<s>
A	O
planetary	B-Device
scanner	I-Device
(	O
also	O
called	O
an	O
orbital	B-Device
scanner	I-Device
)	O
is	O
a	O
type	O
of	O
image	B-Application
scanner	I-Application
for	O
making	O
scans	O
of	O
rare	O
books	O
and	O
other	O
easily	O
damaged	O
documents	O
.	O
</s>
<s>
Originally	O
,	O
such	O
scanners	O
were	O
expensive	O
and	O
could	O
only	O
be	O
found	O
in	O
archives	O
and	O
museums	O
,	O
but	O
with	O
the	O
availability	O
of	O
cheap	O
,	O
high-resolution	O
digital	B-Device
cameras	I-Device
,	O
DIY	O
planetary	B-Device
scanners	I-Device
have	O
become	O
affordable	O
,	O
and	O
for	O
instance	O
are	O
being	O
used	O
by	O
volunteer	O
scan	O
providers	O
for	O
Project	O
Gutenberg	O
.	O
</s>
<s>
However	O
,	O
planetary	B-Device
scanners	I-Device
that	O
allow	O
the	O
book	O
to	O
open	O
to	O
a	O
full	O
180	O
degrees	O
have	O
special	O
features	O
that	O
protect	O
the	O
book	O
binding	O
from	O
being	O
damaged	O
.	O
</s>
<s>
Planetary	B-Device
scanners	I-Device
tend	O
to	O
touch	O
fewer	O
parts	O
of	O
a	O
book	O
,	O
and	O
provide	O
an	O
option	O
of	O
only	O
opening	O
a	O
book	O
partially	O
.	O
</s>
