Ch. 7 Flashcards
What elements make up 96% of the mass of living things?
Hydrogen, carbon, nitrogen, oxygen
Life on Earth uses how many of the 92 elements
25
Essential material for the survival of organisms
Amino acids
Liquid on a planet must be?
Abundant and remain liquid over a reasonable temperature and pressure range
Wide liquid range is good
Due to higher likelihood of remaining liquid through climatic changes
Advantages of water
Wide range in temperature, occurs naturally in all three phases, ice is less dense than liquid water, is a polar molecule
Three major features of the moon
Highlands, maria, craters
Maria
Cover 15-20% of Moon’s surface, lower lying dark areas, have far fewer craters than the other regions of the moon. Predominantly on the Earth-facing side
Highlands
cover 80-85% of Moon’s surface, higher regions of very old rock, heavily cratered
Crater’s indicate what?
The higher the crater density the older the surface
Craters on the Moon show
It’s never had an atmosphere or water to erode the craters
Why is Mercury not habitable?
No liquid water and very high surface temperature
Why is Venus not habitable?
High surface temperature and 90 times Earth’s atmospheric pressure, clouds of sulfuric acid
Why is Mars not habitable?
Too little atmosphere to allow liquid on surface and very harsh radiation
Why are Jupiter and Saturn not habitable?
Significant vertical wind structures, elements of life must be at the right altitude to enable life to develop
Small objects in the solar system are not habitable because?
None of them are sufficiently large enough to have a significant amount of internal heat, neither do they have an atmosphere
Best chances to find life in solar system?
Clouds of venus, large satellites of the Jovian worlds and mars
Types of spacecraft
Flyby, orbiter, lander, sample return
Flyby missions
Inexpensive, uses gravity to change trajectory
Orbiters
More expensive to mount due to more fuel needed, needs a variety of instruments, uses the atmosphere to shape orbit through friction
Landers
Up close look, long term climatic and geologic monitoring
Moons core
200 km, made of mostly Iron so it has a weak magnetic field
Moons mantle is
Warm plastic and thick, it cannot produce plate tectonics or volcanoes.
