Space probes

A space probe is a vessel sent by the Man to the space and intended to investigate objects of our solar system or more widely to study a celestial body: planet, comet, asteroid, star, etc... Numerous attempts remained fruitless so much American side as the Russian side, but it is the Soviet citizens who have the first ones known how to make take out an object made by the man outside fields of Earth' attraction. On January 2nd, 1959, the space probe Lunik 1 approaches in 6000 km of the moon to pursue then its road in the space having passed on some scientific data. Two months later, the American Pioneer probe makes the same route. For almost fifty years, these spatial machines are sent to our solar system, with a rate of high failure but the successful missions of its probes are worth us of magnificent observations which make as much dream about the general public as about the scientists. The images which reach us, often show of our past but also show us our future. A space probe can have various functions according to the type of module which it embarks. We speak about orbiter when it fits in orbit of the target celestial body, the landing when it settles on a solid body, or of probe of comeback when it enters the atmosphere of a gas. As a general rule a probe aims at making measures in situ and to pass on to us these data.

Furthermore they are always equipped with cameras of observations which show us the target object except the ground atmospheric disturbances and in an angle of inaccessible sight for us since the earth and even since the ground orbit. It is important to make the difference with artificial satellites, which they, are only intended to be put on ground orbit. However, certain probes are also intended to be sent into orbit around the other planets, the satellites of planets or even around small asteroids. The United States dominate widely this domain of the exploration of the solar system, by space probes. They send to 1964 a first space probe towards Mars, then in 1972 towards Jupiter, in 1973 towards Saturn and Jupiter, and one other towards Mercury, in 1977 towards Uranus and Neptune as well as Jupiter and Saturn. In the 20th century, only Pluto was not the object of an exploration by space probe yet.

Image: Today these instruments perceive in the detail the forms and the composition of objects of the distant regions and offer us exceptional sights of an unequalled precision, as that of the crater of Terra Sirenum of the southern hemisphere of Mars (Photo taken on October 3rd, 2006 by the probe Mars gratitude to Orbit).

The mission Cassini-Huygens The mission Cassini-Huygens is a joint mission of the NASA, the European Space agency and the Italian Space agency the main purpose of which is to investigate Saturn and its satellites, in particular Titan. The idea of this mission goes back up in 1982. The total duration of the mission is estimated in 11 years, of the launch on October 15th, 1997 until 2008. The Cassini-Huygens probe consists of the orbiter Cassini, equipped all in all with 12 instruments, and with the landing Huygens, equipped with 6 instruments. At the beginning of 2004, the probe entered in orbit around Saturn and on January 14th, 2005, the orbiter settled on Titan. is an automatic spatial mission realized in collaboration by the Jet Propulsion Laboratory ( JPL), the European Space agency ( ESA) and the Italian Space agency ( ASI). its objective is the study of the planet Saturn and of some of its satellites, of which Titan.
The space probe Cassini-Huygens, consisted of the orbiter Cassini and the module Huygens has to take place in orbit around the planet. Huygens has for objective to land on the satellite Titan.
The name of the mission is a tribute to Jean-Dominique Cassini, French astronomer of the 17th century at the origin of fundamental observations concerning Saturn, and to Christian Huygens, Dutch astronomer of the same century, who discovered Titan.
The mission Cassini-Huygens notably already allowed to have the first detailed images of Phoebe, to study in detail the structure of the rings of Saturn, to study Titan in a detailed way and to discover two new moons of Saturn.

New Horizons is a NASA space probe intended to fly over Pluto and its satellite Charon, then to continue in the Kuiper Belt. It will also study Jupiter and its moons. It is the first device specifically designed to transmit data to distant solar system objects. The New Horizons spacecraft was launched Thursday, January 19, 2006 at 20:00 French time and may use a gravity assist from Jupiter in 2007. The probe has a thick triangular shape, is the fastest ever launched from Earth (19 km/s). As the probe from the outer solar system, power generation can be assured by the traditional solar panels, a thermoelectric generator radioisotope (RTG) is then shipped. This generator will convert the heat from the radioactive decay of 10.9 kg of plutonium dioxide 238, which is estimated to provide 190 watts again in 2015. The cylinder containing the generator is fixed on an angle of the triangle. The parabolic antenna having a diameter of 2.5 meters, used for communication with the earth is fixed on one of the triangle sides. Its total weight is 265 kg.

Rosetta will touch the asteroid Steins in 1 700 km, on September 5th, 2008, with a relative speed of 9 km/s.
Lutetia of a diameter of hundred of kilometers, will be touched July 10th, 2010. Rosetta will pass in 3 000 km of the object about km/s 15.
There will be, for reasons of energy saving, no communication with the Earth between 2011 and 2014. In August 2014 it should enter in orbit around the comet.

Image: Image of artist of the probe Rosetta © Mylène Simoès, Art Director.

Mars Reconnaissance Orbiter (MRO), It is the name of this eye of lynx of a new generation of probes intended to photograph the planet red as ever.
This American probe, launched on August 12th, 2005 since base Cap Canaveral in Florida, contributes to enrich our knowledge on the planet Mars, as the history of its water on its surface, its climate or its basement. MRO can track down the best sites of landing for probes or the men to come and will serve, from the end of its scientific, relay mission of communication with the Earth until 2015. This probe is sharply more impressive than the previous ones (Mars Global Surveyor and Mars Odyssey). With a height of 6,50 m and one diameter of 3 m, this monster filled with technology, contains 11 instruments all in all to assure, its scientific mission, its navigation and its communication with the Earth (high resolution stereoscopic camera HiRISE, camera CTX of context, spectro-imager CRISM, camera MARCI, radiomeasures MCS, radar SHARAD, radio transmitter sciences). Of a total mass of 2180 kg in the takeoff, MRO was launched by a rocket Atlas V-401.
Having crossed 500 million km in 7 months in km/s 3, it positioned in orbit Martian.

The Martian MRO probe of the NASA which really began its scientific mission in November, 2006 already sent towards the Earth, in some months, about 8 terabytes of data, as much as MGS (Mars Global Surveyor) in nine years of observation.
With all this embarked technology, the MRO probe meets some difficulties with its instruments. Half of the sensors of the camera HiRISE (High Resolution Imaging Science Experiment) indeed presents abnormal levels of noise but which have only an impact limited on the quality of the images.
The second instrument, Mars Climate Sounder which is in charge of scanning the Martian atmosphere above the horizon, has as for him difficulties of wedging of its field of vision. The total cost of the probe is estimated at 720 million dollars.

Image: The mission MRO is to photograph the planet Mars and to inform us about its history. Image of artist of the probe MRO © Mylène Simoès, Art Director.

The journey of the probe Dawn ("dawn" in English) is going to ligh us a little more on the birth of our solar system as well as on the formation of planets. After several adjournments, the NASA proceeded to the launch of the space probe DAWN to asteroids Vesta and Ceres, two bigger celestial bodies known for the belt of asteroids which is situated between Mars and Jupiter.
A rocket Delta 2, equipped with boosters nine dashed, in the sky of Florida, on Thursday, September 27th, 2007 at 11:34 am UTC. This ambitious mission of the NASA aims at putting into orbit the Dawn probe around Vesta in 2011 then around Ceres in 2015. To reach these two asteroids, an operation of gravitational assistance around Mars will be necessary in 2009. The study of these two objects should allow a better understanding of the initial conditions of the Solar system a little time after its formation and to understand better the stages of the formation of planets. Dawn who is going to cross all in all 5,1 billion km, will evolve 7 months around every asteroid. Flying at low height are planned, at a 15 km height for Vesta and of 40 km for Ceres. Ceres and Vesta is proto planets and formed about at the same time, at the time of the formation of the planets of the solar system there is approximately 4,5 billion years.

Vesta and Ceres are very different. Vesta is big dry and rocky one, irregular rock of shape with a surface which seems to be formed by ice-cold lava. Ceres is almost round ( 960 km diameter) and could have ice-cold poles. Ceres presents the peculiarity to have the double status of asteroid and dwarfish planet since 2006 as Pluto and Eris. The mission is planned to last until July, 2015. This unpublished journey is made possible thanks to engines for Ionic propulsion. The Dawn probe is equipped with cameras, with a spectrometer in infrared, and with a detector with neutrons and gamma rays. The energy of the solar panels of large-scale 19,8 meters is going to allow the functioning of its three engines Ionic propulsion. " For me, it is really the first true interplanetary spatial machine ", explains the chief engineer Marc Rayman. The mission Dawn costs 357 million dollars (252,7 million euro) except cost of launch by the rocket Delta.

Image: The mission of the probe Dawn ("dawn" in English) is planned to last 8 years and its journey of 5,1 billion kilometers is going to inform us about the first moments of the birth of the solar system, there is 4,6 billion years. Image of artist of the probe DAWN © Mylène Simoès, Art Director.

Traditionally, the Moon was a major focus for the man. In 2012, scientists interest in new, to the Moon to establish a permanent base in the near future. Although this is the best known aster in our solar system after Earth question here with the mission GRAIL (Gravity Recovery And Interior Laboratory), to measure the gravity field of the Moon, already measured but with many imperfections. The GRAIL project, 375 million dollars, was launched in 1997. In 2012, the two probes GRAIL (GRAIL GRAIL-A and-B) of NASA, launched in September 2011, were placed on the same lunar orbit, a few hours apart, after four months of travel. They revolve around the Moon at an altitude low enough, about 55 km to better probe the internal layers of the Moon. The two probes are close to each other, between 175 and 225 km, the distance is measured finely, with a precision of one micrometer. Both probes transmit a radio signal to Earth to make permanent their respective positions.

Thanks to the variation of the distance between them, the scientists collected the slight local variations, due to the gravity of the Moon. The Moon is not perfectly homogeneous sphere, the distance between the two probes will be disturbed by small variations in gravity due to the density of the subsoil and the distribution of lunar masses. The various mineral layers of the Moon including the nucleus can be analyzed using the mapping of geological structure. Know perfectly the structure of the Moon and in particular its nucleus will validate the hypothesis of its formation, the most accepted by scientists that a giant impact. Its origin is due to a massive collision with the Earth, of a planet the size of Mars, which is called "Theia".

Image: The two probes GRAIL (GRAIL-A and-B), launched in September 2011, scan the Moon at an altitude of 55 km, to learn about the layers of its subsoil. NASA Image.

GAIA is a project of the European Space Agency (ESA), the satellite was launched December 19, 2013 from French Guiana with a Soyuz rocket. This mission of measures of astronomy, aims to map in 3D Milky Way, i.e. more than one billion stars with a precision of up to 7 arc microseconds, or 7 / 3600th degree for the brightest stars (magnitude 12 and under), 300 microseconds of arc for the fainter stars (magnitude 20). This will allow scientists to better understand the mechanisms of formation of galaxies, the inner workings of stars, the influence of the dark matter and the bending of light rays due to gravitational effects. Probe 2 tons, has 3 sensors installed on the same telescope, which will be about 75 steps astrometry, photometry and spectroscopy on each object observed. It will report the position, speed, brightness and distance from Earth of each star pointing through his telescope. GAIA is the surveyor of the Galaxy, the probe will send for 5 years, more than a petabyte of data (1000 TB) to be processed by CNES and 30 international laboratories.

Through the identification of all these stars, astronomers can identify different generations of stellar populations, and restore their path in space and time. The aim is to produce the most detailed image possible to the structure of our Galaxy and predict its evolution. Measurements of unprecedented accuracy will feed scientists for decades. GAIA is able to measure the thickness of a hair located 1,000 km away. To measure the distance of stars, GAIA uses the method of stellar parallax. This ancient geometrical method consist to aim the star twice, six months apart. In others words, astronomers measure the angle of parallax by measuring the position of a star from a position of the Earth in its orbit and measured again, six months later, when the Earth is the other side of the sun, then it has traveled 300 million km. More star is closer, more the parallax angle is great. This angle gives us directly the distance of the star. By knowing the distance of a star, we can determine its main features, its actual brightness, age, mass, temperature, and more.