Astrobiology and Mars Exploration

Why is Earth unique for life?

It features a thick atmosphere, favorable temperature, pressure, and liquid water.

What are the primary elemental building blocks of life?

Nitrogen, oxygen, hydrogen, and carbon.

How are life's basic elements present in most planets?

Through nebular theory and condensation.

What are the three main energy sources for life?

Chemical energy, solar energy, and organic matter consumption.

What mathematical law does light intensity follow?

The inverse square law.

What properties make water ideal for life?

It is polar, adhesive, has less dense ice, and a reasonable boiling point.

What alternative liquids are sometimes considered for life?

Liquid ammonia, methanol, methane, and ethane.

Why are ammonia, methane, and ethane worse solvents for life than water?

They have lower boiling points.

Why do Mercury and the Moon lack life?

They lack geological activity, an atmosphere, and liquid water.

Why is Venus unlikely to host surface life?

High temperatures from a runaway greenhouse effect and no carbon cycle.

What are the current atmospheric and surface conditions on Mars?

A thin cold atmosphere with frozen water in ice caps.

Could Jovian planets host life in their atmospheres?

Certain atmospheric sections have reasonable temperatures and potential energy sources.

Why might Jupiter and Saturn atmospheres be hostile to sustained life?

Strong winds would move life into the hot center.

Where could Uranus and Neptune potentially host life?

In their liquid inner cores, though no energy source is known.

What makes large moons of Jovian planets promising for life?

Potential subsurface oceans and energy from tidal cooling.

Why might exoplanets host life?

They may possess subsurface oceans and geological activity.

Why did Mars historically draw interest for harboring life?

It has a similar day length and size to Earth.

What were the Martian 'canals' observed by Lowell?

Actually canyons or imagined optical illusions.

What did Mariner 4 reveal about Mars?

It pictured and measured Mars as a cold, dry planet.

Where did the Viking 1 spacecraft land?

At Chryse Planitia.

What have Mars rovers and landers discovered regarding life?

None have found microbial or other life.

What is Mars atmospheric pressure compared to Earth?

About one percent of Earth's atmosphere.

Why are Martian seasons more extreme than Earth's?

Due to its more elliptical orbit.

How do the northern and southern Martian hemispheres differ?

The north has a thin crust and the south has a thick crust.

What are the three geological eras of Mars?

Noachian, middle, and Amazonian.

What is Olympus Mons?

A very large shield volcano on Mars.

What geological structures indicate past water on Mars?

Riverbed-like structures and channels from flowing water.

What are the Mars 'blueberries' discovered by Opportunity?

Spheres formed with hematite that suggest past water.

What did Curiosity find in Gale crater?

Evidence of drinkable water, clay, and sedimentary rocks.

What is a current goal of the Perseverance rover on Mars?

Searching for organic material and caching samples for return.

What does the deuterium-to-hydrogen ratio on Mars indicate?

Water vapor was once much more common.

Why did Mars become much colder over time?

It outgassed massive amounts of carbon dioxide.

What caused Mars to lose its thick atmosphere?

Decreased thermal activity and loss of its protective magnetosphere.

Which spacecraft proved Mars is actively losing oxygen and carbon?

MAVEN.

Why is carbon favored over silicon for life?

Carbon forms stable, diverse, and complex molecular bonds easily.

What are the two main forms of cells?

Prokaryote and eukaryote.

What is the primary energy storage molecule in cells?

Adenosine triphosphate (ATP).

What does the 'RNA World' hypothesis propose?

RNA predated DNA as the first self-replicating molecule.

What are extremophiles?

Organisms that thrive in extreme environmental conditions.