Spacecraft design for multipurpose solar electric propulsion missions

Macpherson, D.; Molitor, J. H.; Schwaiger, L.

doi:10.2514/3.29809

Cited by 4 publications

(4 citation statements)

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“…From k PI we then calculated the susceptibility to photo-inactivation generalized across irradiance levels, as a target size functional absorption cross section for photoinactivation of PSII, σ I = k PI /photons m -2 s -1 . The apparent first order rate constant for PSII repair, k REC (s -1 ) [76] was then estimated following [13,77,78] using subsamples without lincomycin, across the entire treatment trajectory of initial exposure to 1200 μmol photons m -2 s -1 (4 time points) and then recovery at 15 μmol photons m -2 s -1 (2 time points). For fitting of k REC we used the σ I value for each species determined in the presence of lincomycin, on the simplifying assumption that the primary photo-inactivation of PSII is the same in the absence or the presence of PSII repair.…”

Section: Psii Photo-inactivation and Repairmentioning

confidence: 99%

“…Replicate time courses for PSII photo-inactivation in the presence of lincomycin were fit for each species to extract the rate constant for photoinactivation, k PI . These k PI values determined for each species in the absence of PSII repair were then inputted into fit models [13,76] using data captured from culture samples with PSII repair, in order to estimate the apparent first order rate constant for PSII repair, k REC (Table 3). As expected [73], the susceptibility to photo-inactivation (k PI ) decreased with increasing diatom cell size from the smaller T. oceanica and T. pseudonana to the larger T. weissflogii (Table 3).…”

Section: Psii Photo-inactivation and Repairmentioning

confidence: 99%

“…Together, the trade-offs in %LDR and %R DARK from Ig to HL for T. pseudonana resulted in unchanged % Net O2 , whereas the light-dependent changes in %LDR (but not %R DARK ) resulted in an increase and decrease of Net O2 from Ig to HL for T. weissflogii and T. oceanica, respectively (Fig 5). Values derived from curve fits [13,76] of data from 3 independent replicates. Values in parentheses represent SE of the mean.…”

Section: Plos Onementioning

confidence: 99%

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Divergence of photosynthetic strategies amongst marine diatoms

et al. 2020

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Marine phytoplankton, and in particular diatoms, are responsible for almost half of all primary production on Earth. Diatom species thrive from polar to tropical waters and across light environments that are highly complex to relatively benign, and so have evolved highly divergent strategies for regulating light capture and utilization. It is increasingly well established that diatoms have achieved such successful ecosystem dominance by regulating excitation energy available for generating photosynthetic energy via highly flexible light harvesting strategies. However, how different light harvesting strategies and downstream pathways for oxygen production and consumption interact to balance excitation pressure remains unknown. We therefore examined the responses of three diatom taxa adapted to inherently different light climates (estuarine Thalassioisira weissflogii, coastal Thalassiosira pseudonana and oceanic Thalassiosira oceanica) during transient shifts from a moderate to high growth irradiance (85 to 1200 μmol photons m-2 s-1). Transient high light exposure caused T. weissflogii to rapidly downregulate PSII with substantial nonphotochemical quenching, protecting PSII from inactivation or damage, and obviating the need for induction of O2 consuming (light-dependent respiration, LDR) pathways. In contrast, T. oceanica retained high excitation pressure on PSII, but with little change in RCII photochemical turnover, thereby requiring moderate repair activity and greater reliance on LDR. T. pseudonana exhibited an intermediate response compared to the other two diatom species, exhibiting some downregulation and inactivation of PSII, but high repair of PSII and induction of reversible PSII nonphotochemical quenching, with some LDR. Together, these data demonstrate a range of strategies for balancing light harvesting and utilization across diatom species, which reflect their adaptation to sustain photosynthesis under environments with inherently different light regimes.

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Section: Psii Photo-inactivation and Repairmentioning

confidence: 99%

Section: Psii Photo-inactivation and Repairmentioning

confidence: 99%

Section: Plos Onementioning

confidence: 99%

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Divergence of photosynthetic strategies amongst marine diatoms

et al. 2020

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“…Ion electric propulsion systems are one of the mainstream electric propulsion technologies in the world, and belong to electrostatic acceleration [33]- [36]. The input power of the ion electric propulsion system is usually solar energy converted into electricity by photo-electric conversion device, which ensures long-term spacecraft power [37]. Then, in ion electric propulsion system, the electricity would convert into electromagnetic field energy at the discharge chamber to ionize propellant (usually Xe) and generate low temperature plasma with abundant electrons and ions [38]- [40].…”

Section: Basic Working Principlementioning

confidence: 99%

Ion Electric Propulsion System Electric Breakdown Problems: Causes, Impacts and Protection Strategies

Peng,

Li,

Song

et al. 2023

IEEE Access

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Ion electric propulsion systems have been widely used in satellite station keeping, attitude control, and orbit transfer due to their advantages of high specific impulse, good flexibility, and high reliability. The electric breakdown might happen at grids or across isolators due to the disturbing effects of the power source or environment. The electric breakdown can induce spurious effects in the power processing unit (PPU) circuit from the return currents and voltage drops, which could be several orders of magnitude higher than the impulses at normal working conditions. When the electric breakdown happens, it might result in serious electromagnetic interference and damage to the electric and electronic equipment in the spacecraft. This paper provides a comprehensive summary of the various factors that can cause electric breakdown in an ion electric propulsion system, such as environmental factors, manufacturing considerations, and operational conditions of the thruster. Furthermore, a comprehensive analysis of the impact of electric breakdown on the ion thruster, electric propulsion system, and spacecraft mission is explored. The effectiveness of different grounding configurations in safeguarding against ion thruster electric breakdown has also been evaluated. Based on the analysis and discussion, the control and protection strategies are proposed for the ion electric propulsion system electric breakdown problems.

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Characteristics, capabilities, and costs of solar electric spacecraft for planetary missions

Bartz

Horsewood

1970

Journal of Spacecraft and Rockets

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Spacecraft design for multipurpose solar electric propulsion missions

Cited by 4 publications

References 1 publication

Divergence of photosynthetic strategies amongst marine diatoms

Divergence of photosynthetic strategies amongst marine diatoms

Ion Electric Propulsion System Electric Breakdown Problems: Causes, Impacts and Protection Strategies

Characteristics, capabilities, and costs of solar electric spacecraft for planetary missions

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