Comparison between Solar Simulation and Infrared Technique for Thermal Balance Test
The precision of heat flux simulation influences the temperature field and test aberration for TB test and also reflects the test level for spacecraft development. This paper describes TB tests for a small satellite using solar simulator, electric heaters, calrod heaters to evaluate the difference of the three methods. Under the same boundary condition, calrod heaters cases were about 6C higher than solar simulator cases and electric heaters cases for non-external-heat-flux cases (extreme low temperature cases). While calrod heaters cases and electric heaters cases were 5~7C and 2~3C lower than solar simulator cases respectively for high temperature cases. The results show that the solar simulator is better than calrod heaters for its better collimation, non-homogeneity and stability. Keywords—solar simulation, infrared simulation, TB test, TMM
THE MARS PATHFINDER SYSTEM LEVEL SOLAR THERMAL VACUUM TEST
The Mars Pathfinder (MPF) spacecraft, launched in December 1996, is the second launch in NASA's Discovery Program. The MPF mission is primarily an engineering demonstration of key technologies and concepts for eventual use in future missions to Mars. One of the main challenges of the thermal environmental test program was the need to simulate all three mission phases: (a) cruise, (b) entry, descent and landing (EDL) and (c) Martian surface landed operations, each with different thermal environments. This paper concentrates on the first phase of the system level solar thermal vacuum (STV-1) test for the Mars Pathfinder Flight System, which covered the cruise and EDL phases of the mission. The thermal environment simulation of a spinning spacecraft flying at off-Sun angles was one of the major challenges of the STV-1 test implementation. The simulation was handled with a combination of infrared (IR) lamps and a solar simulator. In the interest of minimizing test time and maximizing test return, an accelerated cooldown concept was developed, analyzed and pre-tested. Two significant thermal design problems were discovered during the STV-1 test: the solar array temperatures were hotter than expected and portions of the propellant lines were below the minimum allowable flight temperature limit. A chamber break was used to modify the thermal designs and the spacecraft was retested in the worst-case cold and hot environments. Removal of a micrometeoroid shield on the back of the solar array increased its view to space and reduced its temperatures to acceptable levels. Replacement of embossed Kapton blankets with Mylar-Dacron net blankets and improvements in the blanket installation procedures corrected the propellant lines cold problems. Besides the STV-1 test implementation and results, this paper also discusses the design of the IR lamp system and a proof-of-concept test for the accelerated cooldown.
The Game Planners: Transforming Canada's Sport System.
The Game Planners studies the policy-making process in six Canadian national sports organizations, each of which deals with a different high-profile Olympic event. The authors argue that the creation of a "high-performance" sport system in Canada is due to pressure from three areas: the Canadian government, the physical education profession, and the sports community.