Tag: science

Sponge in space

2:38 pm

Hyperion

On August 25 Cassini did a close fly-by of the small Saturn moon Hyperion, getting as close as 15,500 miles. The mission has just released images from that fly-by.

Looks like a sponge, doesn’t it? This moon is small, only 168 miles across, which makes it about half the size of the asteroid Vesta that Dawn is presently orbiting. Why it is so peppered with craters is of course the big science question. I would guess this has something to do with the environment around Saturn, with its rings and the innumerable particles that come from it. Yet, other moons of Saturn are not as crater-filled, so there is obviously more to this than meets the eye.

This fly-by was the second closest of Hyperion that Cassini has done, the first passing over the the moon’s surface by only 310 miles. Because the irregularly-shaped moon’s rotation is more like a chaotic tumble, scientists could not predict what part of the surface they would see. To their luck the new images captured new territory.

Another fly-by is scheduled in only three weeks, on September 16, 2011. This time, however, the spacecraft won’t get as close, passing at a distance of about 36,000 miles.

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The closest supernovae in almost 25 years

7:56 pm

Astronomers have spotted the closest supernovae in almost 25 years, only 21 million light years away.

The supernova, dubbed PTF 11kly, occurred in the Pinwheel Galaxy, located in the “Big Dipper,” otherwise known as the Ursa Major constellation. It was discovered by the Palomar Transient Factory (PTF) survey, which is designed to observe and uncover astronomical events as they happen. “We caught this supernova very soon after explosion. PTF 11kly is getting brighter by the minute. It’s already 20 times brighter than it was yesterday,” said Peter Nugent, the senior scientist at Berkeley Lab who first spotted the supernova. Nugent is also an adjunct professor of astronomy at UC Berkeley. “Observing PTF 11kly unfold should be a wild ride. It is an instant cosmic classic.”

Astronomers expect the supernova to continue to brighten over the next two weeks, when it should be visible to anyone using binoculars.

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When dust, pebbles, rocks, and boulders act like liquid

3:35 pm

The science team of Lunar Reconnaissance Orbiter released an intriguing picture yesterday of what scientists call a granular flow down the side of a five mile wide crater on the far side of the moon. Looking at the image, one would swear that the darker material flowing down the slope of the crater rim is a lava flow frozen in place.

lunar granular flow

However, according to the scientists, that is not what it is. Instead, this is merely debris left behind from an avalanche.
» Read more

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Capturing an asteroid into Earth orbit

12:30 pm

orbital path after asteroid capture

Want to mine an asteroid? Rather than travel to it with all their mining equipment, three Chinese scientists have proposed a better way. In a paper published today on the Los Alamos astro-ph preprint website, they have calculated the energy required to shift the orbits of the six thousand near-Earth asteroids and place them in Earth orbit for later mining. Of these, they found 46 asteroids that had the potential for such an operation, and two likely candidates for a space mission. One 30-foot-wide asteroid, 2008EA9, will actually be in the right place for this technique in 2049. As they write,

It can be seen that the velocity increment of the 2008EA9 is relatively small (-1.00km/s) and it will very close approach [approximately 645,000 miles] to the Earth in [February] 2049. Moreover the size of the NEO 2008EA9 is very small so that the capturing of it is relatively easy.

The real problem, of course, is adding that small “velocity increment” to the asteroid.
» Read more

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Earthquake in Virginia

2:00 pm

Quake map

A 5.9 magnitude earthquake hit Virginia at about 1:51 pm (Eastern).

I am in Maryland, just outside the beltway, and felt something like an earthquake about five minutes ago. The house started to shake, then settled, then shook again. Quite startling. I opened the front door the same time a neighbor did. She had felt the same thing.

The above quake was more than 90 miles away. I wonder how bad it is there, considering the eastern U.S. rarely experiences quakes and has made no preparations for such a thing.

For updates:
» Read more

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Craters, craters, everywhere

4:13 pm

Below the fold are two images released today, one from Dawn at Vesta and the other from Messenger at Mercury. What makes them interesting to me is that, though the surfaces of both Vesta and Mercury are crater-packed, there are definitely distinct differences between them that one can spot if you look closely, all highlighting the fundamentally different environments of both worlds.

First, the Vesta photograph. The image looks out past the asteroid’s horizon, showing clearly that this dwarf planet is not spherical, with the south pole depression that puzzles scientists just on the planet’s limb. The parallel long deep grooves that are associated with this depression can be seen on the right. Notice also that the inside walls of all the craters slope downward in a very shallow manner. This gives the impression that the impacts that formed these craters smashed into an almost beachlike sandy surface. Note too the that the center of some craters have what appear to be flat small “ponds,” a phenomenon seen by the spacecraft NEAR when it orbited the asteroid Eros. These ponds are not liquid, but are actually made up of fine-grained particles that settle in the hollows of the asteroid.
» Read more

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NASA announces awards for three technology demonstration space missions

2:47 pm

NASA has announced three awards for technology demonstration space missions, all set to fly within four years. More details here.

The three missions are:

  • A solar sail demonstration mission, flying a sail 38 by 38 meter sail.
  • A demonstration of in-space laser/optical communications technologies.
  • The use of a high-precision atomic clock in space.

I especially like the solar sail mission because of its long range possibilities, though the other technologies would probably be put to practical use more quickly.

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New images from Opportunity

7:28 pm

Opportunity begins exploring the rim of Endeavour Crater, taking a bunch of new images . I especially like this one, of which I’ve posted a cropped scaled-down version below. The image looks across the 13-mile-wide Endeavour Crater to its far rim on the horizon. Note the haze. Mars very clearly has an atmosphere, even though it is far thinner than Earth’s. In the foreground are scattered rocks, ejecta produced from the impact that formed a smaller nearby crater now named Opportunity Crater.

Endeavour Crater as seen by Opportunity

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Archeologists reap treasures from a newly-discovered POW camp from the Civil War

8:58 pm

Archeologists reap treasures from a newly-discovered POW camp from the Civil War.

Camp Lawton’s obscurity helped it remain undisturbed all these years. Built about 50 miles south of Augusta, the Confederate camp imprisoned about 10,000 Union soldiers after it opened in October 1864 to replace the infamous Andersonville prison. But it lasted barely six weeks before Sherman’s army arrived and burned it during his march from Atlanta to Savannah.

Barely a footnote in the war’s history, Camp Lawton was a low priority among scholars. Its exact location was never verified. While known to be near Magnolia Springs State Park, archaeologists figured the camp was too short-lived to yield real historical treasures. That changed last year when Georgia Southern archaeology student Kevin Chapman seized on an offer by the state Department of Natural Resources to pursue his master’s thesis by looking for evidence of Camp Lawton’s stockade walls on the park grounds.

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Rats didn’t spread the Black Death

11:02 am

New research has shown that humans, not rats, spread the Black Death in the plague of 1348-1349. Also,

Sloane, who was previously a field archaeologist with the Museum of London, working on many medieval sites, is now attached to English Heritage. He has concluded that the spread of the 1348-49 plague, the worst to hit the capital, was far faster, with an impact far worse than had been estimated previously. While some suggest that half the city’s population of 60,000 died, he believes it could have been as high as two-thirds. Years later, in 1357, merchants were trying to get their tax bill cut on the grounds that a third of all property in the city was lying empty. [emphasis mine]

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The American Eclipse of 2017

10:37 am

2017 Eclipse map

Time to start making your vacation plans. On August 21, 2017 a total eclipse of the sun is going to traverse the entire length of the continental United States, from Oregon to South Carolina. Kentucky will have the longest view, with totality as long as three minutes.

And astronomers are already thinking of ways to harness the help of the American people in observing this event. In a paper published today on the Los Alamos astro-ph website, a team of astronomers are proposing organizing something they have dubbed the U.S. Eclipse MegaMovie, whereby they gather together as many images of the totality as possible and assemble them into a single film, showing the evolution of the sun’s corona as it crosses the continent.
» Read more

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Space Boat: A Nautical Mission to an Alien Sea

10:40 pm

The Titan Mare Explorer: A nautical mission to an alien sea.

If [NASA] green-lights the mission, the capsule will lift off in 2016. By 2023, TiME will be about 800 million miles away in Titan’s north-polar region, home to its biggest lakes and seas. The capsule will take photographs, collect meteorological data, measure depth, and analyze samples. TiME will have no means of propulsion once it is on Titan, so it will float, carried by breezes across the sea’s surface. Then, by the mid-2020s, it will enter a decade-long winter of darkness as the moon’s orbit takes it to the dark side of Saturn, away from the sun and communication. It won’t have a line of sight to Earth to beam back more data until 2035.

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