ENAE 484
Space Systems Design
Spring, 2003

Requirements Document


These are the externally-specified requirements for your system to meet. Be aware that, if you can demonstrate that one or more of these requirements are detrimentally driving your design, you can request relief from those specific requirements. Although the requirements are organized based on the group it affects the most, all team members are bound by all requirements.

These are what are known in the business as the "Level 1" requirements - they're the top-level requirements that drive the program. Based on these and your analyses, you should be deriving increasingly more detailed sets of requirements, focusing down on your specialties and specific tasks.

We reserve the right to add requirements! Ideally, all of the Level 1 requirements would be "cast in stone" at the beginning of the program, but I can't think of a single instance (in this class or in the "real world") where that really happened...

Mission Planning and Analysis

 Requirement #  Requirement  Posted

 All nominal ingress/egress shall be accomplished in shirt-sleeve conditions  1/28/03


 The design reference mission shall consist of the following phases:

  • separation from the docking port and translation across a distance of 1000 m to the assembly site
  • two hours of continual operations in the assembly, systems integration, and checkout of a 25m class infrared space telescope
  • 15 minute break
  • two hours of nominal operations
  • 30 minute lunch
  • two hours of nominal operations
  • 15 minute break
  • two hours of nominal operations
  • translation to host station and docking

 The SCOUT system shall provide the capability for the operator to interact with the work site using his/her own hands

 The SCOUT system shall provide the capability for the operator to interact with the work site via dexterous manipulators

 The SCOUT system shall provide the capability for attaching to the work site via robotic manipulators or other adjustable restraint mechanisms

 The SCOUT system shall be designed for a single operator under nominal conditions.

 Standard operational capabilities for the SCOUT system shall meet or exceed EVA capabilities demonstrated in Hubble Space Telescope and International Space Station operations.

 SCOUT shall be designed not to preclude successive operations on a daily basis for indefinite periods of time.  2/20/03

 SCOUT shall provide attitude control for itself at all times, and for the grappled spacecraft being serviced. For design purposes, the reference size for a grappled target spacecraft will be assumed to be equivalent to Hubble Space Telescope.  4/3/03

Systems Integration

 Requirement #  Requirement  Posted

 The SCOUT system shall be designed to operate from the L1 Gateway system.  1/28/03

 The system shall be designed to be readily modifiable for operations on International Space Station.

 Systems design shall consist of the SCOUT vehicle, and a docking and recharge facility to be attached to the hosting station.

 Systems design shall be conducted in accordance with NASA Standard JSC-28354, Human-Rating Requirements

 All system technologies shall be at a minimum NASA technology readiness level (TRL) of 3 on Jan. 1, 2005, and shall be capable of reaching a TRL of 6 by the technology cut-off date of Jan. 1, 2008

 All components for SCOUT system installation and operation shall be designed for launch on US launch vehicles currently planned to be operational in 2005

 The SCOUT system shall be designed to accommodate servicing access to all components at the host station. Items planned for nominal replacement cycles shall be reachable in shirt-sleeve conditions.

 All SCOUT systems shall be capable of contingency operations without internal pressurization.

 System shall provide for a single-interface replenishment at the docking port.

 System shall provide for single-person checkout and refurbishment between each use. Total time for this activity is not to exceed one hour.

 All safety-critical systems shall be two-fault tolerant. Sufficient sensors shall be incorporated to allow positive diagnosis of all credible failures.  2/4/03

Loads, Structures, and Mechanisms

 Requirement #  Requirement  Posted

 All systems shall be designed to provide a non-negative margin of safety for worst-case loading conditions incorporating the following factors of safety:
- Secondary structure: 1.5
- Primary structure: 2.0
- Pressurized tanks: 3.0
- Pressure lines: 4.0

 All structural systems shall provide non-negative margins of safety for all loading conditions due to launch vehicles



 Requirement #  Requirement  Posted

 The system shall be capable of supporting continual bidirectional transmission of high-definition television plus 1 Mb/sec of digital data to the hosting station continually  1/28/03


 The system shall be capable of operating in any of the following control modes for any or all of the nominal mission segments:
- On-board direct human control
- Teleoperation
- Supervisory control
- On-board autonomous control

 Sufficient sensors shall be incorporated to allow positive diagnosis of all credible failures iin safety-critical systems.  2/4/03

Life Support and Human Factors

 Requirement #  Requirement  Posted

 All crew interfaces shall accomodate 95%ile American males to 5%ile Japanese females  1/28/03

 All crew interfaces shall adhere to NASA-STD-3000, Man-Systems Integration Standards

 The TRAMP vehicle shall provide nominal capabilities for eating, drinking, and waste elimination.

 System shall provide necessary support for extravehicular operations on a daily basis.

 Life support systems shall provide sufficient consumables to support the user for the maximum reference mission duration plus two hours reserve.

 Radiation dosages shall, under all conditions, conform in all respects to the current NASA standards for astronaut radiation limits.

 System shall provide for emergency alternative access and EVA "bailout" options

 System shall be capable of safely initiating operations with zero pre-breathe time.

 If the system accommodates variable pressure levels, it must support in-situ denitrogenation during nominal operations.

Power, Propulsion, and Thermal

 Requirement #  Requirement  Posted

 System shall provide a low-contamination (inert gas) propulsion system for operations in contamination-critical regions.  1/28/03

 Power and thermal control systems shall be non-venting.


 Requirement #  Requirement  Posted

 System shall be designed to accommodate supplemental payload kits to enable extended missions, including
- Extended DV missions
- Extended duration missions
- Cargo transport missions