Un singur lucru este sigur: nu va cadea in America de Nord.
Satelitul UARS (Upper Atmosphere Research Satellite) va reintra necontrolat in atmosfera Pamantului astazi. Expertii spun ca este prea devreme pentru a stii unde anume va pica aparatul de 6.5 tone si ca vor afla exact cu aproximativ doua ore inainte de impact. Ei au reusit, insa, sa afle ca resturile satelitului nu vor cadea in America de Nord, intrucat nu va fi deasupra continentului in acea perioada, potrivit Realitatea TV.
Intre timp, NASA si US Air Force monitorizeaza cu atentie satelitul si orbita sa.
"Cu modelele noastre, incercam sa ne dam seama ce parti ale satelitului - ce materiale - vor interactiona cu atmosfera, care se vor topi si care vor supravietui", a declarat Mark Matney de la NASA pentru space.com.
The Upper Atmosphere Research Satellite (UARS) is an orbital observatory whose mission was to study the Earth’s atmosphere, particularly the protective ozone layer. Operator NASA Major contractors Lockheed Martin Mission type Earth observation Satellite of Earth Orbital insertion date 1991-09-15 Launch date 1991-09-12, 23:11:04 UTC Carrier rocket Space Shuttle Discovery STS-48 Launch site Kennedy Space Center Launch Complex 39A Mission duration 14 years, 91 days COSPAR ID 1991-063B Homepage http://umpgal.gsfc.nasa.gov/ Mass 5,900 kg (13,000 lb) Power 1600.0 W Batteries 3 x 50 A-hour batteries Orbital elements Semimajor axis 600 km Eccentricity 0° Inclination 56.97999954223633° Apoapsis 575.0 km Periapsis 574.0 km Orbital period 95.9 minutes
Predictiile NASA asupra zonei in care se va prabusi satelitul cuprind o mare parte a planetei, oriunde intre latitudinile Canadei si Americii de Sud.
"Structura nu este perfect sferica, asa ca atunci cand se va incalzi, va incepe sa se sparga in bucati. Atunci vom putea stii unde vor cadea", a spus Ray Williamson de la Secure World Foundation, o organizatie dedicata utilizarii in siguranta a spatiului.
Specialistii NASA estimeaza ca satelitul de marimea unui autobuz se va dezintegra in cel putin 26 de bucati. Aproximativ 532 kg de material vor ajunge pe pamant. Aceste ramasite se vor imprastia pe un teritoriu de circa 804 km lungime. Expertii subliniaza ca sansele ca bucatile sa cada intr-un oras sunt extrem de mici. Cel mai probabil vor pica in apa sau in zone nelocuite.
NASA a calculat ca sansele ca un om sa fie lovit de o bucata din satelitul UARS sunt de 1 la cateva trilioane. Daca insa gasiti o bucata din satelit, cel mai bine este sa o lasati acolo, sa nu o atingeti si sa chemati autoritatile.
Dezintegrarea satelitului va oferi un spectacol luminos pe cer, daca va avea loc in timpul noptii, care va rivaliza cu stralucirea Lunii. Daca evenimentul va avea loc in timpul zilei, va fi greu vizibil.
Nasa has said debris from its defunct six-ton satellite which is heading to Earth could land in the United States.
It had been thought the country was out of the zone where up to 26 pieces, weighing a total of half a ton, would come down. But there is now a slim chance that debris which survives the fiery re-entry will fall over America in the next few hours. The US space agency has insisted most of the 20-year-old probe will burn up in the atmosphere. Scientists are unable to pinpoint the time and place where the Upper Atmosphere Research Satellite, or Uars, which is the size of a double-decker bus, will return to Earth. This is due to the satellite's unpredictable tumbles and changes in the thickness of the atmosphere, which is partly down to a powerful solar flare. The flare releases highly charged particles in the direction of Earth.
When the particles hit the atmosphere, they cause it to heat up and expand, which in turn affects the density of the air Uars encounters as it falls in orbit. Nasa said: "The satellite's orientation apparently has changed and that is now slowing its descent. "There is a low probability any debris that survives re-entry will land in the United States but the possibility cannot be discounted because of this changing rate of descent." Satellites as large as Uars re-enter Earth's atmosphere about once a year and Nasa said there have been no reports of any deaths or injuries to people from falling debris. But space expert Doug Millard at London's Science Museum thinks this one is worth watching. He said: "This is one of the largest satellites up there. "It's about the size of a double-decker bus. Most satellites when they come down, they are smaller, they burn up and no one notices. Because of the size it's a little more significant."
Nasa has said the odds of a piece of the Uars debris striking a person is about one in 3,200. The probe is being tracked by radar stations and experts around the world. Flight Lieutenant Mike Farrington and his team at RAF Fylingdales have been monitoring the 35ft long satellite since its launch. He said the tumbling probe is causing tracking difficulty because of its shape, size and speed. "There's a great deal of uncertainty over where it will re-enter. Due to the irregular size and shape of this object it's impossible to say," Fl Lt Farrington said. "These things move at about 4.6 miles (7.5km) per second in space and something moving at that speed is very difficult to predict. "We've got some world-class analysts here who've been working round the clock. "But it's impossible for anyone using any of the resources anywhere across the globe to actually predict when and where this object will land."
Launched in 1991, the satellite has been monitoring chemicals in the atmosphere, slowly losing altitude since completing its mission in 2005. This satellite has caused a scare already. In 2010, it forced the International Space Station into a collision-avoiding manoeuvre. Nasa said, in 50 years of space travel, no one has ever been hurt by falling debris.
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