How might the presence of life on another planet be inferred from ...

[swpotter12]

How might the presence of life on another planet be inferred from the composition of that planet's atmosphere?
 
  What will be an ideal response?

Question 2

A Pentagon memo mentions that Afghanistan could become the Saudi Arabia of ________ (used in making batteries for cell phones and laptops).
 
  A) nickel
  B) cadmium
  C) gold
  D) lithium

[tuate]

Answer to Question 1

Detection of a gas or series of gases at a level which cannot exist outside the influence of biology would be indicative of life. The best example of this is if high concentrations of CH4 and O2 were discovered on a planet. Because O2 and CH4 are highly reactive, this would require high fluxes of both gases. The required fluxes are higher than abiogenic fluxes of these gases. Thus, the detection of both of these gases at significant levels is indicative of a biosphere.

Answer to Question 2

D

[swpotter12]

Excellent

[nyrave]

Gracias!