GEO Test 3

What layers make up Ganymede’s internal structure?

Ganymede's internal structure consists of an iron core, a rock layer, and an ice layer.

What evidence suggests Ganymede is fully differentiated?

The low moment of inertia is evidence for Ganymede's differentiation.

How deep is Ganymede's potential subsurface ocean?

Ganymede may have a possible salt-water ocean approximately 200 km beneath the surface.

What two factors contribute to Ganymede's internal heating?

Faster accretion that trapped heat inside and greater tidal heating due to gravitational interactions contribute to Ganymede's internal heating.

What material is likely responsible for Ganymede's induced magnetic field?

Electrically conductive material, likely saltwater, is likely responsible for Ganymede's induced magnetic fields.

Why is ice alone not sufficient to conduct electricity in Ganymede?

Ice alone is a poor conductor; saltwater conducts electricity well.

What is the 4:2:1 resonance among Io, Europa, and Ganymede?

In the 4:2:1 resonance, Io orbits four times, Europa twice, and Ganymede once.

How does orbital resonance increase tidal heating?

Resonance increases orbital eccentricity, leading to greater tidal and frictional heating.

Why doesn’t Callisto experience significant tidal heating?

Callisto is not part of the resonance system, resulting in little orbital eccentricity and subsequent tidal heating.

What is the composition of Europa’s surface?

Europa has a thin icy crust over a potential subsurface ocean.

What surface features are observed on Europa?

Cracks, ridges, and grooves across Europa's surface suggest tectonic and/or cryovolcanic activity.

What does the low number of impact craters on Europa suggest?

It suggests a young surface.

What is Europa's approximate density?

Europa's density is approximately 2.99 g/cm³.

What are the two proposed internal models for Europa?

One is a thick hard icy shell overlying a liquid water ocean; the other is a warm interior with soft convecting ice.

What feature on Europa resembles icebergs?

The Conamara Chaos region resembles icebergs frozen in ice.

What terrestrial feature does Conamara Chaos resemble?

It resembles Earth's ice shelves.

Why is Europa considered a candidate for life?

Potential deep-sea hydrothermal vents could provide habitats for life.

What mission is scheduled to launch to Europa in 2024?

The Europa Clipper mission is scheduled to launch in 2024.

When is the Europa Clipper mission expected to arrive at Europa?

The mission is expected to arrive in 2030.

What is the ESA JUICE mission?

The ESA JUICE Mission studies Europa, Ganymede, and Callisto.

When was the ESA JUICE mission launched?

It was launched in 2023.

When is the ESA JUICE mission expected to reach Jupiter?

The mission is expected to reach Jupiter in 2031.

What makes Io’s surface unique in the solar system?

Io's surface is the most volcanically active body in the Solar System.

Why are there no impact craters on Io?

Constant resurfacing from volcanic activity prevents the formation of impact craters.

What is Io’s approximate density?

Io's density is approximately 3.53 g/cm³.

What type of atmosphere does Io have?

Io has a thin sulfur dioxide atmosphere.

What volcanic features are observed on Io?

Huge plumes extending hundreds of kilometers are observed.

How were Io’s volcanic activities predicted?

They were predicted due to intense tidal heating.

What is the composition of Io’s interior?

Io's interior consists of an iron core and silicate mantle.

How much of Io’s mantle might be molten?

Io's mantle may be 10-20% molten.

What are Saturn’s rings primarily made of?

Saturn's rings are primarily made of water ice and minor carbonaceous material.

What is the typical particle size in Saturn’s rings?

Particle sizes range from 1 meter to less than 1 micrometer.

How far do Saturn’s rings extend above the equator?

They extend from 7,000 to 80,000 km above Saturn's equator.

How thick are Saturn’s rings?

Saturn's rings are very thin, approximately 10 meters thick.

Name one theory about the formation of Saturn’s rings.

One theory suggests the destruction of a moon/planet within the Roche limit.

What evidence suggests Saturn’s rings might be young?

Their brightness and 'cleanliness' suggest they might be younger than 4.5 billion years.

What is the Roche limit?

the distance from a celestial body within which a satellite, held together solely by its own gravity, will disintegrate due to the stronger gravitational pull of the primary body's tidal forces

How close to Saturn does the Roche limit extend?

It extends within approximately 90,000 km from Saturn.

How large is Titan compared to other moons?

Titan is the second-largest moon.

What is Titan's approximate diameter?

Titan's diameter is approximately 5,150 km.

What is Titan’s density?

Titan's density is about 1.89 g/cm³.

What is Titan’s atmosphere primarily composed of?

It's primarily composed of ~95% nitrogen and ~5% methane.

What causes the organic haze in Titan’s atmosphere?

UV processing of methane and nitrogen causes the organic haze.

What probe landed on Titan in 2004?

The Huygens probe landed on Titan.

What surface features did the Huygens probe observe on Titan?

Dry riverbeds, lakebeds, and rounded ice rocks.

What did Cassini’s radar detect on Titan?

Lakes of liquid methane, ethane, and propane.

Why is the presence of methane in Titan’s atmosphere surprising?

Methane should be destroyed by sunlight, implying active replenishment.

What does Titan serve as a natural laboratory for?

Early-Earth-like chemistry.

What is the Dragonfly mission?

A drone exploration of Titan's surface and chemistry.

When is the Dragonfly mission scheduled to launch?

It is scheduled to launch in 2034.

What evidence suggests Titan has a subsurface ocean?

gravity measurements by the Cassini spacecraft, which revealed unusual tidal effects and deformation patterns indicating a large, likely liquid, interior layer beneath the icy crust

Where are geysers observed on Enceladus?

Near the south pole of Enceladus.

What provides the heat source for Enceladus’s activity?

Resonance with Dione provides heat.

How does resonance with Dione affect Enceladus?

It provides heat for Enceladus's geological activity.

What phenomenon causes localized heating on Enceladus?

Localized heating results from observed heat exceeding expectations, known as 'shear localization'.

What has been detected in the plumes of Enceladus?

Salt and organic molecules.

What does the presence of salt in Enceladus’s plumes suggest?

It suggests a liquid saltwater ocean exists beneath the surface.

What organic molecules have been found in Enceladus's plumes?

Methane, propane, acetylene, and formaldehyde.

Why is Enceladus considered a good candidate for astrobiology?

Its subsurface ocean could be in contact with a rocky core, important for life-supporting chemistry.

Who began the search for Planet X?

Percival Lowell in 1906.

When was Pluto discovered?

Pluto was discovered in 1930.

Who discovered Pluto?

Clyde Tombaugh.

What assumption led to Pluto's discovery?

It was based on incorrect assumptions about Uranus' orbit.

What is Pluto classified as today?

Pluto is classified as a 'dwarf planet'.

How does Pluto’s radius compare to Triton’s?

Pluto's radius is 1153 km, similar to Triton's at 1353 km.

What is Pluto’s approximate density?

Pluto's density is around 2.0 g/cm³.

What is Pluto primarily composed of?

A mix of rock (50-70%) and ice.

What moon of Pluto was discovered in 1978?

Charon.

What two additional moons of Pluto were discovered in 2005?

Nix and Hydra.

What surface variations were observed on Pluto before New Horizons?

Brightness and color variations.

What causes Pluto’s reddish surface color?

Organic molecules formed from methane and ammonia ice exposed to UV.

What are the three layers in Pluto’s internal structure?

Layer 1: Frozen nitrogen, Layer 2: Water ice, Layer 3: Rock and iron core.

What provides internal heat to Pluto?

Radioactive decay of potassium, uranium, and thorium.

What surface feature would Pluto have if no subsurface ocean ever existed?

An equatorial bulge and mostly extensional tectonic features.

What surface feature would indicate the presence of a subsurface ocean on Pluto?

Mostly compressional surface features such as wrinkle ridges.

When was the New Horizons spacecraft launched?

In 2006.

When did New Horizons fly by Pluto?

In July 2015.

What shape is Pluto’s overall structure?

Pluto is almost perfectly spherical.

What does Pluto’s shape suggest about its interior?

It suggests a subsurface ocean may have existed or still exists.

What is Sputnik Planum?

A vast frozen nitrogen sea on Pluto.

What is Sputnik Planum composed of?

Frozen nitrogen.

What atmospheric component dominates Pluto’s atmosphere?

Nitrogen.

How was Pluto’s atmospheric thickness measured?

By light refraction during the flyby.

What surface processes are believed to occur in Sputnik Planum?

Convection within soft nitrogen ice.

What are the surface features of Charon?

Large canyon systems, grabens, and hemispheric differences.

What do Charon’s canyon systems suggest about its crust?

Charon experienced a violent geological past, likely due to internal processes like the expansion of a once-liquid ocean or tectonic activity as its water-ice crust cooled and contracted

What hemispheric differences are seen on Charon?

The southern hemisphere is smoother; the northern hemisphere is rugged.

What evidence on Charon supports a past subsurface ocean?

Similarity to Pluto suggests a possible past subsurface ocean.

Why was Pluto reclassified as a dwarf planet?

Due to the discovery of many similar-sized Kuiper Belt objects.

What Kuiper Belt object is similar in size to Pluto?

Eris.

What is the Planet Nine hypothesis?

It suggests a massive unseen planet is causing strange clustering of distant Kuiper Belt objects.

What clues suggest the existence of Planet Nine?

Strange clustering and non-random orientations in the perihelion of distant Kuiper Belt objects.

How massive is the hypothetical Planet Nine thought to be?

It is thought to be greater than 10 Earth masses.

How far from the Sun might Planet Nine be located?

At approximately 700 AU from the Sun.

How does volcanic activity affect planetary habitability?

Volcanism can create a stable atmosphere necessary for planetary habitability.

What role does Mars’s cooling play in its atmospheric loss?

Decreased volcanic activity led to a diminished magnetic field, allowing solar wind to erode the atmosphere.

What determines the rotation rate of gas giants like Jupiter?

The rate of spin of their magnetic field axes.

What makes Saturn’s magnetic field unusual?

Its behavior is more complex than expected with no precise rotation rate.

What two observations support the idea of an ocean beneath Europa?

A lightly-cratered surface and tidal heating due to orbital eccentricity.

Why are hydrogen and helium absent from terrestrial planet atmospheres?

Their low mass allows them to escape the atmospheres.