Mission Name MGM: Mechanics of Granular Materials MGM Patch LASP MGM Poster (1.2 Mb) LASP Instruments Principal Investigators: Stein Sture & Nick Costes Destination Earth orbit aboard shuttle Launch Date September 16th, 1996(I) January 22nd, 1998(II) January 16th, 2003(III) Launch Location Kennedy Space Center Launch Vehicle Shuttle STS-79 Shuttle STS-89 Shuttle STS-107 Mission Duration 3 seperate flights Mission Description/ LASP involvement   LASP Divisions Involved Engineering * Science LASP Mission Web Page http://civil.colorado.edu/~batiste/Home.html Official Mission Web Page

Unlike materials such as metals, polymers, cementitious concrete, rocks, etc., the strength and deformation characteristics of which are derived mainly from strong cohesive forces from chemical cementation, the constitutive behavior of uncemented granular materials, including strength, stiffness modulus behavior, dilatancy, localization of deformation, shear band formation, and instability behavior are to a large extent derived from interparticle friction resulting from normal forces acting on particles or particle groups. Particle bonding by short or long-term Coulombic forces and van der Waal-type forces may also play a role to a certain extent; however, the main sources of the constitutive relations and stability properties of cohesionless granular materials is interparticle friction, which, in turn, under low confining effective stress levels is highly dependent on gravitational body forces. Erosional processes and off-road locomotion are illustrative examples.

The MGM experiment was initiated by Dr. Nicholas C. Costes in 1976. The PI, Stein Sture joined Dr. Costes' effort in 1977. It was reviewed and adopted by NASA's Physics and Chemistry Experiments in Space (PACE) working group in 1977. The MGM project has in the intervening years been subjected to 7 science peer reviews, including a high level review effort conducted by Dr. Robert Schrieffer (Nobel Prize, 1974). Eighteen different academicians and four industry researchers have participated at the various peer reviews. In addition, the project has been subjected to numerous internal NASA (MSFC, ARC, NASA Headquarters) and NAS/NRC program reviews. While the project started at MSFC, it was for two years (1980-1982) managed by ARC, but returned to MSFC. The project was selected for space flight in 1991, when detailed apparatus concept design efforts began. While all early science efforts took place at MSFC and the University of Colorado at Boulder, apparatus design and manufacturing was carried out at Sandia National Laboratories. The Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado at Boulder became an important partner in the project in 1993, aiding in the first set of MGM experiments on STS-79, where three tests were successfully carried out. LASP has assumed responsibility for missions following STS-79.