Saturday, December 29, 2007

End of the year non-review #2: More Hayabusa data

I played with the first of the Hayabusa data a few days ago (by that I mean in July)--and Emily Lakdawalla at the Planetary Society is too--see their post and the great rotation animation. I've been playing with a single image of the surface. If you just add the colors together, you get a relatively neutral surface:

A relatively colorless image

If you boost the saturation of the image you can begin to see significant differences in the rocks on the surface and the underlying regolith.

(movement of the satellite is the source of the color fringes)

Near-infrared Spectral Results of Asteroid Itokawa..." talks about the rich pyroxene and olivine (olivine being a very simple Fe and Mg silicate) results--suggesting the origin of the asteroid was from the inner asteroid belt, with any variations in spectra due to clast size. (see this graph for an example) (both links may require a subscription).

P.S. See additional Itokawa talk here. And see my synthesis of a color image of Earth from Hayabusa.

P.P.S. Look at that crazy huge boulder sitting on the surface: here and here!

End of the year non-review, #1

A non-review, since I didn't post about things I saved in "starred items" in Google Reader. So, some quick posts about them.

Grist complains Senator Harry Reid is defending the 1872 Mining Law, which is still on the books. Parts of it are stupid; we should hold profitable companies to clean up their messes and begin to increase the tiny rates charged for minerals on public lands. But in parts of Nevada mining is all that keeps the area inhabited. Reid comes from a down and out mining town to the south of Las Vegas that I've spent plenty of time in; and no one would argue it was having a too-hot economy. Reid also gets re-elected by the will of the people of Nevada every six years, and to be honest, it can be a close vote every time. Reid is not perfect; a true politician as I found when I talked with him years ago; but he's fantastic for Nevada--holding off the results of the "Screw Nevada" bill and deflecting the Yucca Mountain nuclear waste dump as long as possible, despite the efforts of many in both parties. He works well with Senator Ensign on nonpartisan issues for the state like smart planning on wilderness and auctioning federal lands in southern Nevada. All these things would be much worse off if he were defeated--there would be no Mining Law reform, no wilderness declarations, no effective attempt at ending the bureaucratic environmental disaster that Yucca Mountain will be.

Sunday, December 23, 2007

Update on the Mars asteroid

New observations reduce the possibility from 1/75 (1.33%) to 0.3%. (via the MPML). The error ellipse has moved from near the center of a large uncertainity to the edge of the ellipse. See a diagram here.

Friday, December 21, 2007

The Mars asteroid thingy

Speaking of 2007 WD5, the orbit is weakly constrained because the observations extend to only 29 days. The object was discovered on November 20th after it passed Earth some 4.5 million miles away on November 2th. It's currently only magnitude 22 and fading, and the moon is getting brighter in the same part of the sky, so there will be no observations for at least a week. In fact, the moon will be two moon diameters away from 2007 WD5 on Saturday evening, if you'd like an idea of where the minor planet is now in the sky. Mars is unmistakable at opposition in the East in the constellation Gemini in the evening. At time of possible impact, Mars will be in the horns of Taurus.

Usually these sorts of things tend to clear up after just a few more observations constrain the orbit better. Since it's so faint, a number of the observatories doing this sort of work (and a lot of them are amateurs doing it for free) won't be able to see it.
A good press release, with the error ellipse, which you can see is very, very long.

Play with this java orbit visualizer:

My old-fashioned planetarium program has a miss by quite a distance, but I wouldn't really be shocked at that.

Anyways, go out and see the Moon and Mars close together on Sunday night. It'll be beautiful. In the right place on Earth, the Moon will occult it.

P.S. This wouldn't be the first impact seen on Mars. The Mars Global Surveyor found 20 new craters over the course of it's mission.

Saturday, December 15, 2007

Why we can't allow the telecoms immunity

The telecoms allowed broad and widescale spying on domestic communications prior to and after the September 11th attacks from the NSA. This illegal action wasn't about terror operations, but just the easy access to constitutionally protected communications that allowed the "war on drugs" to escalate.

New York Times: Wider Spying Fuels Aid Plan for Telecom Industry

None of this is any surprise to anyone watching the wholesale destruction of the American Republic by the current administration. To listen to the director of the NSA is to think that the USA is endangered by discourse and independent thought. God forbid Americans not violate the law--oh wait, that's only for patriots.

Tell your senator that the USA will only survive if companies are required to follow the law.

Don't talk about it either

Monday, December 10, 2007

New Comet? Or is it Comet Holmes outbursting ahead of schedule?

UPDATE #2: It's not a comet, it's a fuel dump from a classified rocket launch.

On the CCD mailing list:

I just went outside and there is at least a mag 2 comet visible at the zenith. I don’t think this is Holmes….Get outside now!!!

Jon Talbot

Is it Comet Holmes outbursting short of 60 days later?

UPDATE: On the AAVSO mailing list, someone pins it down to Lacerta, and probably gets it right (satellite fuel dump):

I just went out at 00:00UT on Dec 11 UT. I looked up and in Lacerta directly between Cygnus and Cas was a large, bright diffuse object, looking similar to a comet. I'm talking bigger than Comet Holmes and probably 2nd mag. I got my 10X50 binocs and checked it out. It is slowly moving past the stars to the NE. It has a bright pin-like jet toward the NW, which can be seen unaided eye. The only thing I can figure out is that this was ejected from a satellite/rocket as some upper atmosheric experiment. It was out there as of 5 miutes ago. Anyone see it??? Any ideas on what it is???

Chris Stephan SET
Robert Clyde Observatory
184 Orday Rd.
Sebring, FL. 33875

New major exoplanet announcement from Corot?

The Corot satellite is a French astroseismology/transit/photometry project.
Steinn SigurĂ°sson over at Dynamics of Cats is pushing rumors of an announcement regarding a whole new bundle of exoplanet discoveries soon, possibly today.

For a sample of Corot data, see this 120-day graph of a star:

Image from CNES
showing various stellar oscillations as well as a periodic transit of something across the face of the star.

More rumors here too, for today.

Stellar Oscillations
Convection cells at the surface of a star create a large acoustic noise. The noise has multiple ways of traveling through the stellar interior, and can interfere constructively on the surface as the star 'rings'. It can also be used to probe the interior of the star just like earthquakes on Earth showed us the existence of the solid inner core and the liquid outer core. And it can be used to see the farside of the Sun! The ringing can have many, many modes--over a thousand. See the cute animated gif of a l=2, m=2 oscillation of a star here.

Transmission of acoustic waves through a stellar interior

Tuesday, December 04, 2007

Space Shuttle and ISS visibility in Chicago

The International Space Station is back being visible in the Chicago evening sky for the next 10 days, and the Space Shuttle is expected to launch in two days, so if the weather clears up here we'll have some great passes. The passes on the 4th, 5th, and 6th are all very good and the ISS will be fairly high in the sky at maximum elevation, although it's snowing heavily right now here for tonight's pass.

Monday, December 03, 2007

Freezing rain

I went out Saturday evening into the freezing rain because I was out of vermouth. Actually I was out of good vermouth, which is as bad as being completely out. So a trip to the good wine/spirits store ensued despite the worsening weather. Earlier in the day there had been a intense but short burst of snow that left a half-inch everywhere. Then it started sleeting, and when I left my apartment it was raining. I thought innocently that the liquid water was good, as it would melt the snow. But as I continued I realized the rain was a silent evil--it was freezing rain, icing anything it hit. Running my hand over a car window showed the rain was freezing as soon as it hit the glass. It's beautiful in addition to being evil as the trees began glazing over--even fallen, rotting leaves were gorgeous, covered in a glossy encapsulation. A flat glass covering a light became scalloped with ice so well that it appeared as if the glass was installed that way, and it wasn't obvious until I saw the flat glass on another pane.

The WGN Weather blog has a description of the processes and temperature profiles that define what precipitation you get in a winter storm such as Saturday's. In nearly all precipitating clouds the precipitation starts out as ice crystals. Depending on how the temperature increases towards the ground you can get snow, rain, or some bizarro type. The storm started cold--it was cold from the top to the bottom, and so the precipitation was all snow. As the storm progressed warm air from the south increased in the midlevel altitudes, melting the snow, but the air close to the ground, where the wind velocity is not so high, was still cold, and the rain droplets (ex-snow crystals) refroze to fall as sleet. Then, as the warm layer got thicker, there wasn't enough cold air to refreeze the rain, leaving it liquid and falling to the ground (which still was below freezing) as freezing rain. Finally later in the evening the cold air on the ground was whisked away and we had just a cold, but liquid, rain.