Natural History Magazine | Natural Selections

Bookshelf

September 2008

By Laurence A. Marschall

Titan Unveiled: Saturn’s Mysterious Moon Explored
by Ralph Lorenz and Jacqueline Mitton (Princeton University Press, 2008; $29.95)

When the Huygens probe entered the atmosphere of Saturn’s largest moon, Titan, on January 14, 2005, there was no one at the controls, and it was nail-biting time at the European Space Operations Center in Darmstadt, Germany, where data from the probe was to be received.

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Since radio signals take more than an hour to travel between Saturn and Earth, detailed landing instructions had been loaded into the probe’s computer prior to its 1997 launch aboard NASA’s Cassini spacecraft. Mindful of recent space failures, most notably the 1999 disappearance of Mars Polar Lander during the final stages of its descent, the mission scientists were understandably apprehensive.

Hurtling downward, Huygens slammed through Mach 1 about 100 miles above Titan’s surface and marked its arrival with the firing of a small “drogue” chute out of its backside. Catching air, the drogue pulled out a larger parachute, slowing the probe to a leisurely 164 feet per second and allowing the craft to jettison its heat shield, still glowing from the friction of its encounter with Titan’s atmosphere. A while later, after a series of last-minute maneuvers and deployments, Huygens touched down, the first human artifact to land on the satellite of another planet. Operating remarkably close to plan, it began transmitting a variety of measurements to Cassini for relay back to Earth, including pictures of a hazy, rock-strewn plain. A few hours later, just as jubilant astronomers in Darmstadt were receiving the first radio transmissions, the lander sent out its last packet of data, its batteries exhausted and its mission accomplished.

Ralph Lorenz, one of the scientists who waited nervously in Darmstadt on that day, has teamed with veteran science journalist Jacqueline Mitton to convey both the human and scientific drama of remote robotic space exploration. His firsthand experience, expressed in a series of bloglike entries, makes one appreciate the compromises that have to be made to design instruments that are durable, lightweight, and effective; the program glitches and course corrections that force well-laid plans to go astray; and the ingenious ways in which Earth-bound engineers turn technical problems into research opportunities. Above all, Lorenz and Mitton reveal a world, perpetually covered with thick ocher clouds, about which practically nothing was known prior to the Cassini mission.

Thanks to the Huygens landing, and to repeated approaches by the Cassini orbiter, we now understand Titan is a unique place, shaped by geological and meteorological forces that are, in some ways, frigid analogues of terrestrial ones. Up close, we see features that resemble dune fields, river channels, lake beds, and mountains, albeit barren, desolate, and cold ones in comparison with Earth’s. At temperatures near –289 degrees Fahrenheit, ice plays the role of rock, methane drizzles from the clouds, and liquid hydrocarbons carve winding channels across the surface. The all-too-brief Huygens mission is now over, but Cassini, still in orbit around Saturn, swings by every now and then. Although Lorenz and Mitton had to end their account at press time, the unveiling of Titan continues to this day.

Thousand Mile Song: Whale Music in a Sea of Sound
by David Rothenberg (Basic Books, 2008; $27.50)

Philosopher David Rothenberg, the author of Why Birds Sing, has now turned his ear to the sea. Enchanted by the siren call of the humpback when it first reached human ears in the late 1960s, he has interviewed a selection of artists and scientists who share his fascination with the vocalizations of whales and dolphins. That’s not all: because he is also a jazz musician of some note, he has tried to communicate with cetaceans directly, joining the undersea chorus on his clarinet via an amplifier and submerged speakers, and listening for a response.

Although cetaceans are fellow mammals, they inhabit a world as alien to us as another planet. Not surprisingly, some of that strangeness rubs off on the humans Rothenberg interviewed. Why else would an otherwise ordinary individual like Paul Knapp spend twenty winters on a raft in the Caribbean listening to whale songs through a hydrophone and inviting strangers to listen? Yet for those of us who are content to admire a snippet of whale music on a CD, aficionados like Knapp serve as interlocutors between species.

Many whales can click, grunt, or squeal, but only two species, bowheads and humpbacks, actually sing structured songs. The humpback song is by far the most complex, lasting up to twenty-three hours, a vocalization longer than that of any animal in the world except perhaps a U.S. senator in full filibuster. Scientists who have analyzed the spectra of these songs describe them as a series of extended, repeated phrases that end with similar syllables or patterns of rising and falling tones—rhyming, at least to cetacean ears.

To human ears, the song of the humpback whale sounds otherworldly, yet strangely appealing. Judy Collins recorded “Farewell to Tarwathie” in 1970 accompanied by a chorus of humpback background singers, and her album Whales & Nightingales quickly rose high on the charts. When, that same year, Alan Hovhaness incorporated recorded whale songs into a classical piece, “And God Created Great Whales,” the New York Times critic commented, “His whales spoke profoundly.”

Profoundly, yes, but what are they saying, exactly? Do the songs aid in attracting females? If so, then why do female humpbacks, which do not sing, show so little evident interest in the songs of the males? Do the songs aid in navigation? In fostering group cohesion? In warning of dangers? No one that Rothenberg interviewed seems to know the answer.

As to the whales themselves, they seem to have cooperated with Rothenberg only grudgingly, if at all. The author barged in, uninvited, on several cetacean jam sessions, most notably among belugas along the coast of the White Sea, in the remote Russian Arctic, and among male humpbacks near the shore of Maui, Hawaii. You can listen to interspecies riffing on the CD that accompanies the book, and you can even watch Rothenberg playing with beluga whales on YouTube. I’m not sure there’s any call-and-response going on, though Rothenberg seems to think so. But musically? Judge for yourself: as Duke Ellington said, “If it sounds good, it is good.”

Flat Earth: The History of an Infamous Idea
by Christine Garwood and Thomas Dunne (St. Martin’s, 2008; $27.95)

Everybody knows that the Earth is a sphere. In fact, despite popular myths about Columbus’s defiance of a supposed flat-Earth establishment, the roundness of the Earth has been conventional wisdom for almost 2,500 years. In ancient Athens, Aristotle cited the always-circular shadow of the Earth on the Moon during a lunar eclipse as just one of several proofs that we live on a globe, and around 200 b.c. the scholar Eratosthenes, using the lengths of shadows at different locations in Egypt, calculated the Earth’s circumference with remarkable accuracy.

One would think that Christine Garwood would find mighty slim pickings for a history of flat-Earth dissent. On the contrary, she’s assembled an entertaining rogues’ gallery of Victorian eccentrics and modern-day fundamentalists who resist evidence virtually anyone else would find conclusive. Even in an era of daily satellite photos from space, you can still find a few serious anti-globe partisans by Googling flat Earth.

Garwood’s flat-Earthers employ a peculiar brand of inverted logic to bulwark their odd beliefs. Samuel Rowbotham, who lectured and wrote widely about the flat Earth in the mid-1800s under the pseudonym “Parallax,” described the Earth as a flat, stationary disk centered on the North Pole, ringed at its outer edges by an impenetrable barrier of ice. The Sun circled overhead, only a few hundred miles up, and the Moon and stars were luminous bodies not much farther away. If challenged during a speech, Rowbotham would confidently cite abstruse technicalities or invent spurious data. What caused day and night if the Earth did not turn? The “expansion and contraction of the solar path” and a “special law of perspective.” Since we can’t see the North Star from south of the equator, isn’t the Earth round? Not so: on 23 January, 1862, the North Star was seen from a spot 23 degrees south of the equator. The speaker’s resolve in the face of tough counterclaims was enough to persuade at least a few members of his audience.

In one of the more poignant episodes of her book, Garwood recounts the story of Alfred Russel Wallace, the great naturalist and contemporary of Darwin, who accepted a wager of £500 to prove that the Earth curved.

Laurence A. Marschall is W.K.T. Sahm Pro- fessor of Physics at Gettysburg College in Pennsylvania, and director of Project CLEA, which produces widely used simu- lation software for education in astronomy.

The test, with two presumably independent judges, was to see if two markers at the same exact height above a straight canal in England, six and three miles from a telescope, would appear to line up when viewed through the telescope. Wallace knew that the far marker would appear lower than the middle one, owing to the Earth’s curve down and away. And so it did; but in a stunning exercise of doublethink, one of the judges—who turned out to be a partisan of Parallax—interpreted what he saw as confirming just the opposite. The ensuing brouhaha was embarrassing to Wallace, and, if anything, strengthened the hand of the contrarians.

Some of Garwood’s characters were charlatans, to be sure. But a good fraction seem to have been genuine believers, most often biblical literalists who found satisfaction in holding fast to a view not shared by what they regarded as an intellectual elite. If that sounds a bit like contemporary creation science, I’m sure there’s something to be learned from Garwood’s book: that while good ideas eventually prevail, bad ideas never die.