Orbital Antares User Manual
Page 49
Antares
®
OSP-3
User’s Guide
Section 5.0
– Payload Interfaces
Release 1.1
July 2013
38
The lateral offset of the payload center of mass is constrained by the payload separation tip-off require-
ments and the structural capability of the particular separation system. If preliminary design assessments
indicate that the lateral center of gravity offset of the payload may exceed one inch, the customer is en-
couraged to contact the Antares Program Office to verify the feasibility of achieving the specific payload
tip-off requirements.
5.4.2. Final Mass Properties Accuracy
As shown in Table 5.4.2-1, the final mass properties statement must specify payload weight to an accura-
cy of better than 10 kg, the payload center of gravity to an accuracy of at least 6.4 mm (0.25 in.) in each
axis, and the products of inertia to an accuracy of at least 0.7 kg-m
2
(0.5 slug-ft
2
). In addition, if the payl-
oad uses liquid propellant, the slosh frequency
must be provided to an accuracy of 0.2 Hz,
along with a summary of the method used to
determine slosh frequency.
5.4.3. Grounding and Isolation
The Antares vehicle provides an earth ground
reference for the payload via the bonded inter-
face and attachment provisions to the launch
facility grounding grid. Antares is mechanically
mated to the payload at the payload interface plane to achieve a resistance of less than 500 milliohm be-
tween the structures.
5.4.4. Payload Electromagnetic Interference/Electromagnetic Compatibility (EMI/EMC)
Constraints
Antares avionics share the volume inside the fairing with the payload such that radiated emissions
compatibility is paramount. The Antares vehicle RF susceptibility levels have been verified by test. The
payload design must incorporate inhibits that are at least single-fault tolerant to inadvertent RF radiation.
While encapsulated within the fairing, payload RF transmissions are not permitted. During flight, payload
RF transmissions are allowed following fairing separation. The exact time after fairing separation when
the payload may transmit is defined during the Mission Integration Working Group (MIWG) process and is
documented within the mission ICD. Prior to launch, Orbital requires review of the payload radiated
emission levels to verify overall launch vehicle EMI safety margins.
All payload RF transmission frequencies must be coordinated with Orbital and Range officials to ensure
non-interference with Antares and other Range transmissions. Additionally, the payload must schedule
all RF tests at the processing facility with Orbital in order to obtain proper Range clearances and frequen-
cy protection.
Table 5.4.2-1. Payload Mass Properties
Measurement Tolerance
Measurement
Accuracy
Mass
±10 kg
Principle Moments of
Inertia
±5%
Cross Products of
Inertia
±0.7 kg-m² (±0.5 slug-ft²)
Center of Gravity X,
Y, and Z Axes
±6.4 mm (±0.25 in)