Space rocks probably finished off the dinosaurs and may well finish off the human race but tonnes of space rocks hammer into our planet every day with little effect. Most never even reach the ground. In all of recorded history no one has ever been killed by a meteorite, though one very unlucky dog was killed by one very rare meteorite from Mars in Egypt in 1911. Not exactly 'War of the Worlds'!

An amazing thing about meteoroids is that most of them vaporise in the atmosphere in a few seconds despite being made of solid rock and/or metal. A meteoroid with a mass of a Space Shuttle (100 tonnes) hitting the atmosphere at 8km per second can lose 99% of its mass.The Space Shuttle itself also enters the atmosphere at this speed but survives with the loss of only one or two of its one hundred million grams. The fireball at the top of this page is not a meteor - its the space shuttle 'Discovery' coming back from mission STS 103!

These resources will let you find out why meteoroids (and Space Shuttles) go so fast and discover how the Shuttle Orbiter is able to survive entry into the atmosphere intact.

Process data in a spreadsheet to find evidence for a theory. Download here (34KB xls file)

Dowload a spreadsheet of Space Shuttle Orbiter re-entry dynamics here (40KB xls file) This displays forward velocity (velocity/time) and altitude (distance/time) graphs. When the interpolated data is confirmed by NASA, this resource will be reformatted to allow students to process the data.

Download data and hand-draw the graphs here (198KB word file)

Download a worksheet of the questions below here (38KB word file)

ENTRY - Questions

How can Space Shuttle Orbiters enter the atmosphere without being vaporised like a meteoroid? Use the results from the spreadsheet to help explain.

Look at the diagram above and use it to work out the answers to these questions:

When would you expect to see more meteors – early evening or early morning?

When would you expect most meteorites to land – early evening or early morning?

The orbital velocity of the earth is 30km/sec. The orbital velocity of a meteoroid can be anything from 30km/sec up to about 70km/sec – which is the escape velocity from the solar system.

What is the maximum collision speed between a meteoroid and the Earth?

People have picked up meteorites just after they land and report that they are only warm to the touch despite having a glassy covering created by intense heat only a minute before. Why do they cool so quickly? Clues: How cold is Space? How could heat enter the meteoroid?

Click here when you are ready for the answers