Space probes fly over hostile environments, sending back pictures, landing where human beings cannot go, they bring back data and samples for analysis. These fabulous devices add to our knowledge of planets, comets, asteroids and many other bodies.
They have names like Pioneer, Voyager, Galileo, Magellan and Ulysses. They are the explorers of our times, successors to Marco Polo, Christopher Columbus, and Ferdinand Magellan, who explored our globe before Renaissance. These modern explorers are robots; as substitutes for our eyes and other senses, they have transformed our ideas about the solar system in a single generation.
Space probes are among our most ingenious technological inventions. They must not only travel hundreds of millions of kilometers in the hostile environment of interplanetary space, but also complete all mission maneuvers – including landing – using onboard computers, with no assistance from Earth. A typical probe has two modules: an orbiter and a lander.
Pioneer 10 and Pioneer 11 were the first probes to venture beyond the orbit of Mars. These small robots (260 kg) were launched in March 1972 and April 1973. Pioneer 10 was the first probe to enter the asteroid belt, which it crossed uneventfully. In December 1973 it passed within 130,000 km of Jupiter and transmitted the first close-up images of the giant planet; it observed Jupiter’s intense magnetic fields and discovered that it has no solid surface.
The Pioneer probes carried a gold plaque bearing a message designed by the American astronomer Carl Sagan. Information on the probe’s origin and launch date and on human civilization was engraved on it, intended to be seen by beings who may intercept the probe outside the solar system thousands of years from now.
Unlike launch vehicles, the Space Shuttle is reused entirely except for the external tank. In more than 30 years, there have been over 100 Shuttle launches, with only two failures (Challenger, in 1986, and Columbia, in 2003). The Shuttle launched the Galileo, Magellan, and Ulysses space probes, and it placed the Hubble Space Telescope in orbit.
Space probes and Shuttles help us measure, to the extent that is possible, the immeasurable space in our small corner of the universe.