Thursday, 31 May 2012

Fire, Darkness, and Starbirth: A whistle stop tour of Cygnus X

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A little while ago I posted this image of the Cygnus X star-spawning region:

















Image above: A grand view of Cygnus-X, a massive complex of star spawning gas and dust, as seen by the ESA Herschel space observatory, in infrared light. Image courtesy of ESA. Yes I know it goes over the border a bit (Edit: It doesn't now!). I couldn't bear to show it any smaller.

It made my brain explode, although not literally. If it had done that I wouldn't have been terribly, terribly, tempted to set it as my desktop background - and I've had to put a moratorium on changing the desktop. I was making a new one every time another jaw dropping space image came down, which meant twice a day some weeks.

It wasn't until a few days ago that this occurred to me: As well as being stunning to look at - in fact one of the things that makes it so stunning - you can tell with a glance that this is a vast, complex, alien realm.
With a lot going on in there that has bearing of our own star systems deep past I ought to talk about some of the things that we know, or strongly suspect, might be hiding in that amazing picture.

So, here is the tour of Cygnus X:

The Milky Way galaxy as imaged by DIRBE (Diffuse Infrared Background Experiment). Cygnus X is circled in green. Image courtesy of NASA.

All good tours start with some background:
The Cygnus X region, located 4,500 light years away in the direction of the Cygnus constellation, was first identified as unusual by two radio astronomers: J. H. Piddington and H. C. Minnett.
They were 'listening' to radio signals from space, and found a diffuse but powerful region of radio emissions in the constellation of Cygnus. Believing the source to be a vast cloud of ionised interstellar gas [1], they christened it Cygnus-X to separate it from the radio emitting galaxy Cygnus-A, which lies in the same part of the sky.

As it turned out, the cloud is one of the biggest and most active in the local galaxy, weighing in at something like three million times the mass of our sun. It is a birthplace for giant blue stars [2], and so the huge complex of gas and dust hums with cosmic rays [3], and electromagnetic radiation [4] on almost every frequency.
As such its a prime target for astronomers, and some of the greatest observatories on Earth, and in space, have devoted time to it. Infra red observations by space observatories like Spitzer [5] and Herschel [6] - using frequencies of infra red light that are blocked by Earths atmosphere - can image otherwise invisible objects behind veils of dust.

The section of Cygnus X studied by the Spitzer infra-red space telescope. Image courtesy of NASA/JPL.

The titanic blue suns shape the cloud around them, bullying the clouds hither and thither by high power stellar winds and high energy radiation. Some of these stars are right on the edge of exploding [7], as gravity and their over grown fusion hearts teeter along a knife edge balance, known as hydrostatic equilibrium. The huge suns determine which of the growing younger stars make it, and which die young, as they push the cloud material about, feeding some stellar embryos and starving others.

Image above: A false colour, infra-red, Spitzer Space Telescope image of Cygnus X. Hugely overpowered stellar winds from blue giants  and angry young protostars have blown voids into the clouds, giving them a foamy texture. Image courtesy of NASA/JPL.

But what else is there? I can't zoomify the image enough to show all the things that are, or could very well be, in there. But here are some examples of the things we know lurk in such chaotic and seething parts of the galaxy:

On the right hand side of the image at the very top of this post we see strings and filaments of gas, where the cloud is collapsing to firm new stars. Some of the young stars are forming inside long tendrils of cloud material - like the famous 'pillars of creation' in the Orion Nebula - and some are forming along huge filaments of cloud, like berries on a vine.


Image above: A close up on the most complex region of filaments in the newest Cygnus-X image. Image courtesy of ESA.

In time the filaments will collapse further, into Bok globules [8], which block out the visible light of the growing stars but can still be pierced - up to a point - by sensitive infra red telescopes like Spitzer:


Image above: Bok globules in the Carina Nebula, as seen by the Hubble Space Telescope . Image courtesy of NASA/JPL/ESA.

Herbig-Haro objects [9] are jets of ultra-hot gas, as much as twenty Earth masses worth, spat out of the poles of new-born stars at hundreds of kilometres per second. Where this blast ploughs into the surrounding gas it excites the gas molecules, causing the green-blue glow. These are more common from growing binary star systems:  

Video above: Hubblecast on Herbig - Haro stars. Video courtesy of ESA.

Propylyds [10] are protoplanetary discs orbiting the infant stars, where the building blocks of new solar systems are growing, even as matter from the inner edge of the disc is gulped down onto the young stars surface by its magnetic field and vapourised:

Hubble images of propylyds in the Orion nebula. Image courtesy of NASA/JPL.

Cygnus OB2-12 is a blue hypergiant star [11], 92 times more massive that the sun, millions of time brighter than our sun, and over 18,000 degrees kelvin at the surface, that may be blowing itself apart as we watch.


Artist impression of a Hypergiant rising over a nearby planet.Image courtesy of Supportstorm

The open cluster [12] NGC 6910, a family of young stars still surrounded by the remnants of the clouds that gave birth to them:

Image above: The open cluster NGC 6910, a gaggle of young stars. Image courtesy of Dr. Franz Gruber.


Image right: The Gamma Cygni supernova, or to be more precise, the still expanding remains of the giant star that caused it.                                                                 The 7000 year old gamma Cygni supernova remnant, a vast zones of destruction almost a hundred light years across, with the stellar core still 'living' in the centre as a pulsar [13]. Pulsars are balls of superdense matter with an iron crust and an interior of neutron super fluid [14], a pinhead of which would outweigh a supertanker. The dead star is still spinning hundreds of times a second, giving off twin lighthouse beams of radiation, and powering a magnetic field up to 1000,000,000,000 Gauss. By comparison the whole of Earths iron core manages a field strength of 0.3 Gauss. Even weirder, its electric field is so strong that it spontaneously decays [15] into matter and antimatter, electrons and positrons 'just' appearing out of the intense electric field.

And where you have lots of unstable stars, and at least one confirmed supernova, you will almost certainly find others, and their 'undead' stellar leftovers: Neutrons stars [16], black holes [17], perhaps even stranger things like quark stars [18].....

Finally, just because space explorers are great, here are a selection of amazing views of Cygnus X, in frequencies across  the electromagnetic spectrum:



Video above: Cygnus X, from a wide variety of instruments. Video courtesy of NASA.

There may be even stranger things in such regions of space. To really push the speculative boat out: A mix of dust and plasma - such as clouds like Cygnus-X are made of -  is known to form 'crystals' where the dust forms a regular repeating pattern in the plasma. Computer simulations have suggested that plasma crystal structures not unlike DNA [19], with some  ability to evolve and replicate, may be possible.

All the above is just a slice of the things at play in Cygnus X, and similar, wilder regions like the Tarantula Nebula [20] . And it amazes me still further to think that our Sun and solar system was probably born in a not dissimilar place, almost five billion years ago...

And ,in other news much, much closer to home: A video of the Sutter's Mill meteorite [21] -a real relic from the solar systems earliest times - has surfaced. I looked for hours for one when I posted on the subject a while back, and I'm thrilled that someone has managed to take a video of the minivan sized space rock hitting our atmosphere. And exploding with the force of small nuclear weapon. Only a small one though. Enjoy!



Video above: Big rock smashes into Earths atmosphere. And you've gotta love that soundrack. Video courtesy of Shon Bollock.
List of links:
[1]http://www-ssg.sr.unh.edu/ism/what1.html
[2]http://www.sciencedaily.com/articles/b/blue_supergiant.htm
[3]http://helios.gsfc.nasa.gov/qa_cr.html
[4]http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html
[5]http://www.spitzer.caltech.edu/
[6]http://herschel.esac.esa.int/
[7]http://www.astronomynotes.com/starsun/s7.htm
[8]http://www.universetoday.com/24499/journey-inside-a-bok-globule/
[9]http://www.stsci.edu/stsci/meetings/shst2/ballyj.html
[10]http://campus.pari.edu/mwc/html/proplyds.html
[11]http://cronodon.com/SpaceTech/Hypergiant.html
[12]http://messier.seds.org/open.html
[13]http://imagine.gsfc.nasa.gov/docs/science/know_l2/pulsars.html
[14]http://physicsworld.com/cws/article/news/2011/mar/02/neutron-star-has-superfluid-core
[15]http://adsabs.harvard.edu/full/1972ApJ...178..809P
[16]http://imagine.gsfc.nasa.gov/docs/science/know_l1/neutron_stars.html
[17]http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-a-black-hole-k4.html
[18]http://news.discovery.com/space/why-are-quark-stars-so-strange.html
[19]http://physicsworld.com/cws/article/news/2007/aug/15/helices-swirl-in-space-dust-simulations
[20]http://apod.nasa.gov/apod/ap051212.html [21]http://apod.nasa.gov/apod/ap120428.html

Tuesday, 29 May 2012

Man weighs asteroid with radio waves

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It's late, so just a deep space quirky (Edit, I added a few pictures):

Astronomer Steve Chesley has managed, using data from the Goldstone Solar System Radar [1], the Spitzer Space Telescope [2], and the Arecibo radio observatory [3], to make the most accurate estimate yet as to the mass of asteroid 1999 RQ36 [4].

 Image left: The titanic Arecibo radio dish, an eye on the universe fit for spaceship Earth. Image courtesy of the National Astronomy and Ionosphere Centre.

The 600 meter wide space rock weighs in at sixty million tons [5], and is set to be visited by the OSIRIS-REx mission, which should begin in 2016. Chesley presented the finding at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan. 

He has also measured the effects of the Yarkovsky force [6], where an asteroid absorbs sunlight and re-emits it as heat causing a small propulsive effect, on this big tiddler of an asteroid: The tiny but real force has moved the rock about one hundred and sixty kilometres off course.

Pinning down the mass of 1999 RQ36, and the size of the Yarkovsky force it feels, will make it easier to determine if this Earth crossing asteroid will ever hit us. There are eight possible impacts in the last thirty years of the 22nd century, although the total chance of any of them happening is less than a tenth of a percent.

OSIRIS-REx [7] is aimed at uncovering our solar systems origins, and how the molecules that pre-cursored life formed. 1999RQ36 is a carbonaceous asteroid [8], potentially rich in these.

Here's a very atmospheric run down on the mission courtesy of the University of Arizona:



List of links:
[1]http://deepspace.jpl.nasa.gov/technology/95_20/gold.htm
[2]http://www.spitzer.caltech.edu/
[3]http://www.naic.edu/
[4]http://www.space.com/11802-nasa-asteroid-mission-dangerous-1999-rq36.html
[5]http://www.nasa.gov/mission_pages/asteroids/news/asteroid20120524.html
[6]http://en.wikipedia.org/wiki/Yarkovsky_effect
[7]http://osiris-rex.lpl.arizona.edu/
[8]http://www.psrd.hawaii.edu/April11/amino_acids.html

Sunday, 27 May 2012

Music of the Spheres...

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A very quick post today, (I spent hours on a long one, realised it was midnight and decided you can wait until tomorrow for the long one - work in the morning. 5.30. Ouch) but one that shows art and astronomy colliding. I don't know if I've posted this before, but it deserves re-posting at least once: Music made from pulsar beats:


Video courtesy of Reimhaus.

List of link:
http://www.jb.man.ac.uk/pulsar/Education/Sounds/sounds.html

Friday, 25 May 2012

The Dragon roars, and how the Moon got its scars...

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As you will probably have heard, SpaceX [1] have become the first private organisation to reach the ISS. The Dragon capsule, with its cargo of supplies, reached the orbiting laboratory and successfully docked there at 16:02 UTC. My heartfelt congratulations to the SpaceX team!


Video above: The capture of a Dragon, courtesy of SpaceX. Note the purple dragon taking part in events at mission control.

The ship first manoeuvred to within ten meters of the space stations hull, and was then captured using the 58 foot long robotic arm. It was carrying scientific equipment, computer hardware, food and sundries. Hopes are high across the world that this represents the dawn of a new era of private transport to LEO, freeing up NASA to push further into the solar system. Hopefully with visits to, just for example, asteroids!

Asteroids, and the ancient Moon, are also the subject of another piece of intriguing news: A re-examination [2] of rock samples, bought back from the moon by the Apollo missions, have found fragments of chondritic asteroids [3] - asteroids made of (nearly) unaltered early solar system materials - embedded in them.


Image above: Astronaut James Irwin fiddling with his lunar rover. Oh, and the desolate majesty of the Moon providing background. Image courtesy of NASA. 

There is a marked contrast between the lunar breccia [4] (rock made of broken up bits of other rocks) samples older than 3.4 billion years, and those that are younger: The older samples show fragments that are almost universally from chondritic asteroids, whereas the younger samples show a much wider diversity of asteroid fragments. The younger samples are also more in line with the current overall composition of the space rocks hitting the Earth today.
This adds weight to the 'Lunar catclysm' [5] idea, which says that the Moon, and probably the Earth to, underwent a 'blip' of very intense bombardment, ending about 3.4 billion years ago. The evidence of the hammering has been removed from Earths surface by billions of years of weathering and plate tectonics, but the Moon has preserved a pristine record. Based on the number of big craters the Moon has from that time the Earth would have been hit by nearly twenty thousand objects, leaving craters up to a thousand kilometres across.

Image right: A map of the 180 Km wide Chicxulub crater. Imagine that, happening 17,000 time over, some smaller, some a lot bigger. Bad hair day for ancient Earth? I think so.

This would have made Earth, with its bigger gravity and larger target, a poor place to stand at that time.

The impacts would have altered the surfaces of both worlds totally. It was that destructive that mountains, seas, whole continents, would have risen and fallen like bedsheets after a bad curry.
Interestingly the earliest evidence of simple life on Earth dates from just after this time, suggesting that life got started (again, perhaps!) quickly after it was all over. Since chondritic asteroids can be rich in carbon compounds, including biologically relevant ones such as nucelobases [6] and amino acids, the bombardment may even have set the stage for the emergence of life.


Image above: The 'blip' in the rate of asteroids hitting the Moon, called the Lunar Cataclysm. As blips go it's fairly big. Image courtesy of NASA/ LPI-JSC.

But, as with all good science, this find leaves us with more questions. The obvious one being: What caused the Earth-Moon system to suddenly become a shooting gallery?

Although there is absolutely no sign of a swarm of massive asteroids on its way here anytime soon, the answer to that question will help determine the answer to the next, which could be - one day long from now - of life and death importance: Will it happen again?

List of links:
[1]http://www.spacex.com/
[2]http://lunarscience.nasa.gov/articles/nlsi-team-detects-actual-remnants-of-ancient-asteroids-on-the-moon/
[3]http://dawn.jpl.nasa.gov/meteorite/explore_meteorites_chondrites.asp
[4]http://curator.jsc.nasa.gov/lunar/letss/breccias.pdf
[5]http://www.lpi.usra.edu/nlsi/publications/InnerSolarSystemCataclysm.pdf
[6]http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html

Wednesday, 23 May 2012

Worlds on the edge of knowledge: Pluto, Charon, Nix, Hydra, and, um.... S/2011 P1

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Image above: The Pluto system, as seen by Hubbles Wide Field Camera 3 ultraviolet visible instrument, showing the motion of tiny little moon S/2011 P1 (labelled 'P4' on the image). Image courtesy of NASA/JPL.

OK, so the last one doesn't even have a real name yet. But that's the point: Our knowledge of the Pluto [1] system is still expanding, and when the New Horizons [2] probe reaches it in 2015 it's going to get a whole lot bigger. 
Pluto first cropped up in  1930, when Clyde Tombaugh [3] was searching for the planet believed to be responsible for unexplained perturbations in the orbit of Neptune. As it turned out Pluto, at just over a fifth the mass of our Moon and about two thousand km across, was much to small to cause the observed changes in the orbit of Neptune. But Clyde had struck it lucky, and for many decades Pluto was regarded as the ninth planet despite its small size.
Image above: The original photographic plates that led to the discovery of Pluto. See it? Well it's got an arrow pointing to it. Which helps. But imagine trying to spot that tiny moving blip without an arrow to point it out. Image courtesy of the Lowell Observatory.

Oh, the name? Suggested by an eleven year old schoolgirl, Venetia Burney, who got £5 for coming up with the winner. That's about £230 in todays terms- who says Astronomy and Greek mythology don't pay off?
Image Left: The negative images that led to the discovery of Charon. The lump on the top of the left hand image is the water ice moon. Image courtesy of the US Naval Observatory.

In 1978 James Christy noticed a lump on the images of Pluto, that moved periodically. This lump turned out to be Charon [4], the largest moon of Pluto. Charon is so large, compared to Pluto, that the two worlds orbit each other, moving around a point in space (called the barycentre [5]) between the two of them. In 1985 evidence of a thin, thin, thin atmosphere [6] was found, and confirmed in 1988.

Then, in 1990 the Hubble space telescope [7] was launched. It had some (coff) 'teething problems' at first, then it opened up a whole new sky for us.
Images left: Top: Hubble, hanging over Earth.
Bottom: A map of the Kuiper belt of icy objects, showing the trajectory of New Horizons. Pluto is definitely not alone out there. Image courtesy of JHU/APL.

Hubble found other objects in the Kuiper belt - the vast torus of icy objects beyond Neptune - as big as, or bigger, than Pluto. So Pluto got downgraded from Planet to Dwarf Planet, under the new IAU definitions [8]...

...Although, being a 2000 km wide world of ice and rock, I don't think it much cared...
At the same time, under the gaze of Hubble, the Pluto system began to flower into a very complex place: In 2005 two much smaller moons, Nix and Hydra were found, and in 2011 S/2011 P1 was found while astronomers were looking for evidence of Plutonian rings.
The discovery of these little moons is an astonishing feat: Pluto is nine light hours away, or about 5 billion kilometers,and while Nix and Hydra are somewhere between 100km and 200km across each, S/2001 P1 is much less than 50 km across.

So, Pluto has gone from being a tiny spot of light on one of Clyde Tombaugh's photographic plates to just one of a the massive family of Kupier belt objects, to a strange, cold, complex place of multiple moons, and perhaps even rings.

Which begs the question: What are these worlds like?

Well, that's why we're sending New Horizons there! But there are some things we already know:

Pluto is a frigid but constantly changing place: The surface varies between white, charcoal black, and vivid orange. It is covered in frozen methane, and has polar caps of solid nitrogen. The atmosphere of methane, nitrogen, and carbon monoxide, freezes and falls as snow as the winter sets in, and may stream away from the planet in a tail, like a giant comet. There may even be clouds of hydrocarbon haze [9], formed by methane breaking down and re-forming into more complex molecules, under the suns distant UV light. Such molecules are thought to have been instrumental in beginning life on Earth.

Video above: Hubbles best resolution images of Pluto, merged into a video map of the whole dwarf planet. Courtesy of NASA/JPL.

Charon, the biggest moon, has a solid water ice surface,  a low density suggesting it is more ice than rock and  is more odd even than Pluto: There are patches of crystalline water ice, and ammonia hydrates, on its surface [10]. Crystalline water ice breaks down into amorphous ice under space radiation, which, bizarrely, suggests that Charon has some form of internal activity. That means heat which is.... surprising to say the least, for a world well under a fifteen hundred km across. But we have seen tiny little worlds with cryo-vulcanism (ice volcanoes erupting ice and cold gas) before, at Enceladus, and at Triton. The ammonia hydrates are, perhaps, a clue: Ammonia is a potent antifreeze, perhaps keeping a very little water/ammonia mix slushy deep beneath the surface, where it might find it's way out to the surface from time to time.


Image above: A reconstructed black and white image of Charon. Image courtesy of the Lowell Observatory.

Which begs a certain question about Charon, given how adaptable we know terrestrial extremophile life to be....

Nix...well that is a real unknown. Perhaps grey, or red in colour, with estimates of size ranging from 45 km to 140 km. Hydra is more or less an unknown to, probably grey-ish in colour, and between 60 and 160km across. S/2011 P1 is truly tiny, only tens of km across.


Video above: A NASA science cast on the /new Horizons mission to Pluto. Courtesy of NASA.

The presence of the the three small moons might imply a system filled with debris, from which the idea of a ring system for Pluto comes. This has caused some headaches for the New Horizons team [11], since they have to navigate their spaceship through the Pluto system - and it may be filled with unknown chunks of rock and ice. When it arrives in 2015, New Horizons is set to reveal this strange system of double-planet and moons in even greater detail than Hubble could. Who knows what Pluto could become to us then?
But one thing is already clear:  Pluto isn't a distant ball of ice and rock. Pluto is a complex, alien, changing planetary system, sitting on the edge of the interstellar dark.

Image above: New Horizons sets out for Pluto, on the dark frontier. Clyde Tombaugh's ashes are aboard. When asked by NASA scientists if they could pay a visit to the planet he discovered he said: "You're welcome to it!". Image courtesy of NASA/JPL. 
List of links:
[1]http://nineplanets.org/pluto.html
[2]http://www.nasa.gov/mission_pages/newhorizons/main/index.html
[3]http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/tombaugh.html
[4]http://solarsystem.nasa.gov/planets/profile.cfm?Object=Plu_Charon
[5]http://en.wikipedia.org/wiki/Barycentric_coordinates_(astronomy)
[6]http://news.discovery.com/space/pluto-has-a-strange-atmosphere-110420.html
[7]http://hubblesite.org/
[8]http://www.iau.org/public_press/news/detail/iau0603/
[9]http://www.dailymail.co.uk/sciencetech/article-2077674/Building-blocks-life-Plutos-surface.html
[10]http://www.sciencedaily.com/releases/2007/07/070719011140.htm
[11]http://www.boulder.swri.edu/~throop/files/nh_rings_whitepaper.pdf

Tuesday, 22 May 2012

Per Ardua Ad Astra.....

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.....But when all that 'ardua' pays off it is sweet. Space eXploration Technologies Corporation [1] has done it, launching the first fully private mission to the ISS [2]. More on this to come, of course, but as I have my driving test at 8 am tomorrow (Yes, I'm 29, have you seen the cost of car insurance these days? I'll need to be manageing director of spmething before I can afford it) I'll content myself, for now, to show you the launch. Enjoy!



Video above: The May 22nd 2012 launch of the private Dragon space vessel to the ISS. Video courtesy of SpaceX. 

List of Links:
[1]http://www.spacex.com/
[2]http://www.nasa.gov/mission_pages/station/main/index.html

Monday, 21 May 2012

Amateur astronomers invited to save the planet........

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Image above: The Dinosaurs. They're all dead. 'Nuff said about why astronomy is important.
Actually it's not quite as cut and dried as 'the asteroid did it'. But the asteroid certainly didn't help things.

The phrase 'planetary defense' always conjures up images of superheroes to my mind, but this is about preventing a more real, and hence more serious, threat than marauding space aliens:
ESA's Space Situational Awareness Office [1] -  the bit of ESA that worries about space hazards like satellite damaging solar flares and asteroid impacts -  is asking teams of amateur astronomers to help it spot, track, and confirm the paths of Near Earth Objects (NEO).

Just in case you don't know what I'm talking about: Go outside and look at the Moon with a pair of binoculars. You see all those holes in the Moon, the holes that hundreds of kilometers across? I'm talking about the things that made them.

Impacts that big are rare, millions of years apart in fact. But even a space rock a hundredth of that size, coming down over a major city, and making it through our atmosphere....unfortunately, on very rare occasions, the universe comes to us hard.

The latest collaboration is with the Faulkes Telescope Project [2], at the University of Glamorgan, to help with observations that were begun with ESA's Tenerife telescope. Spains La Sagra Sky survey [3], who are able to detect hundreds of new NEO's a month, have also joined the operation.

The possibility of something like the Tunguska event [4] happening over a populated area is one that deserves to be taken seriously. But tracking down every chunk of rock - and bear in mind that that includes things as small as fifty meters across - requires a lot of time, and luck, and then confirming and pinning down an objects path is equally challenging.
Few kinds of asteroid have the courtesy to be bright white and on an easy to spot path. Many are pitch black and can come at us from out of the sun, or from unexpected directions most telescopes don't watch. So the more eyes on the sky we have, the better the odds of finding anything potentially dangerous in time to do something about it.

Image above: Barringer (Meteor) crater, in Arizona, created by the impact of the 50 meter wide Canyon Diablo Meteorite. It's amazing how, given enough time, a 10 Megaton explosion can be good for tourism! Image courtesy of Kevin Walsh.

What's more these efforts could also help us identify targets of opportunity, low hanging fruit for space exploration. For example, confirming the recent computer simulations [5] suggesting that (very) small asteroids frequently enter orbit [6] around the Earth could open up literal low hanging fruit for asteroid sample return missions.

Faulkes run both research and educational programs, where UK (and some European) students can get observing time on the telescopes. So if you're teaching science, and fancy having people who work to protect the Earth talking to your students.... go on, the links just there......

Hey, who was in a position to catch Sundays annular eclipse of the Sun? So far the most spectacular image of it I've seen is this one:
Image above: Sundays eclipse, as seen from Japan. Image courtesy of 'Japan - A Foreigners view' [7] 

But ESA's Proba-2 micro-satellite also got a spectacular view:

Video above: Sundays solar eclipse seen from the Proba-2 micro-satellite. Video Courtesy of ESA.

And lastly: Good luck to SpaceX [8] on their first mission to the International Space Station. The last attempt to launch was scuppered at literally the last instant by a faulty turbo pump. Here's hoping this one goes all the way to the ISS!

List of links:
[1]http://www.esa.int/esaMI/SSA/SEMYTICKP6G_0.html
[2]http://www.faulkes-telescope.com/
[3]http://www.minorplanets.org/OLS/
[4]http://science.nasa.gov/science-news/science-at-nasa/2008/30jun_tunguska/
[5]http://www.newscientist.com/article/mg21328464.600-hundreds-of-tiny-moons-may-be-orbiting-earth.html
[6]http://www.sciencedirect.com/science/article/pii/S0019103511004684
[7]http://gaijininkansai.com/2012/05/21/the-annular-eclipse-may-2012/
[8]http://www.spacex.com/

Friday, 18 May 2012

Lyrid meteor shower: Sprinkles of comet Thatcher

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Image above: A Lyrid meteor slams into Earths atmosphere - photographed from above, by one of the crew of the International Space Station. Do yourself a favour, check out the original here [1]. Then do yourself a bigger favour and watch the video [2]. Image courtesy of NASA.

Meteor showers are streams of tiny particles left behind by passing comets -  so when you see one you are literally seeing parts of a comet raining down from the sky. We've just passed through the Lyrid meteor shower, a stream of particles from comet Thatcher [3], a 2600 year old trail of debris with a history of surprising humanity: In 687 BC it was described as being so intense that 'the fixed stars were invisible, and stars fell like rain'. Although the shower usually peaks at around 20 meteors an hour, in 1803 it peaked at 700, and in 1982 at 90. Bigger Lyrid meteors, known as Lyrid fireballs, can throw shadows and leave behind visible trails of smoke.
And this year the van sized Sutters Mill meteorite [5] came down while the shower was on - and blew up rather spectacularly, leaving people seeing spots [4], spraying the ground with pieces of space rock, and with an estimated force of 4 kilotons (Hiroshima's 'Little boy' was about 15 kilotons). It's arrival was probably just a coincidence, but mentioning it gives me an excuse to post a stunning picture its arrival, so there:

Image above: The 70 ton Sutter's Mill Meteorite blows up over Nevada with the force of a small nuke. Pretty, isn't it! Image courtesy of JPL/NASA.

Comets are cryogenic time capsule from the earliest times of our solar systems existence, and Thatcher hails from far reaches of the Kuiper belt [6], so you'd think that the Lyrids would be an excellent opportunity to do some Laz-y-boy deep space exploration.

Well I did, anyway.
And it turns out, I was right!


Video above: NASAs efforts in studying the Lyrid meteor shower. Courtesy of NASA/JPL.

As well as a world wide campaign of ground based observations and the observations from the ISS, Tony Phillips from spaceweather.com [7] has led a team of high school and middle school students in an edge-of-space balloon mission [8], to try and capture images of the Lyrids from 100,000 feet, using an experimental NASA camera. Studying how the brightness and intensity of a meteor shower changes with time tells us about the size and evolution of the swarm of particles, which in turn tells us about the comet that produced it.


Video above: Students launch a near space balloon mission to capture images of the Lyrid meteor shower. Video courtesy of Tony Phillips.

All the above efforts are contributing to producing a 3D image of the Lyrids, as described in this 'NASA chat' transcript [9].

Image right: Three NASA ER2 high altitude research aircraft fly in formation over the golden gate bridge. Image courtesy of the National Oceanic & Atmospheric Administration.

NASA also often fly a high altitude ER2 aircraft around this time of the year, hoping to pick up cosmic dust [10] from the shower using a large, cooled, collector mounted on the wing. The dust is relatively intact, as it's small size lets it float down to Earth rather than streaking in as a meteor, which makes it a great way to get material from space - although a lot of sorting is needed to separate the cosmic dust [11]from the various kinds of Earth dust. The increase in the amount of dust entering the atmosphere during a shower is actually fairly slight, but since any piece of interplanetary material found is a sample from deep space it pays to maximise the chances!



Video above: The Lyrid meteor shower: Real comet dust, falling to Earth. Time lapse video by Mark Zebo.

Incidentally, it's just a small thing but: SpaceX will be attempting to launch it's Dragon space capsule tomorrow! 
The mission is to the ISS, hauling supplies, and hopefully becoming the first commercial entity to fly there.
If they succeed I will attempt to do a back flip with joy, and probably sprain something. If something goes wrong, I hope they will be able to push through - Elon Musk certainly has the drive and ambition to ride out a few mishaps. To SpaceX [12]: Good luck!

Image above: A CGI impression of the Dragon spacecraft docking at the ISS, as it hopefully will later this week. Image courtesy of Discover magazine.
List of links:

[1]http://www.nasa.gov/topics/solarsystem/features/watchtheskies/lyrids1.html
[2]http://www.nasa.gov/multimedia/videogallery/index.html?media_id=143997541
[3]http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=C/1861+G1
[4]http://www.rgj.com/article/20120423/NEWS/304230031/1459/news?nclick_check=1
[5]http://apod.nasa.gov/apod/ap120428.html
[6]http://solarsystem.nasa.gov/planets/profile.cfm?Object=KBOs&Display=OverviewLong
[7]http://www.spaceweather.com/
[8]http://www.nasa.gov/topics/solarsystem/features/watchtheskies/balloon_lyrids_update1.html
[9]http://www.nasa.gov/pdf/642909main_LyridsChat.pdf
[10]http://www.nasa.gov/centers/dryden/Features/ER-2_cosmic_dust.html
[11]http://curator.jsc.nasa.gov/dust/
[12]http://www.spacex.com/

Thursday, 17 May 2012

Small steps to huge dreams


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The Arkyd series 101 minature space telescope, Space Resources Inc's first proposed step towards asteroid mining. Image courtesy of Space resources Inc.


Almost anyone with an interest in space exploration will have heard of Planetary Resources Inc [1] (formerly Arkyd Astronautix), the company that has announced plans to mine asteroids, and will have formed their own opinion on it.
Me? I'm over the moon that someone is trying this, but I don't quite see how the scheme is going to make money. True I have the same grasp of economics as a tazered chicken, and the founders of the company have admitted that this is more about developing their vision for humanities future than short term profit.
So I'm not going to talk much about the company directly. The Internet is abuzz about it, and you can learn far more from their website than you could from me.
What I will do is take a quick peek at some of the developing ideas for moving asteroids about, as pointers to how an asteroid resource extraction effort might eventually take shape:

Gravity power:

Image right: A gravity tractor hangs in space over an asteroid.Image courtesy of Dan Durda. 

Just to complicate things, many asteroids are piles of rubble, not solid rocks, and spin in all three axis at once. So firing bombs at them, or landing a big rocket on the surface, isn't as simple as it might appear.
But in the void of space there is no friction, and the few forces (such as the solar wind) acting on bodies are very slight. So diverting an asteroid doesn't need the colossal force you might imagine.

The gravity tractor [2] takes advantage of this fact: The space craft doing the towing hangs in space, not too far from the surface of the asteroid, and lets the small gravitational attraction between the asteroid and the craft move the asteroid towards it. The craft fires a low thrust engine to keep the distance between itself and the asteroid constant, and so the asteroid slowly follows it. It's a nice, elegant, idea but  it carries the drawback of taking quite a long time to take effect, as too much thrust would just send the towing ship off into space.

Solar power:



Video above: The Sun, the biggest power source in our solar system. Video courtesy of NASA/Solar Dynamics Observatory.

The Sun is the power house at the centre of our star system, and it'd be foolish to miss a trick that even plants manage: Take advantage of that energy. There are a variety of ways that the sun might be used to move an asteroid:

Image left: Solar panels, much like those you might install on your own roof, could power an engine to move an asteroid. Image courtesy of solarenergy.com.

Solar powered thrusters on the surface could move a solid object quite quickly, but encounter problems when moving loosely bound rubble piles, the same as regular thrusters. However the problem of carrying your fuel out there with you is at least avoided. The problems with rubble piles can be mitigated by applying a gentle thrust for a much longer time, such as from an ion engine, and by doing your homework on the asteroids spin and internal mass distribution, so this idea still holds some water. However with current ion engines we'd need a looong time to significantly change the path of a big asteroid.


Image right: A solar reflector kilometres across focuses the Suns energy onto the surface of an asteroid. Image courtesy of sciencephotolibray/Chris Butler.

Another solar powered approach could be to station a huge parabolic reflector near the asteroid. This would focus sunlight onto the surface, vapourising part of it to produce a plume that could push the rock onto a new course. The biggest problem with this idea is getting a large reflector out to the rock, although technologies like those behind the Ikaros solar sail could be useful there.

A solar sail [3] combined with the gravity tractor idea is yet another possible approach. We're still some way off being able to deploy solar sails of the size needed, although, as I blogged about earlier this week, there are people working on innovative sail designs.

Image above: The spaceship Ikaros, the first successful solar sail. Image courtesy of JAXA

Coating the rock in a reflective layer would let it gathered momentum from the pressure of sunlight, but without the high ratio of surface area to mass that an ordinary solar sail would have it needs a good long while to work, and steering with a 'dumb' reflective coating would be hard. Similarly, painting the asteroid white to change the way the YORP effect [4] pushes on it  would require a gigantic bucket of paint, and a long lead time as well.

Nuke it:


Video above: Los Alamos scientist Bob Weaver explains that YES, you could stop an asteroid with a well placed nuke. Courtesy of Los Alamos National laboratory.

Well, as Bob explains above, you could save the world by nuking an asteroid, but moving one for mining might be harder. Nuclear weapons could move an asteroid, although the effects of a nuke in space [5] are quite different than those of one on the ground, in a similar fashion to the Project Orion spacecraft [6]. But once again we run into the problems of the asteroid  breaking apart, and remember we're thinking of mining this thing, so making it radioactive probably isn't a good idea.

Kinetic Impactor:


Image above: Deep Impacts copper 'bullet' puts a big hole in comet Tempel 1. Image courtesy of JPL/NASA.

As NASA's Deep Impact mission [7] showed by blowing a hole in comet Tempel 1, we can crash a big lump of metal into an asteroid, perhaps changing its course. But, well, look at that picture: If you did that to a small or weakly built asteroid you'd just have lot of floating bits. That said, a Deep Impact style mission might be a very useful quick 'n dirty way of finding an asteroids composition.

Cloud power:

This is a relatively recent suggestion by researchers at the University of Strathclyde. Again it's a simple idea in principle: Launch a swarm of tiny space craft that will crash into the asteroid, each one imparting a small change in momentum. It has advantages over sending one big impactor or bomb: The smaller knocks would be unlikely to disrupt even a loose rubble pile, the swarm could still impart a good amount of energy fairly quickly, and such a swarm would be fairly simple to build and  launch. However we are still a way off having the satellite-on-a-chip style space craft needed, although prototypes are being tested on the ISS [8].

Lasers!

Bang! Mwahahahahaha!. Image courtesy of Lucasarts.

OK, we're not talking fielding a huge Death Star type laser. Such things are expensive, and look gaudy in the night sky.
Lasering an asteroid would move it by vapourising material off the surface to produce thrust [9]. The neat thing about using laser light is that you can spread the beam across the entire surface, allowing you to give the asteroid a meaningful nudge without risking it breaking up or absorbing our push by deforming.
Lasers fired from Earth would need to go through our atmosphere, which would absorb part of the power, and Earths rotation would limit the chances to hit the target. A large solar powered laser in orbit has been proposed, but the falling down point is that it would be hard to  build, need a lot of power, and probably maintenance. The University of Strathclyde, who have a bit of a thing for shoving asteroids about, have a new take on the laser power idea: Send up a swarm of smaller lasers, and have them bombard the rock in concert. The difficulty in building and launching such swarm is much lower, and the overall effort can survive a few units going down through extended use.

To view the abstracts for both the Univeristy of Strathclydes asteroid moving proposals, presented at the Astrobiology Science Conference. Pay the ASC website a visit, go to 'scientific program', and put 'Gibbings' into the search engine. No, I'm not him, I just like both the ideas he presented there. I'm John Freeman, and BTW, I just passed my PhD, so I'm going to go and get drunk. Stay tuned for physicist with five alarm bell hangover!

Earth from the International Space station. Will a worker or robot on an asteroid mine one day have a similar view? I hope not; ISS is only four hundred km up, thats too close for a big rock and my comfort. Still, it's pretty, which is why I put it there. Image courtesy of NASA

List of Links:
[1]http://www.planetaryresources.com/
[2]http://news.nationalgeographic.com/news/2005/11/1109_051109_asteroid_tug.html
[3]http://www.planetary.org/explore/projects/lightsail-solar-sailing/
[4]http://www.news.cornell.edu/stories/March07/margot.yorp.html
[5]http://history.nasa.gov/conghand/nuclear.htm
[6]http://www.islandone.org/Propulsion/ProjectOrion.html
[7]http://www.nasa.gov/mission_pages/deepimpact/main/
[8]http://news.discovery.com/space/satellite-on-a-chip-to-launch-with-space-shuttle-110516.html
[9}http://www.strath.ac.uk/space/research/missionsystems/asteroiddeflectiontechnologies/laserablationexperiments/ [10]http://abscicon2012.abstractcentral.com/s1aplanner/com.scholarone.s1aplanner.s1aplanner/S1APlanner.html?&CONFIG_ID=2390&USER_ID=1593989&ROLE_ID=14918&ROLE_TYPE_ID=17&PERSON2ROLE_ID=17696201&WORKFLOW_ID=17&CURRENT_PAGE=BROWSE_THE_PROGRAM&ALLOW_EDIT_INSTRUCTIONS_FL=N&SESSION_ADMIN_PERMISSION_FL=N&DIRECT_LOGIN_FL=Y&HASH_KEY=U3EUGrcX1xIcZLBnWyEoaTkPtRo&STUB_ROLE_ID=0&TIME=1337288817285&SOURCE_URL=http://abscicon2012.abstractcentral.com

Tuesday, 15 May 2012

Space is beautiful

Image above: The Cygnus X star forming region, where stars, planets comets, asteroids, whole solar systems are growing as we watch. On the right the filament structure of the cloud is particularly complex, dust and gas shepherded by stellar winds and light. The knots where the filaments meet are regions where the glowing gas and dust are collapsing, forming protostars and protoplanetary disks.
The white areas are where hot young stars are heating the gas and dust, and the central void is where cloud material  has been cleared by the fierce pressure of stellar winds and light from better established stars, less visible in this infra-red image. It's just...beautiful.

I've made it as big as I can, but I can't do it justice. Please follow the link to the original at ESA. Image courtesy of ESA/.

List of link:
http://www.esa.int/esaSC/SEMXKITWT1H_index_0.html

Sunday, 13 May 2012

Big things can have small beginnings

Firstly, if you're a Dr Who fan and haven't already seen this, I highly recommend it:


Video above: Eric Calderone. Metal time lorrrd man! No I'm not smoking anything illegal. Seriously.

Anything that opens space exploration to a greater section of the world is, frankly, brilliant. Hence I am a big fan of ideas like the cubesat [1], which has bought the cost of putting an experiment into orbit down to the level that a major university- not just a major government or corporation- can afford.

It has done this, at least in part, by providing a standardised, reliable, nano-sat kit in which experiments can be housed, and by piggybacking on larger launches. However there are limits on what such a small vehicle can do, and one of them is propel itself effectively.

Image left: A visualisation of the prototype for the cubesail idea, being deployed. Image courtesy of the University of Illinois and CU Aerospace. They look a bit like the fuzzy dice over your cars rear view mirror don't they? Except in space, doing orbital velocity not 70mph.

So I am over the moon to talk about the work being done by the University of Illinois Aerospace lab, on the cubesail [2]. Click that link people, it's an entire PhD thesis on the subject.
Inheriting ideas from a proposed sail design called Ultrasail, the cube sail is a development of the cubesat,  incorporating solar sailing technology as a 250 m long unrollable sail, as opposed to a folded square sail with its obvious problems of folding ultra thin delicate material. A company called CU Aerospace [3] is working in collaboration with the lab to develop the concept, and the work so far has been funded by a NASA grant. If funding could be found for a demonstration flight then the next step would be a series of cubesats unrolling solar sail 'vanes' from a central core.

OK, there is still a long way to go between here and deep space missions cheap enough for any major university to afford, but this is a great, innovative idea. I'm keeping everything crossed that this flight will become a reality.

Perhaps this is a small beginning.

List of links:
[1] http://www.cubesat.org/index.php
[2] http://www.ideals.illinois.edu/bitstream/handle/2142/18320/Pukniel_Andrzej.pdf
[3] http://cuaerospace.com/

Thursday, 10 May 2012

Vesta - last of its kind

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I couldn't go to bed without including this:


Video above: Simulated flybys of Vesta 'tourist spots'. Courtesy of JPL/NASA

OK, my guess earlier today was well wide of the mark.
However the conference was fascinating all the same, and underscores just what a remarkable protoplanet Dawn [1] is exploring.
In particular I was pleased to see three things highlighted by the conference: That Vesta is indeed a protoplanet [2], just how much the HED meteorites [3]- now all but certain to have come from Vesta- have contributed to our exploration, and how much telescopic observations have contributed.

Sample return missions to an alien world that were no more expensive than bending to pick up a fallen space rock: Sometimes the universe does come to us. But first, some music for the occasion:


Video above: The music is Ironheart, by Two Steps From Hell. Image from the movie 'Your Highness' I think. It's Natalie Portman, which wasn't picked by me, but I do approve. I like Natalie Portman. I'm only human dammit.

So, what has Dawn found?
Firstly, the evidence strongly suggests that Vesta is indeed differentiated like a full grown planet, with a iron rich heart, a mantle, and an outer crust. Estimates for the size of the core put it at about 70 miles across. By comparison, Earths core is 2000 miles across and Mars core is thought to be about 1000 miles across.


Image left: A slice through one of the HED meteorites. Iage courtesy of saharamet.com.

The HED meteorites now look almost certain to have come from Vesta, from different depths in its crust and mantle, and allow the team to draw conclusions about Vesta they otherwise would not have been able to. They are probably the  result of the two massive impacts that have obliterated the Vestan South pole, excavating 250,000 cubic miles of rock. The HED's tell us things that Dawn couldn't easily see: There are small amounts of olivine present in the HEDs, which tells us that the blast punched right through the Vestan crust and into its mantle.

However it is hard for Dawn to spot olivine from orbit for two reasons; the amounts of olivine are fairly small, and, since the giant impacts, smaller blasts have mixed up the surface, grinding everything into smaller pieces.


Image above: the Rheasilvia basin, and its predecessor Vanenia, have completely re-shaped the vestan surface. Image courtesy of JPL/NASA.
The two giant impacts, one on top of the other, have been dated by crater counting of the basins formed (on average impacts happen at a constant rate). The younger, Rheasilvia, is about a billion years old, which is a surprise as massive impacts are thought to have all but stopped around 3 billion years ago. The older crater, Veneneia, is harder to date because Rheasilvia is almost on top of it, but is at least 2 billion years old. The material thrown out by the last big impact sits as a layer of pulverised rock, 5km deep, around the basin.

Image right: This grey scale image of Rheasilvia shows the spiral pattern on its floor slightly better. Image courtesy of JPL/NASA.

The structure of Rheasilvia is unusual, the central peak is almost a third as big as the crater itself. This is because the crater is getting on for as big as Vesta itself, which changes the way the crater forms. And the impact has had another effect: It essentially rejuvenated the southern hemispheres geology, leaving Vesta ancient in the north, and younger in the south. There are massive spiral patterns on the craters floor, and grooves running around the protoplanet that seem to be centred on the impact - the blast literally re-arranged the whole world.

Image left: Massive grooves gives mute testimony to the violence done to Vesta by nature. Image courtesy of JPL/NASA.

Vesta has also surprised the science team with how varied the subtle colours of its surface are, again separating it from smaller asteroids that are relatively monotonous, and pointing to a complex surface. The crust seems to be a complex mix of diogenite [4]and eucrite [5] rocks, but the general dominance of diogenites supports the idea that most Vesta melted early in its history.
The surface is clear of any obvious lava flows or volcanoes, which is likely of a consequence of all the activity being shutdown a long time ago, and Vesta getting one hell of a pounding since then.

The data Dawn has collected, in conjunction with the HED meteorites, paints picture of Vesta as the last survivor of a type of rocky protoplanet. It's brothers and sisters were likely either pulverised by impacts with objects like the one that excavated Rheasilvia, or absorbed into the growing main planets.

So we now know that Vest is a baby planet, it  had geologic activity and a planet like structure, and has stood up to a spectacular beating from the debris in the asteroid belt. And, we have pieces of it here on Earth!

All this coincides with the latest batch of scientific papers released from the Dawn team, over at Science [6]. Be warned, it's a pay to view the whole paper deal.

The data Dawn has collected also contributes, along with data from infrared and optical telescopes, to helping planetary scientists decide where to send future mission to further unravel the history of the solar system.

Image left: An ion engine being test-fired. Image courtesy of NASA/JPL.

A worthy legacy, but the show's not over at Vesta yet: The Vesta phase of the mission has been extended by 80 days, first when the team didn't need the forty days built into the plan to deal with anomalies (the spacecraft going wrong in non space speak), and secondly when they found Dawns ion engines [7] were performing above expectations. So the trip to Ceres [8] (the next target) will need less time. Because of the extensions Dawn will get a chance to image the ancient north polar region, which is currently in winter darkness.

Image right: Ceres, to be visited in 2015 by DAWN, as imaged by the Hubble space telescope [9]. Image courtesy of NASA/JPL.

After that, it's on the Ceres, an even bigger protoplanet than Vesta, with a surface that suggests much less heating and volcanic activity, and possibly large reservoir of ice beneath the surface.

And no, that's not my WAG again, that's the official facts... at least until Dawn gets there and begins to surprise us all over again!

One last thing: The relevance of missions like Dawn to plans, now plans with a lot of cash and determination behind them [11], to extract resources from asteroids was raised, and I really ought to mention those:

It's just too big. I can't decide if its madness or genius, but I am sure it'll be interesting to watch how it all unfolds. More on that when I've got my head around it!

List of links:
[1] http://dawn.jpl.nasa.gov/
[2] http://www.universetoday.com/37053/protoplanets/
[3] http://planetary.brown.edu/pdfs/3446.pdf
[4] http://www.daviddarling.info/encyclopedia/D/diogenite.html
[5] http://www4.nau.edu/meteorite/Meteorite/Eucrite.html
[6] http://www.sciencemag.org/content/336/6082/684
[7] http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/index.html
[8] http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)
[9] http://hubblesite.org/
[10] http://www.planetaryresources.com/

What has Dawn found at Vesta? Could it be ice? (Update: No it's not)

Update: No, it's not ice, but it is an amazing glimpse into a world that records the earliest history of our solarsystem. More to come!

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Video above: DAWNs Low Altitude Mapping Orbit of Vesta. Courtesy of NASA/JPL-Caltech

NASA has announced a press conference to talk about the Dawn [1] spacecrafts latest findings at the humongous, 400km, asteroid-slash-protoplanet Vesta [2].

Kick off is 2pm EDT, 7pm UK time.
So, guesses as to what it's about?
The list of panellists is:

• Carol Raymond, Dawn deputy principal investigator, NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

• Harry McSween, chair, Dawn surface composition working group, University of Tennessee, Knoxville

• Vishnu Reddy, Dawn framing camera team member, Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, and the University of North Dakota, Grand Forks

• David O’Brien, Dawn participating scientist, Planetary Science Institute, Tucson, Ariz.

• Maria Cristina De Sanctis, Dawn co-investigator and visible and infrared mapping spectrometer team lead, Italian National Institute for Astrophysics, Rome

The current phase of DAWNs mission, LAMO (Low Altitude Mapping Orbit), is all about mapping Vestan composition. We have mainly people involved in compositional mapping instruments on the panel, and David O'Brien.
Dr O'Brien lists his research interests as :

Planet formation and the dynamical and collisional evolution of the early Solar System

Collisional and dynamical evolution of asteroids and trans-Neptunian objects

Thermal modelling of geophysical phenomena

Icy satellite geophysics

I think 1 and 2 are the most relevant here. So we have a compositional finding probably relating to either thermal modelling of the Vestan surface, or its collision history. Or both. Hmmm. I recall a recent article on the possibility of water ice at high lattitudes on Vesta [3], I wonder if there’s a link (Composition, temperature, cratering, impact history -important factors in the formation of ice deposits). Ice at Vesta would be big news, as Vesta has been thought to be bone dry after massive basaltic lava eruptions covered its surface early in its history.

Let's see at 7pm! (go to the NASA website for the latest news)


Image above: Vesta. Like a potato, but 400km across, 4.5 billion years old and covered in frozen lava. So not much like. Disagree? What kind of potatoes are you growing?
List of links:
[1] http://dawn.jpl.nasa.gov/
[2] http://www-ssc.igpp.ucla.edu/personnel/russell/papers/CeresVesta.pdf
[3] http://www.space.com/14361-hold-thu-1-26-huge-asteroid-vesta-packed-water-ice.html