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We now offer the Cool It! card game in our Science Store. Cool It! is the new card game from UCS that teaches kids about the choices we have when it comes to climate change.
The Mars Global Surveyor spacecraft measures The Tharsis Ridge.
Click on image for full size
NASA/JPL

Altimetry

Altimetry is a term which describes a method of measuring the altitudes of things with remote spacecraft. It is usually performed with a laser. Laser altimeters bounce beams of light from the surface and back to the spacecraft to measure the heights of mountains and depths of valleys on remote planets. This is even done for our own planet. The figure shown here shows laser altimeter results from the Mars Global Surveyor spacecraft. The red line shows the relative altitudes of the terrain underneath. Other measurements from Mars include such features as Olympus Mons, the bluff separating the southern and northern hemispheres, and other features.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF