Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.
- What are Mars’ “seasonal seeps”?
- Also known as recurring slope linea, these “enigmatic streaks” appear as narrow, dark markings on many of Mars’ steep slopes and crater walls.
- What do scientists think is the source of Mars’ seasonal seeps?
- Probably the Martian atmosphere. In a process called deliquescence, “salts on the surface can absorb atmospheric water vapor and trap it in their crystal structures. Then, when the crystals warm up, they dissolve. The whole liquidy mix surrenders to the tug of gravity, and off it goes, tumbling downhill.”
- Why is the identification of liquid water so important?
- The possibility of extraterrestrial life. According to Nat Geo, “What we know so far, based on the single example of Earth, is that life tends to show up wherever there’s water. That’s why NASA’s search for life beyond Earth has been driven by the mantra, ‘Follow the water.’”
- Why water?
- Water is [one of] our only naturally occurring inorganic liquids, the only one not arising from organic growth.
- Water dissolves just about anything.
- Water is the only chemical compound that occurs naturally on Earth’s surface in all three physical states: solid, liquid, and gas. Good thing, otherwise the hydrological cycle that most living things rely on to ferry water from the oceans to the land and back again would not exist.
- Water also has an extremely large liquid range. Pure water freezes at 0°C (32°F) and boils at 100°C (212°F). Add salt and you can lower the freezing temperature. Add pressure and you can raise the boiling temperature. . . [This means that temperatures] can undergo extreme variations—between night and day, say, or between seasons—without water freezing or boiling away.
- Unlike most other liquids when they freeze, water expands and becomes less dense. [Frozen water floats, not sinks.] If it sank, ice, being unable to melt because of the insulating layer of water above it, would slowly fill up lakes and oceans in cold climates, making sea life in those parts of the world a challenging prospect.
- Water plays another key role in the biochemistry of life: bending enzymes. Enzymes are proteins that catalyze chemical reactions, making them occur much faster than they otherwise would. To do their handiwork, enzymes must take on a specific three-dimensional shape. Never mind how, but it is water molecules that facilitate this.
- Why liquid?
- The biochemical reactions that sustain life need a fluid in order to operate. In a liquid, molecules can dissolve and chemical reactions occur. [Liquid also] effectively conveys vital substances . . . from one place to another, whether it’s around a cell, an organism, an ecosystem, or a planet.
Nat Geo: Martian Map
(extra credit!) Gazetteer of Planetary Nomenclature: Mars