List at least two mechanisms by which the accomodation coefficients for a spacecraft material can change...

List at least two mechanisms by which the accomodation coefficients for a spacecraft material can change due to the vacuum environment. How might these changes be avoided or minimized? Why does the rate of change in the accomodation coefficient decrease with satellite lifetime?

Expert Solution

Two mechanisms can be:(1) Sublimation and evaporation

(2)Radiation and particle damage

Radiation and thermal cycling must not degrade thermal-control surfaces or joints in materials possessing different coefficient of expansion.The presence of atomic oxygen in low Earth orbits, a relative newcomer in environmental effects, has been seen to lead to the erosion/corrosion/oxidation of many material surfaces, and more coatings with good atomic oxygen durability need to be developed.The minimum altitude for an Earth-orbiting satellite is 200 km (125 miles), and, once this altitude has been reached, appreciable changes can be produced in common engineering materials, whether they be metals, plastics, or ceramics. The vacuum in space is very high, the pressure falling from 10?6 mm Hg at 200 km to less than 10?12 mm Hg beyond 6500 km. Some polymers will decompose and some metals will tend to sublimate under vacuum. The rate at which the molecules or atoms leave a surface in vacuum will rise rapidly with an increase in temperature.

genius_generous answered 2 years ago

Define the term ‘goitrogen’ and provide two mechanisms by which a goiter can be formed. List...

Define the term ‘goitrogen’ and provide two mechanisms by which a goiter can be formed. List two consequences of hypothyroidism in an animal.

Define protein denaturation and list at least four specific mechanisms that can cause it. Please show...

Define protein denaturation and list at least four specific mechanisms that can cause it. Please show all work and explain your responses.

List at least five variables that affect change in resolution between two compounds and their retention...

List at least five variables that affect change in resolution between two compounds and their retention time when working with HPLC (High Performance Liquid Chromatography).

Discuss the mechanisms by which the flux through a metabolic pathway can be controlled. Which mechanisms...

Discuss the mechanisms by which the flux through a metabolic pathway can be controlled. Which mechanisms can rapidly alter flux? please answer the question in BioChem way, and no handwriting, please type it, thanks! (it will be fine to draw the graph to help explain it, but still type the explanation please)

list at least two weaknesses of using sound to image an object. can these weaknesses be...

list at least two weaknesses of using sound to image an object. can these weaknesses be overcome, how?

a) There are about 15 or so mechanisms by which metabolism can be controlled at different levels. which are the 15 mechanisms by which metabolism can be controlled?

1. Try to answer the following questions as accurately as possible a) There are about 15 or so mechanisms by which metabolism can be controlled at different levels. which are the 15 mechanisms by which metabolism can be controlled? b) identify three mechanisms that can control metabolism with immediate effect c) identify three mechanisms that require more time to exert their effects d) Humans have 4 isoenzymes that differ in how they function. why do we need 4 isozymes? e) ...

Identify at least four mechanisms by which a healthy host resists infection.

2. In the PLD method, among the mechanisms under which the material is ablated, I wonder...

2. In the PLD method, among the mechanisms under which the material is ablated, I wonder what is the conditions for the exfoliation sputtering.

Which of the barriers to change is the most likely to occur? Which are the least...

Which of the barriers to change is the most likely to occur? Which are the least likely to occur? Why? The barriers to change?: Complacency? Organizational silence? Knowledge/information deficits? Risk perception ? Uncertainty? Contradictions and misalignments? Active resistance? Passive resistance? Organizational leaders? Organizational trust? Organizational decline? Organizational crisis?

1. Which mechanisms can lead to adaptations in populations? Which can lead to speciation? [which of...

1. Which mechanisms can lead to adaptations in populations? Which can lead to speciation? [which of these is microevolution and which is macroevolution?] 2. What is fitness and which mechanism is it most associated with? Why is the concept of fitness important? 3. How do heterozygote advantage and indirect selection work? Why are they important? [think about deleterious alleles, too]

Question