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Mars Express es una misión de exploración de Marte de la Agencia Espacial Europea y la primera misión interplanetaria europea. El término "Express" se acuñó originalmente por la relativa corta trayectoria interplanetaria Tierra-Marte, pues el lanzamiento de la nave se produjo cuando las órbitas de la Tierra y Marte estaban más próximas en los últimos 60.000 años. "Express" también se refiere a la velocidad y eficiencia con la que la nave fue diseñada y construida.
Mars Express consiste de dos partes, el Mars Express Orbiter y el Beagle 2, un aterrizador diseñado para investigar exobiología y geoquímica in situ en la superficie marciana. El Beagle 2 falló al intentar aterrizar en la superficie de Marte, pero el orbitador ha estado realizando investigaciones científicas satiisfactoriamente desde entonces. Beagle hubiera facilitado información acerca de la posible vida de organismos en el pasado marciano.
Algunos de los intrumentos de la nave, incluyendo la cámara y algún espectrómetro son heredados de la fallida misión rusa a Marte Marsnik 96 en 1996. El resto de instrumentos así como la totalidad de la Plataforma son diseños europeos. El diseño básico esta basado a su vez en la nave Rosetta (sonda interplanetaria). Dada la versatilidad y fiabilidad del diseño, se reutilizó también para la sonda Venus Express.
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La misión Mars Express está enfocada a la inserción orbital y posible estudio in situ del interior, subsuperficie, superficie, atmósfera y el ambiente del planeta Marte. Los objetivos científicos de la misión Mars Express son el completar las metas científicas de la misión rusa Marsnik 96 y que se completaría con investigación de exobiología de la misión fallida de Beagle 2.
La exploración de Marte es crucial para un mejor entendimiento de la Tierra desde un punto compasivo en Planetología. El orbitador Mars Express posee "imagen de alta resolución" y mapeo de minerologia de la superficie, sondeo de radar de la subsuperficie justo debajo de la capa permafrost, una determinación precisa de la composición de la atmósfera y un estudio de la interacción de la atmósfera interplanetaria.
La nave espacial lleva 7 instrumentos científicos, un pequeño lander, un Lander Relay y una cámara de monitoreo Visual, todos ellos ayudaran a resolver el misterio de la desaparición del agua en Marte. Todos los instrumentos tomaran mediciones de la superficie, atmósfera y la media interplanetaria, desde la nave principal en orbital polar, la cual permitirá cubrir todo el planeta gradualmente.
El presupuesto total del proyecto Mars Express excluyendo el Lander es de 150 millones de euros (aproximadamente US$185 millones de dólares)
El principal constructor de la sonda fue EADS Astrium Satellites. La nave se construyó con restos de metales de barcos.
En el año de la preparación del lanzamiento de la nave, numerosos grupos de expertos distribuidos en las compañías contribuyentes y organizaciones prepararon los segmentos espaciales y de tierra. Cada uno de esos grupos se concentraron en el área de sus responsabilidades y en la coordinación. Requerimientos adicionales se elevaron para la Fase de Lanzamiento y Primeras Órbitas (LEOP) y todas las fases operacionales críticas: no era suficiente el intercambio, fue fundamental integrar los grupos en un Equipo de Control de la Misión. Todos los diferentes expertos deben trabajar juntos en un ambiente operacional, y la interacción entre todos los elementos del sistema (software, hardware, humano) deben correr suave para que ocurriera:
La nave espacial fue lanzada el 2 de junio de 2003 a las 23:43 tiempo local (17:45 UT, 1:45 pm EDT) desde el Cosmódromo de Baikonur en Kazajstan usando un cohete Soyuz Fregat, el propulsor FREGAT fue disparado a las 19:14 UT para impulsarlo y se separa de Mars Express a las 19:17 UT
Se desplegaron los paneles solares y se realiza una corrección de trayectoria el 4 de junio para poner en trayectoria interplanetaria a la sonda.
Cerca de la Tierra se encargó fase se extiende desde la separación de la nave espacial de la etapa superior del lanzador hasta la finalización de la comprobación inicial de la nave y la carga útil. Incluye la matriz solar despliegue, la actitud inicial de la adquisición, la declamping de la Beagle - 2 beneficios de un mecanismo complementario, la inyección de corrección de errores de maniobra y el primer encargo de la nave espacial y de la carga útil (servicio definitiva de la carga útil tiene lugar después de Mars Orbit Insertion) . La carga útil se comprueban a cabo uno de los instrumentos a la vez. Esta etapa dura alrededor de 1 mes.
Este pahse dura de la final de la fase Commissioning cercanos a la Tierra hasta un mes antes de la captura de Marte maniobra. Incluye maniobras de corrección de trayectoria y de las cargas útiles de calibración. La carga útil es principalmente apagado durante la fase de crucero, con la excepción de algunos intermedios check-outs. Esta etapa dura alrededor de 5 meses.
Aunque originalmente se había pensado para ser un "tranquilo crucero" fase, pronto se hizo evidente que esta "de crucero" sería realmente muy ocupado. Star Tracker problemas, de energía eléctrica de problema, maniobras adicionales, y sobre el 28 de octubre, el Vehículo espacial fue alcanzado por una de las erupciones solares más grandes jamás registradas. Más acerca de esto, consulte "documentos publicados" en la parte inferior del artículo.
El Beagle 2 fue lanzado en December 19 a las 8:31 UTC (9:31 CET) desde un cohete balistico hacia la superficie. On 20 de diciembre, Mars Express fired a short thruster burst to put it into position to orbit the planet. The Mars Express Orbiter the fired its main engine and go into a highly elliptical 250 km × 150.000 km initial capture orbit with an inclination of 25 degrees on 25 de diciembre a 03:00 UT (10:00 p.m., 25 de diciembre EST).
The Beagle 2 lander was supposed to coast for five days after release and enter the martian atmosphere on the morning of 25 de diciembre. Landing was expected to occur at about 02:45 UT on 25 de diciembre (9:45 p.m. EST 24 de diciembre). A signal was to be sent to Mars Express after landing and another the next (local) morning to confirm that Beagle 2 survived the landing and the first night on Mars. No signals were received and the lander was declared lost.
Mars Express arrived at Mars after a 400 million km journey and a course correction in septiembre, en diciembre de 2003.
The orbiter entered Mars orbit on 25 de diciembre de 2003, and Beagle 2 entered Mars' atmosphere the same day. After repeated attempts to contact the lander failed, it was declared lost on 6 de febrero de 2004, by the Beagle 2 Management Board. On 11 de febrero, ESA announced an inquiry would be held into the failure of Beagle 2.
First evaluation of the orbital insertion showed that the orbiter reached its first milestone at Mars. The orbit was later adjusted by four more main engine firings to the desired 259 km × 11.560 km near-polar (86 degree inclination) orbit with a period of 7,5 h. Near periapsis the top deck is pointed down towards the Martian surface and near apoapsis the high gain antenna will be pointed towards Earth for uplink and downlink.
After 440 days the apoapsis will be lowered to 10,107 km and periapsis will be raised to 298 km to give an orbital period of 6.7 hours. Aerobraking can be used to modify the orbit if there are any problems with the main engine. Nominal mission duration is planned to be 1 Martian year (687 días terráqueos).
El 4 de mayo de 2005, Mars Express desplegó el primero de sus dos tubos de radar de 20 m. de longitud para su instrumento MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding). Al principio el tubo no encajó por completo en su sitio; sin embargo, el 10 de mayo fue expuesto a la luz solar durante unos minutos y se solucionó el problema. El segundo tubo fue desplegado con éxito el 14 de junio. Ambos tubos eran necesarios para crear una antena dipolo de 40 m. necesaria para que MARSIS pudiera funcionar; un menos crucial tubo de 7 m. para otra antena fue desplegado el 17 de junio. En la planificación original, los tubos deberían haberse desplegado en abril del 2004, pero se decidió aplazar por miedo a que el despliegue pudiera dañar a la sonda. Due to the delay it was decided to split the four week commissioning phase in two parts, with two weeks running up to 4 de julio and another two weeks in diciembre de 2005.
The Deployment of the booms have been a critical and high complex task and has shown the efficiency of interagency cooperation ESA, NASA, Industry and public Universities Nominal science observations began during julio de 2005. (For more info, see [1], [2], and ESA press release.)
Operations for Mars Express are carried out from ESA’s Operation Centre (ESOC) is in Darmstadt. Here a multi-national team of engineers starts building-up about 3 to 4 years before launch, preparing the ground segment and the operational procedures for the whole mission.
The Mission Control Team is comprised of the Flight Control Team, Flight Dynamics Team, Ground Operations Managers, Software Support and Ground Facilities Engineers, who are located at ESOC, as well as external teams like the Project and Industry Support teams, who have designed and built the spacecraft.
The Flight Control Team consists of:
The team build-up started about 4 years before launch, a task for the Spacecraft Operations Manager. He has to find suitable engineers for all the different tasks and form a team out of them. The word “Team” cannot be stressed enough when it comes to spacecraft operations. Only when the team functions correctly as a whole, can success be achieved. For Mars Express, the engineers came from various other missions, mainly Earth orbiting satellites. Different personalities, ages, cultural backgrounds and characters had to be integrated. The dedication of the Mars Express team to overcome problems in a very flexible way and their willingness to accept a lot of personal sacrifices and work for a common goal made the success possible.
Since orbit insertion Mars Express has been progressively fullfilling its original scientific goals. Nominally the spacecraft points to Mars while acquaring science and then slews to earth-poitning to downlink the data, although some instruments like Marsis or Radio Science might be operated too while spacecraft is earth-poitning.
Refer to "scientific discoveries" bullet down the article
The Mars Express Orbiter is a cube-shaped spacecraft with two panel solar wings extending from opposite sides. The launch mass of 1123 kg includes a main bus with 113 kg of payload, the 60 kg lander, and 457 kg of propellant. The main body is 1,5 × 1,8 × 1,4 m, with an aluminium honeycomb structure covered by an aluminum skin. The solar panels measure about 12 m tip-to-tip. Two 20 m long wire dipole antennas extend from opposite side faces perpendicular to the solar panels as part of the radar sounder.
Most of the energy needed to propel Mars Express from Earth to Mars was provided by the four-stage Soyuz/Fregat launcher. The Fregat upper stage separated from the spacecraft after placing it on a Mars-bound trajectory. The spacecraft used its on-board means of propulsion solely for orbit corrections and to slow the spacecraft down for Mars orbit insertion.
The body is built around the main propulsion system, which consists of a bipropellant 400 N main engine. Los dos tanques de 267 L de propelente tienen una capacidad total de 595 kg. Approximately 370 kg are needed for the nominal mission. Pressurized helium from a 35 liter tank is used to force fuel into the engine. Trajectory corrections will be made using a set of eight 10 N thrusters, one attached to each corner of the spacecraft bus. The spacecraft configuration is optimized for a Soyuz/Fregat, but is fully compatible with a Delta II launch vehicle if necessary.
Spacecraft power is provided by the solar panels which contain 11,42 m² of silicon cells. The originally planned power was to be 660 W at 1,5 AU but a faulty connection has reduced the amount of power available by 30%, to about 460 W. This loss of power is not expected to significantly impact the science return of the mission. Power is stored in three lithium-ion batteries with a total capacity of 64.8 A/h for use during eclipses. The power is fully regulated at 28 V, the peak power requirement at Mars is 450 W.
Attitude control (3-axis stabilization) is achieved using two 3-axis inertial measurement units, a set of two star cameras and two Sun sensors, gyroscopes, accelerometers, and four 12 N·m·s reaction wheels. Pointing accuracy is 0.04 degree with respect to the inertial reference frame and 0.8 degree with respect to the Mars orbital frame. Three on-board systems help Mars Express maintain a very precise pointing accuracy, which is essential to allow the spacecraft to communicate with a 34-metre dish on Earth up to 400 million km away.
The communications subsystem is composed of 3 antennas: una antena de alta ganancia parabólica de 18 dm de diámetro y dos antenas omnidireccionales. The first one provide links (Telecommands uplink and Telemmetry downlink) in both X-band (7.1 GHz) and S-band (2.1 GHz) and is used during nominal science phase around Mars. The low gain antennas are used during Launch and cruise to Mars and for eventual contingencies once in orbit. Two Mars lander relay UHF antennas are mounted on the top face for communication with the Beagle 2.
Although communication with the Earth were originally scheduled to take place with ESA 34 m diameter Ground Station in New Norcia (Australia) New Norcia Station, the mission profile progressive enhancement and science return flexiblity have triggered the use of the newest ESA ESTRACK Ground Station in Cebreros Station, Madrid, Spain.
In addition, further agremeents with NASA Deep Space Network made possible the use of american stations to the nominal mission planning, thus increasing complexity but with a clear postive impact in science return.
Esta cooperación entre agencias ha resultado ser efectiva, flexible y enriquecedora para ambas partes. En la parte técnica, ha sido posible (entre otras razones) gracias a la adopción por ambas agencias de los estándares para comunicaciones espaciales definidos en el CCSDS.
Thermal control is maintained through the use of radiators, multi-layer insulation, and actively controlled heaters. The spacecraft must provide a benign environment for the instruments and on-board equipment. Two instruments, PFS and OMEGA, have infrared detectors that need to be kept at very low temperatures (about -180 °C). The sensors on the camera (HRSC) also need to be kept cool. But the rest of the instruments and on-board equipment function best at room temperatures (10-20 °C).
The spacecraft is encapsulated in thermal blankets made from gold-plated aluminium-tin alloy, to keep the interior at 10-20°C. The instruments that need to be kept cold are thermally insulated from the warm interior of the spacecraft and attached to radiators that lose heat to space, which is very cold (about -270°C).
The spacecraft is run by two Control and Data management Units with a 10 gigabit solid state mass memory for storage of data and housekeeping information for transmission. The on-board computers control all aspects of the spacecraft functioning including switching instruments on and off, assessing the spacecraft orientation in space and issuing commands to change it.
The Beagle 2 lander objectives were to characterize the landing site geology, mineralogy, and geochemistry, the physical properties of the atmosphere and surface layers, collect data on martian meteorology and climatology, and search for possible signatures of life. However, the landing attempt was unsuccessful and the lander was declared lost. An underdimension on the parachuting device had been deemed as plausible cause of the loss.
The scientific objectives of the Mars Express Payload are to obtain global high-resolution photo-geology (10 m resolution), mineralogical mapping (100 m resolution) and mapping of the atmospheric composition, study the subsurface structure, the global atmospheric circulation, and the interaction between the atmosphere and the subsurface, and the atmosphere and the interplanetary medium. The total mass budgeted for the science payload is 116 kg.[1]
For more than 4000 orbits, MArs Express Payload instruments have been nominally and regulary operated.
HRSC camara has been stubbernly mapping the Martian surface with unprecedented resolution and has taken dozens of breath-taking pictures.
In 2005, ESA scientists reported that the OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer)(Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument data indicates the presence of hydrated sulphates, silicates and various rock-forming minerals.
The Fourier spectrometer has detected methane in the atmosphere coming from areas near the equator with subsurface ice, a very important discovery indicating either some form of active vulcanism or subsurface microorganisms.[2]
In november 2005, with just a few months of measurements having been taken thus far, ESA released data from MARSIS which included buried impact craters, and hints of the presence of underground water-ice.
These image, taken by the High Resolution Stereo Camera (HRSC), show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole. [Express/SEMGKA808BE 0.html]
ESA's Mars Express High Resolution Stereo Camera (HRSC) has obtained images of the Cydonia region, site of the famous 'Face on Mars.'. The massif became famous in a photo taken in 1976 by the American Viking 1 Orbiter. The image recorded with a ground resolution of approximately 13.7 metres per pixel. [10]
The Mars Express spacecraft has emerged from an unusually demanding eclipse season introducing a special, ultra-low-power mode nicknamed 'Sumo' - an innovative configuration aimed at saving the power necessary to ensure spacecraft survival. This mode was developed through tight teamwork between ESOC mission controllers, principal investigators, industry and mission management. [Express/SEMRSP8LURE 0.html]
En octubre de 2006 the Mars Express spacecraft has encountered a superior solar conjunction (alignment of Earth-Sun-Mars Express). The angle Sun-Earth-MEX reached a minimum on D23-Oct at 0.39 deg. at a distance of 2.66 AU. Operational measures were undertaken to minimize the impact of the link degradation, since the higher densitiy of electrons in the solar plasma heavily impacts the radio frequency signal. More on [11]
Following the loss of NASA JPL Mars spacecraft Mars Global Surveyor (MGS), Mars Express team was requested to perform actions in the hopes of visually identifyng the american spacecraft. Based on last Ephemeris of MGS provided by JPL, the on-board high definition HRSC camera swept a region of the MGS orbit. Two attempts were made to find the craft, both unseccesful.
*Enero
First agreements with NASA-SPL undertaken for the support of Mars Express on the landing of the american lander Phoenix in May 2008
The small camera VMC (used only once to monitor the lander ejection) has been recomissioned and first steps had been taken to offer students the posibility to participate in a contest "Command Mars Express Spacecraft and take your own picture of Mars". Details to come.
As result of the important science return, the Science Programm Commitee (SPC) has granted a mission extension until May 2009 to Mars Express. [Express/SEMZT4N0LYE 0.html]
The Flight Control Team (FCT) in chargued of operating Mars Express has encounter and solved countless engineering problems derived from the challeging task of maintenance of a Spacecraft in Orbit around Mars. The following papers published by the FCT gather invaluable expertise gained during the operational phase of the mission: