From the last few decades, the space science community has shown considerable interest in missions which take place in the vicinity of the Lagrangian points in the restricted three-body problem (RTBP) of the Sun-Earth and the Earth-Moon systems [1]. Designing trajectories for these missions is a challenging task due to inadequacy of the conic approximations. The RTBP deals the situation where o...

We describe a new method to improve radiometric accuracy for spaceborne Earth-viewing hyperspectral imaging to help achieve CLARREO mission benchmark measurements of climate in the shortwave spectral region by using on-orbit crosscalibrations to spectral solar irradiances in the near-ultraviolet to near-infrared. Unlike traditional solar diffuser-based calibrations, the methods described here u...

Advanced Radio Interferometry Between Space and Earth (ARISE) is a space very long baseline interferometry (VLBI) mission with a nominal launch date of 2008. It consists of an inflatable 25-m radio telescope circulating in a highly elliptical Earth orbit with a perigee of 5,000 km and an apogee of 40,000 km. The objective is to observe in conjunction with Earth-based telescopes to obtain high-r...

Orbits for satellites o f the Global Positioning System (GPS) have been determined with submeter accuracy. Tests used to assess orbit accuracy include orbit comparisons from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked for 8 hours each day shows rms errors below I m even when predicted more than 3 days outside of a 1-week data ...

Future satellite communication systems proposed use geosynchronous (GEO) satellites, medium earth orbit (MEO), and low earth orbit (LEO) constellations. Most of the next generation satellite systems will use fast packet switching with onboard processing to provide full two-way services to and from earth stations. One of the major service drivers is a high data rate internet access carried over ...

We estimated the rate of comet and asteroid collisions with the terrestrial planets by calculating the orbits of 13000 Jupiter-crossing objects (JCOs) and 1300 resonant asteroids and computing the probabilities of collisions based on random-phase approximations and the orbital elements sampled with a 500 yr step. The Bulirsh-Stoer and a symplectic orbit integrator gave similar results for orbit...

From the last few decades, the space science community has shown considerable interest in missions which take place in the vicinity of the Lagrangian points in the restricted three-body problem (RTBP) of the Sun-Earth and the Earth-Moon systems [1]. Designing trajectories for these missions is a challenging task due to inadequacy of the conic approximations. The RTBP deals the situation where o...

Migration of trans-Neptunian objects to the Earth is considered. Due to the gravitational influence of large trans-Neptunian objects and mutual collisions, some objects can get such orbits, from which they can be moved inside the Solar System under the gravitational influence of planets. About 10-20% or even more 1-km Earth-crossers could have come from the Edgeworth-Kuiper belt and can move in...