Tag: science

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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Legal rabbit farm raided and destroyed

3:38 pm

The abuse of power: A legal rabbit farm raided and destroyed by Colorado police.

“They’ve destroyed me emotionally, socially and professionally,” Bell said, listing numerous ways in which local animal rights activists have publicized information about the case in an effort to make her and her four children — all adults who haven’t lived under her roof for several years — look bad. But that’s not all.

“They’ve made 4-H kids all across Colorado just sob,” she said, “because I am their 4-H connection.” Bell noted that 12 of the seized rabbits belong to 4-H kids who were planning to show them at upcoming fairs — two at the Jefferson County Fair that begins Thursday and the remaining 10 at the Colorado State Fair which runs from Aug. 26 to Sept. 5 in Pueblo.

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Hubble captures a necklace in space

12:55 pm

necklace in space

Who needs aliens and imagined cities on the moon when you have a reality that produces such strange and beautiful things as the image on the right?

On July 2, the Hubble Space Telescope took this image of a planetary nebula, aptly dubbed the Necklace Nebula. As the caption explains,

A pair of stars orbiting close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.

The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star’s equator, producing a ring. The embedded bright knots are dense gas clumps in the ring.

The binary still exists, and can be seen as the star in the center of the necklace. The two stars are now only a few million miles apart and complete an orbit around each other in about a day.

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The very slow ramp up to maximum

10:38 am

an active sun

As it does every month, NOAA’s Space Weather Prediction Center released today its monthly updated graph of the Sun’s solar cycle sunspot activity. I have posted the July graph below.

For the first time in four months there was a increase in sunspot activity, albeit small. The sun has been even more active in August, as shown by the flurry of sunspots on its face from August 1 (shown on the left) and the August 8 solar flare, the most powerful produced in four years.

This monthly graph, however, continues to suggest that the next solar maximum will be very very weak, even weaker than the most up-to-date predictions for the next solar maximum.

The sunspot graph for July 2011

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Lying for Politicians

1:49 pm

With the recently passed debt ceiling deal, there are going to be a lot of news reports talking about how that deal is going to force cuts and reductions in government spending. Everyone one of these stories will be a lie.

Take for example this story today in Nature, discussing the fate of science research under the deal. Here is how they describe what will happen if the Congressional “super-committee” cannot come up with an agreement and across-the-board “cuts” are triggered:

“Then there will be extraordinary pain,” says Michael Lubell, director of public affairs for the American Physical Society in Washington DC. “And it will get worse in 2014.”

The two-stage structure of the debt deal explains both the short-term reprieve and the long-term worry. The first set of agreed cuts, totalling US$917 billion, will be spread over 10 years, but two factors mitigate their effect. First, reductions to defence spending will account for a significant share of the cuts — meaning that other US agencies won’t bear the entire burden. Second, the cuts are heavily loaded forward onto the 2014 fiscal year and beyond, in an apparent effort to shelter the current fragile economy. Only minimal cuts will be implemented in fiscal years 2012 and 2013.

The trouble with this is that it is simply not true. There will be no cuts at all, under any condition, according the debt deal.
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Endeavour Crater at last!

8:31 am

The science team for the rover Opportunity have released their first image taken from the rim of Endeavour Crater.

Since this picture looks south from Spirit Point less than a football field’s distance from the rim, it appears to look into the crater, the mountains on the right being the crater’s rim. What looks like a debris field running across the center of the image looks to me to be a combination of exposed patches of bedrock and boulders on the plateau above the rim. For the scientists, those boulders will be the prime research targets, as they are possibly ejecta produced at crater impact and could therefore be material thrown out from deep within the Martian crust.

a view of Endeavour Crater

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Nebraska rare earth mineral discovery to challenge China’s monopoly

1:46 pm

A discovery in Nebraska of rare earth minerals appears set to challenge China’s monopoly.

To me these were the key quotes from this article:

The U.S. used to produce rare earths through the Mountain Pass Mine in California, but it was shut down in 2002, primarily because of environmental concerns, including the spillage of hundreds of thousands of gallons of water carrying radioactive waste into a nearby lake.

and

Although studies have shown the U.S. has 13 million metric tons of rare-earth minerals, National Mining Association spokeswoman Carol Raulston said it does not mine any of it – partly as a result of the difficulty of obtaining permits. “One of the key problems that investors tell us about is that the permitting regime in this country is so complicated and time-consuming that it has hurt investments here in the United States,” Ms. Raulston said.

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Getting closer to Vesta

5:30 pm

close-up thumbnail

The Dawn mission team released another image today of the giant asteroid Vesta, this time taken from about 2,300 miles away. At this distance the resolution is still somewhat coarse, with the smallest visible detail about 0.43 miles in size.

To the right is a cropped section of the full image, focusing in on what appears to be a very strange geological feature, indicated by the arrows. From what I can tell, the dark meandering streak looks like a rille or flow coming out of the mound or peak near the bottom of the image. Yet, this dark meander continues directly across a crater as if it were a wind-blown dust streak.

I really have no idea what geological process created this. I also suspect that the scientists don’t quite know yet either, though I am sure they have some good theories, mostly based on the very light gravity that should exist on a world only 330 miles in diameter. As I’ve already noted, however, it is going to take them a couple of months to digest the data they are getting and come up with some reasonable conclusions. It will be fun to finally find out what they have learned.

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More evidence that there are active flows of water on Mars

2:34 pm

flow features on Mars

More evidence that there are active flows of water on Mars.

Dark, finger-like features appear and extend down some Martian slopes during late spring through summer, fade in winter, and return during the next spring. Repeated observations have tracked the seasonal changes in these recurring features on several steep slopes in the middle latitudes of Mars’ southern hemisphere.

Though there are a number of unsolved issues about these features, the best explanation appears to be a liquid brine.

Saltiness lowers the freezing temperature of water. Sites with active flows get warm enough, even in the shallow subsurface, to sustain liquid water that is about as salty as Earth’s oceans, while pure water would freeze at the observed temperatures.

Go here to see the full image.

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