Pathfinder spacecraft

On July 4, 1997, after a 7-month trip, the Pathfinder spacecraft landed on Mars and released a small robot rover called Sojourner. The weight of an objea on Mars is about 38% of the weight of the same object on Earth. 

Global GRS maps of Mars, for (a) silicon, (b) iron, and (c) /Th. Letters represent spacecraft landing sites V1 and V2 Viking, PF Mars Pathfinder, M Merdiani (Opportunity), and G Gusev (Spirit). The line in (b) separates the southern highlands from the northern lowlands. White areas above 50° N and S were not analyzed. 

The accepted mean density of Mars, based on its measured volume and determination of its mass from spacecraft orbits, is 3.9335 0.0004 g cm (Lodders and Fegley, 1998). The density of the elastic lithosphere (approximately equivalent to the crust), estimated from models of the relationship between gravity and topography from Mars Global Surveyor data, is 2.95-2.99 g cm (McKenzie et al., 2002), which is similar to the density of basalt. The planet s dimensionless moment of inertia (0.3662 0.0017), calculated from Mars Pathfinder measurement of the rate at which its spin pole precesses (Folkner et al., 1997), constrains the core radius to —1,300-1,500 km, depending on core composition. 

The Mars Pathfinder probe landed on Mars on July 4,1997. Pathfinder was second in the Discovery series of robotic spacecraft, which the United States National Aeronautics and Space Administration (NASA) began to develop in the mid 1990s. Costing an average of 150 million per project, the Discovery shift to faster, cheaper, less-ambitious probes was prompted by the catastrophic failure in 1993 of the 1-billion Mars Observer mission. Pathfinder was the third spacecraft ever to land successfully on Mars NASA s Viking I and Viking II spacecraft... 

A relatively recent use of curium was in the Mars Pathfinder that was sent to Mars in 1997 to smdy that planet s surface. Some of the equipment on the spacecraft was powered by a curium battery. 

Jenkins, Dennis R. Space Shuttle The History of the National Space Transportation System—The First One Hundred Missions. 3d ed. Dennis R. Jenkins, 2001. A history of the space shuttle from a spacecraft-design perspective. Detailed schematic diagrams and voluminous photos of construction, maintenance, and operation of the shuttle reveal much about the art of manned spacecraft engineering. Mishkin, Andrew. Sojourner An Insider s View of the Mars Pathfinder Mission. New York Berkeley Books, 2003. The author is a senior systems engineer for NASA. His book is a personal glimpse of spacecraft engineering and operations. 

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