NASA Hubble Space Telescope (HST) Robotic Vehicle Mission Level II/III Requirements Document – DRAFT

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1. INTRODUCTION

1.1 GENERAL

This Contract End Item (CEI) Specification establishes the
requirements for the design, performance, and verification of the
Hubble Space Telescope (HST) Robotic Vehicle (HRV), which will be
launched from an Expendable Launch Vehicle (ELV) and will
Autonomously Rendezvous and Capture (AR&C) with the HST.
For the purpose of this document, autonomous is defined as the
independent or self-directed execution of a sequence of commands
with Authority to Proceed (ATP) points to be confirmed by ground
operations where the complete independent set of commands and ATPs
would define an operational or mission phase (e.g., pursuit or
capture).

For the purpose of this document, the capture phase includes
docking the HRV to HST.

The primary requirement of the HRV is to provide a controlled
reentry capability to the HST. The secondary requirement is to
extend the scientific life of HST with a focus on battery and
gyroscopic change out and/or augmentation. This includes ensuring
that the scientific performance of the observatory is not degraded
by adding these capabilities, i.e. “Do no harm”. In the event of
an unanticipated or unlikely contingency case, providing the
controlled reentry capability takes precedence over all other HRV
requirement. The HRV shall be able to accomplish its objectives
during all phases of its mission independent of the operating
state of the HST. This includes: pursuit, proximity operations,
capture, servicing, and de-orbit operations.

The HRV shall provide additional HST life extension, capability
for change out of enhanced Orbital Replacement Instruments (ORIs)/Orbital Replacement Units (ORUs) and safely dispose of the HST at
the end-of-life.

Figure 1-1. HRV Concept

Ejection Module (EM), which provides the a) Launch storage

The HRV, see Figure 1-1, consists of: 1) a Deorbit
Module (DM), which provides HRV control functions during
pursuit, proximity operations, capture, and servicing (including
controls for the grapple arm and robot), the AR&C sensor suite,
and the HST controlled reentry propulsion and control system; 2)
an Ejection Module (EM), which provides the a) Launch storage for the
ORIs/ORUs and the robot, b) the robotic arm mechanical and
electrical interfaces, c) pursuit, proximity, capture, and
servicing Guidance Navigation and Control (GN&C) actuators
including propulsion, and d) EM disposal propulsion and GN&C
system; 3) a robotic arm for the capture of HST at either grapple fixture, and robotic servicing; and 4) a robot for servicing
implementation.