re: IABS???

Philip Chien (
Mon, 3 Nov 1997 17:19:53 -0400

Allen Thomson <> said:

>Apparently the recent Titan IVA from Vandenberg carried an
>unclassified satellite called IABS (1997-065C, 25021) in
>addition to the presumed Lacrosse-3.

IABS should be the apogee stage for the DSCS-III satellite which was
launched on the Atlas IIA from Cape Canaveral - not the Lacrosse launch.

Originally the DSCS-III satellites were supposed to be launched in pairs,
either a DSCS-III and a DSCS-II with an IUS on a Titan 34D, or two
DSCS-IIIs with an IUS on either the shuttle or a Titan IV.

Due to the high cost of the Titan IV the decision was made to launch the
DSCS-IIIs individually on medium launch vehicles.  The Atlas II won the
contract, but an Atlas II only goes to geosync transfer orbit- not the
geostationary orbit of the IUS.

Instead of reconfiguring the DSCS-III satellite the decision was made to
build separate apogee stages.  For some reason they came up with this
incredibly expensive design - the Integrated Apogee Boost System (IABS).
While it's only used for a couple of orbits it has its own solar arrays (in
addition to the power generated from the outermost panels of the DSCS-III
satellite in its stowed configuration) attitude control system (pitch and
yaw) with roll being handled by the parent DSCS satellite and a liquid
engine.  The obvious question is why all of the overkill instead of just a
a plain 'ole spin-stabilized solid propellant motor?  Certainly a solid
motor would be physically longer - but is it really worth that much extra
money ($30 Million each I seem to recall) just to have a slightly shorter

The obvious alternative is that IABS is being used for another purpose
_after_ DSCS is deployed (e.g. as a platform for some clandestine black
experiments).  The IABS is left in a slightly sub-synchronous orbit and
presumably still has power and some consumables (e.g. propellant) which
could be available for a secondary payload.  At a post-launch DSCS-III
press conference the Air Force denied that the IABS has any othe purpose
than the launch of the DSCS-III and acknowledged the high price tag.  (the
general impression I got was that IABS was approved in an era when budget
was a secondary concern).

Philip Chien [M1959.05.31/31.145//]