Chapter 3 Questions Flashcards
True/False: For the example above, assume the Cube Sat’s mission is designed to last for 30 days, at one orbit each 90 minutes. True or False, the exposed Epoxy caulk will survive at or above 80% thickness.
True
True/False: SPEs and GCRs are a direct result of the interaction between charged particles and the Earth’s magnetic field.
False
What is the main reason why molecules that outgas from materials used in a spacecraft’s interior and/or exterior threaten infrared sensors?
a. Only volatile chemicals outgas in the space environment
b. Contaminants are deposited at the single-molecule level and so cannot be filtered against
c. IR sensors better trap floating contaminants when the covers come off
d. Contaminants tend to stick to the supercooled sensor surfaces
e. All of the above
f. Only b, c and d
b. Contaminants are deposited at the single-molecule level and so cannot be filtered against
Name three effects possible to occur from an Earth-orbiting spacecraft encountering atomic oxygen:
a. Orbit degradation through atmospheric drag,
Visible glow on surfaces that may affect optical sensors,
Material degradation through erosion of surface molecules
b. Visible glow on surfaces that may affect optical sensors
Loss of sensor calibration through saturation in the O2 absorption bands
Development of an ‘oxygen fog’ on glass surfaces
c. Material degradation through erosion of surface molecules
Loss of sensor calibration through saturation in the O2 absorption bands
Development of an ‘oxygen fog’ on glass surfaces
d. Loss of sensor calibration through saturation in the O2 absorption bands
Development of an ‘oxygen fog’ on glass surfaces
Orbit degradation through atmospheric drag
a. Orbit degradation through atmospheric drag,
Visible glow on surfaces that may affect optical sensors,
Material degradation through erosion of surface molecules
Space-rated epoxy with poor reaction efficiency (RE) has been used around the base of a cable pass-through on the outside casing of a Cube Sat, to guard against vibration and moisture migrating from outside the casing to the sensitive interior. Assume an average Epoxy RE = 2 x 10-24; then, if the erosion rate dx/dt = 0.0001 cm/sec for exposed materials, what is the resulting AO flux?
a. 5 x 10^19
b. 2 x 10^-28
c. 2 x 10^21
a. 5 x 10^19
Solution: dx = RE φ dt ==> dx/dt = RE φ ==> (dx/dt) / RE = φ
where dx/dt = 0.0001 cm/sec = 10^-4 cm/sec
and RE = 10^-24 cm3 / AO atom
==> [10^-4 cm/sec] / [2 x 10^-24 cm3 / AO atom]
==> 5 x 10^19 AO atom / cm^2 · sec
The International Space Station (ISS) has massive solar panel arrays with a cross-sectional area of 3,567.8 m2. If the ISS is orbiting at 400 km (between reboosts) during a solar maximum year, then using an approximation for its encountered atmospheric mass density, and assuming a drag coefficient of 2.40, what is the drag force exerted by just the solar arrays on the ISS when the arrays are oriented normal to the orbit velocity vector?
a. 1.00 N
b. 548.0 N
c. 2.74 N
c. 2.74 N
Reference Eq. 3-2: F = 1/2 ρ v2 Cd An where:
ρ = atmospheric mass density = 10^-11 kg/m3 (by Figure 3-3),
v = 8.0 km/sec (by Section 3.2, para. 2), and
Cd = drag coefficient = 2.40, and
An = 3.5678 x 10^3 m2, then
F = 0.5 * 10^-11 kg/m3 * (8.0 x 10^3 m/sec)2 * 2.40 * 3.5678 x 10^3 m2 ==>
2.74 kg m/sec^2 = 2.74 N
For our Cube Sat in problem 4, if the design cannot be changed to replace the epoxy material with one less AO erosion-sensitive, what are acceptable remediation approaches to enable the Cube Sat to complete its mission?
a. Relocate the cable pass-through point so that the epoxy does not face the relative AO ‘wind’ during the stable portions of the orbit
b. Thicken the epoxy around the base of the pass-through so that much more epoxy may remain at EOL
c. Coat the epoxy with a much lower RE paint
d. All of the above
e. Only a and c
f. Only b and c
e. Only a and c
Why is controlling the floating potential of surfaces in lower-orbiting spacecraft so important?
a. Bigger and bigger solar arrays generate more potential but also increase atmospheric drag, causing fuel expenditure for reboosting the orbit
b. Higher voltage systems such as those used on the Space Station are more susceptible to arcing at low thresholds (below 200V)
c. Arcing with no provisions for safe discharge of electrical potential can cause breakdown of thin dielectric materials
d. Only a and c
e. Only b and c
e. Only b and c
The main difference(s) between the radiation environments in LEO and HEO is/are:
a. Plasma density increases but kinetic energy decreases once the spacecraft is completely free of the exoatmosphere
b. Plasma particles in the magnetosphere are nearly all ionized
c. Solar ultraviolet exposure increases as the orbit increases
d. Solar storms affect spacecraft only with direct effects of the solar wind
e. All of the above
f. Only b and c
g. Only a, b and c
f. Only b and c
What is/are the salient points illustrated by Fig. 3-6 Converting Fluence to Radiation Dose for Silicone?
a. The amount of energy deposited in a material depends both on the radiation and the material considered
b. Fluence to Particle Energy relationships are variable and do not progress uniformly higher together
c. Dosage can be calculated for silicone from any type of radiation by multiplying the fluence by its corresponding conversion factor
d. All of the above
e. Only a and c
d. All of the above
Which statements about the Van Allen Belts are false?
a. The Earth’s perfect magnetic dipolar field ensures even dosage at all points in an orbit that transits the Van Allen belt.,
Human beings are no more susceptible to the effects of the trapped charged particles than other equipment on the interior of a manned spacecraft.
b. All charged particles trapped in the Van Allen belts make their way to the Earths’ North Magnetic Pole.,
The Earth’s perfect magnetic dipolar field ensures even dosage at all points in an orbit that transits the Van Allen belt.,
Human beings are no more susceptible to the effects of the trapped charged particles than other equipment on the interior of a manned spacecraft.
c. The magnetic mirroring phenomenon traps charged particles along the lines of Earth’s magnetic field lines.
Human beings are no more susceptible to the effects of the trapped charged particles than other equipment on the interior of a manned spacecraft.
All charged particles trapped in the Van Allen belts make their way to the Earths’ North Magnetic Pole.,
d. The magnetic mirroring phenomenon traps charged particles along the lines of Earth’s magnetic field lines.
Human beings are no more susceptible to the effects of the trapped charged particles than other equipment on the interior of a manned spacecraft.
b. All charged particles trapped in the Van Allen belts make their way to the Earths’ North Magnetic Pole.,
The Earth’s perfect magnetic dipolar field ensures even dosage at all points in an orbit that transits the Van Allen belt.,
Human beings are no more susceptible to the effects of the trapped charged particles than other equipment on the interior of a manned spacecraft.
The only feasible approach(es) to counter the dangers to human crew members of Solar Particle Events (SPEs), which originate as coronal mass ejections (CMEs) and can be lethal even to shielded and space-suited crew, is/are:
a. Specifically design volumes to shield crew during high SPE periods should be added to any habitable spacecraft environment
Warning systems based on solar observatories and deep space detectors can be established and maintained to give sufficient warning of extreme GCR events
b. Warning systems based on solar observatories and deep space detectors can be established and maintained to give sufficient warning of extreme GCR events
Design and fly only robotic spacecraft beyond High Earth Orbit (HEO)
Specifically design volumes to shield crew during high SPE periods should be added to any habitable spacecraft environment
c. Radiation budgets must be established for all manned spacecraft, with the understanding that no spacecraft design can ensure 100% protection
Warning systems based on solar observatories and deep space detectors can be established and maintained to give sufficient warning of extreme GCR events
d. Specifically design volumes to shield crew during high SPE periods should be added to any habitable spacecraft environment,
Radiation budgets must be established for all manned spacecraft, with the understanding that no spacecraft design can ensure 100% protection
d. Specifically design volumes to shield crew during high SPE periods should be added to any habitable spacecraft environment,
Radiation budgets must be established for all manned spacecraft, with the understanding that no spacecraft design can ensure 100% protection
Micrometeoroids and orbital debris (MMOD) are an increasing threat to spacecraft in Earth orbit because
a. Thousands of objects, including dead satellites, spent rocket stages, deployable shrouds and covers, and even tools lost on EVAs, are crowding certain orbits,
Chemical particles, such as paint flecks, outgassed fuel, etc. can cause real damage to unshielded exterior areas, such as viewports and sensor lenses
b. Thousands of objects, including dead satellites, spent rocket stages, deployable shrouds and covers, and even tools lost on EVAs, are crowding certain orbits,
Collisions between orbiting objects are generally of high velocity, resulting in even more debris,
Chemical particles, such as paint flecks, outgassed fuel, etc. can cause real damage to unshielded exterior areas, such as viewports and sensor lenses
c. Thousands of objects, including dead satellites, spent rocket stages, deployable shrouds and covers, and even tools lost on EVAs, are crowding certain orbits,
Native space debris that originates from comet degradation or meteoroid collisions is on a steady and steep increasing curve
Chemical particles, such as paint flecks, outgassed fuel, etc. can cause real damage to unshielded exterior areas, such as viewports and sensor lenses
d. Native space debris that originates from comet degradation or meteoroid collisions is on a steady and steep increasing curve
Collisions between orbiting objects are generally of high velocity, resulting in even more debris,
Chemical particles, such as paint flecks, outgassed fuel, etc. can cause real damage to unshielded exterior areas, such as viewports and sensor lenses
b. Thousands of objects, including dead satellites, spent rocket stages, deployable shrouds and covers, and even tools lost on EVAs, are crowding certain orbits,
Collisions between orbiting objects are generally of high velocity, resulting in even more debris,
Chemical particles, such as paint flecks, outgassed fuel, etc. can cause real damage to unshielded exterior areas, such as viewports and sensor lenses
Match the descriptions to the appropriate terms.
Quantify required absorptance and emittance of surfaces at end of life and most likely value at beginning of life.
a. Contamination of solar arrays
b. Contamination of thermal-control surfaces
c. Contamination of optical sensors (UV, visible, IR)
d. Solar UV degradation
b. Contamination of thermal-control surfaces
Match the descriptions to the appropriate terms.
Estimate total solar UV illumination of exterior surfaces. Compare to manufacturer’s data to verify that no significant degradation will occur
a. Contamination of solar arrays
b. Contamination of thermal-control surfaces
c. Contamination of optical sensors (UV, visible IR)
d. Solar UV degradation
d. Solar UV degradation
