The first uncontrolled re-entry of a European Space Agency air craft in more than 25 years occurred this weekend when satellite Goce ran out of fuel and entered the Earth’s atmosphere. Initially studies have concluded that any debris that did not burn up during the fall could have landed in a path through East Asia and the Western Pacific reaching towards Antarctica.
Goce, which was nicknamed the “Ferrari of Space” for its slender, lustrous designer, needed to constantly expel electric energy to propel itself away from the Earth’s atmosphere. The satellite was known for its unique arrow shape and fins that were designed to keep Goce stable during its unique trajectory around the Earth. The mission was orbiting in an extremely low projector, 224KM altitude, the lowest of any other satellite. When Goce’s fuel ran out it was inevitable that it would re-enter.
Initially estimates, that were made pre-entry, suggest that anywhere from a fifth to a quarter of Goce’s mass could have survived the fiery crash.
Goce was equipped with an advanced gradiometer, an instrument used to make gravity measurements, with composite materials that can be expected to withstand the fires that ravage these components upon an unplanned re-entry. The gradiometer was the satellite’s most noteworthy feature, causing headlines within the science community upon its completion. This gradiometer contained three different pairs of accelerometers which could measure gravity along three different axes.
During Goce’s mission the satellite probed different volcanic regions and made close studies of ocean behavior. By using gravity data along with found sea surface levels, Goce was able to help scientists determine “geostrophic ocean currents.” To obtain this kind of precise gravitational data the Goce was forced to make a low orbit around the Earth, which eventually caused its destruction.
It is generally believed that one piece of so-called “space junk” enters the Earth’s atmosphere everyday, of course the vast majority of these entries incinerate before reaching the ground. It is also speculated that each week an intact, albeit retired, spacecraft or remnants of a rocket body re-enters the atmosphere.
This satellite was the first uncontrolled re-entry of an ESA aircraft since 1987, when the magnetosphere explorer Isee-2 came back. Of course, ESA does controlled re-entries constantly as part of their regular programming. The Automated Transfer Vechicle, their freighter, weighs can weigh up to 13 tons of found debris readmitted into the Earth’s atmosphere.
Goce was last observed at 22:42 GMT on Sunday while it passed 75 miles (121 km) above Antarctica. Goce was launched as a part of a series of modern research satellites focusing on the environment back in 2009.
The maps of the ocean that were produced as a result of data obtained from Goce have been able to show ocean currents in much greater detail than ever before. Man Eddy, “a persistent pocket of water in the Atlantic that just goes around and around,” and effects of Hurricane Igor (2010) were finally seen on these maps thanks to Goce. Goce also recorded infrasound waves from the Thohoku Earthquake in 2011. Goce stands for Gravity Field and Steady-State Ocean Circulation Explorer.
By Nick Manai