The possibility of analyzing the node Ω of the GP-B satellite in order to measure also the Lense-Thirring effect on its orbit is examined. This feature is induced by the general relativistic gravitomagnetic component of the Earth gravitational field. The GP-B mission has been launched in April 2004 and is aimed mainly to the measurement of the gravitomagnetic precession of four gyroscopes carri...

We present a conceptual design for a scalable (10-50 meter segmented filled-aperture) space observatory operating at UV-optical-near infrared wavelengths. This telescope is designed for assembly in space by robots, astronauts or a combination of the two, as envisioned in NASA's Vision for Space Exploration. Our operations concept for this space telescope provides for assembly and check-out in a...

The aim of this work is to create a tool that can simulate the transmission of both connectionoriented and connection-less traffic over a constellation of LEO/MEO (Low Earth Orbit/ Medium Earth Orbit) satellites. We hope to provide a performance evaluation of various constellation access techniques and routing policies. The simulator, named GaliLEO, will be written in Java and will integrate re...

This paper describes the essential segments of a satellite based communication and asset management system. The Low Earth Orbit satellite used for such a system is the ORBCOMM low earth orbit (LEO) constellation. The architecture and network structure of the satellite system is described. The satellites themselves are very small and are launched using the Pegasus launch vehicle. This makes the ...

Several strategies have been implemented or proposed to tackle the space debris problem. However, there is still debate on the feasibility, cost and effectiveness of these mitigation measures, especially in light of the increasing use of small satellites in low Earth orbit (LEO) and the drive towards space debris remediation. This work presents a statistical source-sink debris evolutionary mode...

A mission design technique that uses invariant manifold techniques together with the optimal control algorithm DMOC produces locally optimal, low ∆V trajectories. Previously, invariant manifolds of the planar circular restricted three body problem (PCR3BP) have been used to design trajectories with relatively small ∆V . Using local optimal control methods, specifically DMOC, it is possible to r...

S pace nuclear power is a doubleedged sword. Although it has played a constructive role in the exploration of space and could continue to do so, it has been burdened by an extensive history of aCCidents and failures, both Soviet and American. Numerous nuclear-powered spacecraft have released radioactive materials. Spent reactors now in Earth orbit exacerbate the threat posed by orbital debris. ...

The possibility of analyzing the node Ω of the GP-B satellite in order to measure also the Lense-Thirring effect on its orbit is examined. This feature is induced by the general relativistic gravitomagnetic component of the Earth gravitational field. The GP-B mission has been launched in April 2004 and is aimed mainly to the measurement of the gravitomagnetic precession of four gyroscopes carri...

Several low earth orbit (LEO) satellite constellations have been proposed for mobile satellite systems (MSS’s). Due to nonstationary coverage regions of individual LEO satellites, the offered traffic load for each cell varies continuously. The variation of the traffic load essentially requires dynamic channel assignment. Furthermore, extremely frequent handover requests require specific techniq...

The rapid growth of Internet-based applications pushes broadband satellite networks to carry on IP traffic. In previously proposed connectionless routing schemes in satellite networks, the metrics used to calculate the paths do not reflect the total delay a packet may experience. In this paper, a new Satellite Grouping and Routing Protocol (SGRP) is developed. In each snapshot period, SGRP divi...