Mars edging in for 'close-up'

0 Comments | Deseret News (Salt Lake City), Aug 26, 2003 | by David Perlman San Francisco Chronicle

Sixty thousand years ago, the Neanderthal people and early modern humans must surely have watched a faint but familiar point of light in the southeastern sky grow brighter and brighter until its brilliant topaz-yellow light outshone everything in the nighttime heavens save the moon.

We will never know what those people may have thought or feared, because they left no record among their rare artifacts. But today we do know what they were seeing: It was the distant planet Mars, flying on its elliptical track around the sun and closing its gap on Earth's orbit while it appeared to blaze in brightness as the two planets neared.

That same phenomenon is occurring once again as Mars draws closer to Earth day by day, and on Wednesday at precisely 3:51 a.m. MDT, the fabled Red Planet will pass 34,646,437 miles from Earth -- closer than it has been in the past 60 millennia.

Few recent astronomical events have excited people on Earth more than this close encounter of the planetary kind. For weeks, stargazers have been fascinated by the growing brilliance of the ordinarily dim planet. Watchers in the High Sierra report that it already seems brighter than the Jupiter and Venus.

Amateur astronomers have been observing and photographing the Martian approach. The Hubble Space Telescope will be beaming back fresh Martian images this week, and every astronomical observatory in the world has trained telescopes on the planet at least once each night and will continue observations for weeks.

Already amateur astronomers all around Northern California are holding "star parties" where they unlimber their own telescopes to watch the brilliant planet and invite the public to share the sight.

Deseret News

graphic

Shuttle safety measures

Requires Adobe Acrobat.

Mars rises in the southeastern sky while it is still twilight, so its brightness will not be apparent until well after dark -- about 10 or 10:30 p.m. MDT, according to Andrew Fraknoi, chairman of the Foothill College Astronomy Program, and it is best seen low in the south-southeastern sky well after 11 p.m. MDT as it moves toward the west-southwest until dawn. The phenomenon will be visible well into September.

Although amateurs with relatively decent telescopes should be able to spot the Martian south polar ice cap and perhaps some of the roughest features of the planet's red surface, people equipped only with good binoculars will see little more than an exceptionally bright orange-yellow spot where a much fainter Mars would ordinarily be, Fraknoi said.

In fact, something somewhat similar occurs about every two years because of the difference in relative speeds of Mars and Earth as each orbits the sun. Earth takes a year by our calendar to revolve around the sun, while the Martian orbit takes almost twice as long -- 687 Earth-days -- because it lies farther from the sun than Earth.

Taking advantage of this close approach to Earth, two new NASA spacecraft are approaching Mars. Early next year, they will land two robot vehicles to trundle across the planet's surface under radio commands from NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Their cargoes of tiny, sophisticated instruments and cameras will sniff out the chemistry of the Martian rocks, the weather in the Martian sky, and the nature of the terrain where they may detect the strongest evidence of subsurface water -- the key ingredient of life as we on Earth know it.

Dust storms have been swirling across the Martian surface for months, but earlier observations by the orbiting Mars Global Surveyor have given Earth-bound scientists some tantalizing new clues to the existence of ancient water on the planet.

Last week, for example, scientists at Arizona State University reported in the journal Science that they have analyzed data from an instrument called the Thermal Emission Spectrometer aboard the Surveyor and found evidence of carbonate minerals in Martian dust on the planet's surface.

Carbonates are a signature that the rocky material was formed in water, but the Arizona scientists said their data showed much too small a proportion of carbonates to indicate that any lakes or oceans once abounded on the planet, as some scientists have long held.

"This really points to a cold, frozen, icy Mars that has always been that way, as opposed to a warm, humid ocean (on) Mars sometime in the past," said Philip Christensen, one of the authors of the Arizona State report.

"People have argued that early in Mars history, maybe the climate was warmer and oceans may have formed and produced extensive carbonate rock layers. If that were the case, the rocks formed in those putative oceans should be somewhere. It seems unlikely that the carbonate rocks could all be hiding out of view," Christensen said.

Nevertheless, the lure of Mars as a onetime abode of life remains - - from "The War of the Worlds" by H.G. Wells and the famed 1938 radio broadcast version by Orson Welles, to John Carter and Thuvia, Maid of Mars, in the Edgar Rice Burroughs novels, to Ray Bradbury's outstanding "Martian Chronicles," which remain popular today.