| Gallery Images of Jupiter taken by Galileo |
| Saturn seen from the Cassini
spacecraft on 21 october 2002 at 285 million km from its destination Click to view |
My Astronomy Emotions |
| Gallery Images of Jupiter taken by Galileo |
| Saturn seen from the Cassini
spacecraft on 21 october 2002 at 285 million km from its destination Click to view |
The sky fascinates humankind since prehistoric times. In the Antique, the Greek Hipparcos discovered more than 1000 stars with the naked eye. With other well-known Greek scientists, he was a precursor of modern astronomy. At the end of the nineteenth century, Giovanni Schiaparelli observed a network of lines on Mars. Percival Lowell thought that these structures were belts of vegetation several kilometers broad surrounding water-trenches digged by intelligent creatures to drag water from the polar caps.
The channels of Mars weren't observed by the space probes of the following century. Mariner 4, in 1965, and then Mariner 6 and 7 didn't observe more than a craterized surface.
The Viking probes in 1976, first to land on the martian surface, couldn't detect any trace of water, despite all the chemical analyses that were made.
However, Mars Global Surveyor, which was set on orbit around the red planet in september 1998, to study the landscape and atmospheric phenomena, observed structures on the surface that many specialists interpret as the evidence of ancient rivers carrying big flows of water. There could be liquid water beneath the surface.
Many projects have been set up to search traces of water under the martian soil or even fossils of ancient life on the red planet. The NASA plans to send one mission on two years.
The 2001 Mars Odyssey spacecraft has been set in orbit around Mars, as expected, on 23 October 2001.
Its main goal is to detect if there's water under the surface of the red planet. Water has been detected on February 2002, probably in an icy form, in a region near the southern pole.
The Mars Express mission of the European Space Agency was set in orbit around Mars in December 2003.The rover Spirit landed on Mars on 4 January 2004 in the Gusev Crater.
The rover Opportunity landed on Mars on 24 January 2004 in Meridiani Planum.
Mars Reconnaissance Orbiter was set in orbit around Mars on 10 March 2006.
The Phoenix mission landed successfully on Mars on 25 May 2008. It is the first spaceprobe sent from the Earth to a polar region of Mars. A robotic arm digs in the martian soil that will be analyzed.
The goal is to find water in the martian soil. The mission will determine if the place where it landed had been a possible habitable zone for the life in the past.
A weather station studies the martian climate.The Mars Science Laboratory is a project.
It will search for a trace of microbial life now or that would have existed in the past in the martian soil.
It will reach Mars in October 2010.
It is the project of a next mission to send back some martian rocks to Earth to be analyzed in terrestrial laboratories.
The next step is the first manned mission to Mars, with Europe and the United States.
Hubble Space Telescope, launched in 1990, observes our Universe in visible light and infrared wavelenghts above the Earth's atmosphere. It has completely changed our understanding of astronomy and astrophysics. It revealed regions of star formation in our galaxy.
At radio wavelengths, it's possible to study interstellar clouds in the neighborhood of our Sun. The radioastronomers discovered an unexpected chemistry with organic molecules like ethanol. This is possible because the molecules are adsorbed by the dust grains where the chemical reactions take place. The light from the surrounding stars can modify these processes sometimes by dissociating the molecules formed on the dust grains, that leads to a complicated chemistry.
The Hubble Deep Field ,photographed by the Hubble Space Telescope in orbit around the Earth, showed primeval structures and galaxies of our big scale Universe. The more distant we can see, the more time the light spent to come to us. And the farther we go back in time. Very distant galaxies and quasars were seen before one billion years after the big bang.
The Galileo Missions began in december 1995, when the probe set in orbit around the biggest planet of our Solar System, Jupiter. Although there was an accident with the main gain antenna during the space travel, Galileo could send the data from the jovian environment and magnetosphere and the satellites. The galilean satellites were photographed at an unprecedented high resolution with many details that were never seen before.
Io was flown over at slightly less than 200 km. It was possible to observe the evolution of the volcanic activity on Io's surface, that is continually reshaped
Europa revealed networks of fractures at first sight in all directions and icy structures that experts consider as sorts of icebergs. There would be an ocean of liquid water under the icy surface of this satellite. Perhaps a probe will be sent to land on this moon and analyze what is under the icy soil.
The mission Cassini-Huygens was launched in October 1997
The mission Cassini-Huygens made a flyby of Jupiter on December 2000. The first image of the giant planet has been taken on the beginning of October. It's possible to see the present locationof the probe with simulated views of and from Cassini-Huygens.
Cassini-Huygens reached Saturn in 2004. The orbiter Cassini reduced its speed to be captured by Saturn's gravitational field. It entered its orbit around Saturn. On 25 December 2004, the spaceprobe Huygens separated from it. On 14 January 2005, the european module rushed on the very mysterious moon Titan, protected with a shield from the increasing heating during the descent in Titan's orange atmosphere. After nearly an hour, during which the atmospere was studied the spaceprobe landed on the satellite's surface.
Videos of the descent can be seen to discover how Huygens discovered Titan's surface.
Nobody knew what would happen next.
The module could land on a solid icy surface and be broken if it landed too quickly or sink in a sea of liquid hydrocarbonates. It finally landed on the frozen surface of a lake of liquid methane and ethane. The first image shows a flat surface with a few stones in an orange landscape.
Titan is one of the unique moon in the Solar System having an atmosphere. The latter is so thick that the Voyager 2 probe couldn't see anything on the surface. Recently, Titan's surface has unveiled some details to a radar survey at the radiotelescope of Arecibo (Puerto Rico). Has it got a liquid ocean of hydrocarbonates and continents of solid rocks ?
The Cassini orbiter does flybys of Titan at some times to discover new details on Titan's surface.
Titan remains a mysterious moon to Cassini.
Enceladus and Dionea are other intriguishing Saturn's moons.
The first one, Enceladus, seems to have a cryovolcanic activity on its surface.
Reference : a very interesting site on Enceladus
Dionea
The second satellite, Dionea, is an icy moon with a very thin atmosphere that has nothing to do with Titan's, but chemical reactions lead to the formation of ozone, on places in craters where the ultraviolet light of the Sun doesn't destroy it.
In july 1995, the first planet around another star very like the Sun was discovered in the visible spectrum. A system of three planets was detected before that, in february 1993, but with a radiotelescope and around a pulsar, which is a type of star very different from our Sun. Since then, many planets were discovered around other stars in our neighborhood. But the mass of these bodies is rarely less than the mass of Jupiter, so they must be giant planets very unlike from the Earth.
To detect planets around other stars than the Sun, Darwin, european project for space interferometry and the Program Origins of the NASA will be launched in some years. Another goal of these missions would be to study the physical features of the newly discovered planets. They could reveal bodies of the mass of the Earth. The following step would be to analyze if there's an atmosphere around those planets and if it contains oxygen, which could be favourable to life.
Resources on Extrasolar planets
http://www.empire.net/~whatmoug/Extrasolar/extrasolar_visions.html
http://exoplanets.org/exoplanets_pub.html
Note : This page is dedicated to astronomy for amateurs.
Updated : 6/8/2008
