Orig. Qs.

Question 1

In a closed-loop control system the actuators receive commands from the sensors: True or False?

Answer 1

False

Question 2

Identify one example of a disturbance torque that acts to gradually degrade a spacecraft’s attitude.

Answer 2

Gravity gradient torque

Question 3

The angular momentum of a spacecraft is always conserved: True or False?

Answer 3

False

Question 4

Identify the process that combines message data with the carrier frequency before radiowave transmission.

Answer 4

Modulation

Question 5

Identify the antenna performance parameter that specifies how much energy from the transmitter is radiated.

Answer 5

Gain

Question 6

Identify the device inside a radioisotope generator that converts heat into electrical power.

Answer 6

Thermocouple or Radioisotope Generators

Question 7

Identify the thermal actuator that provides a modified form of heat convection on a spacecraft.

Answer 7

Heat pipe

Question 8

Identify one disadvantage of using composite materials for construction of a spacecraft structure.

Answer 8

Delamination

Question 9

Identify the name given to the slope of the stress versus strain curve for a material.

Answer 9

Young‚ modulus

Question 10

Explain the difference between passive and active actuators. Provide an example of each.

Answer 10

Passive actuators operate without feedback (e.g., magnets); active actuators use feedback control (e.g., reaction wheels).

Question 11

Explain why a spacecraft may contain multiple GPS receivers, instead of just one. What is their purpose?

Answer 11

To increase redundancy and improve position accuracy in 3D space.

Question 12

Define antenna gain. What is it referenced to? What are its two components?

Answer 12

Gain measures how effectively an antenna directs energy, referenced to isotropic radiator; consists of directivity and efficiency.

Question 13

Explain the physics & math of gravity-gradient stabilization. When is it used? Why? What is the equation?

Answer 13

Used in low Earth orbit to stabilize attitude using Earth’s gravity; Earth’s pull rotates the satelitle into alignment, torque = (3 mu / 2r^3) (l_max-l_min) (sin(2theta))

Question 14

Explain the physics & math of vibrational resonance. When is it a problem? Why? How can it be avoided?

Answer 14

Occurs when excitation frequency matches natural frequency; causes large oscillations; avoided via damping or stiffening.

Question 15

Explain the physics & math of thermal conduction & radiation. How do they work? What are the equations?

Answer 15

Conduction: Q = kAΔT/L,
Radiation: Q = σεAT⁴

Question 16

Mission constraints are external factors that are not controllable and simply must be met: True or False?

Answer 16

True

Question 17

Identify the dominant form of pressure inside a low beta plasma.

Answer 17

Magnetic pressure

Question 18

Identify the region of the solar atmosphere in which the temperature gradient is highest.

Answer 18

Transition region

Question 19

Identify the photosphere solar activity feature that is abnormally cold because of strong magnetic field.

Answer 19

Sunspot

Question 20

The Babcock model describes how the solar wind is generated: True or False?

Answer 20

False

Question 21

Identify the name given to a sudden brightening of electromagnetic waves from the sun.

Answer 21

Solar flare

Question 22

Identify when the average solar wind is faster: solar maximum or solar minimum.

Answer 22

Solar minimum

Question 23

The interplanetary magnetic field (IMF) is more azimuthal at Neptune than Earth: True or False?

Answer 23

true

Question 24

Identify the most likely repetition period for high-speed streams at Earth.

Answer 24

27 days

Question 25

Explain what it means to “scope” a space mission. What are the start and end points?

Answer 25

Scoping defines objectives, constraints, and timelines from initial concept to mission end.

Question 26

Define and distinguish coronal holes and coronal streamers. What are their features? Why?

Answer 26

Holes: open field lines, high-speed wind. Streamers: closed loops, slow wind.

Question 27

Identify the two influences that combine to produce the Parker spiral shape of the IMF.

Answer 27

Solar wind outflow and solar rotation.

Question 28

Hand-sketch the internal structure of the sun. What are the regions? What happens in each?

Answer 28

Core (fusion), Radiative Zone, Convective Zone, Photosphere, Chromosphere, Corona.

Question 29

Hand-sketch a diagram showing the relationship between solar granules and spicules.

Answer 29

Granules: convection cells; spicules: jets in chromosphere.

Question 30

Explain the physics and math of why the sun’s corona is not in hydrostatic balance.

Answer 30

Thermal pressure > gravity; use hydrostatic eq: dP/dr = -ρg

Question 31

Charged particles never cross magnetic field lines: True or False?

Answer 31

False

Question 32

Identify the direction of the electric current across the dayside magnetopause.

Answer 32

Dawn to dusk

Question 33

Which radiation belt is produced by cosmic rays: inner or outer?

Answer 33

Inner

Question 34

Identify the primary heat source for the troposphere.

Answer 34

Infrared radiation from Earth

Question 35

Identify the layer of the ionosphere that completely disappears at night.

Answer 35

D layer

Question 36

How long does an isolated auroral substorm typically last: hours, days or weeks?

Answer 36

Hours

Question 37

Identify the dataset the Space Weather Prediction Center uses to classify Solar Radiation Storms.

Answer 37

GOES proton flux

Question 38

Identify the space weather influence most likely to shorten the life of astronauts.

Answer 38

Solar radiation

Question 39

Polar cap absorption is produced by solar flare x-rays: True or False?

Answer 39

True

Question 40

Identify the two quantities that are in perfect balance at the location of the dayside magnetopause.

Answer 40

Magnetic pressure and thermal pressure

Question 41

Identify the three types of alerts issued by the Space Weather Prediction Center.

Answer 41

Solar radiation storm, geomagnetic storm, radio blackout

Question 42

Explain how space weather can adversely affect spacecraft electronics. What is the most likely cause?

Answer 42

Charged particles cause single-event upsets or damage electronics.

Question 43

Hand-sketch the physics of auroral substorms. When do they occur? What happens during each phase?

Answer 43

Growth (tail stretching), expansion (brightening), recovery (calm)

Question 44

Sketch a diagram explaining why the ionosphere is structured in layers. What are the competing influences?

Answer 44

Ionization vs recombination rates by altitude

Question 45

Sketch a diagram of shortwave fadeout. Where and when does it occur? Why? What are its effects?

Answer 45

Occurs on dayside, D-layer overionized by solar flare, causes radio blackout