<s>
The	O
Corrective	B-Algorithm
Optics	I-Algorithm
Space	I-Algorithm
Telescope	I-Algorithm
Axial	I-Algorithm
Replacement	I-Algorithm
(	O
COSTAR	B-Algorithm
)	O
is	O
an	O
optical	O
correction	O
instrument	O
designed	O
and	O
built	O
by	O
NASA	O
.	O
</s>
<s>
It	O
was	O
created	O
to	O
correct	O
the	O
spherical	O
aberration	O
of	O
the	O
Hubble	O
Space	O
Telescopes	O
primary	O
mirror	O
,	O
which	O
incorrectly	O
focused	O
light	O
upon	O
the	O
Faint	B-Algorithm
Object	I-Algorithm
Camera	I-Algorithm
(	O
FOC	O
)	O
,	O
Faint	O
Object	O
Spectrograph	O
(	O
FOS	O
)	O
,	O
and	O
Goddard	O
High	O
Resolution	O
Spectrograph	O
(	O
GHRS	O
)	O
instruments	O
.	O
</s>
<s>
When	O
launched	O
,	O
the	O
HST	O
carried	O
five	O
scientific	O
instruments	O
:	O
the	O
Wide	B-Algorithm
Field	I-Algorithm
and	I-Algorithm
Planetary	I-Algorithm
Camera	I-Algorithm
(	O
WFPC	O
)	O
,	O
Goddard	O
High	O
Resolution	O
Spectrograph	O
(	O
GHRS	O
)	O
,	O
High	O
Speed	O
Photometer	O
(	O
HSP	O
)	O
,	O
Faint	B-Algorithm
Object	I-Algorithm
Camera	I-Algorithm
(	O
FOC	O
)	O
and	O
the	O
Faint	O
Object	O
Spectrograph	O
(	O
FOS	O
)	O
.	O
</s>
<s>
It	O
was	O
eventually	O
determined	O
that	O
with	O
the	O
HST	O
still	O
in	O
orbit	O
that	O
they	O
could	O
replace	O
the	O
WFPC	O
with	O
the	O
improved	O
Wide	B-Algorithm
Field	I-Algorithm
and	I-Algorithm
Planetary	I-Algorithm
Camera	I-Algorithm
2	I-Algorithm
which	O
would	O
incorporate	O
corrective	O
optics	O
.	O
</s>
<s>
Once	O
back	O
in	O
America	O
he	O
explained	O
his	O
idea	O
,	O
which	O
was	O
immediately	O
taken	O
up	O
by	O
other	O
engineers	O
who	O
began	O
to	O
develop	O
what	O
by	O
1990	O
had	O
become	O
the	O
Corrective	B-Algorithm
Optics	I-Algorithm
Space	I-Algorithm
Telescope	I-Algorithm
Axial	I-Algorithm
Replacement	I-Algorithm
,	O
or	O
COSTAR	B-Algorithm
.	O
</s>
<s>
The	O
budgeted	O
cost	O
of	O
the	O
COSTAR	B-Algorithm
was	O
US$	O
50,000,000	O
.	O
</s>
<s>
To	O
fit	O
the	O
COSTAR	B-Algorithm
system	O
onto	O
the	O
telescope	O
,	O
one	O
of	O
the	O
other	O
instruments	O
had	O
to	O
be	O
removed	O
,	O
and	O
astronomers	O
selected	O
the	O
High	O
Speed	O
Photometer	O
to	O
be	O
sacrificed	O
,	O
which	O
was	O
the	O
least	O
important	O
of	O
the	O
four	O
axial	O
detectors	O
.	O
</s>
<s>
A	O
total	O
of	O
ten	O
correction	O
mirrors	O
with	O
diameters	O
ranging	O
in	O
size	O
from	O
approximately	O
18	O
to	O
24mm	O
were	O
used	O
as	O
the	O
Faint	B-Algorithm
Object	I-Algorithm
Camera	I-Algorithm
and	O
Faint	O
Object	O
Spectrograph	O
each	O
had	O
two	O
apertures	O
for	O
each	O
of	O
their	O
two	O
measuring	O
channels	O
whereas	O
the	O
Goddard	O
High	O
Resolution	O
Spectrograph	O
only	O
had	O
one	O
aperture	O
for	O
both	O
of	O
its	O
channels	O
.	O
</s>
<s>
In	O
January	O
1991	O
Ball	O
Aerospace	O
Corp	O
.	O
was	O
selected	O
by	O
NASA	O
as	O
the	O
prime	O
contractor	O
to	O
undertake	O
the	O
entire	O
development	O
,	O
production	O
and	O
verification	O
of	O
COSTAR	B-Algorithm
,	O
a	O
process	O
which	O
took	O
26	O
months	O
.	O
</s>
<s>
Once	O
complete	O
the	O
entire	O
COSTAR	B-Algorithm
was	O
then	O
tested	O
in	O
the	O
COSTAR	B-Algorithm
Alignment	O
System	O
(	O
CAS	O
)	O
.	O
</s>
<s>
To	O
check	O
for	O
any	O
error	O
in	O
the	O
CAS	O
the	O
COSTAR	B-Algorithm
was	O
then	O
mounted	O
in	O
the	O
specially	O
developed	O
Hubble	O
Opto-Mechanical	O
Simulator	O
(	O
HOMS	O
)	O
which	O
simulated	O
the	O
errors	O
in	O
the	O
faulty	O
primary	O
mirror	O
,	O
to	O
allow	O
an	O
end	O
to	O
end	O
test	O
and	O
thus	O
verification	O
of	O
the	O
output	O
image	O
.	O
</s>
<s>
The	O
European	O
Space	O
Agency	O
also	O
contributed	O
to	O
the	O
verification	O
process	O
by	O
providing	O
an	O
engineering	O
model	O
of	O
the	O
Faint	B-Algorithm
Object	I-Algorithm
Camera	I-Algorithm
to	O
provide	O
additional	O
verification	O
.	O
</s>
<s>
COSTAR	B-Algorithm
replaced	O
the	O
High	O
Speed	O
Photometer	O
during	O
the	O
first	O
Hubble	O
Servicing	O
Mission	O
in	O
1993	O
.	O
</s>
<s>
The	O
resulting	O
images	O
confirmed	O
that	O
the	O
COSTAR	B-Algorithm
had	O
corrected	O
the	O
spherical	O
aberration	O
in	O
the	O
primary	O
mirror	O
.	O
</s>
<s>
COSTAR	B-Algorithm
was	O
removed	O
from	O
HST	O
in	O
2009	O
during	O
the	O
fifth	O
servicing	O
mission	O
and	O
replaced	O
by	O
the	O
Cosmic	O
Origins	O
Spectrograph	O
.	O
</s>
