A Case Study in NASA-DoD - The Black Vault

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payload or propulsion, is about 5 ft. The HMS design is suitable only
for operation in the main payload bay of the space shuttle.
The third standard spacecraft design included in the initial phase
of the study was the AEM (Fig. 3). Boeing is currently building two
versions of the AEM: the HCMH and the SAGE. The outward physical appearance
of the two versions is very similar in that most of the differences
involve components housed within the spacecraft. The AEM is three-axis
stabilized and can be matched with appropriately sized solid rocket motors
for orbital translation. In its current design, it is limited to operational
altitudes less than 1000 n mi because it relies on magnetic
torques rather than reaction jets to unload the momentum wheels (Appendix
D). It is a low-cost expendable design that uses off-the-shelf components
throughout. The physical configuration of the AEM is a "hexagonal nut"
36 in. across the flat and 25 in. long (excluding payload and propulsion).
It weighs about 210 lb.
The fourth standard spacecraft, the L-AEM, is a derivative of the AEM
that has been increased in diameter to a nominal 5 ft (Fig. 4). The L-AEM
design can be procured in three different configurations: the baseline
option (L-AEM-BL), the spin-stabilized option (L-AEM-S), and the precision
option (L-AEM-P). The configuration changes are achieved by modifying the
equipment list. The L-AEM-BL weighs about 670 lb without propulsion or payload.
SPACECRAFT COMPARISONS
Spacecraft Requirements
The nominal spacecraft requirements for the AEM, L-AEM, STPSS, and MMS,
categorized by mission, comunication, electrical power, stabilization and
control, and reaction control system and propulsion, are shown in Table 1.
Of the four spacecraft, the A' is the smallest and has the least capability.
It is about 3 ft in diameter, can carry a 150 lb payload, and is limited
to operating altitudes less than 1000 n mi.
All three configurations of the L-AEM have a minimum life of one
year and a payload capability of 1000 lb. Both the L-AEM-S and L-AEM-P
can operate from low earth orbit to geosynchronous altitude; the L-AEM-BL
is restricted to altitudes less than 1000 n mi.