and organics, or sputtering and/or outgassing of CO2 endogenic to Rhea’s ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism. (see source-requires subscription)

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27
Nov 10

A new model from Very Low Mass Stars to Brown Dwarfs

Source: arXiv

Since the discovery of brown dwarfs in 1994, and the discovery of dust cloud formation in the latest Very Low Mass Stars (VLMs) and Brown Dwarfs (BDs) in 1996, the most important challenge in modeling their atmospheres as become the understanding of cloud formation and advective mixing.

Many cloud models have been constructed to address this problem in brown dwarfs over the past decade, but none treated the mixing properties of the atmosphere, and the resulting diffusion mechanism realistically enough to reproduce the properties of the spectral transition from M through L and T spectral types without changing cloud parameters. One of the most important challenge in modeling the atmospheres and spectral properties of VLMs and brown dwarfs is the formation of dust clouds and its associated greenhouse effects making the infrared colors of late M and early L dwarfs extremely red compared to colors of low mass stars. The cloud composition, according to equilibrium chemistry, is going from zirconium oxide (ZrO2 ), to refractory ceramics (perovskite and corundum; CaTiO3 , Al2O3 ), to silicates (forsterite; Mg2SiO4 ), to salts (CsCl, RbCl, NaCl), and finally to ices (H2O, NH3 , NH4 SH).

An international team leaded by France Allard, co-authored by Homeier and Freytag has now proposed a 2D a new model atmosphere grid, named BT-Settl, computed using an updated version of the atmosphere code Phoenix and compared it to the AMES-Cond/Dusty models, on several parameters and found that the model is quite god on covering the whole range of VLMs and brown dwarfs and beyond: 1000,000 K < T eff < 400 K; -0.5 < logg <5.5; and +0.5 < [M/H] < -4.0, including various values of the alpha element enhancement. (read full article)

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