Oldies & Oddities: Closer to Mars
- By David S.F. Portree
- Air & Space magazine, November 2001
It’s a little past midnight on June 14, 2001, and Mars is a fiery orange dot in the Arizona sky. Tonight, if a line were drawn between Mars and the sun, it would pass through Earth. This geometry, called an opposition, occurs every 26 months. Telescopic observers eagerly await Mars oppositions, because they signal that the Red Planet is near Earth, making it bright in the sky and large in telescopes. Space explorers like oppositions because they are opportunities for Mars flights requiring relatively low energy. In this opposition, Mars is about 42 million miles away—the closest it has been in a dozen years.
As telescopes both in back yards and professional observatories focus on our shy little neighbor, I’m privileged to be squinting through the eyepiece of the
105-year-old telescope that truly made Mars come alive in the human imagination. It was here at Lowell Observatory in Flagstaff that Percival Lowell (1855–1916) began two decades of Mars observations, and where he set off worldwide speculation about the possibility of an advanced civilization inhabiting its surface.
I sit at the eyepiece waiting for random, surprising moments of clarity. Sometimes the dark surface areas on Mars’ orange disk look greenish, suggesting vegetation. At other times they look brown and linked by pale broad lines that fade quickly. The lines hint at some pattern, like a hieroglyph carved by a lost civilization. Over a region called Elysium I think I see clouds, but it’s tough to be sure.
Lowell was a Boston aristocrat drawn to things exotic. As a young man he lived in Japan and Korea. At mid-life, Lowell became passionate about Mars, and he journeyed into the mountains of the Arizona Territory in quest of clear skies. He established an observatory on a pine-covered ridge overlooking Flagstaff. The site, in tribute to Lowell’s lifelong pursuit, became known as Mars Hill.
Lowell’s telescope thrives today as part of the observatory’s public outreach program, for which I work as a tour guide. (Research is conducted with the facility’s other telescopes.) The six-ton instrument is still aimed by hand, creaking as it pivots on its mount. A brass eyepiece holder caps the bottom of its 30-foot steel tube, and two stacked 24-inch-wide glass lenses cap the top. It’s a refracting telescope, the last made by the respected Alvan G. Clark and widely rated the best of the Clark breed. In addition to its Mars observations, the telescope helped gather the earliest data showing the redshift of galaxies, which pointed to the expansion of the universe and the Big Bang. It was also used by the U.S. Air Force to map the moon for the Apollo program.
The current observatory director, Robert Millis, a co-discoverer of the rings of Uranus, told me that the Clark is an important artifact that represents a virtually extinct breed. “Ninety-five percent of all professional telescopes nowadays are reflectors,” he says. Reflecting telescopes, with big curved mirrors instead of smaller, pricier lenses, began edging out refractors in the 1920s, as astronomers looked beyond the planets to dim, distant objects such as galaxies and nebulas.
Lowell’s telescope traveled by train to Mexico to get a better look at the 1896 opposition—that year, Mars was low in the southern sky for northern observers, just as it was this year. There, Lowell glimpsed the mysterious lines on Mars first noted by Italian astronomer Giovanni Schiaparelli in 1877, and began careful cataloguing and mapping. Schiaparelli had called the lines canali, Italian for “grooves,” but the English-language press mistranslated this as “canals.”