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Space Resources > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What is the equatorial surface gravity of Earth, Moon and Mars?

A
  • Earth: 9,78033 m/s^2
  • Moon: 1,622 m/s^2
  • Mars: 3,711 m/s^2
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2
Q

What is the rotation period of Earth, Moon and Mars?

A
  • Earth: 23,93 siderial hours
  • Moon: 655,72 siderial hours
  • Mars: 24,62 siderial hours
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3
Q

What is the surface temperature of Earth, Moon and Mars?

A
  • Earth: 185/331 K
  • Moon: 26/396 K
  • Mars: 145/294 K
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4
Q

What is the ambient pressure at sea level of Earth, Moon and Mars?

A
  • Earth: 1013 mbar
  • Moon: 10^-11 to 10^-10 mbar
  • Mars: 6 mbar
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5
Q

What are the 7 main environmental factors on an astronomical object?

A
  1. Vacuum
  2. Gravity
  3. Illumination
  4. Temperature
  5. Radiation
  6. Impacts
  7. Dust
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6
Q

What are the effects and consequences of vacuum?

A
  • No oxygen –> life support system
  • Pressure difference –> pressure suit, reinforced structures
  • No convection –> highly variable thermal stress (sunlit planes/shadowed craters)
  • Material outgassing –> degradation, damage, contamination
  • No atmospheric drag –> meteoroid bombardment
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7
Q

When did vacuum start to be intensively studied and what are 3 experiments on vacuum?

A
  • 17th century
  • 1654: Magdeburg hemispheres, air/vacuum pump
  • 1646: First human-made vacuum
  • 1660: No sound in vacuum
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8
Q

What happens to a human in space?

A
  • Air sucked out of lungs (holding breath causes tissue rupture)
  • Blood boils off
  • Other liquids boil off (Eyes, Tongue)
  • Local freezing
  • Ultimately full freezing, slower
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9
Q

What are effects and consequences of gravity?

A
  • Reduced contact to ground –> reduced traction and control, risk of bouncing off
  • Increased dust aggregation –> compromised vision, increased contamination
  • Varied fluid behaviour –> bubble growth/detachment and reduced convection (for reactors)
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10
Q

How long is a day on all planets in the solar system relative to Earth?

A
  • Mercury: 175.9
  • Venus: 116.8
  • Earth: 1
  • Mars: 1.03
  • Jupiter: 0.41
  • Saturn: 0.44
  • Uranus: 0.72
  • Neptune: 0.67
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11
Q

What is the relation between radiation intensity and distance from radiating object?

A

I = 1/r^2
(Intensity I, Distance r)

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12
Q

What are effects and consequences of illumination?

A
  • Limited power supply –> energy storage, other power sources
  • Reduced radiation intensity –> other power sources
  • Extreme temperature gradients –> thermal stress, damage, wide design envelope
  • Psychological effects –> psychological stress, mood
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13
Q

How are the illumination conditions on the Moon?

A
  • 14 days illumination vs. 14 days darkness
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14
Q

What are PEL’s and PSR’s?

A
  • PEL: Peaks of Eternal Light
  • PSR: Permanently Shadowed Regions
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15
Q

Where can PEL’s and PSR’s be found and what are their benefits?

A
  • No evidence for “eternal light”, but peaks with illumination 80% of the time
  • Moon, Mercury, Ceres
  • Benefit: continuous power close to potential resource deposits
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16
Q

What are effects and consequences of temperature?

A
  • Temporal/spatial gradients –> thermal stress (dynamic/static), thermal expansion
  • Extreme values –> enhanced outgassing, increased power demand
17
Q

What are sources of radiation?

A
  • High energy galactic cosmic rays (GCR) –> Mainly protons (85%) and alpha particles (14%)
  • Solar particle events (SPE) –> X-rays, gamma rays, protons and electrons
18
Q

What are effects and consequences of radiation?

A
  • DNA and cell damage –> Cataracts, gene mutations, increased chance of cancer, sterility
  • Jamming/damage of electronics –> Computer errors (glitches, bit flips, latchups, burnouts)
19
Q

What are some effects of Earth’s magnectic field?

A
  • Shields radiation
  • Traps highly energetic particles in the Van-Allen Belts
20
Q

Where are the 2 Van-Allen Belts located and where is a relatively safe zone?

A
  • Inner belt: 0.2 to 2 Earth radii, mainly protons
  • Outer belt: 3 to 10 Earth radii, protons and electrons with highest intensity around 4 to 5 Earth radii
  • Safe zone inbetween
21
Q

How much radiation dose is experienced on a trip to Mars compared to the recommended value for an average career?

A

> 60%

22
Q

What are some radiation effects on CMOS (Complementary Metal-Oxide Semiconductor)?

A

Ionisation process causes energy to be trapped in the materials (dose), leading to:
- Oxide doping (fixed charge, leading to lower barrier, threshold shifts)
- Leakage current (device stays „on“ even with no gate voltage)

23
Q

What are some single event effects on CMOS (Complementary Metal-Oxide Semiconductor)?

A
  • Single Event Transients (heavy ion creates voltage pulse along its path)
  • Single Event Upsets (device changes its logical state, e.g. bitflip)
  • Single Event Latch Up (low impedance, electric short, loss of device functionality)
24
Q

In what sense was the Apollo-Program “lucky”?

A
  • No major solar-particle events occurred during Apollo
25
Q

Can individual solar eruptions be forecasted and what is the time between an observation of an eruption and its arrival in the Earth-Moon system?

A
  • Impossible to forecast
  • Time between observation of an eruption and arrival in
    the Earth-Moon system is <1 h up to 4 h
26
Q

How many of the solar flares result in a particle event?

A

About 20%

27
Q

What was the maximum operational dose (MOD) limit for each of the Apollo missions?

A
  • 400 rads (~ X-ray) for skin
  • 50 rads for blood forming organs
28
Q

What was the average operational dose for all Apollo missions?

A

0.38 rad (~ 2 CT scans of the head)

29
Q

What are some countermeasures against radiation exposure?

A
  • Timing of a mission
  • Careful planning of orbital trajectory
  • Shielding (Aluminum provides limited shielding, Propellant tanks much more efficient)
  • Risk of secondary radiation depending on material and thickness
  • Different materials for different types of radiation
30
Q

How can electrical components be protected from radiation?

A
  • Radiation hardening by architecture
  • Radiation hardening by design
  • Radiation hardening by process
31
Q

How can radiation hardening by architecture be achieved?

A
  • Redundancy (increases overhead in voting logic, power consumption, mass)
  • Multiple levels of redundancy (i.e. component, board, system, spacecraft level)
32
Q

How can radiation hardening by design be achieved?

A
  • Triple Modular Redundancy (TMR) strategies within the chip layout
  • Dopant wells and isolation trenches in the chip layout
  • Error detecting and correction circuits
  • Device spacing and decoupling
33
Q

How can radiation hardening by process be achieved?

A
  • Employ specific materials, processing techniques
  • Usually performed on dedicated rad-hard foundry fabrication lines
34
Q

What is triple modular redundancy?

A

Three systems perform a process and the result is processed by a majority-voting system to produce a single output

35
Q

How do radiation-hardened components and commercial components compare?

A

Radiation-hardened components lag behind commercial devices by several technology generations (~ 10 years)

Space Resources (3 decks)

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