The Space Program and Iridium

Much of our knowledge of the Solar System and outer space has come from the use of unmanned spacecraft.

Since the 1960s, the United States and other countries have used robotic spacecraft to explore the moon, the planets, and the universe beyond. Unmanned spacecraft are actually a very efficient and practical way to conduct research – these craft are much less expensive to construct than spacecraft that would need life support systems and they can continue to transmit information for years, rather than having to return to earth after a relatively short trip out.

Most unmanned spacecraft are equipped with a radioisotope thermoelectric generator (RTG), which is actually a small nuclear reactor. This reactor generates a good deal of heat from the radioactive decay of elements within the reactor, and this heat is subsequently used to produce electricity to power the craft. Because of the high temperatures caused by radioactive decay, it was found necessary to use iridium in the construction of these generators. Iridium is capable of withstanding extreme temperatures of up to 2,000 C, so it has proved to be a good servant in this case.

The Voyager spacecraft were all equipped with RTGs and have been faithfully sending information back to earth from their launching in the 1970s. Although originally planned to simply visit Jupiter and Saturn, both Voyager 1 and Voyager 2 have continued on and it is thought that both of the craft have passed the termination shock, which would put them officially outside the Solar System. Thanks in part to the iridium in the RTG, both Voyagers seem likely to continue their explorations for some time to come.

Iridium has also been used for parts of the Chandra X-ray Observatory. This satellite was launched in a joint United States/India project and it is meant to record x-ray images with its telescopes. This observatory was launched in 1999, and has been returning valuable data back to earth ever since. The Chandra Observatory makes use of a Wolter telescope which consists of mirror surfaces coated with iridium, which is the reason why the images sent back by Chandra are so astoundingly beautiful and detailed. The Hand of God, an image of neutron star is just one of the pictures sent back by the observatory. The power source for the Chandra Observatory is the RTG, once again showing the important role that iridium has played in the space program.