scholarly journals Multiphase Trajectory Optimization of a Lunar Return Mission to an LEO Space Station

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Luyi Yang ◽  
Haiyang Li ◽  
Jin Zhang ◽  
Yazhong Luo
Keyword(s):  
Trajectory Optimization ◽  
Space Station ◽  
Low Earth Orbit ◽  
Hybrid Optimization ◽  
Target Space ◽  
Mission Design ◽  
Optimization Scheme ◽  
Initial State ◽  
Bank Angle ◽  
Entire Trajectory

Lunar exploration architecture can be made more flexible and reliable with the support of a low-Earth orbit (LEO) space station. This study therefore evaluated a proposed hybrid optimization scheme to design the entire trajectory of a reusable spacecraft starting from trans-Earth injection (EI) at the perilune and ending at an LEO space station. As such a trajectory has multiple constraints and multiple dynamical models, it is divided into the trans-Earth phase, aerocapture phase, and postatmospheric phase. The optimization scheme is performed at two levels: sublevel and top level. At the sublevel, two novel pseudo rules are proposed to optimize the trans-Earth trajectory so that it satisfies the coplanar constraints of the space station. Then, in the aerocapture phase, the bank angle is optimized to satisfy the mission constraints, and in the atmospheric phase, the one-impulsive maneuver is performed and optimized to insert the spacecraft into the target space station orbit. The multiple phases are connected to each other by boundary conditions where the terminal state of the previous phase is transformed into the initial state of the following phase. At the top level, the vacuum perigee height is selected as the mission design variable based on problem characteristics analysis and a hybrid optimization scheme is conducted to minimize the total velocity increment. The simulation results demonstrate that the proposed hybrid optimization method is effective for the design of an entire trajectory with acceptable velocity cost which is less than that in the previous study. The coplanar constraints of the space station and other mission constraints in each phase are also satisfied. Furthermore, the proposed trajectory design method is shown to be applicable to a reusable spacecraft returning to an LEO space station parked in any arbitrary orbital plane.

Challenges in Clinical Management of Radiation-Induced Illnesses During Exploration Spaceflight

2019 ◽  
Vol 90 (11) ◽  
pp. 966-977
Author(s):  
Rebecca S. Blue ◽  
Jeffery C. Chancellor ◽  
Rahul Suresh ◽  
Lisa S. Carnell ◽  
David P. Reyes ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Clinical Management ◽  
Space Station ◽  
Clinical Manifestations ◽  
Low Earth Orbit ◽  
Acute Radiation ◽  
Mission Design ◽  
Prodromal Symptom ◽  
Solar Particle Events ◽  
Radiation Induced

INTRODUCTION: Analysis of historical solar particle events (SPEs) provides context for some understanding of acute radiation exposure risk to astronauts who will travel outside of low-Earth orbit. Predicted levels of radiation exposures to exploration crewmembers could produce some health impacts, including nausea, emesis, and fatigue, though more severe clinical manifestations are unlikely. Using current models of anticipated physiological sequelae, we evaluated the clinical challenges of managing radiation-related clinical concerns during exploration spaceflight.METHODS: A literature review was conducted to identify terrestrial management standards for radiation-induced illnesses, focusing on prodromal symptom treatment. Terrestrial management was compared to current spaceflight medical capabilities to identify gaps and highlight challenges involved in expanding capabilities for future exploration spaceflight.RESULTS: Current spaceflight medical resources, such as those found on the International Space Station, may be sufficient to manage some aspects of radiation-induced illness, although effective treatment of all potential manifestations would require substantial expansion of capabilities. Terrestrial adjunctive therapies or more experimental treatments are unavailable in current spaceflight medical capabilities but may have a role in future management of acute radiation exposure.DISCUSSION: Expanded medical capabilities for managing radiation-induced illnesses could be included onboard future exploration vehicles. However, this would require substantial research, time, and funding to reach flight readiness, and vehicle limitations may restrict such capabilities for exploration missions. The benefits of including expanded capabilities should be weighed against the likelihood of significant radiation exposure and extensive mission design constraints.Blue RS, Chancellor JC, Suresh R, Carnell LS, Reyes DP, Nowadly CD, Antonsen EL. Challenges in clinical management of radiation-induced illnesses during exploration spaceflight. Aerosp Med Hum Perform. 2019; 90(11):966–977.

Modelling of Io’s Atmosphere for the IVO Mission

2021 ◽  
Author(s):  
Peter Wurz ◽  
Audrey Vorburger ◽  
Alfred McEwen ◽  
Kathy Mandt ◽  
Ashley Davies ◽  
...  
Keyword(s):  
Mass Loss ◽  
Dynamic Range ◽  
Detection Threshold ◽  
Mass Range ◽  
Mission Design ◽  
Integration Time ◽  
Many Worlds ◽  
Initial State ◽  
Atmospheric Escape ◽  
Tidal Heating

<p>The Io Volcano Observer (IVO) is a proposed NASA Discovery-class mission (currently in Phase A), that would launch<span> in early 2029, arrive at </span> Jupiter in the early 2033, and perform ten flybys of Io while in Jupiter's orbit. IVO's mission motto is to 'follow the heat', shedding light onto tidal heating as a fundamental planetary process. Specifically, IVO will determine (i) how and where heat is generated in Io's interior, (ii) how heat is transported to the surface, and (iii) how Io has evolved with time. The answers to these questions will fill fundamental gaps in the current understanding of the evolution and habitability of many worlds across our Solar System and beyond where tidal heating plays a key role, and will give us insight into how early Earth, Moon, and Mars may have worked.</p><p>One of the five key science questions IVO will be addressing is determining Io's mass loss via atmospheric escape. Understanding Io's mass loss today will offer information on how the chemistry of Io has been altered from its initial state and would provide useful clues on how atmospheres on other bodies have evolved over time. IVO plans on measuring Io's mass loss in situ with the Ion and Neutral Mass Spectrometer (INMS), a successor to the instrument currently being built for the JUpiter Icy moons Explorer (JUICE). INMS will measure neutrals and ions in the mass range 1 – 300 u, with a mass resolution (M/ΔM) of 500, a dynamic range of > 10<sup>5</sup>, a detection threshold of 100 cm<sup>–3</sup> for an integration time of 5 s, and a cadence of 0.5 – 300 s per spectrum.</p><p>In preparation for IVO, we model atmospheric density profiles of species known and expected to be present on Io's surface from both measurements and previous modelling efforts. Based on the IVO mission design, we present three different measurement scenarios for INMS we expect to encounter at Io based on the planned flybys: (i) a purely sublimated atmosphere, (ii) the 'hot' atmosphere generated by lava fields, and (iii) the plume gases resulting from volcanic activity. We calculate the expected mass spectra to be recorded by INMS during these flybys for these atmospheric scenarios.</p>

A Flight Test Challenge: Aeroassist for Reuseable, Space-Based Transportation

1986 ◽  
Vol 29 (5) ◽  
pp. 26-31
Author(s):  
Robert Ried
Keyword(s):  
Space Shuttle ◽  
Fluid Dynamic ◽  
Space Station ◽  
Flight Test ◽  
Transportation Systems ◽  
Low Earth Orbit ◽  
Future Challenges ◽  
Ground Test ◽  
Test Flight ◽  
Level Of Understanding

NASA and its predecessor, NACA, have relied on testing to address challenges ranging from early aeronautics to the lunar landing. This is a necessary ingredient to success. Current and future challenges, coupled with technology advances, dictate reliance on productive combinations of testing and analysis. An example of this is provided by the necessary combination of ground test, flight test and computational fluid dynamic analyses required to achieve an efficient, space-based aerobraking orbital transfer vehicle. As the Space Shuttle is key to the Space Station, the Space Station is key to transportation beyond low earth orbit. Now is the time to develop the level of understanding adequate for the next generation of space transportation systems.

NASA sets sights on private space stations

2019 ◽  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
The Moon ◽  
Private Space ◽  
Content Type ◽  
International Space ◽  
Foreign Governments ◽  
Corporate Clients

Subject Space stations. Significance As Washington returns its sights to the moon, it is reforming its policies regarding the International Space Station (ISS) with a view to jump-starting a 'low-earth orbit economy' in which private firms offer services to corporate clients, foreign governments and wealthy individuals. Impacts China's space station, due for completion in 2022, could draw third-country projects away from commercial US space stations. Governments are more promising clients for commercial crewed spaceflight than 'space tourists' are. Commercial stations and passenger spacecraft could make human spaceflight accessible to allied states. Spaceflight will remain politicised.

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