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RIO – NASA's New Horizons probe begins in 2019 with a rendezvous at the edge of the solar system. At dawn on New Year's Day Tuesday, the spacecraft – launched in January 2006 in Pluton, where it pbaded in July 2015 – will cross the space about 3,500 kilometers from the dwarf planet "Ultima Thule , "on the last flyby of a celestial object by human equipment up to now.
The maneuver will be
transmitted "live" by the US Space Agency
in two key moments: from 15:15 to 15:45 that day (Brasilia), with a countdown and animations of the maximum real approximation of New Horizons of Ultima Thule, scheduled at 3:33; and from 12:45 to 13:15, when NASA expects to receive the signal of success of the operation and its first data, which take a little over 6 hours to cross the 6.63 billion kilometers that separate today the probe of our planet, even traveling at the speed of light. Due to the closure of the US government, however, broadcasts will not be broadcast on the NASA website and only through "unofficial" channels, such as
YouTube from the Applied Physics Laboratory of Johns Hopkins University (JHUAPL)
, whose scientists led the mission with colleagues from the Southwest Research Institute (SwRI).
Ultima Thule – officially designated 2014 MU69 – is one of millions of small, dark, icy worlds that incorporate the Kuiper Belt, in addition to the orbit of Neptune, which also calls them transneton objects. Like the asteroids of the belt between Mars and Jupiter, they are remnants of the formation of the solar system, real fossils of this process, which makes them particularly interesting for scientists. His nickname was chosen in March of this year on the basis of a public consultation organized by NASA in memory of the mythical island of Thule, located in medieval literature and cartography in the far north of the planet and beyond, which would be in unknown territory.
Thus, because of the enormous distance, current knowledge about Ultima Thule is very limited. Previous observations with the Hubble Space Telescope and other instruments on Earth and in space, as well as with New Horizons' own navigation camera – looking for small moons or debris that could endanger the Space Shuttle when it pbades on Tuesday – indicate that it has a diameter of between 20 and 35 kilometers in bilobed (two-lobed) format, and can also be binary, i.e. formed of two separate bodies in orbit very close to each other and reddish but very dark, reflecting only about 10% of the low light of the sun.
In addition, scientists do not know more, as if Ultima Thule was spinning and what would be its rotation period if it was a fragment of a larger object destroyed by a collision in the first stages of the formation of the solar system or if it resulted: a slow accumulation of matter in the period since, about 4.6 billion years ago.
– All of this is about to change drastically since yesterday and New Year's Day, said Alan Stern, chief scientist at SwRI, in a recent statement – New Horizons will map Ultima, the composition of its surface, will determine if and how many moons it has and will determine whether it has rings or even an atmosphere.The probe will also conduct further studies on the measurement of temperature and perhaps even the Ultima Mbad. In a period of only 72 hours, the Ultima will be transformed from a bright spot, a spot in the distance, into a fully explored world.You will lose your breath.
To this end, 25 new horizons have entered the "mode of meeting" since the last day. Due to the long distance, since radio signals take more than six hours to travel and take a long time to return from the probe, it can not be manually controlled during the flyby and must automatically perform all observations and measurements in the brief. transit time through the neighborhood. Ultima Thule at a relative speed of about 52,000 km / h.
For the program, which begins 72 hours before the meeting, but especially in the last 24 hours, New Horizons cameras will produce Ultima Thule's infrared color and grayscale images with maximum projected resolutions of 330 meters , 140 meters and 1.8 kilometers per pixel respectively. It is also possible that the high-resolution navigation camera, called Lorri (long-range reconnaissance imager), can obtain more detailed images of 33 meters per pixel if the probe can direct it directly to the dwarf planet – there is some uncertainty as to whether it will be in the expected position for overflight.
Meanwhile, the instruments aboard the New Horizons will collect data on the object, looking for information such as the temperature of its sides of the "day" and "night", the radar reflectivity, the absorption of ultraviolet radiation from the Sun by a possible atmosphere or the eruption of gas as in comets, which can give more details on its composition, enters at very characteristic.
It is only about four hours after the overflight that the probe will briefly return to Earth to indicate that the mission was successful and, a few hours later, to begin transmitting the images and data collected, in a process that should last less than two years in its entirety for the expected 7 gigabytes expected with observations, at an average transfer rate of only 800 bits per second (bps) because of the large distance – to obtain a For example, a High speed internet connection at 10 Mbps means that data transmission takes place at a nominal bit rate of 10 million bits per second.
Thus, on the first day, NASA will only announce images previously received from the New Horizons approach of Ultima Thule, the dwarf planet still appearing as a far distant and diffuse distant point. The first photos of the latest Ultima Thule should only be released on Wednesday, or even Thursday, depending also on the obstacles encountered in the use of official channels with the US government shutdown and the low reflectivity of the United States. ;object. and the low light available, which represents an additional challenge in terms of quality.
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