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Epilogue
Published in Louis Brennan, Loizos Heracleous, Alessandra Vecchi, Above and Beyond, 2018
Louis Brennan, Loizos Heracleous, Alessandra Vecchi
Historically, space related endeavours had tended to be focused on the exploration of space rather than the exploitation of space. Such exploration was undertaken through terrestrial observation or human missions in space or through the journeying of craft in space equipped with instruments directed towards exploring our neighbouring planets and beyond. Still, the exploitation of space has been undertaken by means of space satellites in earth orbit for activities such as communications, earth observation and navigation, weather and climate monitoring. With the increasing proliferation of smaller sized satellites, the downstream segment of the space sector is continuously expanding such exploitation of space, driving growth in the business of space.
Fundamentals of Solar Radiation
Published in Daryl R. Myers, Solar Radiation, 2017
Earth orbits the sun in a very slightly elliptical orbit, with an eccentricity ε (ratio of major to minor axis) of 0.0167. Earth also rotates once every 23 h 56 min, with respect to the distant stars (a sidereal day), and a period of 24.0 h (the definition of the solar day) about an axis titled at an angle of 23.5° to the plane of that orbit. The average distance between the Earth and the sun is the astronomical unit (AU) of 93 million miles (or 149,597,870.7 km).
A new Arctic MSS model derived from combined Cryosat-2 and ICESat observations
Published in International Journal of Digital Earth, 2022
Guodong Chen, Zhijie Zhang, Stine Kildegaard Rose, Ole Baltazar Andersen, Shengjun Zhang, Taoyong Jin
The ICESat mission is the first low-earth-orbit satellite with three laser altimeters on board. It NASA launched in January 2003 and stopped its operation in October 2009. Unlike radar altimeters, the laser altimeter had much smaller footprints and did not penetrate the snow, hence it had better accuracy and precision on polar ice (Brenner, DiMarzio, and Zwally 2007). Due to unexpected manufacturing defects of the lasers, ICESat only operated 18 campaigns (about 33 days for each campaign) during 2003–2009. For the sake of simplicity, the ICESat campaigns are identified by the last two digits of the year and the initials of the month in this paper. For example, 03FM represents the campaign operated in February and March 2003. ICESat GLA13 release 34 products are used in our study, which can be downloaded from National Snow and Ice Data Center (NSIDC). Since ICESat data suffered from severe saturation and forward scattering (Zwally et al. 2008), strict data editing is implemented. Any observations with more than one peak, reflectivity higher than 1.0 or lower than 0.05, or pulse broadening parameter larger than 0.8 (Zwally et al. 2008) are removed. Due to the energy decline of the lasers (Abshire et al. 2005), most of the observations collected in campaigns 04MJ, 08O, 08ND, 09MA and 09SO were rejected by our data-editing approach. Therefore, these five campaigns are not involved in our research, and consequently, the time span of ICESat data in this paper is between February 2003 and March 2008, consisting of 13 campaigns.
Error analysis of exterior orientation elements on geolocation for a Moon-based Earth observation optical sensor
Published in International Journal of Digital Earth, 2020
Huadong Guo, Hanlin Ye, Guang Liu, Changyong Dou, Jing Huang
Another peculiar factor is the changing observation angle. Unlike the low Earth orbit satellite, the orbit of the Moon does not have a fixed inclination. As the Earth moves around the Sun, with its rotational axis tilted about 23.5° from the ecliptic plane. The angle between the ecliptic plane and the Earth equator plane changes from 23.5° to −23.5°. The Moon also changes in inclination, with an inclination about 5.15° to the ecliptic plane. In consequence, the maximum inclination of the Moon varies from 18.35° (i.e. 23.5°−5.15°) to 28.65° (i.e. 23.5°+5.15°). This is enough to observe the total Arctic or Antarctic Region. Every about two weeks, the Moon will move from a maximum positive inclination to a maximum negative one. However, the maximum positive or negative inclination is not a coincidence with the apogee or perigee. Thus, there are four specific nodes during one orbital period, which are the apogee, the perigee, the maximum positive inclination, and the maximum negative inclination. Besides, there exists another longer observation period. The orbit of the Moon changes its inclination during the period of 18.6 years. Every 18.6 years, the angle between the orbit of the Moon plane and the Earth equator plane reaches a maximum of 28.65°. 9.3 years later, the angle between the orbit of the Moon plane and the Earth equator reaches its minimum, 18.35°. The nadir points of the Moon-based platform make a circle around the Earth surface. The latitudinal range of the nadir point is about 18.35° to 28.65° and all longitudes of the nadir points can be covered.
Ground resource optimization for navigation constellation based on satellite link scheduling
Published in Engineering Optimization, 2019
Tianjiao Zhang, Jing Li, Yikang Yang, Hengnian Li, Jisheng Li, Zexi Li
Hong et al. (1998) modelled a low Earth orbit satellite network as a finite state automaton (FSA) framework. They evaluated link assignments and routing schemes within that framework. A simulation indicated that the optimized link assignment combined with static routing achieved competitive performance in terms of a continual call-blocking probability. Shi, Xiang, and Tang (2011) developed a link assignment algorithm that considers both cross-link ranging and data exchange for the satellite navigation system. Wang et al. (2014) proposed a three-dimensional matrix method for GNSS constellation ISL topological design.