November 1993 science anniversaries

This month’s science anniversaries begin with a first that was also a last. November 4 marked the 20th anniversary of the launch of Mariner 10, the first interplanetary probe to visit Mercury — and the last of the Mariners.

Mariner 10’s main purpose was to photograph Venus, which it did from 5,770 kilometres on February 5, 1974, revealing new details of the planet’s cloud cover. But while planning the Venus flyby, mission scientists realized that with careful timing, Mariner 10 could be given an orbital period around the sun exactly twice as long as Mercury, which meant it could not only visit the innermost planet, it could do so over and over, every second time Mercury went around the sun.

Before its fuel ran out, Mariner 10 was able to look at Mercury three times, on March 29, 1974, September 21, 1974 and March 16, 1975. Mercury, as you might expect in that part of the solar neighborhood, turned out to be a pretty dismal rock, but with a few surprises: an unexpected magnetic field, a very, very thin atmosphere, and cliffs apparently formed by the wrinkling of Mercury’s skin as the planet contracted, a feature seen on no other planet.

Twelve days after Mariner 10 went up, NASA launched Skylab 4, the final Skylab mission. Gerald Carr, Edward Gibson and William Pogue’s main task was studying Comet Kohoutek. You may remember that Kohoutek was touted on Earth as the “comet of the century.” It wasn’t. The Skylab crew had an ideal view, however, and gathered a ton (or tonne, if you prefer) of new data about comets.

The astronauts returned on February 8, 1974, after 2,017 hours in space, still a record for American astronauts. One day later the space station’s telemetry transmitter was switched off, and in 1979 it plunged out of orbit, parts of it making a big splash in the Indian Ocean.

Speaking of big splashes, this year marks the 60th anniversary of Nessiemania. Although there are records of sightings of something strange in Loch Ness going back to 565, it was in 1933 that a couple driving along the lochshore noticed a huge commotion in the water and for several minutes watched “an enormous animal rolling and plunging.” The press picked up on the story, and “Nessie” has been in the spotlight ever since — or would have been, except spotlights, telescopes, cameras, sonar and even submarines have never quite managed to confirm the creature exists. There are a few fuzzy photographs, however, and the first one was taken 60 years ago on November 12.

From Scotland, leap to the Caribbean for two more anniversaries: the 80th anniversary of the opening of the Panama Canal (though it wasn’t quite finished yet) on November 17, and the 500th anniversary of Christopher Columbus’s arrival on the island the resident Taino Indians called Borinquen, but which he called San Juan Bautista. We know it better by the name Juan Ponce de Leon gave it in 1508: “Rich Port” — Puerto Rico.

We tend to think of the Panama Canal more in terms of politics than scientific achievement, but many still consider it the greatest engineering feat of the modern age. It connects the Atlantic and Pacific Oceans across the Isthmus of Panama. Sixty-four kilometres long from shoreline to shoreline (82 kilometres from deep water to deep water), it shortens the trip from ocean to ocean by 11,270 kilometres.

The idea of a canal surfaced in the early 1500s, but technology didn’t catch up with imagination for 300 years. A French company headed by Ferdinand de Lesseps, who built the Suez Canal, tried to build a sea-level waterway in 1881, but malaria, yellow fever and tough terrain took their toll and the company went bankrupt.

In 1904, the U.S. government (which had negotiated an agreement with the newly independent Panama after tacitly supporting its rebellion against Colombia) began work on a lock-type canal (where boats wait in locks while the water is raised or lowered to the level of the next stage of the canal). Ten years later, under the direction of chief engineer George Washington Goethals, the canal was finished, at a cost of $336,650,000. As you might expect of something that shortens travel by more than 11,000 kilometres, it was an immediate commercial success. It’s still the property of the U.S., but a treaty ratified in 1978 turns it over to Panama in 2000.

Finally, two birthdays: November 18 was the 70th birthday of Alan Shepard, the first American into space (and the first man to golf on the moon, during the Apollo 14 mission) and November 29 was the 190th birthday of Christian Johann Doppler.

Doppler, an Austrian physicist, figured out why the pitch of a sound changes as an object moves toward or away from a listener (as when a train speeds past). As the source and listener get closer together, the sound waves between them are scrunched up, increasing the number of waves the listener receives in a given time, which is what determines pitch. As the sound source and listener move apart, the waves spread out and the listener receives fewer over a given time. This also applies to electromagnetic waves such as light: distant galaxies hurtling away from Earth appear reddish because the light waves are more spread out.

Oh, yeah, and the “Doppler effect” is also the principle behind police radar guns.

Thanks a lot, Doppler.

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