# Questions for ‘A trail of cosmic dust may lead to alien life’

## SCIENCE

### Before Reading:

1. What is outer space? What kinds of things can you find there?

2. Do some research on the planet Saturn. Find three ways that this planet is different from Earth.

### During Reading:

1. What is Cassini, and what is it doing in space?

2. How did scientists figure out 50 years ago that space is full of dust?

3. What does the story point to in early 2004 that was notable as Cassini approached Saturn?

4. Why is the moon Enceladus so bright and white?

5. What is beneath the surface of Enceladus?

6. What are two things that happen to the ice spraying out of Enceladus?

7. Scientists were surprised to find that the dust grains from the moon are all the same size. Why? What did it suggest to them?

8. What is the Lost City Hydrothermal Field? What can be found there?

9. Why do scientists think that there could be alien life in the oceans of Enceladus?

10. What will happen to Cassini in 2017?

### After Reading:

1. Do you think that scientists will ever find living organisms in the oceans of Enceladus? Explain your answer.

2. Enceladus is not the only place (other than Earth) in the universe where scientists think that life might exist. Find a moon or exoplanet (non-Earth planet) that scientists have said might harbor life. Why do they think that place is life-friendly? Compare and contrast with Enceladus — and with Earth.

## MATHEMATICS

1. The Cassini spacecraft left Earth in October 1997. In February 2004, after 6 years and 4 months (or 2,314 days), the spacecraft had traveled 2 billion kilometers (1.2 billion miles) on its way to Saturn. Calculate, in either kilometers or miles per hour, how fast (on average) Cassini was traveling. Show your work.

2. The cracks on Enceladus spew out 2.5 kilograms (5.5 pounds) of mineral dust every second. At that rate, how much dust do the cracks release in a day? In a year? Show your work.