Tag: science

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:
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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.
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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.
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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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Using a solar sail to deflect an earth-destroying asteroid

10:35 am

solar sail mission to Apophis

In a paper published today on the Los Alamos astro-ph preprint website, two Chinese scientists have proposed using a solar sail for deflecting any asteroid that happens to be aimed at the earth. The diagram to the right is their simulated mission to impact the asteroid Apophis, which will pass close to the earth in 2029 and — depending on whether that flyby puts it through a very small 600 meter-wide mathematical “keyhole” — could then return in 2036 on a collision course.

The idea is to use the sail to slow the spacecraft down enough so that it starts to fall towards the sun. The sail is then used to maneuver it into a retrograde orbit. When it impacts the asteroid the impact will therefore be similar to a head-on collision, thereby imputing the most energy in the least amount of time with the least amount of rocket fuel. In their Apophis simulation, a mission, weighing only 10 kilograms (about 22 pounds), launched around 2025, and hitting the asteroid in this manner in 2026, would deflect its flyby in 2029 enough to guarantee it will not fly through the “keyhole” and therefore eliminate any chance of it hitting the earth in 2036.

Obviously many questions must be answered before such a mission should fly.
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Strange craters on Vesta

4:13 pm

strange craters on Vesta

The images from Dawn keep rolling in. The picture on the right, released two days ago, shows the asteroid’s terminator. What makes it intriguing is the weird looking crater near the bottom of the image. It appears to have formed at impact on the wall of a cliff, something that at first glance seems impossible.

This is what I think happened: The impactor sliced down the wall of the cliff, but because of Vesta’s low gravitational field the impact scar never collapsed downward, filling in.

I once wrote an article about asteroids for Astronomy where I described these objects as having the consistency of mashed potatoes and ice cream sundaes. This image illustrates this nicely. The asteroid’s weak gravitational field limits the density of its material, so that puffy strange formations such as this crater can form.

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A blank sun during solar maximum

9:06 am

Though it is not yet official, it appears the sun is blank of sunspots today, for the first time since January 16.

Solar scientists have concluded that the solar minimum of the past four years has ended and that the sun is now moving towards solar maximum. The recent activity in August has seemed to confirm this. However, once the minimum has ended, the sun should not have any further blank days until the maximum is over and the sun is ramping back down to solar minimum. That the sun should appear blank again during its ramp up to solar maximum is quite unusual, probably unprecedented, and is further evidence that the sun is heading towards a period of little or no solar activity.

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