NASA has also put several other telescopes in space, including the Spitzer Space Telescope,
the Chandra X-Ray Observatory, and the Compton Gamma Ray Observatory. The biggest
and most advanced space telescope yet, the James Webb Telescope, is scheduled to be
launched into orbit around 2013. The James Webb will replace the Hubble Space Telescope
and will have an even greater ability to view distant objects. Other countries, including
Russia, Japan, and several European countries have also put space telescopes in orbit.
Solar System Exploration
We have continued to explore the solar system in recent years. In 1997, the Mars Pathfinder
roverlanded on Mars. A rover is like a spacecraft on wheels (Figure23.35). It can move
around on the surface of a moon or planet and collect data from different locations. Two
more rovers—Spirit and Opportunity—landed on Mars in 2004, and as of 2008 are still
sending data back to Earth. Amazingly, both rovers were only designed to explore Mars for
90 days — they have now worked for more than 15 times their intended lifespan. Several
spacecraft are currently in orbit around Mars, studying its surface and thin atmosphere.
Figure 23.35: This artists’ painting of one of the two Mars rovers shows the six wheels, as
well as a set of instruments being extended forward by a robotic arm. ( 29 )
The Cassini mission has been studying Saturn, including its rings and moons, since 2004.
The Huygens probe, built by the European Space Agency, is studying Saturn’s moon Titan.
Titan has some of the conditions that are needed to support life.
Some missions are studying the smaller objects in our solar system. The Deep Impact probe
was sent to collide with a comet, collecting data all the way. When it hit the comet, the