International Space Station Structure Research Articles

Mechanism of rapid-charging events for international space station

The high negative amplitude rapid-charging events (RCEs), which were observed by the floating potential measurement unit (FPMU) on the International Space Station (ISS) and occurred at the eclipse exit, have attracted a lot of attention recently and are not yet understood. The RCEs are most serious of all types of ISS charging phenomena. Compared with the normal-charging events (NCEs) which occurred on morning sector, the RCEs are characteristic of rapid rise time (<10 seconds) and higher amplitude (30—70 V). In particular, their occurrence at the morning terminator indicates that they are related to the solar panel excitation process at the moment of receiving solar illumination. In this paper, an electric circuit model for the charging of the ISS structure and solar panel is established, based on which a differential equation is developed, with the different charging mechanisms included and also the way of solar panel excitation considered. The calculation results for the RCEs agree well with the typical waveforms.

Zero-propellant maneuver guidance

Maintain its orbit and control its attitude, the International Space Station (ISS) is equipped with thrusters as well as four control moment gyroscopes (CMGs). The CMGs can be used only for attitude control, while the thrusters can be used for either attitude control or orbit corrections. For attitude control, thrusters can complete reorientations much more rapidly than the CMGs since the torque capability of the thrusters is at least an order of magnitude larger than the torque capability of the CMGs. However, using thrusters has signifi cant disadvantages, such as consumption of propellant, solar array contamination, and stressing of the ISS structure. CMGs can avoid these disadvantages as long as they operate within their angular momentum capacity because they are powered by electricity generated by the ISS solar arrays. If the CMG momentum becomes saturated, that is, the total angular momentum of the CMGs reaches its maximum value, the control authority of the CMGs is considered lost. For further information about CMGs and saturation, see "CMGs, Momentum Saturation, and Robotics Analogy." Even at a slow rate of rotation, large-angle ISS maneuvers performed with CMGs can result in momentum saturation because the CMGs must compensate for the environmental disturbance torques on the ISS along the fl ight-software-generated attitude trajectory. As a result, until 2006 all large-angle ISS rotations were performed using thrusters.

How Earth remote sensing from the International Space Station complements current satellite‐based sensors

The International Space Station (ISS) will provide an Earth‐ and space‐observing platform that will support sensors built by 16 different countries and deliver data and images for local, regional and global research. When complete, it will be an exceptional platform for conducting remote sensing of the Earth, astrophysics, and space physics research programmes. Additionally, the ISS will operate as a testbed for engineering studies and complex technological developments that will benefit future Earth‐observing capabilities. The key question addressed here is: What can the ISS give the Earth Science community that current and planned satellite platforms do not already offer? To answer this query we provide characteristics of the ISS structure, current and proposed instruments, orbital characteristics, and instrument accessibility by crew. We show how the Earth‐observing instruments on ISS complement current satellite‐based Earth‐observing sensors.

The International Space Station as a platform for space science

The International Space Station (ISS) has a number of locations for external payloads that are suitable for astronomical and space science observations. Each of the international partners providing science facilities to the United States on Orbit Segment (USOS) section of the ISS have included opportunities for external payloads. One attribute that all the sites have in common is that the ISS acts as the spacecraft, allowing the science team to concentrate on the science instrumentation. Physically, the various facilities available have somewhat different accommodations in terms of the size and mass of the payload accommodated and the resources of power and data services. In addition, each location has a different field of view due to the self-blockage by ISS elements and structures.