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Ast$281$Review$for$Exam$1$–$Tuesday,$February$25,2014...

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Ast 281 Review for Exam 1 – Tuesday, February 25, 2014 – in class The Exam will be a CLOSED BOOK exam, lasting the whole period. You will be allowed to have calculators and the sheet of planetary data, but I doubt that you will need either of them. The exam will consist of the following types of questions: 15 True / False (2 points each; 30 points total) 15 Multiple Choice (3 points each; 45 points total) Short answer questions (total of 75 points) My exams tend to be fairly long, so answer what you can first and then go back to the more dif ficult things. Don’t write too much on any one question, but write enough to get your point across. Single word answers on the essays will not be good enough! Likewise, don’t justify T/F or multiple choice questions. The exam will cover all material up through our last lecture. The ex am is intended to test how well you understand the concepts, so in general I don’t expect you to spend time furiously memorizing all the little details we have discussed. A good way to study would be to read through the lecture notes again and be sure you really understand all the con cepts. Also, as you study each lecture, ask yourself the highlevel question of what were the 23 big important concepts from that lecture. This is what I do when I make the exam, and I write my questions based on that. I will often introduce you to a new situation on the exam and ex pect you to use your understanding of the material to figure out the answer (I love transporting you to alien worlds...). Useful review topics: You should know the order of the EM spectrum (gamma rays to radio), and the approximate wavelengths. This is important when you are looking at a transmission spectrum graph so you know if the gas absorbs in the IR for example, for a greenhouse effect. Understand the interaction of EM radiation and matter: when do we get a continuous spectrum, absorption and emission. How do we get remote compositional information from space? Know the difference between the Greenhouse effect and the ozone problem Understand the basics of the structure of the atom, and the differences between differ ent isotopes. Understand why atoms are unstable and how we can use this to date ma terials. How important is the presence and chemical make up of an atmosphere on a planet to the planet’s surface temperature, to climate and habitability? How would you define life, and do we need a definition? What are the characteristics of Earth life and how does this translate to requirements for a habitable world that could support life? What is meant by biological evolution; how this relates to our search for life elsewhere? What is special about water that makes it useful for life What are the basic steps that had to occur in the origin of life? Which ones do we think we understand Which steps were the hardest How have we traced the history of life on Earth?
Transcript

Ast  281  Review  for  Exam  1  –  Tuesday,  February  25,  2014  –  in  class    The  Exam  will  be  a  CLOSED  BOOK  exam,   lasting  the  whole  period.  You  will  be  allowed  to  have  calculators  and  the  sheet  of  planetary  data,  but  I  doubt  that  you  will  need  either  of  them.  The  exam  will  consist  of  the  following  types  of  questions:  

• 15  True  /  False  (2  points  each;  30  points  total)  • 15  Multiple  Choice  (3  points  each;  45  points  total)  • Short  answer  questions  (total  of  75  points)  •  

My  exams  tend  to  be  fairly  long,  so  answer  what  you  can  first  and  then  go  back  to  the  more  dif-­‐ficult   things.   Don’t  write   too  much   on   any   one   question,   but  write   enough   to   get   your   point  across.  Single  word  answers  on  the  essays  will  not  be  good  enough!  Likewise,  don’t  justify  T/F  or  multiple  choice  questions.  The  exam  will  cover  all  material  up  through  our  last  lecture.    The  ex-­‐am  is  intended  to  test  how  well  you  understand  the  concepts,  so  in  general  I  don’t  expect  you  to  spend   time   furiously  memorizing  all   the   little  details  we  have  discussed.  A  good  way   to   study  would  be  to  read  through  the  lecture  notes  again  and  be  sure  you  really  understand  all  the  con-­‐cepts.  Also,  as  you  study  each  lecture,  ask  yourself  the  high-­‐level  question  of  what  were  the  2-­‐3  big   important  concepts  from  that   lecture.  This   is  what  I  do  when  I  make  the  exam,  and  I  write  my  questions  based  on  that.  I  will  often  introduce  you  to  a  new  situation  on  the  exam  and  ex-­‐pect  you  to  use  your  understanding  of  the  material  to  figure  out  the  answer  (I  love  transporting  you  to  alien  worlds...).      Useful  review  topics:    • You  should  know  the  order  of  the  EM  spectrum  (gamma  rays  to  radio),  and  the  approximate  

wavelengths.  This   is   important  when  you  are   looking  at  a   transmission  spectrum  graph  so  you  know  if  the  gas  absorbs  in  the  IR  for  example,  for  a  greenhouse  effect.  – Understand  the   interaction  of  EM  radiation  and  matter:  when  do  we  get  a  continuous  

spectrum,  absorption  and  emission.    – How  do  we  get  remote  compositional  information  from  space?  – Know  the  difference  between  the  Greenhouse  effect  and  the  ozone  problem  – Understand  the  basics  of  the  structure  of  the  atom,  and  the  differences  between  differ-­‐

ent  isotopes.  Understand  why  atoms  are  unstable  and  how  we  can  use  this  to  date  ma-­‐terials.    

– How  important  is  the  presence  and  chemical  make  up  of  an  atmosphere  on  a  planet  to  the  planet’s  surface  temperature,  to  climate  and  habitability?  

 • How  would  you  define  life,  and  do  we  need  a  definition?      

– What  are   the  characteristics  of  Earth   life  and  how  does   this   translate   to   requirements  for  a  habitable  world  that  could  support  life?    

– What  is  meant  by  biological  evolution;  how  this  relates  to  our  search  for  life  elsewhere?  – What  is  special  about  water  that  makes  it  useful  for  life  

 • What  are  the  basic  steps  that  had  to  occur  in  the  origin  of  life?  

– Which  ones  do  we  think  we  understand  – Which  steps  were  the  hardest    – How  have  we  traced  the  history  of  life  on  Earth?  

– What  are  conditions  that  are  good  for  the  origin  of  life?    

• What  are  the  basic  steps  that  had  to  occur  in  the  origin  of  life?  – Which  ones  do  we  think  we  understand  – Which  steps  were  the  hardest    – How  have  we  traced  the  history  of  life  on  Earth?  – What  are  conditions  that  are  good  for  the  origin  of  life?  

 • What  are  the  basic  classification  (group  names)  for  extremophiles  (in  terms  of  Temperature  

and  other  extreme  conditions).  – How  do  microbes  make  a  living  –  what  is  metabolism?    Where  do  they  get  energy?  – What  sort  of  environmental  variables  can  affect  the  energy  availability?  – Are  there  any  type  of  environments  that  would  be  totally  inhospitable  to  life?  

 • Understand  the  types  of  exogenic/endogenic  processes  and  how  we  can  use  them  to  infer  

characteristics  about  the  interior  and  properties  of  worlds  we  can  only  observe  remotely.  – Why  are  tectonic  and  volcanic  processes  important  for  habitability?  – Do  we  see  similar  processes  on  all  planets  and  large  moons  in  the  solar  system?  – What  drives  plate  tectonics?  – What  is  volcanism?    What  influences  what  type  of  volcanism  we  have?  – What  are  the  types  of  exogenic  processes?  

 • Understand  the  basic  structure  of  Earth’s  atmosphere  –  including  the  altitudes  at  which  the  

temperatures  change  and  what  causes  the  temperature  increases  at  specific  altitudes.    – How  is  this  different  for  other  terrestrial  planets?    – What   is   scale  height   and  how  does   this  depend  on  Temperature,   planet  mass   and  at-­‐

mospheric  composition?  – Which  planets  have  atmospheres,  and  how  were  they  created?  How  does  this  affect  the  

planet’s  evolution?  – How  has  Earth’s  atmosphere  and  surface  changed  throughout  time  and  why?  

 • What  were  the  4  major  time  divisions  in  Earth’s  history  (and  approximate  years)    

– What   was   Earth   like   during   each   of   these   periods   (and   how   do   we   know   the   infor-­‐mation)?  

– What  big  event  occurred  in  each  of  these  time  periods?  – Where  did  Earth  possibly  get  its  ocean  water  – Be  familiar  with  the  concept  of  radioactive  dating,  and  why  you  would  use  one  material  

over  another  for  dating    

• What  are  comets  and  why  are  they  important  to  study  from  an  astrobiology  context?    – What  physical  process  is  occurring  when  a  comet  develops  a  tail?  – What  big  event  occurred  in  each  of  these  time  periods?  

         

Sample  Exam  Questions:    1. Which  of  the  following  statements  regarding  life’s  biochemistry  is  NOT  true?  

(a) The  elements  CHON  account  for  the  majority  of  biomass  of  life  on  earth  (b) The  elements  CHON  are  among  the  most  abundant  within  the  universe  (c) Water  is  the  most  abundant  volatile  molecule  within  the  cosmos  (d) Amino  acids  are  produced  in  significant  quantity  throughout  the  universe  (i.e.  

by  nonbiological  processes)  (e) Nucleic   acids   are   produced   in   significant   quantity   throughout   the   universe  

(i.e.  by  nonbiological  processes)    2. Which  of  the  following  provided  definitive  proof  of  plate  tectonics  on  Earth?  

(a) apparent  fitting  together  of  the  coastlines  of  continents  (b) similarity  of  plant  and  animal  species  from  continent  to  continent  (c) paleomagnetic  measurements  (frozen  magnetic  field  in  rocks)  (d) the  lack  of  a  runaway  greenhouse  (e) all  of  the  above  

 3. Why  doesn’t  the  Deep  Impact  Mission  carry  explosives  to  make  the  crater?  

(a) public  concern  over  launching  weapons  (b) comets  are  made  of  such  dense  material  that  explosives  would  be  ineffective  (c) not  necessary  because  the  energy  from  the  impactor  mass  and  velocity  is  suf-­‐

ficient    4. What   type   of   spectra   are   shown   at  

the  right?  (a) emission  (b) absorption  (c) blackbody  only  

 5. What   is   the   source   (or   sources)   of  

Earth’s  atmosphere?  (a) Comet  impacts  (b) Volcanic  outgassing  (c) accretion  of  gases  in  planetesimals  (d) gravitational  capture  of  gases  from  the  solar  nebula  (e) all  of  the  above  

 6. Which  of  the  following  statements  is  true?  

(a) Water  and  Carbon  are  required  for  life  (b) Life  is  made  of  the  most  abundant  cosmic  elements  (c) Only  living  systems  can  replicate  (d) Earth  is  exceptional  because  it  has  water  (e) All  of  the  above  

7. Why  might  silicon  be  a  possible  alternative  to  Carbon?  (a) It  has  the  same  atomic  mass  (b) It  is  common  in  the  atmosphere  (c) It  can  bond  with  4  different  atoms  like  carbon  (d) It  is  more  abundant  than  carbon  (e) B+C  

 8. Sort   the   following   from   earliest   (closest   to   Earth’s   formation)   to   latest   (closest   to  

present):   1  Phanerozoic       2  Archean   3  Hadean   4  Proterozoic,    (a) 1,  2,  3,  4  (b) 3,  2,  1,  4  (c) 3,  2,  4,  1  (d) 1,  4,  2,  3  (e) 2,  1,  3,  4  

 9. Why  was  it  so  difficult  to  find  Precambrian  fossils?  

(a) Nobody  cared  about  the  origins  of  life  (b) No  life  existed  in  the  Pre-­‐Cambrian  (c) Hard  to  distinguish  early  life  from  geological  formations  (d) The  organisms  had  soft  bodies  and  biology  recycled  organics  (e) C+D  

 10. Which  of  the  following  factors  control  the  extent  of  a  planetary  atmosphere?  

(a) temperature  (distance  to  the  sun)  (b) mass  of  planet  (gravity)  (c) composition  of  the  atmosphere  (d) all  of  the  above  (e) (a)  and  (b)  only  

 11. A  terrestrial  body  the  size  of  Mercury  would  lose  its  internal  heat  through:  

(a) Convection  (b) Conduction  (c) Hot  spot  volcanism  (d) (b)  and  (c)  (e) (a),  (b),  and  (c)  

 12. Finish  the  following  sentence  by  filling  in  the  blanks  (a)  and  (b)  with  the  options  be-­‐

low:  Plate  tectonics  (a)  currently  unique  to  Earth  &  (b)  important  for  creating  a  hab-­‐itable  environment  

(a) (a)  is;  (b)  is  not  (b) (a)  is;  (b)  is  (c) (a)  is  not;  (b)  is  (d) (a)  is  not;  (b)  is  not  

 

Sample  Discussion  Questions:    

1. What  makes  water  a  good  solvent  for  life?  What  are  the  minimum  requirements  for   life?  What   are   amino   acids   for   and  where   did   they   come   from   before   life  started?  

2. A  lone  volcano  which  is  five  times  the  size  of  Mt.  Everest  is  observed  during  your  exploration  of  a  planet   in  a  distant  galaxy.    What  can  you  tell  about  the  planet  from  the  endogenic  signature  you  observe?    What  is  your  reasoning?  

3. Given  the  table  of  planetary  properties   for  a  group  of  planets  around  antother  star  similar  to  our  Sun.    The  TCalculate  represents  the  equilibrium  temperature  of  a  body   at   that   distance   from   the   sun   with   the   albedo   given.     The   TMeas   is   the  measured  temperature  either  at  the  “surface”  of  the  planet,  or  in  the  case  of  a  gas  giant,  at  a  depth  in  the  atmosphere  where  the  pressure  is  1  atm.  (1  bar).  

a. Which  of  the  following  planets  likely  have  atmospheres  and  why?  b. Which  ones  might  be  habitable  and  why?  

 Planet   TCalculate  

[K]  TMeas  

[K]  Gravity  [rel  ⊕]  

H  [km]   Dist  to  star  [AU]  

Density  [g/cm3]  

Diameter  [km]  

Albedo  

Earth   290   300   1   8.4   1.0   5.5   12,756   0.39  A   721   725   0.4   190   0.2   8.7   3,230   0.1  B   315   550   2.5   13.2   0.7   5.5   32,302   0.6  C   256   285   0.9   6.0   1.4   5.3   12,154   0.3  D   206   215   1.0   4.5   2.2   4.6   15,124   0.27  E   125   200   2.3   35.1   4.6   1.3   125,020   0.57  F   78   150   3.2   30.0   6.7   1.5   145,730   0.86  G   100   130   0.7   28.1   8.4   0.9   55,903   0.41  H   84   110   0.7   25.6   11.2   0.8   60,203   0.47  I   49   50   0.8   237   14.5   6.7   8,203   0.9  J   42   38   0.1   50   22.6   6.2   1,206   0.87  

 4. The   pictures   at   the  left   show   various   planetary  landscapes.   Which   of   the  features   are   endogenic,   or  exogenic.     What   can   these  images   tell   us   about   the  potential   for   habitability   on  these  worlds?        


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