Launched in 2009 to measure the severity of our planet, the GOCE satellite at the edge of the dry down, will complete his journey by crushing it, a comeback which the day and the place is still unknown, but experts believe little risky for Earthlings.
According to the latest estimates from the European Space Agency (ESA), Friday, 41 kilos of the tank contained only 350 grams of xenon, a noble gas.
minimum pressure of 2.5 bar in the tank is normally required for the propulsion system, and is just down below, told AFP Christoph Steiger, CEO of GOCE. “The engine still works, but it means that we are very near the end,” he added.
260 km altitude
In theory, the pressure in the tank should drop to 0 at the latest on 26 October, but the engine can now stop at any time before then.
Long
5.3 meters and weighing more than a ton, GOCE running originally on an extremely low orbit, just 260 km altitude, to map the Earth’s gravity field and provide scientists with critical data to study climate change and earthquakes.
These data were notably used to create the world’s first high-resolution map of the boundary between the crust and mantle of the Earth, the Moho. GOCE was also able to detect waves from earthquake that struck Japan on 11 March 2011.
The mission was originally scheduled to last 20 months, but the ESA decided to extend until 2012.
Imposible locate
Featuring an ion engine “that grows continuously,” GOCE “is in a stable orbit as it has fuel,” said Fernand Alby, responsible for the activities space debris and space surveillance of the French Space Agency (CNES).
Since the engine will stop pushing, the satellite will begin to lose altitude and begin its return to Earth. “From the moment when the tank is empty, it may take roughly two or three weeks,” said Christoph Steiger. Impossible today to predict how the GOCE Earth, or rather what is left, will land.
few hours before the fall, we can determine the “ground track” of the object, ie a line where it will inevitably fall … but that is nothing less than around the Earth, told Fernand Alby.
not quite zero risk
experts however consider the risk to “very low” Earthlings, but not quite zero. “The risk of being hit by an unbridled spacecraft is 65,000 times smaller than that of being struck by lightning,” says Christoph Steiger.
satellite should break up around 80 km altitude. According to Christoph Steiger, a quarter of its mass is 250 kg should survive re-entry into the atmosphere, disintegrating into fifty fragments.
as the event has nothing exceptional. “Objects of the GOCE mass, it falls a week on average,” said Fernand Alby, old satellites or launcher stages.
luminous phenomenon
specialist points out that since the beginning of the space era, “there never was no damage or casualties.”
-lucky or not that could be close to may be able to observe “a fairly large luminous phenomenon” in the sky, much like a meteorite.
major space agencies (ESA, CNES, NASA, the Russian and Chinese agencies) will monitor the return of GOCE, an exercise that will allow them to compare their measurements.
AFP
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