ScienceFreePrintable

Life Beyond Earth

A free science worksheet ready for your classroom. Open in Kuraplan to grab the print-ready PDF, customize it for your students, or generate a fresh version in seconds.

Download now

Name:Date:

Life Beyond Earth

Read the briefing, then complete the mission challenges. Use evidence from the briefing and your own scientific reasoning. Remember: scientists have not yet found confirmed evidence of life beyond Earth.

Mission briefing: What counts as a clue?

Astrobiology is the study of life in the universe. To search for life beyond Earth, scientists look for places where life might be able to survive and for signs that could have been made by living things. Life as we know it needs liquid water, useful chemical ingredients and an energy source. These conditions make a place worth investigating, but they do not prove that life is there. Earth life can survive in places once thought too harsh. Some microbes live in very hot springs, salty lakes or deep-sea vents. Some microbes can live without oxygen. Organisms adapted to extreme environments are called extremophiles. They show that life can cope with a wider range of conditions than many people expect. However, Earth extremophiles still need suitable conditions for their own kind of life. Mars is cold and dry today, but evidence suggests that liquid water flowed there long ago. Scientists study its rocks for clues about ancient environments. Jupiter's moon Europa has a thick icy surface and may have a salty ocean beneath it. Saturn's moon Titan has lakes of liquid methane and ethane on its surface, not liquid water; its chemistry is interesting, but it is a very different environment from Earth. A possible sign of life must be checked carefully. For example, methane can be made by some living things on Earth, but it can also form through non-living geological processes. Scientists gather several kinds of evidence and test other explanations before making a claim.

Mission challenges

Use the briefing to help your research team decide what to investigate.

1.What is an extremophile? Choose the best definition.

An organism adapted to live in an extreme environment
A machine designed to travel through space
Any organism that lives on another planet
A rock that contains water

2.According to the briefing, name two conditions that make a place worth investigating for life as we know it.

3.A spacecraft finds a place with liquid water and an energy source. True or false: this proves that life lives there. Explain your choice.

4.Match each world with the clue described in the briefing.

Mars
Europa
Titan

A moon with lakes of liquid methane and ethane on its surface.
Evidence suggests liquid water flowed here long ago.
An icy moon that may have a salty ocean beneath its surface.

5.A rover detects methane on Mars. Give one possible living explanation and one non-living explanation for the methane.

6.A news post says, “Methane has been found on Mars, so scientists have proved there is life there.” Rewrite this as a more scientifically careful claim.

7.True or false: oxygen in the atmosphere is always necessary for life to exist. Use an example from the briefing to support your answer.

TrueFalse

8.Your team can investigate only one target first: Mars, Europa or Titan. Choose one and use two details from the briefing to explain why it is worth investigating. There is more than one reasonable choice.

9.Write one question a spacecraft could investigate to look for clues of past or present life on Mars. Then name one kind of evidence it could collect to help answer your question.

10.Complete the sentence: “Finding a place with conditions that could support life is a , not .”