Deck 9: Life on Jovian Moons

Question 1

Tidal friction between the Earth and the Moon causes

A) the Earth's rotation to slow gradually and the Moon to move gradually closer to the Earth
B) the Earth's rotation to quicken gradually and the Moon to move gradually farther from the Earth
C) the Earth's rotation to slow gradually and the Moon to move gradually farther from the Earth
D) the Earth's rotation to quicken gradually and the Moon to move gradually closer to the Earth

Answer 1

the Earth's rotation to slow gradually and the Moon to move gradually farther from the Earth

Question 2

The first Jovian moons were discovered by

A) Galileo
B) Tycho
C) Huygens
D) Cassini

Answer 2

Galileo

Question 3

Triton, the largest moon of Neptune was probably once

A) a Kuiper Belt Object
B) a planet
C) an asteroid
D) a comet

Answer 3

a Kuiper Belt Object

Question 4

The fact that many of the larger Jovian moons orbit nearly in the equatorial plane of their host world, moving in the same direction as their planet's spin, suggest that they

A) formed from a rotating disk of gas and dust like a miniature solar system
B) were spun out from the rapidly spinning host world as it formed
C) formed elsewhere in the solar system and were later captured
D) were formed from a giant impact between the host world and another body

Question 5

Many of the smallest Jovian moons are most likely

A) captured asteroids and comets
B) captured objects from outside the solar system
C) small clumps of gas left over from the formation of the host planet
D) fragments of other moons

Question 6

Which of the following is not a moon of Jupiter?

A) Ganymede
B) Callisto
C) Titan
D) Io

Question 7

What is an indication that a planetary moon may have been captured?

A) it revolves in retrograde direction, opposite to the direction of planetary spin
B) it has a highly elliptical orbit
C) it has an orbit which is inclined to the equator of the host planet
D) all of these are indications

Question 8

Io experiences strong internal tidal heating because of

A) large amounts of radioactive decay occurring inside the moon
B) the large amount of internal heat left over from its formation
C) the strong tidal forces exerted by the outer Galilean moons, Europa, Ganymede, and Callisto
D) the strong tidal force from the massive Jupiter combined with its elliptical orbit which causes the strength and direction of the force to constantly change

Question 9

Like our own moon, many Jovian moons exhibit what is called synchronous rotation. This means that they rotate at the same rate

A) that their host planet rotates
B) as all other moons around the host planet
C) that the host planet orbits about the Sun
D) that they orbit their host planet

Question 10

The Jovian moons Ganymede and Titan are

A) larger than the Earth
B) larger than Mercury but smaller than the Earth
C) larger than the Moon but smaller than Mercury
D) about the same size as Mars

Question 11

Calculate the tidal force in Newtons that Jupiter exerts on Io (per kilogram) and compare that force to the effect of Io's own gravity. (Useful data: MJᵤpᵢtₑᵣ = 1.899 10²⁷ kilograms, rIₒ = 3.642 10⁶ meters, the average Jupiter-Io distance is 4.216 10⁸ meters, and MIₒ = 8.932 10²² kilograms)

A) 18.0 N
B) 32.5 N
C) 12.1 N
D) 99.6 N

Question 12

The largest Jovian moon that appears to have been captured is

A) Titania, the moon of Uranus
B) Io, the moon of Jupiter
C) Triton, the moon of Neptune
D) Titan, the moon of Saturn

Question 13

Compared to the moons of Jupiter, the moons of the more distant Jovian planets

A) contain a higher proportion of rock
B) are made of a mixture of rock and methane ice
C) contain higher overall proportions of water ice as well as methane and other ices
D) are made completely of methane ice

Question 14

Why is the innermost Galilean moon Io made mostly of rock while the outermost Galilean moon, Callisto made of a mixture of ice and rock?

A) Io formed close to Jupiter where the temperatures were too high for ices to form
B) Callisto was captured as it wandered in from the Kuiper Belt
C) Io once had ice on its surface which was vaporized away by volcanism
D) Callisto experience many impact by icy comets which built up a layer of ice on its surface

Question 15

Which of the following is a moon of Neptune?

A) Titan
B) Triton
C) Europa
D) Ganymede

Question 16

Jovian moons are typically made of

A) solid ice
B) ice and rock
C) rock and iron
D) solid rock

Question 17

The Jovian moons Io, Europa, Callisto and Triton are

A) larger than Pluto but smaller than Mercury
B) smaller than Pluto
C) about the same size as Pluto
D) larger than Pluto but smaller than the Moon

Question 18

Even though Jupiter's moon Io is similar in size to our geologically dead Moon, it is more geologically active than the Earth. How can this be?

A) because Io orbits very close to Jupiter, it still has a lot of heat trapped inside from its formation
B) Io is tidally heated by tidal forces exerted by the outer Galilean moons, which flex and distort its interior
C) Io has much more radioactive decay occurring inside it than does the Earth
D) Io is tidally heated due to its elliptical orbit, which causes the large tidal forces exerted by Jupiter to constantly change, flexing and distorting its interior

Question 19

The fact that the strength of gravity decreases with distance means the force of gravity exerted by one object on another (e.g., the Earth and Moon) is greater on the near side than the far side. This effect is commonly referred to as a

A) tidal force
B) differential force
C) distortive force
D) tractive force

Question 20

What is the relationship between density and distance for the four Galilean moons of Jupiter?

A) density increases with increasing distance
B) density remains constant with distance
C) density first decreases and then increases with distance
D) density decreases with distance

Question 21

Much of Europa's surface appears chaotic and clogged with huge iceberg-like blocks. This is consistent with

A) a thin icy crust that has been broken into pieces by tidal forces below which is a subsurface ocean of water
B) the surface thawing due to heat emitted by Jupiter
C) the breaking up of the surface due to plate tectonics
D) a giant impact that has recently shattered the crust into pieces

Question 22

The complexity of any life present in Europa's subsurface ocean is mainly limited by the

A) amount of water in the ocean
B) amount of available energy to sustain it
C) average temperature of the water
D) amount of organic material present

Question 23

The lack of large impact craters on the surface of Europa is consistent with

A) active volcanism that is constantly resurfacing the crust
B) the surface being covered with an ocean of liquid water
C) the crust being so thick and hard that impacts leave no marks on the surface
D) a subsurface ocean of water because large impacts will break the thin crust causing water and slushy ice below to flood out and resurface the crust

Question 24

Which Galilean moon of Jupiter is volcanically active?

A) Io
B) Europa
C) Ganymede
D) Callisto

Question 25

Which of the following best describes the most likely internal structure of Europa?

A) thin icy crust, subsurface ocean of water, thick iron mantle, central rocky core
B) thin icy crust, subsurface ocean of water, thick rocky mantle, central iron core
C) thin icy crust, thick rocky mantle, central iron core
D) surface ocean of water, thick rocky mantle, central iron core

Question 26

In the subsurface ocean beneath Europa's icy crust, if life exists, it most likely originated

A) close to volcanic vents on its ocean floor
B) on the surface and then migrated down into the ocean
C) just below the surface of its thin icy crust where sunlight is still able to penetrate
D) via panspermia from impacts

Question 27

Energy to support a reasonable total biomass of ongoing life in a Europan ocean would probably come from

A) sunlight filtering through the ice
B) organic material filtering down from the surface
C) deep-sea volcanic vents
D) meteoroid impacts on the surface

Question 28

Which of the following is seen on the surface of Europa suggests the existence of a briny ocean below?

A) eruptions of water onto the surface from below
B) spectroscopic signatures of salts on the surface
C) pools of water seen on the surface
D) all of these

Question 29

Tidal heating is not important for which of the following Galilean moons?

A) Callisto
B) Io
C) Europa
D) Ganymede

Question 30

Which of the features is seen on the surface of Europa?

A) impact craters
B) giant cracks
C) water ice
D) all of these are seen

Question 31

A mission that NASA is planning to launch between 2022 and 2025 will be able to confirm the presence of a subsurface ocean on Europa by using a

A) spectrometer to detect the spectral signature of liquid water at and beneath the surface
B) camera to observe the formation and breakup of icebergs on the surface
C) projectile to break the thin icy crust to reveal the water below
D) laser altimeter to detect the regular bulging of the thin icy crust on top of the ocean due to tidal forces

Question 32

Compared to the total energy available to support life on Earth, the total energy available to support life in a Europan ocean would be

A) about the same
B) much larger
C) slightly larger
D) much smaller

Question 33

Europa is most likely made of

A) pure water ice
B) rock and water ice
C) rock and iron
D) pure rock

Question 34

Energy to support an origin of life in a Europan ocean would probably come from

A) deep-sea volcanic vents
B) sunlight filtering through the ice
C) meteoroid impacts on the surface
D) heat generated from Jupiter's magnetic field

Question 35

Which of the three key environmental requirements for life might Europa possess?

A) a source of elements and molecules from which to build living organisms
B) a source of energy for metabolism and growth
C) a liquid medium for transporting the molecules of life
D) all of these

Question 36

Life in the subsurface ocean of Europa will most likely consist of

A) creatures similar to seals and penguins which enter the ocean through holes in the icy crust
B) plants on the ocean floor
C) simple single-celled organisms
D) fish and other complex aquatic organisms

Question 37

Perhaps the MOST convincing piece of evidence suggesting that Europa has a subsurface ocean is the

A) fact that the magnetic field of Jupiter is able to induce a magnetic field in Europa consistent with a salty ocean beneath its crust
B) fact that calculations suggest that there is enough internal heat to keep the ice melted beneath the crust
C) lack of impact craters on its surface
D) observation of iceberg-like features on its surface

Question 38

If Europa turns out to have a subsurface ocean which is a 100 km deep or more, how much water would this correspond to, compared to the amount of water in the Earth's oceans?

A) about the same
B) roughly twice as much
C) about ten times as much
D) roughly half as much

Question 39

The possibility of life in a Europan ocean probably rests on the question of

A) whether there is enough energy in a useful form to support biology
B) whether there is enough water present
C) whether there is enough raw materials to build biological molecules
D) the level of salinity present

Question 40

Why is Io's orbit about Jupiter slightly elliptical?

A) because of tidal forces due to Jupiter
B) because Io was captured
C) because of orbital resonances with the other three Galilean moons
D) because of a giant impact which occurred in the past

Question 41

How is Titan, the moon of Saturn, similar to the Earth?

A) like the Earth, Titan has an atmosphere made mostly of molecular nitrogen
B) Titan, like the Earth, has an internal magnetic field
C) like the Earth, Titan has oceans of liquid water on its surface
D) Titan is almost the same size as the Earth

Question 42

What is believed to have been the main source of Titan's atmosphere?

A) outgassing from the interior
B) gas captured from the solar nebula
C) we have no idea
D) comet impacts

Question 43

Which is the largest moon in the solar system?

A) Titan
B) the Earth's moon
C) Ganymede
D) Triton

Question 44

Which of the following is the most convincing observation that suggests that like Europa, Ganymede may also have a subsurface ocean?

A) the detection of salts on the surface that may have been brought up from below the crust
B) the presence of young grooved terrain that may be the result of cryovolcanism
C) the fact that it is the largest moon in the solar system and, hence, should have plenty of internal heat to maintain liquid water beneath its surface
D) in addition to its internal magnetic field, Ganymede has a magnetic field induced by Jupiter which is consistent with a salty ocean beneath its crust

Question 45

How do the surface temperatures and pressures on Titan compare to those on the Earth?

A) higher temperatures and higher pressures
B) lower temperatures and lower pressures
C) higher temperatures and lower pressures
D) lower temperatures and higher pressures

Question 46

If a future orbiter mission confirmed the existence of a subsurface oceans beneath Europa's icy surface, the next mission would most likely be

A) another orbiter
B) a lander
C) a flyby
D) a sample return mission

Question 47

The most abundant component of Titan's atmosphere is

A) methane
B) carbon dioxide
C) nitrogen
D) oxygen

Question 48

What source of energy might keep an ocean beneath the surface of Callisto liquid?

A) tidal heating only
B) radioactive decay only
C) tidal heating and radioactive decay
D) heat released from a partially molten core

Question 49

In addition to being the largest moon in the solar system, Ganymede, the Galilean moon of Jupiter, is

A) the only moon to have its own internal magnetic field
B) the only moon to have its own atmosphere
C) more geologically active than the Earth
D) the only moon to show evidence for a subsurface ocean of water

Question 50

Compared to life on Europa, if life exists on Ganymede it will probably be

A) less abundant and less evolved
B) more abundant and more evolved
C) less abundant but more evolved
D) more abundant but less evolved

Question 51

What is the origin of the nitrogen in Titan's atmosphere?

A) gas captured from the solar nebula
B) breakdown of ammonia (NH₃) by ultraviolet light from the Sun
C) outgassing from Titan's interior
D) impacts from comets

Question 52

The Hubble Space Telescope has recently strengthened the case for a subsurface ocean on Ganymede by observing

A) changes in time of auroras surrounding the moon
B) a thin atmosphere of water vapor above the surface
C) salts on its surface
D) jets of water erupting from the surface

Question 53

Which of the four Galilean moons is least likely to harbor life beneath its surface?

A) Europa
B) Io
C) Callisto
D) Ganymede

Question 54

In addition to nitrogen, the other main components of Titan's atmosphere are

A) ammonia and water vapor
B) hydrogen and helium
C) oxygen and carbon dioxide
D) hydrocarbons like methane and ethane

Question 55

Which of the following would make finding life in an ocean beneath the surface of Ganymede more difficult than finding life in an ocean beneath the surface of Europa?

A) a thicker ice layer above the ocean
B) the presence of high-density forms ice at the bottom of any ocean
C) fewer nutrients transported down from the surface
D) all of these

Question 56

Which Galilean moons of Jupiter show evidence for subsurface oceans of water beneath their icy crusts?

A) Europa and Ganymede
B) all four show evidence for subsurface oceans
C) Europa
D) Europa, Ganymede, and Callisto

Question 57

What source of energy might keep an ocean beneath the surface of Ganymede liquid?

A) tidal heating only
B) radioactive decay only
C) tidal heating and radioactive decay
D) heat released from its partially molten core

Question 58

The overall composition of Titan's atmosphere is most similar to the atmosphere of which terrestrial planet?

A) Venus
B) Earth
C) Mars
D) Mercury

Question 59

In addition to being the second-largest moon in the solar system, Saturn's moon Titan, is

A) the only moon to have its own internal magnetic field
B) the only moon to have its own atmosphere
C) more geologically active than the Earth
D) the only moon to show evidence for a subsurface ocean of water

Question 60

If a future lander mission to Europa confirms the existence of organic molecules at the surface, the next mission would most likely deploy a probe that resembled

A) a submarine
B) a ship
C) a car
D) an airplane

Question 61

Triton's retrograde orbit is consistent with it having

A) been spun out from a rapidly rotating Neptune
B) been captured by Neptune's gravity
C) undergone a massive impact
D) formed from a rotating disk of gas and dust around Neptune

Question 62

Most of the key energy-generating chemical reactions used by life on Earth are

A) rearrangement reactions
B) redox reactions
C) decomposition reactions
D) combination reactions

Question 63

Neptune's moon Triton

A) rotates in the opposite direction to Neptune's rotation
B) orbits in the opposite direction to Neptune's rotation
C) orbits about Neptune's rotational axes
D) orbits in the same direction to Neptune's rotation

Question 64

During its descent into Titan's atmosphere, the Huygens probe found

A) large oceans of liquid methane covering the entire surface
B) small pools of liquids directly beneath its descent path
C) a completely smooth, frozen surface with no sign that any liquids had ever been present
D) no sign of flowing or pooled liquids currently on the surface although channels carved in the past by fluids were seen

Question 65

From a chemical energy standpoint, the basic requirement for life is a situation in which chemicals naturally exist in a state of

A) instability
B) disequilibrium
C) equilibrium
D) stability

Question 66

If Triton has a subsurface ocean, it will most likely consist of

A) water mixed with ammonia, methane, or other melted ices
B) liquid nitrogen
C) liquid ammonia and methane
D) liquid water

Question 67

Even though Titan has liquid methane on its surface, some internal heat, and plenty of carbon-containing compounds, it is not a suitable place for life because

A) Titan orbits within Saturn's radiation belt so its surface is completely sterilized by high-energy particles
B) there is too much volcanic activity on the surface
C) it has no ozone layer to protect the surface from harmful UV rays from the Sun
D) it is far too cold, and methane is not a very good biological solvent

Question 68

Chemical disequilibrium inevitably exists near deep-sea volcanic vents, because

A) there are unequal concentrations of minerals and water
B) the high-temperature vent water causes water molecules to break down into hydrogen and oxygen
C) mixing between the high-temperature vent water and the surrounding low-temperature ocean water creates conditions in which minerals and water will undergo chemical reactions
D) the high pressures existing at the ocean floor cause chemical reactions between minerals and water

Question 69

Saturn's icy moon Enceladus

A) has an ancient, heavily cratered surface reminiscent of the Moon
B) is small and irregular in shape like an asteroid
C) has a smooth, icy surface criss-crossed with dark cracks
D) has fountains of ice particles and water vapor spraying out from its surface

Question 70

In chemistry, oxidation occurs when a substance

A) loses electrons
B) rearranges its electrons internally
C) accepts electrons
D) breaks into its constituent atoms

Question 71

What source of energy might keep water beneath the surface of Enceladus liquid?

A) tidal heating only
B) radioactive decay only
C) tidal heating and radioactive decay
D) heat released from a partially molten core

Question 72

Which of the following discovered surrounding Enceladus by the Cassini space suggest the presence of liquid water beneath the surface?

A) ice particles
B) sodium compounds
C) silica particles
D) all of these

Question 73

Most of the liquid hydrocarbons on Titan are concentrated in

A) lakes
B) surface oceans
C) subsurface oceans
D) ponds

Question 74

Methane should be rapidly destroyed in Titan's atmosphere, yet it is still present in appreciable amounts. How can this be?

A) on the surface of Titan live cows that are constantly producing methane gas
B) larger hydrocarbons like ethane and propane are being broken down by ultraviolet light into methane
C) methane may be continually evaporating from the surface and the interior
D) comet impacts are constantly supplying the atmosphere with fresh methane

Question 75

When the Huygens probe touched down on Titan, it landed

A) in a vast ocean of liquid methane
B) on a solid surface of frozen water and methane ices that resembled a streambed
C) in a shallow pool of liquid methane
D) on the slopes of an icy volcano covered with water and methane ice

Question 76

In chemistry, reduction occurs when a substance

A) accepts electrons
B) loses electrons
C) rearranges its electrons internally
D) breaks into its constituent atoms

Question 77

Features called "Tiger Stripes" are found on the surface of which Jovian moon?

A) Europa
B) Ganymede
C) Enceladus
D) Triton

Question 78

Triton's source of internal heat is mostly associated with

A) tidal heat associated with its elliptical orbit around Neptune
B) tidal heat left over from it being captured into orbit around Neptune
C) radioactive decay
D) heat left over from its formation

Question 79

Titan is roughly the same size as Mercury, yet Titan has an atmosphere while Mercury does not. How can this be?

A) Although Titan is roughly the same size as Mercury, it is much denser, making its gravitational field stronger
B) Unlike Mercury, Titan is constantly being bombarded by icy comets that evaporate and maintain its atmosphere
C) On its surface, Titan has volcanism that is constantly replenishing its atmosphere while Mercury does not
D) Even though Titan's gravity is weak, it is much colder, allowing molecules to be trapped in its atmosphere

Question 80

Which of the following energy sources might supply energy for life on the surface of Titan?

A) asteroid and comet impacts
B) cryovolcanism
C) chemical reactions in the upper atmosphere
D) all of these