FC - MarsIntroduction (2)

A set of 40 question-and-answer flashcards reviewing Mars’ orbit, seasons, morphology, volcanism, water, atmosphere, climate, magnetic and gravity fields, and satellites.

What is the approximate length of a Martian solar day (sol)?

Nearly 24 hours (about 24 h 39 min).

What is the tilt of Mars’ rotational axis with respect to its orbital plane?

23.98 degrees.

What is the mean distance of Mars from the Sun?

Approximately 1.5 astronomical units (AU).

How long is a Martian year in Earth days?

About 687 Earth days (~22 months).

Because of its orbital eccentricity, between what distances does Mars’ orbit around the Sun vary?

Roughly 1.38 AU (perihelion) to 1.67 AU (aphelion).

Roughly how often do oppositions of Earth and Mars occur?

Approximately every 26 months.

During particularly favorable oppositions, what is the minimum Earth–Mars distance that can be reached?

About 55 million kilometres.

What main factor produces Mars’ pronounced seasons?

Its 23.98° axial tilt, combined with orbital eccentricity.

Which global surface feature divides Mars into northern lowlands and southern highlands?

The Martian crustal dichotomy.

By how much is Mars’ center of mass offset from its center of figure?

About 3 km toward the north.

Give one chief characteristic of Mars’ northern lowlands.

Flat, dust-covered plains with generally dark surface material.

On average, how much higher are the southern highlands than the northern lowlands?

Approximately 6 km higher.

What is the name of Mars’ largest tectonic graben system?

Valles Marineris.

State the approximate dimensions of Valles Marineris.

~4,000 km long, up to 700 km wide, and up to 7 km deep.

Which volcanic province hosts Olympus Mons?

The Tharsis region.

What is the summit elevation of Olympus Mons above the Martian datum?

About 21.3 km, tallest volcano in the Solar System.

Name three major Tharsis shield volcanoes besides Olympus Mons.

Ascraeus Mons, Pavonis Mons, and Arsia Mons.

What is the approximate diameter of Alba Patera volcano?

Roughly 1,200 km.

What causes long-period oscillations in Mars’ obliquity and orbital eccentricity?

Gravitational perturbations (notably from Jupiter) and the absence of a large stabilizing moon like Earth’s.

Which layered geologic deposits testify to past climate cycles at Mars’ poles?

Polar layered deposits ("polar layers").

Of what material are Mars’ permanent polar caps primarily composed?

Water ice, overlain seasonally by CO₂ ice.

What are the summer extent and thickness of Mars’ water-ice polar caps?

Roughly 1,000 km in diameter and about 5 km thick.

How thick is the transient seasonal CO₂ layer on the northern polar cap in winter?

Approximately 1 meter thick.

Which Martian pole retains a permanent CO₂ ice cap?

The south pole.

List two lines of evidence that Mars once had a warm, wet climate.

Outflow channels & fluvial deposits; minerals such as carbonates, salts, or hematite formed in water.

Name three present-day reservoirs of water on Mars.

Polar ice deposits, trace amounts in the atmosphere, and extensive subsurface ground ice extending into mid-latitudes.

If all current Martian water were melted, how deep an ocean could it form globally?

Enough to cover Mars with about a 10-metre-deep ocean.

What is Mars’ surface gravity as a percentage of Earth’s?

Approximately 38 % of Earth’s gravity.

What is the average surface atmospheric pressure on Mars relative to Earth’s?

About 1⁄150th of Earth’s pressure (~6 mbar).

What is the dominant gas in Mars’ atmosphere?

Carbon dioxide (≈ 95 %).

Why is stable liquid surface water impossible under present Martian conditions?

The atmospheric pressure is too low, causing water to boil or freeze quickly.

Near which orbital position does Mars experience its most intense dust-storm season?

Near perihelion (its closest approach to the Sun).

What small-scale atmospheric vortices commonly leave dark tracks on the Martian surface?

Dust devils.

Instead of a global dipole, what kind of magnetic field signatures does Mars exhibit?

Localized crustal magnetic anomalies (fossil magnetization).

Which primary technique is used to map a planet’s gravity field remotely?

Tracking spacecraft orbits via radio range and Doppler measurements.

Which laser altimeter supplied the first global topographic map of Mars?

MOLA (Mars Orbiter Laser Altimeter) on Mars Global Surveyor.

What are the names of Mars’ two natural satellites?

Phobos and Deimos.

Which Martian moon orbits faster than Mars itself rotates?

Phobos (orbital period ~7 h 39 min).

What common orbital characteristic is shared by Phobos and Deimos?

Both follow near-circular, near-equatorial orbits and are tidally locked to Mars.