<s>
The	O
Gravity	O
Field	O
and	O
Steady-State	O
Ocean	O
Circulation	O
Explorer	O
(	O
GOCE	O
)	O
was	O
the	O
first	O
of	O
ESA	O
's	O
Living	O
Planet	O
Programme	O
heavy	O
satellites	B-Application
intended	O
to	O
map	O
in	O
unprecedented	O
detail	O
the	O
Earth	O
's	O
gravity	O
field	O
.	O
</s>
<s>
By	O
combining	O
the	O
gravity	O
data	O
with	O
information	O
about	O
sea	O
surface	O
height	O
gathered	O
by	O
other	O
satellite	B-Application
altimeters	O
,	O
scientists	O
were	O
able	O
to	O
track	O
the	O
direction	O
and	O
speed	O
of	O
geostrophic	O
ocean	O
currents	O
.	O
</s>
<s>
The	O
satellite	B-Application
's	O
unique	O
arrow	O
shape	O
and	O
fins	O
helped	O
keep	O
GOCE	O
stable	O
as	O
it	O
flew	O
through	O
the	O
thermosphere	O
at	O
a	O
comparatively	O
low	O
altitude	O
of	O
.	O
</s>
<s>
After	O
running	O
out	O
of	O
propellant	O
,	O
the	O
satellite	B-Application
began	O
dropping	O
out	O
of	O
orbit	O
and	O
made	O
an	O
uncontrolled	O
re-entry	O
on	O
11	O
November	O
2013	O
.	O
</s>
<s>
To	O
increase	O
resolution	O
,	O
the	O
satellite	B-Application
flew	O
in	O
an	O
unusually	O
low	O
orbit	O
.	O
</s>
<s>
Initial	O
results	O
of	O
the	O
GOCE	O
satellite	B-Application
mission	O
were	O
presented	O
at	O
the	O
American	O
Geophysical	O
Union	O
(	O
AGU	O
)	O
2010	O
Fall	O
(	O
Autumn	O
)	O
Meeting	O
by	O
Dr	O
Rory	O
Bingham	O
from	O
Newcastle	O
University	O
,	O
UK	O
.	O
</s>
<s>
The	O
satellite	B-Application
's	O
orbit	O
then	O
decayed	O
over	O
a	O
period	O
of	O
45	O
days	O
to	O
an	O
operational	O
altitude	O
,	O
planned	O
at	O
270km	O
.	O
</s>
<s>
In	O
February	O
2010	O
a	O
fault	O
was	O
discovered	O
in	O
the	O
satellite	B-Application
's	O
computer	O
,	O
which	O
meant	O
controllers	O
were	O
forced	O
to	O
switch	O
control	O
to	O
the	O
backup	O
computer	O
.	O
</s>
<s>
In	O
July	O
2010	O
,	O
GOCE	O
suffered	O
a	O
serious	O
communications	O
malfunction	O
,	O
when	O
the	O
satellite	B-Application
suddenly	O
failed	O
to	O
downlink	O
scientific	O
data	O
to	O
its	O
receiving	O
stations	O
.	O
</s>
<s>
The	O
satellite	B-Application
ran	O
out	O
of	O
its	O
xenon	B-Protocol
propellant	O
in	O
October	O
2013	O
,	O
at	O
which	O
time	O
it	O
would	O
take	O
to	O
re-enter	O
.	O
</s>
<s>
Subsequently	O
,	O
end	O
of	O
mission	O
was	O
formally	O
declared	O
on	O
21	O
October	O
when	O
the	O
spacecraft	O
ran	O
out	O
of	O
fuel	O
;	O
deprived	O
of	O
xenon	B-Protocol
,	O
the	O
ion	O
drive	O
stopped	O
working	O
at	O
03:16UTC	O
.	O
</s>
<s>
On	O
9	O
November	O
2013	O
,	O
a	O
published	O
report	O
indicated	O
that	O
the	O
satellite	B-Application
was	O
expected	O
to	O
re-enter	O
within	O
a	O
day	O
or	O
two	O
.	O
</s>
<s>
Its	O
descending	O
orbit	O
on	O
11	O
November	O
2013	O
passed	O
over	O
Siberia	B-Application
,	O
the	O
western	O
Pacific	O
Ocean	O
,	O
the	O
eastern	O
Indian	O
Ocean	O
and	O
Antarctica	O
.	O
</s>
<s>
The	O
satellite	B-Application
finally	O
disintegrated	O
around	O
00:16UTC	O
on	O
11	O
November	O
near	O
the	O
Falkland	O
Islands	O
.	O
</s>
<s>
The	O
satellite	B-Application
's	O
main	O
payload	O
was	O
the	O
Electrostatic	B-Algorithm
Gravity	I-Algorithm
Gradiometer	I-Algorithm
(	O
EGG	O
)	O
to	O
measure	O
the	O
gravity	O
field	O
of	O
Earth	O
.	O
</s>
<s>
Other	O
payload	O
was	O
an	O
onboard	O
GPS	O
receiver	O
used	O
as	O
a	O
Satellite-to-Satellite	O
Tracking	O
Instrument	O
(	O
SSTI	O
)	O
;	O
a	O
compensation	O
system	O
for	O
all	O
non-gravitational	O
forces	O
acting	O
on	O
the	O
spacecraft	O
.	O
</s>
<s>
The	O
satellite	B-Application
was	O
also	O
equipped	O
with	O
a	O
laser	O
retroreflector	O
to	O
enable	O
tracking	O
by	O
ground-based	O
Satellite	B-Application
laser	O
ranging	O
stations	O
.	O
</s>
<s>
The	O
ion	O
propulsion	O
electric	O
engine	O
,	O
designed	O
and	O
built	O
at	O
QinetiQ	O
's	O
space	O
centre	O
in	O
Farnborough	O
,	O
England	O
,	O
ejected	O
xenon	B-Protocol
ions	O
at	O
velocities	O
exceeding	O
,	O
which	O
compensated	O
for	O
the	O
orbital	O
decay	O
losses	O
.	O
</s>
<s>
GOCE	O
's	O
mission	O
ended	O
when	O
the	O
xenon	B-Protocol
fuel	O
tank	O
emptied	O
.	O
</s>
