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NATS 1530 > Unit 6 > Flashcards

Unit 6 Flashcards

1
Q

Why explore other planets

A

To understand:

  • How our solar system was formed
  • Variety of planets and complexity of planetary motion
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2
Q

Mars

A

Has similar characteristics to Earth

  • Has seasonal activity
  • Visible changes to the surface because of seasonal activity

The most likely location for life beyond earth

After the moon, the next location in our solar system that will see humans on its surface

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3
Q

Mars: Pre-spacecraft era

A

This has been observed for a long time

Has a distance orange-red dusty hue

  • Led to its name Mars (Ares), God of War

Has a retrograde behavior

  • westwards motion rather than eastwards

The ice caps were seen to shrink and grow suggesting seasonal activity

The dark surface was also seen to change/occur rhythmically

  • possibility of vegetation
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4
Q

Mars: Facts, before the space age

A

Diameter: 6,792 km
Density: 3.93 gm/cm^3
Year: 687 Days
Day: 24h 37m
Average distance from the sun: 1.53 AU
Number of satellites: 2 (Phobos and Deimos)

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5
Q

Mars: Spacecraft exploration

A

Mariners 4, 6, and 7 were flyby missions

Mariner 9:

  • An orbital mission
  • Volcanoes and Rift valleys and signs of past water (dried-up rivers and lakes)

The largest volcano is on Mars

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6
Q

Volcanism on Mars

A

Olympus Mons

  • The largest volcano in the solar system
  • 30km higher than the mean Mars surface
  • It was active relatively recently 100 million years ago
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7
Q

Viking life science experiment

A

One of the main missions was to search for signs of life

  • Looked for signs of respiration, absorption of nutrients, and gas exchanges

Results were largely inclusive for life but suggested chemical reactivity instead

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8
Q

Two Martin Moons

A

Phobos and Deimos

Mars has two small, football-shaped satellites that move in orbit close to the surface of the planet

They may be captured asteroids, or formed in orbit around Mars

Partial Eclipse

  • Either Phobos or Deimos pass in front of the sun, some of the bright surface is obscured but not all
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9
Q

Liquid water on Mars

A

Runoff channels

  • Estimated at ~4 billion years old

Outflow Channels

  • Much larger than runoff channels, suggesting “flood water” volume

Gullies

  • Young features are found on steep mountains and cloff faces
  • Hydrated salts detected in the gullies
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10
Q

Surface Topography

A

Areas are comparable to continental land areas on Earth

2 hemispheres are quite different

  • Range elevation of 31km

Northern hemisphere

  • Smoother
  • Younger
  • Lower elevation

Southern hemisphere

  • More rugged
  • Mountainous
  • Older

Dust stories can envelop the planet for weeks

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11
Q

MEER mission

A

Expected to last at least 90 sols (Martian Days)

  • lasted 7 - 14 years

Establish geological evidence for past presence of water

  • Both rovers found copious evidence of standing and flowing water in the past
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12
Q

Ice caps

A

Permanent

  • smaller water ice cap

Seasonal

  • larger
  • Dry ice carbon dioxide cap

The northern ice cap is larger, colder of the 2 caps, and many km thick

When CO2 cap sublime the atmospheric pressure rises considerably

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13
Q

More fact about Mars

A

Atmosphere is about 1% as thick as Earth

Carbon dioxide (95%)
Nitrogen (3%)
Argon (2%)

No global magnetic field

  • Indication of one in the past

Soil

  • Mostly clays and iron oxides
  • Giving Mars its characteristic color
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14
Q

Why did Mars change

A

Once a lot like Earth

  • About 4 billion years ago

small planet

  • cools quickly solidifying their cores, and removing magnetosphere

so the atmosphere can be stripped away by the solar wind

Low gravity also contributes to atmospheric loss

  • water mist evaporates
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15
Q

7 minutes of terror

A

Having to go from Mars orbiting speed to a speed of 0 in 6 - 7 minutes without direct communication

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16
Q

Mars helicopter

A

Scout terrain where rovers cant go

17
Q

Sample return

A

Perseverance is to create rock samples in sample tubes that can be returned to Earth for analysis

NASA and ESA plan the sample return mission by the end of the decade

Mars rock already exists on Earth in the form of meteorites

18
Q

ALH 84001

A

Fromed at around a temperature of 18C based upon oxygen- 18 and carbon - 13 isotope measurements in carbonate nodules

Left Mars 17 million years ago and made it to earth 13 00 years ago

suggests the existence of nanobacteria

  • 20 - 100 nanometers in length
  • Much smaller than the equivalent bacterial structures on Earth

Had magnetic crystals

Contains polycyclic aromatic hydrocarbons

19
Q

Searching for life

A

Prebiotic chemistry

  • process from nonliving to living

Sample evidence for life turning “underground’ away from the harsh surface conditions

Methane on Mars

20
Q

Methane on Mars

A

A surprising amount of variation was detected in methane levels on Mars

Methane can’t survive in the Mars atmosphere meaning some source of replenishment is occurring

Geologic and or biological processes could be contributing so no definitive detection of life can be claimed at this time based on methane detection

21
Q

Going to Mars

A

~ 8 months to mars

  • ~1+ year on Mars is required before returning
  • ~8 months back
  • such mission would be ~34 months in length

In 2010 cost of 500 billion was estimated for such a mission

A One - way mission has been suggested

The existing record for the longes consecutive space flight is 438 days by cosmonaut Valeri Polyakov, and the most accrued time in space is 878 days by Gennady Padalka

  • Enough for the Mars mission and back
22
Q

Human on the surface of Mars

A

Need to be able to grow adequate food

An environment that restricts radiation exposure will be required

Technological challenges exist

Communication with Earth will be possible for most of the time

  • Except when the planet is in conjunction with the sun
  • The direct line of sight to Earth will be interpreted by the sun

Instantaneous communication is not possible

23
Q

Where on Mars should we settle

A

In lava tubes or cave system

low elevation like Hellas Plantia

  • Where atmospheric pressure is relatively high for Mars

where ice can be excavated easily and solar energy is available all year long

NATS 1530 (13 decks)

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