Search Results

Spacecraft are typically designed with a primary focus on weight in order to meet launch vehicle performance parameters. However, for pressurized and/or man-rated spacecraft, it is also necessary to have an understanding of the vehicle operating environments to properly design the pressure vessel. Proper sizing of the pressure vessel requires an understanding of the space vehicle’s life cycle and compares the physical design optimization (weight and launch “cost”) to downstream operational complexity and total life cycle cost. This paper provides an overview of some major environmental design drivers and presents a generic set of cracking pressures for both positive and negative pressure relief valves that encompasses environmental effects for a variety of launch and landing sites. In addition, an example is provided to compare up-front launch weight penalties against downstream operational constraints.

The Multi-Purpose Logistics Module (MPLM) is the primary carrier for “pressurized” logistics to and from the International Space Station (ISS). Transported in the payload bay of the Space Shuttle, the 15 foot diameter and 20 feet long habitable module is removed and docked to the ISS for unloading and reloading of contents within the ISS shirt sleeve environment. It is then placed back into the Space Shuttle for return to Earth. Within this role, a unique opportunity exists for collection and evaluation of data on the current hardware performance. This data can then be used to tune the current system's performance, as well as determining how future carrier systems can be developed, to provide an optimized hardware and process solution for a space-based logistics transportation system. This paper will focus directly on the thermal performance of the first five MPLM flights, occurring over a fifteen-month period and displayed in Table 1.

The efficiency of re-useable aerospace systems requires a focus on the total operations process rather than just orbital performance. For the Multi-Purpose Logistics Module, this activity included special attention to terrestrial conditions both pre-launch and post-landing and how they inter-relate to the mission profile. Several of the efficiencies implemented by the MPLM Mission Engineering Team were NASA firsts and all served to improve the overall operations. This paper provides the integrated engineering/operations solutions to several key issues. Topics range from statistical analysis of over 30 years of atmospheric data at the launch and landing site to a new approach for operations with the Shuttle Carrier Aircraft. In each situation, the goal was to “tune” the thermal management of the overall flight system for minimizing requirement risk while optimizing power and energy performance.