Mars comes down to Earth

For more than 30 years, lasers and their associated technologies have had strong ties with both the space program and the general aerospace industry. And many news stories about lasers and space have appeared on television. In fact, so pervasive is the association of lasers with space, it's hard to judge which came first—as in the classic conundrum of the chicken and the egg. Early industrial lasers created at aerospace companies were used to make better airplane engines, and laser rangefinding was used to measure the distance to the moon. Once scientists successfully landed a mission on the moon, they turned to laser-based analytical techniques to characterize samples retrieved from the surface. Now, lasers of some sort are on board nearly every spacecraft, and laser-based analytical techniques are applied to more than just moon rocks.

As the next planet from Earth in the solar system, Mars has always fascinated Earthlings. Years ago, a popular television show in the USA—"My Favorite Martian"—featured Uncle Martin, a friendly visitor from outer space who, except for his ears and a few odd behaviors, seemed much like the rest of his Earth family. The same might be said of Mars meteorite ALH84001 after laser-based analysis revealed the presence of carbonaceous compounds, leading scientists to speculate about the possibilities of past life on the "Red Planet." Ongoing studies of that meteorite are based on Raman spectroscopy (see cover and p. 15) and other techniques.

As I write this column, results from the Mars Pathfinder mission have trickled to a halt, but the amount of data already generated by that mission is enormous. So far, it seems the rocks on Mars look much like some of our Earth rocks. And another Mars mission now underway, the Mars Global Surveyor, has already detected the presence of a previously unknown magnetic field on Mars. Speculation abounds as to what it means. Further data gathered by this mission will include detailed surface mapping with a laser altimeter (see p. 42).

A current TV show—"Third Rock from the Sun"—is even more far-fetched than "My Favorite Martian." It details the exploits of an alien family that somehow has come to live on Earth. If laser-based technologies provide concrete evidence that Mars was once inhabited by more than just rocks, it seems safe to speculate that a future TV show might be called something like "Red Planet—Fourth Rock from the Sun!"