Sunbeams from Space Mirrors Feeding Solar Farms on the Ground at Dusk and Dawn

For 40 years, the systems designers of space solar power have given their greatest attention to wireless power as microwave transmission from space to earth. The approach taken in this application is to place space satellites in lower sunsyncronous orbits for the purpose of gathering and focusing sun’s rays into a beam of reflected sunlight. The simple idea and application of this design is to extend the solar day of terrestrial solar farms, thereby increasing solar production capacity to 60 percent and reducing solar electricity costs to under 6 cents/kWh by delivering sunlight to a given location some 14 (rather than 6 or 7) hours per day. Advisors: Lewis Fraas, Prof. Don Flournoy, Kyle Perkins Reflected Sunlight from Space Journal on Vimeo

Measurement of Cohesion in Asteroid Regolith Materials

There is increasing evidence that a large fraction of asteroids, and even Phobos, have such low densities (<2 g/cu cm) that the are unlikely to be consolidated rocks in space.-Water is unlikely due to close orbits to the sun. Instead, many of these asteroids are thought to be made up of unconsolidated smaller particles of varying size referred to as rubble piles. Images of the asteroid Itokawa reinforce this hypothesis. What holds the rubble piles together? Gravitational forces alone are not strong enough to hold together rubble pile asteroids, at least not those that are rapidly spinning Van der Waals forces and or Electrostatic forces must therefore be responsible for holding them together. Previous work suggests that electrostatic forces, which are orders of magnitude stronger are far more likely. Charge build-up is a likely consequence of the interaction of airless bodies with the solar wind plasma, analogous to what has been proposed to occur on the moon. Objective: Experimentally measure cohesive forces relevant to those holding rubble pile asteroids togethe

From Uranium Enrichment To Renewable Energy

The goal of this Science/Engineering visualization is to show how gigawatt quantities of renewable energy can be generated at former nuclear processing sites as they are repurposed into industrial scale electrical power generation stations. The breakthrough product of this research is the design of an integrated terrestrial solar/space energy receiving station that will produce “baseload” electricity 24 hours a day. This research focuses attention on a Cold War-era uranium enrichment facility located on 3,700 acres of land in a rural area of SE Ohio. This site is judged to be suitable for research leading to the first-ever combination ground-based and space-based solar energy production facility. Were this research to be successful in designing, constructing and testing a space solar power receiving antenna (rectenna) mated to the operational structures of a terrestrial photovoltaic farm, this facility (and others like it) could be transformed from an environmental hazard to a societal benefit. In the case of the former Portsmouth Gaseous Diffusion Plant (PORTS), it is projected that the site has the capability to produce as much renewable energy as it once consumed in the form of coal-produced electricity, when two plants were installed on the Ohio River to sustain its operation. Faculty Mentors Don Flournoy and Kyle Perkin

Atomically Precise Graphene Nanoribbon Transistors with Long-Term Stability and Reliability.

Atomically precise graphene nanoribbons (GNRs) synthesized from the bottom-up exhibit promising electronic properties for high-performance field-effect transistors (FETs). The feasibility of fabricating FETs with GNRs (GNRFETs) has been demonstrated, with ongoing efforts aimed at further improving their performance. However, their long-term stability and reliability remain unexplored, which is as important as their performance for practical applications. In this work, we fabricated short-channel FETs with nine-atom-wide armchair GNRs (9-AGNRFETs). We revealed that the on-state (ION) current performance of the 9-AGNRFETs deteriorates significantly over consecutive full transistor on and off logic cycles, which has neither been demonstrated nor previously considered. To address this issue, we deposited a thin ∼10 nm thick atomic layer deposition (ALD) layer of aluminum oxide (Al2O3) directly on these devices. The integrity, compatibility, electrical performance, stability, and reliability, of the GNRFETs before and/or after Al2O3 deposition were comprehensively studied. The results indicate that the observed decline in electrical device performance is most likely due to the degradation of contact resistance over multiple measurement cycles. We successfully demonstrated that the devices with the Al2O3 layer operate well up to several thousand continuous full cycles without any degradation. Our study offers valuable insights into the stability and reliability of GNR transistors, which could facilitate their large-scale integration into practical applications

Science Operations Planning and Implementation for the OSIRIS-REx Mission, Part 1: Process

The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft arrived at the near-Earth asteroid (101955) Bennu in December 2018 and executed a science observation campaign to comprehensively characterize the asteroid. Proximity operations at Bennu included orbital phases and flyby phases with various viewing geometries and altitudes. The complexity of the mission plan, integrated instrument operations, and the challenges of spacecraft navigation in the microgravity environment required an intricate planning and implementation process that included participation and coordination among all mission elements. The Science Planning Team (SPT) and the Implementation Team (IpT) at the University of Arizona planned and implemented all science and most optical navigation observations. Prior to the formal planning process, science requirements were mapped to mission phases and observation geometry constraints. During development of the mission phases, the navigation team produced a spacecraft trajectory, and the SPT developed the pointing and attitude profile to meet the specified constraints. In the strategic planning process, which began three months prior to execution, the SPT conducted sensitivity analysis of the observation designs against a set of perturbed trajectories delivered by the navigation team to ensure that they were robust to navigational uncertainties. Planning of the specific observations to occur within each phase was divided into units of weeks, and the plans for each week were developed and implemented on a rolling eight-week tactical planning and implementation cycle, ending with execution and data downlink. This cycle included a standardized schedule of activities and gateways to ensure that every observation plan underwent a full suite of analysis, verification, and approval in the allocated timeframe. Checklists guided the SPT and IpT through the build and verification process to confirm plan safety and fidelity. The SPT led the first four weeks of the tactical process, with participation from the IpT and other stakeholders. During the first two weeks, the SPT gathered information from stakeholders, conducted preliminary planning to confirm the science observations were feasible and obeyed spacecraft constraints, and determined how to integrate instrument commanding with the spacecraft pointing profile. The SPT started the final observation design and planning six weeks prior to execution. Once complete, plan walkthroughs were conducted with stakeholders, which culminated in a go/no-go decision to proceed with implementation at the four-week point. In the last four weeks of the tactical planning and implementation process, the IpT led the final processing of science plans with participation from stakeholders. The IpT compiled the plans, performed comprehensive safety checks against established spacecraft and instrument flight rules, and generated flight products and artifacts. After IpT delivered the flight products, the spacecraft team integrated them with the spacecraft sequencing, performed ground testing, and produced an integrated report. IpT reviewed the report, verifying instrument health and safety and confirming nominal plan execution in the ground simulation. The final flight products were uplinked to the spacecraft a few days prior to the execution week. During execution, the IpT and other stakeholders monitored instrument performance and viewed science and navigation data. Resulting science data products were used for operational decisions and science investigations.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]