13. What is the highest radio frequency (during the day and solar max) which will be reflected by the ionosphere at the following altitudes: a. 75 km b. 150 km c. 250 km d. 350 km 14. Assume a spacecraft from the SDS (Satellite Data System) is placed in orbit with an initial absorptivity on an silverized surface of 0.25. The surface has an area of 1 m2. Calculate how much solar power is absorbed by the material if it is oriented normal to the sun. After 4 years on orbit how much change in solar absorptivity is expected on the spacecraft material? What percent increase or decrease in absorbed solar energy is expected?
15. Assume your spacecraft is orbiting in a circular orbit at an altitude of 350 km. How long will it take for atomic oxygen to remove five monolayers of Teflon on a surface in the RAM direction? The reaction efficiency for Teflon is 3×10-24 cm3/atom and the monolayer diameter is 7 angstroms. List all assumptions. 16. A satellite is in a nearly circular orbit with an altitude of 400 km. The material engineers believe the Teflon速 surface is the major contamination source for a sensor on the spacecraft. The Teflon surface is a rectangular piece with a length of 5 cm and a width of 4 cm. It is at a temperature of 275 K and has a mass of 30.0 grams. The major outgassed species is the Teflon monomer (C2F4) with a n activation energy of 10 kcal/mol. Calculate the number flux (molecules/sec) leaving the Teflon block, assuming the Teflon surface meets the ASTM E 595 standard (research this standard) with a total mass loss of 1%.
Typical midlatitude daytime and nighttime electron density profiles for solar maximum and minimum conditions. (Tascione, 1994) Degradation of several silverized fused silica mirrors as a function of time (Naegeli, 1992).
The solar spectrum in the EUV region showing the transition from continuum dominated emission to the region dominated by discrete transitions