Different types of satellite orbits have different uses: while the synchronous orbit is best for communication satellites, Lagrangian point orbits help monitor the solar wind before it reaches Earth. A low altitude polar orbit is widely used for monitoring the Earth because each day, as the Earth rotates below it, the entire surface is covered. ... A different choice was made for MAGSAT, orbited 1979-80 to survey the Earth's own magnetic field near its surface. ...

... Spacecraft . ... To space by cannon? Finally, the deep space explorers --spacecraft which break away from the Earth's gravity . ... The "Luna" series of the USSR conducted 7 soft landing of unmanned probes, two of them with wheeled robotic "Lunokhods," and two of those missions returned samples to Earth. Others spacecraft have visited the major planets of the Solar system. ... The Mariner series have explored Venus and Mars--and Mariner 10 even reached Mercury, for three separate encounters! ...

... Taken from the NASA/JPL information summary "Our Solar System at a Glance". The National Aeronautics and Space Administration's (NASA's) automated spacecraft for solar system exploration come in many shapes and sizes. ... Electrical power is required to operate the spacecraft instruments and systems. ... Between 1959 and 1971, NASA spacecraft were dispatched to study the Moon and the solar environment; they also scanned the inner planets other than Earth -- Mercury , Venus and Mars . ...

Cosmic Research, Vol. 42, No. 5, 2004, pp. 435­488. Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 5, 2004, pp. 453­508. Original Russian Text Copyright © 2004 by Veselovsky, Panasyuk, Avdyushin, Bazilevskaya, Belov, Bogachev, Bogod, Bogomolov, Bothmer, Boyarchuk, Vashenyuk, Vlasov, Gnezdilov, Gorgutsa, Grechnev, Denisov, Dmitriev, Dryer, Yermolaev, Eroshenko, Zherebtsov, Zhitnik, Zhukov, Zastenker, Zelenyi, Zeldovich, Ivanov-Kholodnyi, Ignat'ev, Ishkov, Kolomiytsev, Krasheninnikov, Kudela,