Bidding Adieu to the NASA Satellite that Fell

Ever heard about a satellite that fell? If not, then hear it now. Yes, it is true that a NASA satellite fell off and hit Canada on the 24th of September 2011, Saturday. This 6-tonne Upper Atmosphere Research Satellite plunged through the atmosphere of the Earth, broke and scattered huge debris over Okotoks (a town in western Canada that is south of Calgary), early on Saturday (Eastern Daylight time), after being in orbit for around 20 years. It is believed that the UARS entered the atmosphere somewhere between 11:45 p.m. EDT of Friday and 12:45 a.m. EDT of Saturday. This was between 0345 to 0445 of the Greenwich Mean Time on Saturday.

Radar stations across the world, including the North Yorkshire’s RAF Fylingdales, had been tracking the object. Space agency IADC (Inter-Agency Space Debris Co-ordination Committee) had also been working out the place where this spacecraft would hit. They had predicted that it will be most likely that the remains of the space object will drop into any ocean (as most of the planet’s surface is water), or be scattered across any of the planet’s desolate regions, such as the Canadian tundra, Siberia or the Australian outback.

However, as the orientation of the science satellite had changed and it was unpredictably tumbling during its travel towards and in the upper atmosphere of the Earth, the scientists were unable to determine the exact place and time where it would fall.

As it plunged fierily through the Earth’s atmosphere, most of the spacecraft was burnt up before it reached the ground. The only 26 possibly lethal individual pieces that survived the incineration and remained intact landed on the Earth with a total weight of 1,100 pounds (nearly half a tonne or 532 kg). Among the parts that may have survived the flaming re-entry are 2 steel flywheel rims, 4 titanium fuel tanks, as well as an aluminium structure with a weight of 158 kg (349 pounds). These components may have struck the surface of the Earth at a speed between 55 mph (or 90km/h) and 240 mph (or 385km/h), depending on their shapes and sizes. The debris field extends up to 500 miles corridor (or 805 km) of the surface of the Earth.

The 13,000 pound (or 5,897 kg) UARS was an orbital observatory that was sent off into the orbit from the Kennedy Space Center by a space shuttle Discovery STS-48 in September 1991. After entering the orbit on 15th of September 1991 with an orbital inclination of 57 degrees and an operational altitude of 600 km, this NASA satellite was into a mission of observing the ozone layer and studying the chemicals in the Earth’s atmosphere. It flew over a large area of the planet Earth. Its mission was completed in 2005 within duration of 14 years and 91 days. Since then, it had been slowly moving towards the Earth by losing its altitude due to being pulled by the planet’s gravity. With a stretch of 10.6 metres (35 feet) and diameter 4.5 metres (15 feet), this spacecraft was amongst the largest spacelab.

This bus-sized NASA satellite was one among the 22,000 pieces (larger than 4 inches or 10 cm) of space debris in the orbit around the Earth which are traced by the US Space Surveillance Network. Similar sized objects fall back into the atmosphere once every year, but only 1,000 of these pieces are operational spacelabs; the rest are orbital fragments. In future, NASA intends to design such space crafts that can be controlled when they re-enter the atmosphere. This had not been done when UARS was designed.

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