Ritmo de caídas de meteoritos en los últimos 500 años: ¿hay periodicidad?



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CONFERENCIAS
Allan Boss
A New Scenario for the Origin of the Solar System
José López Ruiz
Procesos de acreción y diferenciación en La Tierra
Juan Pérez-Mercader
Claves para la búsqueda de vida en el Universo (día 26 de octubre)
Kurt Marti
Mars-Earth connection
Carlos Martín Escorza
Ritmo de caídas de meteoritos en los últimos 2.500 años: ¿hay periodicidad?. Los registros de caídas de meteoritos de los que se dispone la fecha de ocurrencia del fenómeno no son todo lo abundantes que se desearía para realizar un estudio de frecuencias y posibles periodicidades. Los datos, por el contrario, son escasos y se encuentran muy distribuidos, aunque son mucho más numerosos en épocas recientes que las pasadas, y conforme vamos retrocediendo en el tiempo se dispone de menos referencias. Desde hace décadas se conocían sólo las caídas producidas en la parte del planeta que recogían las noticias hsitóricas en los países europeos primero y norteamericanos después, pero su límite no traspasa la Edad Media. Recientemente se han añadido a estos los datos obtenidos de los registros de caídas en China, que amplian el tiempo de estos sucesos registrados con la fecha de caída hasta los años cercanos a los 500 a.C. En base a todos estos datos se presentará un análisis general que muestra cual ha sido el ritmo global de caídas y una propuesta de posible periodicidad temporal para todas ellas.

Agustín Fernández-Chicarro


THE MARS EXPRESS MISSION AND ASTROBIOLOGY
A.F. Chicarro, European Space Agency, Space Science Department, ESTEC/Code SCI-SB, Postbus 299,

2200 AG Noordwijk, The Netherlands (email: agustin.chicarro@esa.int).


The European Space Agency and the scientific community have performed concept and feasibility studies for more than ten years on potential future European missions to the red planet (Marsnet, Intermarsnet), focusing on a network of surface stations complemented by an orbiter, a concept which is being implemented by the CNES-led Netlander mission to be launched in 2005. Before that, however, the ESA Mars Express mission includes an orbiter spacecraft and a small lander module named Beagle-2 in remembrance of Darwin’s ship Beagle. The mission, to be launched in 2003 by a Russian Soyuz rocket, will recover some of the lost scientific objectives of both the Russian Mars-96 mission and the ESA Intermarsnet study, following the recommendations of the International Mars Exploration Working Group (IMEWG) after the failure of Mars-96, and also the endorsement of ESA's Advisory Bodies that Mars Express be included in the Science Programme of the Agency.

The specific scientific objectives of the Mars Express orbiter are: global high-resolution imaging with 10 m resolution and imaging of selected areas at 2 m/pixel, global IR mineralogical mapping, global atmospheric circulation study and mapping of the atmospheric composition, sounding of the subsurface structure down to the permafrost, study of the interaction of the atmosphere with the surface and with the interplanetary medium as well as radio science. The goals of the Beagle-2 lander are: geology, geochemistry, meteorology and exobiology of the landing site.

The scientific payload on the Mars Express orbiter includes a Super/High-Resolution Stereo Colour Imager (HRSC), an IR Mineralogical Mapping Spectrometer (OMEGA), a Planetary Fourier Spectrometer (PFS), a Subsurface-Sounding Radar Altimeter (MARSIS), an Energetic Neutral Atoms Analyser (ASPERA), an UV and IR Atmospheric Spectrometer (SPICAM) and a Radio Science Experiment (MaRS). The Beagle-2 lander includes a suite of imaging instruments, organic and inorganic chemical analysis, robotic sampling devices and meteorological sensors (see Table 1).

The Mars Express mission will address the issue of astrobiology on Mars both directly and indirectly. The majority of instruments on the orbiter will look for indications of favourable conditions to the existence of life, either at present or during the planet’s past, and in particular for traces of liquid, solid or gaseous water. Therefore, the HRSC camera will take pictures of ancient riverbeds, the OMEGA spectrometer will look for minerals with OH- radicals formed in the presence of water, the MARSIS radar will look for subsurface ice and liquid water, the PFS and SPICAM spectrometers will analyse water vapour in the atmosphere, and finally ASPERA and MaRS will study neutral atom escape from the atmosphere, in particular O2 coming from water and carbonates. The instruments on Beagle-2 will also look for the presence of water in the soil, rocks and the atmosphere, but will also try to find traces of life with direct measurements, such as presence of methane (CH4) indicative of extanct life and a larger amount of the light C12 isotope compared to the heavier C13, which would even indicate the existence of extinct life. Since NASA’s Viking mission in 1976, it is the first time that the exhaustive search for life is so central to a space mission to Mars.

Current design estimates allow for an orbiter scientific payload of about 110 kg and 65 kg total lander mass (at launch) compatible with the approved mission scenario. The Beagle-2 lander was selected due to its innovative scientific goals and challenging payload. Beagle-2 will deploy a sophisticated robotic-sampling arm, which could manipulate different types of tools and retrieve samples to be analyzed by the geochemical instruments mounted on the lander platform. One of the tools to be deployed by the arm is a ‘mole’ capable of subsurface sampling to reach soil unaffected by solar-UV radiation, another is a corer/grinder to reach the rock under the weathering varnish.

A Soyuz-Fregat launcher will inject a total of about 1200 kg into Mars transfer orbit in early June 2003, which is the most favorable launch opportunity to Mars in terms of mass in the foreseeable future. The Mars Express orbiter is 3-axis stabilized and will be placed in an elliptical martian orbit (250  10142 km) of 86.35 degrees inclination and 6.75 hours period, which has been optimized for communications with Beagle-2, the Netlanders, as well as NASA landers or rovers to be launched both in 2003 and 2005. The Beagle-2 lander module will be independently targeted from separate arriving hyperbolic trajectory, enter and descend through the martian atmosphere in about 5 min, and land with an impact velocity <40 m/sec and an error landing ellipse of 100  20 km. A preliminary Beagle-2 landing site has been selected in the Isidis Planitia area (10.6° N, 270° W). The nominal mission lifetime of one martian year (687 days) for the orbiter investigations will be extended by another martian year for lander relay communications and to complete global coverage. The Beagle-2 lander lifetime will be of a few months.

ESA provides the launcher, the orbiter and the operations, while the Beagle-2 lander is delivered by an UK-led consortium of space organizations. The orbiter instruments are provided by scientific institutions through their own funding. In addition to relaying the data from the Beagle-2 lander to Earth, Mars Express will also service landers and rovers from other agencies during its nominal/extended lifetime. The ground segment includes the ESA station at Perth, Australia, and the mission operations centre at ESOC. The Mars Express mission is now in Phase-C/D, with Astrium (formerly Matra Marconi Space) in Toulouse, France, as its Prime Contractor and involving a large number of European companies.

International collaboration, either through the participation in instrument hardware or through scientific data analysis is very much valued to diversify the scope and enhance the scientific return of the mission, such as NASA’s major contribution to the subsurface-sounding radar, and the use of its DSN for increased science data downloading and critical manoeuvres. Also, arriving at Mars at the very end of 2003, Mars Express will be followed by the Japanese Nozomi spacecraft a few days later. Both missions are highly complementary in terms of orbits and scientific investigations; Nozomi focusing on the study of the upper atmosphere of Mars as well as the interaction of the solar wind with the ionosphere from a highly elliptic equatorial orbit. Close cooperation, including scientific data exchange and analysis, is foreseen by the Nozomi and Mars Express teams within a joint ESA-ISAS programme of Mars exploration.

For more details on the Mars Express mission and its Beagle –2 lander:

http://sci.esa.int/marsexpress/ and http://www.beagle2.com/



Table 1: MARS EXPRESS SCIENTIFIC PAYLOAD

Acronyms

Instruments

Principal

Investigators

Countries













Orbiter

HRSC

Super/High-Resolution Stereo Colour Imager

G. Neukum

D, F, RU, US, FI, I, UK

OMEGA

IR Mineralogical

Mapping Spectrometer



J.P. Bibring

F, I, RU

PFS

Atmospheric Fourier

Spectrometer



V. Formisano

I, RU, PL, D, F, E, US

MARSIS

Subsurface-Sounding

Radar/Altimeter



G. Picardi

& J. Plaut



I, US, D, CH, UK,DK

ASPERA

Energetic Neutral Atoms

Analyzer


R. Lundin &

S. Barabash



S, D, UK, F, FI, I, US, RU

SPICAM

UV and IR Atmospheric

Spectrometer



J.L. Bertaux

F, B, RU, US

MaRS

Radio Science Experiment

M. Paetzold

D, F, US, A

Lander

BEAGLE-2


Suite of imaging instruments, organic and inorganic chemical analysis, robotic sampling devices and meteo sensors

C. Pillinger &

M. Sims


UK, D, F, HK, CH

WORKSHOP
"Astrobiología Amateur y Profesional, presente y futuro"

Equipo de Astrobiología Espacio Para Todos

Jordi Llorca, Antonio Delgado Huertas, Giussepe Pesce, y Daniel Slepikas


GANIMA. Plataforma aerobótica de investigación estratosférica,

definición de lineas de investigación en aplicaciones terrestres, y

perspectivas de aplicaciones marcianas".

Duración estimada: 1 hora.

Josep María Trigo i Rodríguez (UJI, TMSE), Jordi Llorca Piqué

(UB, TMSE), Mark Richard Kidger (IAC, TMSE), Cayetano Santana Gil (TMSE), Antonio Delgado Huertas (OEPT), Ignacio Lirio Barajas (SISC, OEPT), Daniel Osvaldo Slepikas (OEPT), Giuseppe Pesce (OEPT).


PONENCIAS
Francisco Miguel de Sousa Goncalves
The Planetary Society in Portugal: future activities and cooperation
Daniel Osvaldo Slepikas (Presidente y fundador de EPT)

"Explorando el Espacio desde el Ciberespacio"


Cayetano Santana Gil (TMS)

Iniciativa privada no lucrativa en la exploración espacial


Vera Assis Fernandes
Can the Period of Lunar Mare Volcanism Be Extended?
Recent age determination of lunar meteorite Northwest Africa 032

(NWA032) and of basaltic samples collected by the Luna 24 mission

samples have extended the period of lunar volcanism from ~650 Ma to ~

1000 Ma. NWA032 was extruded at ~2.8 Ga, making it one of the

youngest lunar basalts ever analysed. Mare lava extrusions within the

Mare Crisium may have occurred for a period of at least ~800 Ma. The

continued use of lunar meteorites found on Earth deserts (e.g. Sahara

and Antarctica) has the potential of giving new (and possibly

improved) insights of the lunar bulk chemistry and ages of volcanism

on the Moon as well as the extent of bombardment of the lunar surface.

Despite the unknown provenance of this type of sample, they have

shown to be an important complement to the samples collected by the

Apollo and Luna missions and impose less sampling bias.
Causes, processes and consequences of tsunamis.

Studies on the AD 1755 Tsunami (Lisbon).


Costa P.*, Leroy S.*, Dinis J.**
*Department of Geography and Earth Sciences, Brunel University,

Uxbridge, UB8 3PH, Middlesex, United Kingdom ** Departamento de Ciencias da Terra, Universidade de Coimbra,

Largo Marques de Pombal 3000-272 Portugal
A tsunami is an oceanic gravity wave generated by earthquakes, volcanoes, landslides and meteorite impact. A phenomenon like a tsunami can provoke vast destruction in coastal areas owing to the height of the wave and its speed.
Historically, Portugal and Spain, being countries intimately related to the sea, have always had concerns with natural hazards in their coastal areas. However the study of tsunamis in Iberia is relatively recent. The most important event, in the last 500 years, for the Iberian Atlantic coast was the AD 1755 tsunami that followed a magnitude 8 earthquake. The historical description and consequences of the AD 1755 tsunami and a brief review of the tsunamis that occurred in the Iberian Peninsula coasts is presented.

Although not frequent in the Portuguese and Spanish shores, approximately 40 tsunamis have been registered by historical and field survey data in the last 2000 years in the Atlantic and in the Mediterranean coasts of Iberia. The Gorringe Bank (SW of Cape St. Vincent) has been the source of many earthquakes and tsunamis that struck the Iberian Atlantic Coast. It is probably the most important tsunamigenic area in Europe.


Due to their huge power, tsunamis can transport marine organisms and sediments far inland. The study of sediments deposited by past tsunamis in lakes and lagoons provides vital information about potential changes either in the coastal morphology or in the environment of coastal areas.
A series of lakes and coastal lagoons are being studied along the Portuguese coast with the aim of:

- Discovering and studying the 1755 tsunami sediment layer

- Understanding the environmental effects of the 1755 tsunami

- Detecting major environmental changes in that geographical area, since then.


The sites selected will allow conducting a multiproxy study with a high time resolution.

The techniques to be used include magnetic susceptibility, sediment visual description, Pb210 and Cs137 dating and a range of sedimentological and palaeoecological proxies with the focus of obtaining well-dated tsunami indicators such as salinity changes, grain size changes, erosive and compaction microstructures. We will also use historical data to collect complementary information about the effects of the tsunami and to reinforce the age-depth model of the sedimentary sequences.


José Fernando Monteiro




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