نتایج جستجو برای: earth orbit
تعداد نتایج: 130177 فیلتر نتایج به سال:
Networks of spacecraft are necessary to characterize and constantly monitor near-Earth threats such as Coronal Mass Ejections (CMEs) from the Sun, or impacts by large meteoroids. A network of CubeSat is ideally suited because of the low development cost and for demonstrating continuous monitoring of rare phenomena. In this paper, we describe the ongoing development of a single prototype spacecr...
Space is an unforgiving environment – one of harshest known to mankind. Yet, space is far less understood than other service environments in which DOD systems operate. It has been known to limit the useful life of satellites, with 20 to 25% of all mission failures being attributed to the effects of the space environment.[1] Since access to space is so costly, materials and components must funct...
Context. Recognizing the transport of Energetic Neutral Atoms (ENA), from their place of birth to Earth orbit, has become an important issue in light of the forthcoming launch of the NASA SMEX mission IBEX, which is devoted to imaging of the heliospheric interface by in-situ detection of ENAs. Aims. We investigate the modifications of both energy of survival probability of the hydrogen ENA (H E...
-This paper summarizes the Voyager 1 and Voyager 2 orbit determination activity extending from encounter minus 60 days to the Jupiter encounter, and includes quantitative results and conclusions derived from mission experience. The major topics covered include an identification and quantification of the major orbit determination error sources and a review of salient orbit determination results ...
An Internet router was integrated into the UK-DMC remote-sensing satellite as a secondary experimental payload. This commercial product has been orbiting in space for over three years. We describe the integration of the router and satellite and the successful on-orbit testing of the router, which took place using the Virtual Mission Operations Center (VMOC) application as part of a larger syste...
The performance of sensors for Earth Observation Missions is constantly improving. This drives the need for a reliable, high-speed data transfer capability from a Low Earth Orbit (LEO) spacecraft (S/C) to ground. In addition, for the transfer of time-critical data to ground, a low latency between data generation in orbit and data reception at the respective mission control center is of high imp...
The recently discovered asteroid 2013 LX28 is in 1:1 resonance with Earth, but has large eccentricity and inclination. These lead to unusual dynamics in which the Kozai resonance plays a large role on long time-scales, while interaction with the terrestrial planets causes shorter term orbital changes. For the nominal orbit, an interaction with Venus changed the nature of the Kozai resonance and...
A frequency synchronization method is proposed and analyzed for global satellite communications systems employing low earth orbit satellites or medium earth orbit satellites. In these systems, the Doppler shift varies randomly and can be more than ten times larger than the symbol rate. The proposed method uses the satellite as the reference point and corrects frequency errors accordingly. It is...
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