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- Genre: Masters Thesis
Description
CubeSats are a newly emerging, low-cost, rapid development platform for space exploration research. They are small spacecraft with a mass and volume of up to 12 kg and 12,000 cm3, respectively. To date, CubeSats have only been flown in Low Earth Orbit (LEO), though a large number are currently being designed to be dropped off by a mother ship on Earth escape trajectories intended for Lunar and Martian flyby missions. Advancements in propulsion technologies now enable these spacecraft to achieve capture orbits around the moon and Mars, providing a wealth of scientific data at low-cost. However, the mass, volume and launch constraints of CubeSats severely limit viable propulsion options.
We present an innovative propulsion solution using energy generated by onboard photovoltaic panels to electrolyze water, thus producing combustible hydrogen and oxygen for low-thrust applications. Water has a high storage density allowing for sufficient fuel within volume constraints. Its high enthalpy of formation provides more fuel that translates into increased ∆V and vastly reduced risk for the launch vehicle. This innovative technology poses significant challenges including the design and operation of electrolyzers at ultra-cold temperatures, the efficient separation of the resultant hydrogen and oxygen gases from liquid water in a microgravity environment, as well as the effective utilization of thrust to produce desired trajectories.
Analysis of the gas combustion and flow through the nozzle using both theoretical equations and finite-volume CFD modeling suggests an expected specific impulse of 360 s. Preliminary results from AGI's Satellite Toolkit (STK) indicate that the ΔV produced by the system for an 8kg CubeSat with 6kg of propellant in a LEO orbit (370 km altitude) is sufficient for an earth escape trajectory, lunar capture orbit or even a Mars capture orbit. These results suggest a promising pathway for an in-depth study supported by laboratory experiments to characterize the strengths and weaknesses of the proposed concept.
We present an innovative propulsion solution using energy generated by onboard photovoltaic panels to electrolyze water, thus producing combustible hydrogen and oxygen for low-thrust applications. Water has a high storage density allowing for sufficient fuel within volume constraints. Its high enthalpy of formation provides more fuel that translates into increased ∆V and vastly reduced risk for the launch vehicle. This innovative technology poses significant challenges including the design and operation of electrolyzers at ultra-cold temperatures, the efficient separation of the resultant hydrogen and oxygen gases from liquid water in a microgravity environment, as well as the effective utilization of thrust to produce desired trajectories.
Analysis of the gas combustion and flow through the nozzle using both theoretical equations and finite-volume CFD modeling suggests an expected specific impulse of 360 s. Preliminary results from AGI's Satellite Toolkit (STK) indicate that the ΔV produced by the system for an 8kg CubeSat with 6kg of propellant in a LEO orbit (370 km altitude) is sufficient for an earth escape trajectory, lunar capture orbit or even a Mars capture orbit. These results suggest a promising pathway for an in-depth study supported by laboratory experiments to characterize the strengths and weaknesses of the proposed concept.
ContributorsPothamsetti, Ramana Kumar (Author) / Thangavelautham, Jekanthan (Thesis advisor) / Dahm, Werner J.A (Committee member) / Solanki, Kiran N (Committee member) / Arizona State University (Publisher)
Created2015
Description
New forms of carbon are being discovered at a rapid rate and prove to be on the frontier of cutting edge technology. Carbon possesses three energetically competitive forms of orbital hybridization, leading to exceptional blends of properties unseen in other materials. Fascinating properties found among carbon allotropes, such as, fullerenes, carbon nanotubes, and graphene have led to new and exciting advancement, with recent applications in defense, energy storage, construction, and electronics. Various combinations of extreme strength, high electrical and thermal conductivity, flexibility, and light weight have led to new durable and flexible display screens, optoelectronics, quantum computing, and strength enhancer coating. The quest for new carbon allotropes and future application persists.
Despite the advances in carbon-based technology, researchers have been limited to sp3 and sp2 hybridizations. While sp3 and sp2 hybridizations of carbon are well established and understood, the simplest sp1 hybridized carbon allotrope, carbyne, has been impossible to synthesize and remains elusive. This dissertation presents recent results in characterizing a new sp1 carbon material produced from using pulsed laser ablation in liquid (PLAL) to ablate a gold surface that is immersed in a carbon rich liquid. The PLAL technique provides access to extremely non-thermal environmental conditions where unexplored chemical reactions occur and can be explored to access the production of new materials. A combination of experimental and theoretical results suggests gold clusters can act as stabilizing agents as they react and adsorb onto the surface of one dimensional carbon chains to form a new class of materials termed “pseudocarbynes”. Data from several characterization techniques, including Raman spectroscopy, UV/VIS spectroscopy, and transmission electron microscopy (TEM), provide evidence for the existence of pseudocarbyne. This completely new material may possess outstanding properties, a trend seen among carbon allotropes, that can further scientific advancements.
Despite the advances in carbon-based technology, researchers have been limited to sp3 and sp2 hybridizations. While sp3 and sp2 hybridizations of carbon are well established and understood, the simplest sp1 hybridized carbon allotrope, carbyne, has been impossible to synthesize and remains elusive. This dissertation presents recent results in characterizing a new sp1 carbon material produced from using pulsed laser ablation in liquid (PLAL) to ablate a gold surface that is immersed in a carbon rich liquid. The PLAL technique provides access to extremely non-thermal environmental conditions where unexplored chemical reactions occur and can be explored to access the production of new materials. A combination of experimental and theoretical results suggests gold clusters can act as stabilizing agents as they react and adsorb onto the surface of one dimensional carbon chains to form a new class of materials termed “pseudocarbynes”. Data from several characterization techniques, including Raman spectroscopy, UV/VIS spectroscopy, and transmission electron microscopy (TEM), provide evidence for the existence of pseudocarbyne. This completely new material may possess outstanding properties, a trend seen among carbon allotropes, that can further scientific advancements.
ContributorsFujikado, Nancy (Author) / Sayres, Scott G (Thesis advisor) / Rege, Kaushal (Thesis advisor) / Green, Matthew D (Committee member) / Arizona State University (Publisher)
Created2018