Mars - PowerPoint PPT Presentation

1 / 20
About This Presentation
Title:

Mars

Description:

Mars. Astronomy 311. Professor Lee Carkner. Lecture 14 ... energy/crater size = 0.11 J / 7 cm = 0.016 J/cm ... Red dust in atmosphere gives sky a pink tint ... – PowerPoint PPT presentation

Number of Views:509
Avg rating:3.0/5.0
Slides: 21
Provided by: LeeCa1
Category:
Tags: mars | tint

less

Transcript and Presenter's Notes

Title: Mars


1
Mars
  • Astronomy 311
  • Professor Lee Carkner
  • Lecture 14

2
Moon Impactor Exercise
  • My data
  • height 50 cm 0.5 m
  • crater diameter 7 cm
  • mass of marble 22.4 g 0.0224 kg
  • Energy
  • PE mgh (0.0224)(9.8)(0.5) 0.11 J
  • Velocity
  • v (2gh)½ (2)(9.8)(0.5)½ 3.13 m/s
  • Energy-crater size relationship
  • energy/crater size 0.11 J / 7 cm 0.016 J/cm
  • for every 0.016 J of energy in your impact the
    crater size increases by 1 cm

3
Mars -- The God of War
  • Shows color more strongly than other planets

4
The Canals of Mars
  • He called them canali, Italian for channels
  • Percival Lowell built an observatory near
    Flagstaff, AZ and published elaborate maps of a
    network of canals and oasis on Mars
  • Mars was thought to be very dry, so naturally the
    inhabitants needed to carefully manage water

5
Mars Facts
  • Size 1/2 Earth size
  • Orbit 1.5 AU
  • Description red, dusty, thin atmosphere

6
Spacecraft to Mars
  • Viking 1 and 2 (1975) extensively imaged Mars and
    also sent landers to the surface
  • Recent missions
  • Spirit and Opportunity (2003, rover)
  • Phoenix (2008, lander)

7
Surface Features
  • Volcanoes -- Mars has many shield volcanoes, but
    they are not active today
  • Canyons -- Mars shows deep canyons, the result of
    volcanic activity stressing the crust
  • Craters --The northern hemisphere is less heavily
    cratered than the southern
  • Why?
  • Dust storms alter the Martian craters

8
The Surface of Mars
  • Red dust in atmosphere gives sky a pink tint
  • Surface is covered with reddish soil and is rocky
    and broken

9
Temperature of Mars
  • TM RS/(2 DS)½ TS
  • Assumes that Mars absorbs all sunlight incident
    upon it and then radiates the energy freely back
    into space
  • Mars is cold
  • Mars has seasons due to the tilt of its axis

10
Marss Atmosphere
  • Pressure 0.007 atmospheres
  • Early Mars may have had a thicker CO2 and H2O
    atmosphere
  • Mars has no plate tectonics to return the CO2 to
    the atmosphere

11
Volatiles on Mars
  • Water cannot exist on the surface of Mars as
    liquid
  • Even though it is very cold, the low atmospheric
    pressure makes it easy for water to escape the
    liquid form into a gas
  • Carbon dioxide frost

12
Was Mars Wet?
  • Surface features indicate that water once flowed
    freely on the Martian surface
  • Due to
  • Spot flooding (water frozen underground and
    sometimes comes to the surface)?
  • Most likely due to a greenhouse effect
  • Where could the water be now?
  • In the polar caps
  • Mars may warm up periodically allowing water to
    form (Mars may now be in an ice age)

13
Life on Mars?
  • Could life have formed on Mars when it was
    wetter?
  • Could that life have survived?
  • If life was microscopic it might be hard to find

14
Marss Interior
  • Mars has a lower density than the other
    terrestrial planets (4000 compared to 5000 kg/m3)
  • No evidence for plate tectonics
  • There are no seismometers on Mars
  • Mars may have only a small solid iron core or no
    iron core at all

15
Future Mars Exploration
  • MAVEN (Mars Atmosphere and Volatile EvolutioN)
    orbiter planed for 2013
  • Sample return?
  • Manned mission?

16
A Possible History of Mars
  • Mars forms
  • Volcanism creates volcanoes and lava flows
  • Mars losses internal heat, crust cools
  • Atmosphere loses CO2, atmosphere cools
  • Lava flows stop

17
Next Time
  • Read Chapter 14.1 and 14.4
  • Quiz 2 on Friday
  • Same basic format as Quiz 1, plus some matching
    questions

18
Summary
  • Red, dusty, thin atmosphere
  • Mars is a medium-sized world allowing it to
    retain an atmosphere (unlike Mercury and the
    Moon), but not a thick atmosphere (like Venus and
    Earth)
  • Mars shows signs of being habitable in the past,
    but no good evidence of life has been found

19
Summary Surface
  • Mars has a red surface composed of dust, soil and
    rocks
  • Mars has large volcanoes and deep chasms
  • Dust storms often cover the surface
  • Mars has a low density and may not have an iron
    core

20
Summary Climate
  • Mars has a very thin atmosphere and is cold
  • Low temperature and pressure prevent liquid water
    on the surface
  • Mars may have had a thicker, warmer atmosphere in
    the past since there is substantial evidence for
    water flows
  • Early thicker CO2 greenhouse atmosphere gradually
    washed out by rainfall
  • The temperature on Mars may change over time due
    to orbital variations
Write a Comment
User Comments (0)
About PowerShow.com