LYCOS RETRIEVER 
Phobos: Mission
built 276 days ago
The launch of the Phobos vehicle will be made with a Titan IV/Centaur G launch vehicle. The 3800 kg fully loaded mass of the Phobos vehicle is well within the capability of the Titan IV/Centaur G for the chosen trajectory for this mission. A buffer of several hundred kilograms between the 3800 kg loaded mass of the Phobos vehicle and the total capability of the Titan IV/ Centaur G for the chosen trajectory/launch date has been allowed for the possible increased DV requirements of contingency trajectories/launch dates. The change in required DV between the chosen trajectory and contingency trajectories can be handled with a variation in the total impulse imparted by the liquid propellant Centaur upper stage.
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The last mission undertaken by the USSR was that of Phobos - a mission involving two probes (Phobos 1 and 2) that were of a next-generation Venera design. The purpose of these probes was to:
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As part of the U.S./USSR cooperation in solar system exploration under the 1987 U.S./USSR space cooperation agreement, NASA participates in the Phobos mission in a number of ways. A major investigation called the Dynamics Experiment, developed largely by a U.S. scientist, will use precision ranging and very long baseline interferometry (VLBI) with the Phobos lander, together with data from the lander's sun sensor.
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