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What Mars is made of

Radiation and the atom · level 1, lesson 6 of 6

A question to start

Mars is called the Red Planet. If you scooped up a handful of its ground, what would you be holding?

The idea

The rover Curiosity scooped up some Mars soil and looked at it inside its own little laboratory. It found:

  • tiny bits of volcanic rock, a lot like the volcanic soils of Hawaii;
  • fine dust, which the wind blows all over the planet;
  • iron in the rock and dust. Like an old nail left out in the rain, the iron has rusted, and rust is red. That is why Mars looks red.

What is missing? So far, no living things have been found in Mars soil, and no rotted plants. And there is no liquid water in the gaps, though in some places there is ice just under the surface.

Soil Mars Earth
Bits of rock yes, mostly volcanic yes
Rotted plants and animals none found yes
Living things none found yes, huge numbers
Colour red-brown, from rusty iron brown, black, red or yellow
the Red Planeta rover scoops some soil

Worked examples

1. Why red. The iron in Mars rock has rusted, like a nail left outside. Rust is red-brown.

2. Like Hawaii. The bits of rock in Mars soil came from volcanoes, so the soil is like soil near volcanoes on Earth.

3. Growing plants. To grow food on Mars, people would need to add water, food for the plants, and air with the right gases, and wash out some harmful salts.

Try it

  1. What did Curiosity find Mars soil is made of?
  2. Why is Mars red?
  3. What is in Earth soil that has not been found in Mars soil?
  4. Which place on Earth has soil a lot like the Mars soil Curiosity tested?
Answers
  1. Tiny bits of volcanic rock and dust, with rusted iron in it.
  2. The iron in its rock and dust has rusted, and rust is red.
  3. Living things and rotted plants.
  4. Hawaii, where the soils come from volcanic rock.

Common mistake

"Mars is red because it is hot." Mars is very cold. It is red because of rusty iron in its dust.

Where it leads