Engineering topics
Cobb, Sharon
Publications and source records attributed to Cobb, Sharon.
Space Launch System Update
NASA has a phased approach to ensure our nation's leadership in space exploration, beginning in Earth orbit, developing our skills in lunar space, and extending those skills and technologies to a human mission to Mars. We're currently in Phase 0, using the ISS to better understand living and working in space. You may have heard about our "twin study" with astronauts Scott and Mike Kelly that's giving us valuable information on the effects of microgravity environments on the human body during long stays in LEO. During Phase 1 in the 2020s, SLS will be used to lift the pieces of a "deep space gateway" outpost to lunar orbit. Developing and operating the gateway will get us to Mars in a step-by-step fashion, with lessons learned in each phase of the process informing the next steps. First step of moving humans farther into the solar system is completing and flying SLS and Orion.
Advanced Extravehicular Activity Breakout Group Summary
This viewgraph document summarizes the workings of the Advanced Extravehicular Activity (AEVA) Breakout group in a Martian environment. The group was tasked with: identifying potential contaminants and pathways for AEVA systems with respect to forward and backward contamination; identifying plausible mitigation alternatives and obstacles for pertinent missions; identifying topics that require further research and technology development and discuss development strategies with uncertain Planetary Protection (PP) requirements; Identifying PP requirements that impose the greatest mission/development costs; Identifying PP requirements/topics that require further definition;
Crystal Growth of HgZnTe Alloy by Directional Solidification in Low Gravity Environment
A Hg0.84Zn0.16Te alloy crystal was back-melted and partially resolidified during the first United States Microgravity Laboratory (USML-1) mission in the Marshall Space Flight Center's Crystal Growth Furnace. The experiment was inadvertently terminated at about 30% of planned completion. Nonetheless, it was successfully demonstrated that a HgZnTe alloy ingot partially grown and quenched on the ground can be back-melted and regrown in space under nearly steady state growth conditions. An identical "groundtruth" experiment was performed following the mission and a comparison between the properties of the crystals is described. The results indicate the importance of residual microgravity acceleration (approx. less than 0.4 mg) even in the sub-microgravity range for the slow solidification velocities and large density gradients.