When Stardust Met Tempel, a Love Story

Comet Tempel 1 near Stardust-NExT close approach (NASA)

Comet Tempel 1 near Stardust-NExT close approach (NASA)

A NASA spacecraft, a lonely comet and a Valentine’s date with no comparison.

Last night, NASA’s veteran Stardust-NExT mission successfully visited its second comet, Tempel 1. Having already been visited by NASA’s Deep Impact mission in 2005, it’s hard not to wonder whether Tempel 1 was a little apprehensive. Deep Impact did lob a refrigerator-sized copper impactor into the comet’s surface during the 2005 encounter, so I think we can forgive the comet some pre-date jitters.

Fortunately, Stardust was the perfect date (no impactors, silverware, dishes or bottles were thrown), just a peaceful flyby, during which the spacecraft beamed dozens of photos back to Earth. To quote Joe Veverka, Stardust-NExT principal investigator: “It was 1,000 percent successful!”

Alas, although the date was a success, there won’t be the sound of wedding bells any time soon. Stardust is now powering away from the comet at a breakneck speed. Was it something Tempel 1 said?

For more on this Valentine’s rendezvous, have a read of my Discovery News article “Stunning Photos from a Comet Near-Kiss.”

Oh yes, and I got bored, so I created a rough animation of the flyby. Enjoy!

Could P/2010 A2 be the First Ever Observation of an Asteroid Collision?

Something rather bizarre was observed in the asteroid belt on January 6. Ray Villard at Discovery News has just posted an exciting article about the discovery of a comet… but it’s not your average, run-of-the-mill kinda comet. This comet appears to orbit the Sun, embedded in the asteroid belt.

Comets don’t usually do that, they tend to have elliptical and inclined orbits, orbits that carry them close to the Sun (when they start to heat up, creating an attractive cometary tail as volatile ices sublimate into space, producing a dusty vapor). They are then flung back out into the furthest reaches of the Solar System where the heating stops and the comet tail disappears until the next solar approach.

But P/2010 A2 — discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey — has a circular orbit and it still appears to be venting something into space.

P/2010 A2 (LINEAR): A comet or asteroid debris? (Spacewatch/U of Arizona)

There is the possibility that it is a member of a very exclusive bunch of objects known as main belt comets (MBCs). MBCs are confused asteroid/comet hybrids that appear to spontaneously vent vapor and dust into space and yet stay confined to the asteroid belt. But, if P/2010 A2 is confirmed to be one of these, it will only be the fifth such object to be discovered.

So what else could it be? If the potential discovery of an MBC doesn’t excite you enough, it could be something else entirely: the dust produced by a hyper-velocity impact between two asteroids. If this is the case, it would be the first ever observation of an asteroid impact in the Solar System.

The asteroid belt isn’t the same asteroid belt you might see in science fiction; although there are countless rocky bodies in our asteroid belt, it is rare that these rocky bodies encounter each other. Space is very big, and although the density of asteroids in this region might be considered to be “high”, this is space we’re talking about, you can fly a spaceship through the region without having to worry that you’ll bump into something. The average distance between asteroids is huge, making it a very rare occurrence any two should hit. But given enough asteroids, and enough time, eventually asteroid collisions do happen. And in the case of P/2010 A2, we might have been lucky.

Asteroid collisions: Rare, but possible.

Asteroid collisions: Rare, but possible.

The chatter between comet/asteroid experts is increasing, and on one message board posting, Javier Licandro (Instituto de Astrofísica de Canarias, Spain) reports observing a secondary asteroid traveling with the cloud-like P/2010 A2.

The asteroid moves in the same direction and at the same rate as the comet,” reports Licandro on The Minor Planet Mailing List. “In addition, the P/2010 A2 (LINEAR) image does not show any central condensation and looks like a ‘dust swarm’.”

A short lived event, such as a collision, may have produced the observed dust ejecta.”

Therefore, this ‘comet’ may actually be the debris that was ejected after a collision between two asteroids. Although these are preliminary findings and it’s going to take some serious observing time to understand the true nature of P/2010 A2, it’s exciting to think that we may just have observed an incredibly rare event, 250 million miles away.

Source: Discovery News

Laboratory Ice Links Comets with Life On Earth

Artist impression of the nucleus of Comet Tempel (NASA)

It is an established theory that comets may have, in some way, seeded life on Earth. Some extreme ideas support the panspermia concept (where bacterial organisms hitched a ride on comets, asteroids or some other planetary debris, spreading life throughout the Solar System), while others suggest comets may have contributed the chemical building blocks essential for life to form 4 billion years ago. We know these icy bodies are also awash with organic compounds, so it’s not a huge leap of the imagination to think comets may have donated life-making material to the early Earth.

In an effort to study cometary material and its possible influence for nurturing early life on Earth, Prof. Akiva Bar-Nun of the Department of Geophysics and Planetary Sciences at Tel Aviv University has been creating his own comets in the laboratory. By doing this, Bar-Nun is hoping to gain a better perspective on how comets acquired their composition of the noble gases Argon, Krypton and Xenon.

The proportion of these elements are found in the Earth’s atmosphere, but are not thought to have originated from the rocky material our planet consists of. By understanding the proportions of these elements that formed in the icy laboratory environment, if the proportions match that of what we’ve measured on Earth, it goes to some way in explaining how comets formed in space and how they delivered organic compounds to the surface.

Now if we look at these elements in the atmosphere of the Earth and in meteorites, we see that neither is identical to the ratio in the sun’s composition,” said Bar-Nun. “Moreover, the ratios in the atmosphere are vastly different than the ratios in meteorites which make up the bulk of the Earth.”

So we need another source of noble gases which, when added to these meteorites or asteroid influx, could change the ratio. And this came from comets.”

Prof. Bar-Nun and his team carried out the research using a comet-making machine unique to Tel Aviv University, and although the original press release is light on the details, it is assumed the chemical composition of the early Solar System was recreated and then deep-frozen.

Comets bombarded the Earth 4 billion years ago. Organic chemicals were therefore deposited, possibly kick-starting life (NASA)

Comets bombarded the Earth 4 billion years ago. Organic chemicals were therefore deposited, possibly kick-starting life (NASA)

Comets formed some distance from the Sun (and a vast number of them populate the Oort Cloud), water vapour would have condensed and frozen, in temperatures as low as -250°C, trapping a primordial collection of chemicals inside their dusty, icy interiors. Some time after, these comets may have fallen into the inner Solar System, many impacting the Earth. Amino acids may have been introduced to the surface and oceans, or vital chemical components from the comets combined with chemicals already on Earth and life was sparked. When this happened, these comets would have left a chemical fingerprint.

Bar-Nun’s team were successful in creating their own synthetic comet, freezing water vapour, creating a natural ratio between the three elements. Then a link could be made, from the laboratory comet, with the very definite noble gas proportions, and the proportions of these gases found in the atmosphere.

The pattern of trapping of noble gases in the ice gives a certain ratio of Argon to Krypton to Xenon, and this ratio — together with the ratio of gases that come from rocky bodies — gives us the ratio that we observe in the atmosphere of the Earth,” added Bar-Nun.

Judging by the information available (the paper is published in the journal Icarus), Bar-Nun’s research has provided evidence that comets left a unique ratio of stable noble gases in the atmosphere, a ratio of necessary materials for life to eventually form.

Source: Tel Aviv University, EurekAlert via @Avinio

Tonight’s Paranormal Radio Show Postponed

Tonight for my monthly Paranormal Radio slot, Captain Jack and I will be having a discussion about the threat of asteroids and comets to the Earth. It’s not a question of if we’ll get hit by an extinction-level event, it’s a question of when

Due to technical problems with the “voice of darkness” in the depths of Texas, tonight’s show about asteroids and interplanetary shooting galleries will have to be postponed for a couple of days. I hope it’s got nothing to do with those damn aliens or 2012 activists… Anyhow, for some reason Jack had to drive to Dallas, breaking all sorts of land-speed records, to buy a server…?!

Watch this space, I’ll update you with news as I get it…

In the mean time, check out the breadth of news items about space, politics, conspiracies, big foot and ghostly happenings at WPRT Radio

Why Can’t we see the Oort Cloud?

Hubble Space Telescope observation of Polaris – looking through the Oort Cloud, but not resolving any comets (Hubble)

The Oort Cloud is a mysterious entity. Located on the outskirts of the Solar System, this hypothetical region is probably the source of the long-period comets that occasionally pass through the inner planets’ orbits. The strange thing about these comets is that they have orbits inclined at pretty much any angle from the ecliptic which suggests their source isn’t a belt confined to the ecliptic plane (like the asteroid belt or Kuiper belt). Therefore, their proposed source is a cloud, acting like a shell, surrounding the Solar System.

OK, so we think the Oort Cloud is out there, and there is a lot of evidence supporting this, but why can’t we see the Oort Cloud objects? After all, the Hubble Space Telescope routinely images deep space objects like stars, galaxies and clusters, why can’t we use it to see embryonic comets within our own stellar neighbourhood?
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