Washington (AFP) – After a journey of about three billion kilometers, Juno NASA probe approaching Jupiter Monday, a few hours before going into orbit around the largest planet solar system it must unravel the mysteries.
“After a journey of five years, we finally arrived at Jupiter, which raises a very great excitement,” he told Monday at a press conference Scott Bolton, chief scientist for the mission at Southwest Research Institute in San Antonio (Texas), without concealing a certain nervousness.
“We are in uncharted territory,” he admitted, refusing to encrypt the chances of mission success.
Tuesday at 3:18 GMT –lundi night in the United States– the probe of 3.6 tonnes, powered by solar energy and advance to 64 km / second, turn on its main engine for 35 minutes to slow its course. It will thus be caught by the gravity of Jupiter and will fit into a polar orbit of 53.5 days.
Because of some 869 million kilometers that separate it from Earth, radio signals confirming ‘engine firing will reach flight controllers that 48 minutes later, at 4:06 GMT.
But, said Scott Bolton, “we definitely know if it’s a success when Juno will be returned to point its three large solar antennas towards the sun “which it depends for its energy, or 4:30 GMT.
After two revolutions of 53.5 days, Juno will fit from October in an orbit of 14 days that will make him graze successively both poles of the planet hidden under a thick cover layer.
the probe will make 37 flybys, mostly between 10 000 and 4667 km above the clouds the gas giant, for a total of 18 months.
overflights Juno will be much closer than the previous record of 43,000 km set by the American probe Pioneer 11 in 1974.
during approaches Jupiter, the instruments of the probe will study its gigantic aurora borealis, atmosphere, magnetosphere and its huge red spot.
one of the main objectives of the mission will be to better understand what consists inside hitherto unobserved, the giant planet
-. New instruments on board –
Juno, a mission to $ 1.1 billion launched on 5 in August 2011, and will map the gravitational and magnetic fields of Jupiter to determine the internal structure.
the new instruments of the orbiter, including French and Italian, will also measure the radiometric emission of deep atmosphere of the planet, which will reveal its composition, its thermal structure and ionized environment.
“Today we do not know whether or not Jupiter has a central core,” had noted last week Tristan Guillot, director of research at the French National Centre for scientific research (CNTS) and member of the scientific team of the mission.
Not only Juno help uncover the secrets Jupiter, but should also provide new clues about the conditions at the beginning of the solar system.
the mission officials have again said Monday the risks to the probe by approaching too near.
They cite the hydrogen layer –90% of atmosphère– suffering such pressure it acts as a powerful electrical conductor.
This, combined the rapid rotation of Jupiter, would generate a very strong magnetic field that surrounds the planet and can threaten Juno.
in addition to the radiation, the ship must also cross a debris belt.
“If the risk of collision is low, it is not zero,” noted Scott Bolton.
to protect against high radiation, Juno is equipped with a solid titanium armor around its facilities and electronic instruments, its onboard computer and electrical wiring.
Weighing 172 kilos, this vault will reduce exposure to radiation –l’équivalent one million radiology at the dentiste– 800 times compared to the unprotected part.
Juno also has on board three Lego figurines aluminum. They represent Jupiter, king of the gods in Roman mythology, Juno, his wife and his sister, and Galileo, the Italian scientist who discovered Jupiter’s four large moons in 1609
Source.: AFP
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