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The mystery of Mars’ missing oceans

Reuters, March 22, 2021 6:45PM Kids News

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A tall outcrop of rock, with layered deposits of sediments in the distance, signs of an ancient, long-vanished river delta in Jezero Crater, Mars, taken by NASA’s rover Perseverance. Picture: NASA/JPL-Caltech media_cameraA tall outcrop of rock, with layered deposits of sediments in the distance, signs of an ancient, long-vanished river delta in Jezero Crater, Mars, taken by NASA’s rover Perseverance. Picture: NASA/JPL-Caltech

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Scientists have a new idea about how Mars went from being a wet world to the desert it is today.

Billions of years ago there was a lot of water on the surface of Mars. Until now, many scientists thought the water had escaped out into space.

The new idea is that it could have been absorbed into the Martian crust.

Researchers have released a study in recent days that suggests between about 30 per cent and 99 per cent of Mars’ water may now be trapped within minerals in the Martian crust.

“We find the majority of Mars’ water was lost to the crust. The water was lost by 3 billion years ago, meaning Mars has been the dry planet it is today for the past 3 billion years,” said California Institute of Technology PhD* candidate Eva Scheller, lead author of the NASA-funded study published in the journal Science.

Early in its history, Mars may have had liquid water on its surface about equivalent in volume to half the Atlantic Ocean — enough to have covered the entire planet with water perhaps up to nearly 1.5km deep.

media_cameraMars imaged using the Hubble Space Telescope. Picture: NASA

HOW DID THE SCIENTISTS COME UP WITH THE IDEA?
Water is made up of one oxygen and two hydrogen atoms*, which is why its scientific symbol is H2O.

The amount of a form of hydrogen (called deuterium) present on Mars provided some clues about the water loss.

Most hydrogen atoms have just a single proton* within each atom’s nucleus*. Deuterium is different. It’s called “heavy” hydrogen because it has both a proton and a neutron* in the nucleus of each atom.

Ordinary hydrogen can escape through the atmosphere into space more easily than deuterium. Water loss through the atmosphere, according to scientists, would leave behind a very large ratio of deuterium compared to ordinary hydrogen. The researchers used a model that simulated* the deuterium composition and water volume of Mars.

“There are three key processes within this model: water input from volcanism*, water loss to space and water loss to the crust,” Ms Scheller said.

The scientists used the model to help them calculate how much water was lost to space and to the crust.

The researchers suggested that a lot of the water did not actually leave the planet, but rather ended up trapped in various minerals that contain water as part of their mineral structure, clays and sulfates in particular.

IS THIS WATER USEFUL?
Though in total there is thought to be a lot of this trapped water on Mars, it still may not be useful for future astronaut missions to the planet.

“The amount of water within a rock or mineral is very small. You would have to heat a lot of rock to release water in an appreciable amount,” Ms Scheller said.

media_cameraValley networks on Mars, imaged by NASA’s Viking I orbiter in September 1976. They may have been formed by subglacial water. Picture: NASA/JPL

GLOSSARY

  • PhD: qualification achieved through research that results in becoming a doctor in that field
  • atoms: the building blocks of molecules
  • proton: a positively charged particle that makes up part of and is smaller than an atom
  • nucleus: the middle (of an atom)
  • neutron: a neutral (no charge) particle that makes up part of and is smaller than an atom
  • simulated: modelled
  • volcanism: eruption of molten rock from beneath a planet’s crust

EXTRA READING

NASA rover touches down on Mars

Make some noise Mars, we’re listening

Mars InSight lander hits itself with a shovel

Ocean world discovered between Mars and Jupiter

Massive Mars lake discovery

QUICK QUIZ

  1. Which planet is the story about?
  2. Is this planet currently wet or dry?
  3. Where do scientists think the water went?
  4. What did scientists once think happened to the water?
  5. How useful is the water?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Vocabulary challenge
There are lots of scientific words used in this article. Use this partner challenge activity to help you better understand and remember some of them!

Choose five words from the story that are new or interesting to you.

Write a “clue” for each word. You may use your own pre-existing knowledge, things you learnt from the article, dictionaries and other sources to help you write your clues. (e.g. Clue: There is one in a normal hydrogen atom’s nucleus. Answer: proton)

Pair up with a partner. Take turns to give each other a clue. See if you can give the correct word to answer each of your partner’s clues.

Repeat step 3 with a different partner.

Time: allow 30 minutes to complete this activity
Curriculum Links: English; Science

2. Extension
Verbally retell this news story (to a partner or as an audio recording), ensuring you include all 5 of your chosen vocabulary challenge words from the activity above.

Time: allow 10 minutes to complete this activity
Curriculum Links: English; Science

VCOP ACTIVITY
Read with Kung Fu Punctuation
Pair up with the article between you and stand up to make it easy to demonstrate your Kung Fu Punctuation.

Practice reading one sentence at a time. Now read it again, while acting out the punctuation as you read.

Read and act 3 sentences before swapping with your partner.

Have 2 turns each.

Now as a challenge ask your partner to read a sentence out loud while you try and act out the punctuation. Can you keep up?

Swap over?

Try acting out 2 sentences.

Are you laughing yet?

Have fun acting out your punctuation.

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