A space telescope to observe the ultraviolet Universe.
In March 2007, Spain and the Russian Federation signed a collaboration agreement aimed at the development of the space telescope World space Observatory-Ultraviolet (WSO-UV). This telescope will be launched during 2015 and it will be operating until 2025, providing access to the Spanish astronomical community to the only ultraviolet facility available for that decade. The WSO-UV will be more sensitive than the Hubble Space Telescope. Behind the WSO-UV there is an international consortium headed by Russia, and in which Spain, Germany, China, and Ucraine are involved.
In this page you will find an introdution to the ultraviolet astronomy and the WSO-UV project:
Ultraviolet astronomy.
Earth's atmosphere blocks the UV radiation from the universe that can only be observed from space. This radiation transmits unique information about the Universe chemical composition and it is extremely sensitive to the diffuse matter in the Intergalactic Medium.
Determining the composition and the distribution of the intergalactic matter is fundamental to comprehend the nature of the dominant forces in the Universe, the nature of dark matter and the chemical evolution of the Universe from its original composition, hydrogen and helium, to the present chemical richness.
The Ultraviolet astronomy is also fundamental to study stars and planets atmospheres. Most of the planets detected up to this moment are gaseous giants, as Jupiter, orbiting very close to their parent star. Stellar radiation evaporates the atmosphere of planets leaving traces that can be detected in this range.
Ultraviolet astronomy is also essential to investigate the astronomical engines: plasma engines which are capable to accelerate ionized gas up to velocities close to the light speed by converting gravitational energy into mechanical energy.
Previous ultraviolet missions.
 The longest living ultraviolet telescopes have been IUE and HST. IUE was a 45 cm diameter telescope launch into a geosynchronus orbit in 1978. The telescope was operating until September 1996. HST is still in operation and has flown the most sophi st i cated ultraviolet instrumentation ever built.
WSO-UV. World Space Observatory - Ultraviolet.
The World Space Observatory - Ultraviolet (WSO-UV) is an international space telescope that will be launched in 2015, to guarantee observatorytype access in the ultraviolet (UV) range to astronomers after the end of the Hubble Space Telescope mission.
The WSO-UV is a multipurpose observatory consisting of a 1.7 maperture telescope and three instruments for high-resolution spectroscopy, long-slit low-resolution spectroscopy, and deep UV and optical imaging. The WSO-UV mission will last for five years with a planned extension of five years more.
The WSO-UV will provide observations that are of exceptional importance for the study of many astrophysical problems. The mission has five key scientific objectives:
- The study of galaxy formation and the chemical evolution of the Universe, covering the last 80% of its lifetime (0< z < 2).
- The measurement of the properties of diffuse matter in the Universeand its distribution in galactic haloes.
- The formation and evolution of the Milky Way.
- The role of discs in astronomical engines.
- The chemical composition and properties of the atmospheres of giantextrasolar planets.
The Spanish participation is funded by the Ministry of Industry, Tourism and Commerce (industrial activities) and the Ministry of Science and Innovation (scientific activities) through the Spanish Space Plan. The Universidad Complutense de Madrid (UCM) is the scientific responsible of the Spanish participation in the project. Shared mission and science operations between Russia and Spain are planed for the whole WSO-UV mission lifetime. UCM hosts the Spanish science and mission operations center for the ground segment of the WSO-UV.
Telescope characteristic.
 The telescope (T-170M) consists of optical system, structural module and service complex.
The primary mirror unit (PMU) is the main telescope structural element. There are three attachment points of the telescope to the spacecraft service module in the bottom frame part. The optical bench with the scientific instrumentation and the primary mirror baffle are mounted on the PMU.
The secondary mirror unit contains a light cover with the deployment mechanism. A rotary external baffle is also located in the upper part of the telescope tube. The external rotary baffle has an oblique cut for light exposures prevention of the telescopes internal cavity.
Chemical enrichment of the Universe - Intergalactic medium.
One of the most relevant issues in modern astrophysics is the investigation of the chemical evolution of the Universe and, especially of the diffuse baryonic content in the intergalactic medium. Gas and stars are the dominant baryonic components of the Universe; both interact through gravitation, starbirth and stardeath. Gas mixing is fundamental for the chemical enrichment of diffuse matter in space. The most sensitive features to measure the properties of the IGM, such as the resonance spectral lines of the most abundant species in nature, are in the ultraviolet.
WSO-UV instruments will allow:
- To map the gas distribution and the characteristic structure scales (physical forces triggering Galaxy formation).
- To determine the ionization fraction and to describe the UV radiation field.
- To study the heavy elements enrichment in the Universe (taking into account the fraction of different species with respect to iron and silicon).
HIRDES will detect the absorption of Lyman-alpha radiation by diffuse hydrogen in the intergalactic medium. In this manner the characteristics of galactic haloes and the location of diffuse clouds in the space among the galaxies will be studied. HIRDES will provide the best sensitivity ever reached for such studies in the redshift range (0.5<1). It will also allow to measure the abundance of very relevant elements such as oxigen or zinc.
Star formation history & the Milky Way.
The investigation of the chemical evolution is important also at Galactic scale, since the Milky Way disk and halo represent a close laboratory where to start the comprehension of what happens in the rest of the Universe.
For example, phenomena of hot outflows occurs due to the interaction of the disk interstellar medium with the halo, the UV absorption lines are the most sensitive probes for understanding such processes.
Also the chemical abundances of stars in open and globular clusters is a powerful tool to understand the Galaxy evolution: progress requires to measure the abundance and ionization stage of heavy elements which requires access to the ultraviolet range.
The origin of live. Extra-solar planets.
A key question affecting the human race regards the possible presence of life outside of the Earth. Our planet clearly represents a peculiar exception in our Solar System, since other planets do not host a comfortable atmosphere. Nevertheless, in the last two decades, more than 100 extra-solar planets have been detected, spanning a wide range of orbital periods and masses. Given these characteristics, there is no reason to expect similar atmospheres for this large variety of objects; the Solar System is a clear proof of it, showing very different planetary environments.
It is commonly accepted that the Earth formed its own atmosphere simultaneously with the planet formation, while the subsequent evolution is still under debate. However, the final evolution lead to an enrichment in enrichment in oxygen which is considered as a main life markers.
Observations of exoplanet atmospheres will allow us to understand the physical processes at work, and the role of the various parameters involved such as effective temperature, stellar type and metallicity of the hosting star. In this 2010 decade, dedicated astrophysical programs (Corot, Kepler, Gaia) will provide new information about a large number of exoplanets transiting their parent stars: ISSIS at WSO-UV will allow us to observe UV absorption occurring during the transit, a very powerful diagnostic for studying the planetary atmosphere.
Abundances of species such as H, H , CO, OH, C, O can be revealed and, in general, the evolution of planet atmospheres will be investigated, in order to establish:
- The nature of intermediate mass planets.
- The atmospheric content of low-density planets.
- The evolution of oceans rich planets.
- The evaporation process in gaseous planets.
The origin of live. The astrophysical engines.
Several objects in the Universe act as gravitational engines: stars (T Tauri, interactive binaries), black holes, AGN, quasars
These engines can accelerate large masses up to velocities close to light speed, and generate highly collimated outflows and jets: energy of various forms (gravitational, thermal, radiative, magnetic) is indeed converted into mechanical energy. These mass ejections are hot because the energies involved are huge. The efficiency of the engines is about a 10% and there are thermal loses that heat the outflowing gas. The hot gas radiates in the UV range.
T Tauri stars (primitive Solar Systems) show a clear UV and X-ray excess due to the presence of the engine. The mass outflow can be investigated by some forbidden lines in the UV (e.g. Si III and C III features) which appear to be produced by the presence of a strong magnetosphere. These studies are related also to the comprehension of the role of high energy radiation in the first phases of Solar evolution, as well as to the evolution of atmospheric chemistry in forming planets.
Other interesting astronomical engines act in AGNs and microquasars, where the mass output is produced by the accretion disk, and also in accreting white dwarfs, where a similar process occurs.
Ground Segment of the WSO-UV proyect.
The Ground Segment is being designed by a consortium of Spanish industries led by GMV and funded by the Ministerio de Industria, Turismo y Comercio (MITYC).The science contractor is the UCM.
The WSO-UV ground segment is comprised of all the infrastructure and facilities involved in the preparation and execution of the WSO-UV mission operations, which typically encompass real-time monitoring and control of the spacecraft as well as reception, processing and storage of the scientific data.
The Ground Segment, including mission and science operations, is a very important component of the WSO-UV project. The mission operations center (MOC) with control centers and ground stations is to be set up by Spain and Russia. The Science Operations Center (SOC) is the scientific core of the project and manages the interaction with the onboard instruments as well as the scientific data and the interaction with the astronomical community at large. End-users are astrophysicists who either have on-going scientific projects with the WSO-UV or who just wish to access the data stored in the archives via communication links (e.g., via Internet).
WSO-UV will be launched by a Zenith-2SB rocket from Baikonur in 2015 into a geosynchronous orbit. There will be two different ground stations that will receive the information from the space observatory, one in Russia, and another one in Spain.
Information received in either ground stations will be sent via a fast, secure data link to the two control centres of the Mission Operation Centres (MOC). Russia and Spain will also hosts the twin MOC. The Russian one will be located in Moscow, and the Spanish one will be sited at the "WSO-UV Spain headquarters", hosted by the Universidad Complutense de Madrid.
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