AirSpaceMag.com

The Cassini probe to Saturn and Titan is just one of those spacecraft that keeps returning very cool stuff, such as the beautiful view of Saturn during its equinox a few months ago.

Now, the mission has just released tantalizing footage of Saturn’s moon Janus, which is about 111 miles across, overtaking another of the planet’s larger moons, Rhea, about 949 miles across. The video is actually 12 frames snapped by Cassini over a 24-minute period on November 8, 2009.

Scientists later reformatted the series of images on a computer to smooth out the moons’ motions between the frames. Janus is the tiny white dot coming from the far left to the far right, about 1.4 million miles away from the spacecraft, while Rhea was about 1.2 million miles away from it. Janus orbits Saturn at about 36,000 miles per hour, double the speed of Rhea. For a better, slower version of the video, go to this page and click on “Flash 2.0 MB.”

“As yet another year in Saturn orbit draws to a close,” said Cassini imaging team leader Carolyn Porco, “these wondrous movies of an alien place clear across the solar system remind us how fortunate we are to be engaged in this magnificent exploratory expedition.”

Ellyson testing a seaplane on the Potomac River in 1911. (Photo: Library of Congress)

On this day in 1910, Theodore “Spuds” Ellyson, a 25-year-old Navy Lieutenant from Richmond, Virginia, was ordered to report to Glenn Curtiss’s flying school in San Diego as the first Naval officer assigned to aviation.

“What was accomplished [in San Diego] is now history,” Ellyson wrote later, “namely the development of a machine that could rise from, or land on, either the land or the water, a feat that had never before been accompished.” A month after he reported to camp, Ellyson was the first passenger to fly in a floatplane, with Curtiss at the controls.

Ellyson had six classmates, three from the Army and three civilians. “All of us who were learning to fly were also interested in the construction of the machines, and when not running “Lizzy” (our practice machine) up and down the field, felt honoured at being allowed to help work on the experimental machine. You see it was not Curtiss, the genius and inventor, whom we knew. It was “G. H.,” a comrade and chum, who made us feel that we were all working together, and that our ideas and advice were really of some value.”

Even though he was a pioneer of naval aviation, Ellyson’s forecasting ability was a little off. In 1912 he predicted:

In my opinion the aeroplane will be used by the Navy solely for scouting purposes, and not as an offensive weapon as seems to be the popular impression. This impression is probably enhanced by the recent newspaper reports of the damage inflicted upon the Turks in Tripoli, by bombs dropped from Italian aeroplanes. Even could an explosive weighing as much as one thousand pounds be carried and suddenly dropped without upsetting the stability of the aeroplane, and were it possible to drop this on a ship from a height of three thousand feet, which is the lowest altitude that would ensure safety from the ship’s gun fire, but little damage would be done. The modern battleship is subdivided into many separate water-tight compartments, and the worst that would be done would be to pierce one of these, and destroy those in that one compartment, without seriously crippling the gunfire or manoeuvring qualities of the ship. In only one way do I see that the aeroplane can be used as an offensive weapon, and that is when on blockade duty, with the idea of capturing the port, ships out of range of the land batteries could send out machines with fire bombs and perhaps set fire to the port.

More coolness in Google Earth: A virtual helicopter flight over the Chamonix Valley in France, including Mont Blanc, the highest mountain in western Europe. Take the whole tour at this site (you’ll need the Google Earth plug-in, which is easy to install) or watch a short YouTube video below:

Little telescopes, little planets: The MEarth array on Mt. Hopkins, Arizona (Photo: Dan Brocious, CfA)

Announcements of newly discovered planets come so frequently these days that it’s hard to tell which ones are significant. But GJ 1214b deserves its moment of fame.

Discovered by a team led by David Charbonneau of the Harvard-Smithsonian Center for Astrophysics, the planet is only 5.4 times the diameter of Earth, one of the smallest ever found. Its mass is just 6.5 times Earth’s, yielding a density about twice that of water, which leads to speculation that the planet has deep oceans. It orbits very close to its host star—a red dwarf called GJ 1214 located 40 light years away in the constellation Ophiuchus—so its surface should be as hot as Venus. And that’s actually pretty cool for such a close-in planet.

All of this adds up to what planet-hunter Geoff Marcy, writing in the current issue of Nature (which published Charbonneau’s paper), calls “the most watertight evidence so far for a planet that is something like our own Earth, outside our Solar System.”

Almost as impressive is how the planet was discovered—with an array of telescopes no bigger than what many serious amateurs have at home. The new MEarth (pronounced “mirth”) project hopes this is just the first Earthlike planet to be discovered around a small, nearby star—which is exciting news.

Not your ordinary space rock. (NASA image)

In 1982, the idea that a chunk of rock could be hurled from the moon to Earth by a lunar impact was considered pretty far out. For one thing, wouldn’t such a massive, high-energy explosion destroy the evidence by turning the excavated rocks to glass? Besides, meteorites were well known to come from small bodies like asteroids.

On January 18 of that year, a pair of geologists hunting for meteorites on the icy ground in Antarctica’s Allan Hills region came across a greenish-tan sample they tagged as ALHA81005. It was the last stone they found that day before returning to camp—in fact, the last one of 373 specimens collected during the 1981-82 field season.

Back in the lab at NASA’s Johnson Space Center, scientists immediately recognized the rock as unusual. When a thin section was sent to the Smithsonian’s Brian Mason, an internationally known expert on lunar geochemistry, he commented in a scientific bulletin: “Some of the clasts resemble the anorthositic clasts described from lunar rocks.” Mason, who died last week at the age of 92, was the first to make a connection between a meteorite found on Earth and the samples returned by the Apollo astronauts a decade earlier.

Later analysis confirmed Mason’s suspicion. The types of glass particles in the meteorite matched those in lunar rocks exactly, as did the ratios of iron and manganese. Impact experts even came up with an explanation for how ALHA81005 got here in one piece. It turns out that rocks lying close to the moon’s surface would be spared the worst shock effects in an impact. In fact, the lunar meteorite was no more damaged than other rocks Apollo astronauts had picked off the ground, even though it blasted off the moon at a speed exceeding 1.5 miles per second (lunar escape velocity).

When scientists presented these and other results at a conference more than a year later, “No one in the large crowd even stood to object to the provocative claim,” according to Science magazine. “The psychological barrier to the idea that meteorites can originate on large bodies [including Mars] had been broken.”