Orbital Antares - Manual (Page 30)

Antares
®
OSP-3
User’s Guide
Section 3.0
– Performance
Release 1.1 July 2013 19
are also improved to within ±0.08 degrees. When made a targeting priority, RAAN errors are similar to
the other configurations at less than 0.2 degrees. Furthermore, this stage allows the explicit targeting of
argument of perigee to within ±0.5 degrees.
3.5.3. Insertion Accuracies for Antares Configurations 122 and 132
The Antares enhanced configurations with the ATK STAR 48BV as a third stage are used primarily for
missions where high energy is required such as high apogee altitude or escape missions. Payload inser-
tion accuracies for these unique requirements will be provided on a mission-specific basis.
3.6. Payload Deployment
Following orbit insertion, the Antares avionics sub-
system executes a series of ACS maneuvers to
provide the desired initial payload attitude prior to
separation. This capability may also be used to
incrementally reorient the upper stage for the dep-
loyment of multiple spacecraft with independent
attitude requirements. Antares is capable of orient-
ing to a wide range of deployment attitudes includ-
ing inertial, orbit track relative, and sun pointing. An
inertially-fixed or spin-stabilized attitude may be
specified by the customer. Typical accuracies are
shown in Table 3.6-1.
The maximum spin rate for a specific mission depends upon the spin axis moment of inertia of the payl-
oad and the ACS propellant budget but cannot nominally exceed 30 degrees per second. Greater spin
rates are possible as a mission unique service.
As part of the Standard Launch Service, Orbital performs a mission-specific payload separation tip-off
analysis to determine the expected maximum payload attitude rates immediately following payload sepa-
ration. The post separation rates are a function of pre-deployment rates, separation system performance,
and payload mass properties.
3.6.1. Payload Separation
Payload separation dynamics are highly dependent on the mass properties of the payload and the partic-
ular separation system utilized. The primary parameters to be considered are payload tip-off and the
overall separation velocity.
Payload tip-off refers to the angular velocity imparted to the payload upon separation due to payload cen-
ter-of-gravity (CG) offsets and an uneven distribution of torques and forces. If an optional Orbital-
supplied Marmon Clamp-band separation system is used, payload tip-off rates are generally under 1°/sec
per axis. Separation system options are discussed further in Section 8.1. Orbital performs a mission-
specific tip-off analysis for each payload.
Separation velocities are driven by the need to prevent recontact between the payload and the Antares
upper stage after separation. Typical separation velocities are 0.6 to 0.9 m/sec (2 to 3 ft/sec).
Table 3.6-1. Antares Payload Deployment
Pointing and Rate Accuracies
Error Type Angle Rate
3-Axis
Pitch ±1.0° ±0.5 °/sec
Yaw ±1.0° ±0.5 °/sec
Roll ±1.0° ±0.5 °/sec
Spinning
Spin Axis ±1.0° -
Spin Rate - ±3 °/sec