Updated Theory: A Huge Chunk Of Earth, Blasted Away In A Collision, Is Now The Moon

By Rebecca BoylePosted 10.17.2012 at 3:02 pm

New simulations of a crash between Earth and a protoplanetary sister long ago could have produced a moon that’s chemically similar to our planet, according to a new analysis. It bolsters a theory that the moon is part of Earth, and it helps settle a question about how this could be physically possible.

Since around the time of the Apollo missions, lunar scientists have theorized that our moon formed after a horrendous collision between Earth and another world, which sheared off part of this planet. But all the while, there’s been a major disconnect with reality and the satisfying theoretical explanation of this concept. If that’s what happened, then the moon should be primarily composed of material from the collider, which would have been reincarnated as our natural satellite. Theoretical models and computer simulations of this catastrophic impact say the moon would be about 20 to 40 percent Earth parts and 60 to 80 percent non-Earth parts.

But the moon and the Earth have identical isotopes of key elements, proving the moon was made from Earth’s mantle. A host of theories have tried to explain this, even one suggesting that Earth generated its own internal thermonuclear reaction and blew itself apart.

Some scientists have suggested that Earth and moon material mixed together, so the Earth also contains some foreign matter. But very recent studies cast doubt on this, too. There was another problem in that Earth-sized planets should have been spinning faster than this one did, if that model is correct. Matija Ćuk and colleagues at the SETI Institute started over, and envisioned a very fast-spinning Earth colliding with a smaller-than-Mars planet, nicknamed Theia.

In their computer simulations, which you can see in part below, it all works out. The moon can form from mostly Earth material, and a faster-spinning proto-Earth can lose some angular momentum thanks to tidal interactions with the sun, explaining its slower-than-expected speed.

In this animation, Earth and Theia are represented by the agglomerations of particles. Earth is spinning super-fast–its day is only 2.3 hours long. Theia, which has about half the mass of Mars, careens toward Earth at 44,740 MPH. It penetrates all the way to Earth’s core and excavates a massive hole in our planet, throwing material out in the process. Theia is mostly vaporized, along with part of our planet, and the iron from its core merges with Earth’s core.

Some material escapes Earth and forms a huge disk around it. The disk has almost no iron, but is made mostly of Earthly material. This would explain the moon’s composition, which very neatly matches that of Earth.

To test this hypothesis, a separate group of researchers ran further simulations with slower-moving impactors that were a little larger. This also produces a moon with the same chemical makeup as Earth’s mantle, they found. Taken together, the results suggest that our moon-formation theories may be spot on.

http://bcove.me/6r8mgmwi

Thanks to Logan Ellis for sending this my way…

A Fifth Moon For Pluto!

By Phil Plait


Astronomers have just announced that tiny Pluto has a fifth moon! It was discovered using the Hubble Space Telescope:

You can see it in that image (click to enhadesenate) in the green circle. Pluto was targeted by HST for several observations in late June and early July, and P5 – also called S/2012 (134340), the moon’s designation until it gets a proper name – was seen moving around the tiny world. This image is from July 7.

As moons go, it isn’t much: it’s probably only about 10 – 25 kilometers (6 – 15 miles) across, making it one of the smallest moons detected in the entire solar system. That’s actually pretty amazing, given Pluto was 4.7 billion km away (2.8 billion miles) when these images were taken!

Pluto was observed in part to look for more moons. In 2015, the New Horizons probe will zip past Pluto, and scientists want to know as much about the system as they can before it gets there. The odds are low of them hitting any of those moons – space is big, and the moons and spacecraft are small – but a) better safe than sorry, and 2) if there are more targets to observe we want to know now so they can be added to the itinerary!

Observations like this are good for discovering moons and getting their locations, but size is a different matter. Literally. We know how far away the moon is, and how bright, but it’s far too small to directly get the size. Its diameter has to be estimated by assuming how reflective the surface is. If it’s dark like coal, it has to be bigger to be so bright, and if it’s shiny like ice, it’s smaller. That’s why we don’t know P5′s size to even within a factor of 2! But once New Horizons zips past, it may be able to nail down the size far better.

The first moon of Pluto, Charon, was discovered in 1978. Nix and Hydra were found using Hubble in 2006, and the fourth moon just last year, in 2011.

As for the argument about Pluto being a planet or not, this will no doubt provide grist for the mill. However, number of moons does not a planet make; Mercury and Venus have none and they’re planets. Mars has twice as many as Earth does, but it’s not twice the planet! And many very small asteroids have moons, too.
My feelings about this are on record: the word “planet” is not and can not be defined; it’s a concept, not a definition. It’s like the word “continent”: it’s more of an idea than something you can rigidly define. There is no sharp border that you can use to divide objects into planet and not planet.

So I actually don’t care if you call Pluto a planet or not. It is what it is: a very cool object, perhaps the biggest in the Kuiper Belt of frozen icy comet-like bodies past Neptune. It’s an oddity, since it’s so bright, and yes, has so many moons.

And it’s absolutely worthy of study, no matter what you call it.

Private company does indeed plan to mine asteroids… and I think they can do it!

By Phil Plait – an astronomer, lecturer, author, and the creator of Bad Astronomy

Planetary Resources, Inc. is not your average startup: its mission is to investigate and eventually mine asteroids in space!

Last week, the company issued a somewhat cryptic announcement saying they “will overlay two critical sectors – space exploration and natural resources – to add trillions of dollars to the global GDP”. I predicted this meant they wanted to mine asteroids, and yes, I will toot my own horn: I was right. They’re holding a press conference Tuesday morning to officially announce they’re going asteroid hunting.

The company had a pretty fierce amount of credibility right off the bat, with several ex-NASA engineers, an astronaut, and planetary scientists involved, as well as the backing of not one but several billionaires, including a few from Google… not to mention James Cameron. The co-founders of Planetary Resources are Peter Diamandis — he created the highly-successful X-Prize Foundation, to give cash awards to incremental accomplishments that will help achieve technological breakthroughs, including those for space travel — and Eric Anderson, X-Prize board member and Chairman of the Board of the Space Spaceflight Federation.

These are very, very heavy hitters. Clearly, they’re not screwing around.

So what’s the deal?

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Step 1

I spoke with Planetary Resources President and Chief Engineer Chris Lewicki on the phone Monday. He has an excellent pedigree: Lewicki was Flight Director for the NASA’s Spirit and Opportunity Mars rover missions, and also Mission Manager for the Mars Phoenix lander surface operations. So when he says he’s confident the company can and will succeed, I’m willing to listen.

“This is an attempt to make a permanent foothold in space,” he said. “We’re going to enable this piece of human exploration and the settlement of space, and develop the resources that are out there.”

The plan structure is reminiscent of that of Apollo: have a big goal in mind, but make sure the steps along the way are practical.

The key point is that their plan is not to simply mine precious metals and make millions or billions of dollars– though that’s a long-range goal. If that were the only goal, it would cost too much, be too difficult, and probably not be attainable.

Instead, they’ll make a series of calculated smaller missions that will grow in size and scope. The first is to make a series of small space telescopes to observe and characterize asteroids. Lewicki said the first of these is the Arkyd 101, a 22 cm (9″) telescope in low-Earth orbit that will be aboard a tiny spacecraft just 40 x 40 cm (16″) in size. It can hitch a ride with other satellites being placed in orbit, sharing launch costs and saving money (an idea that will come up again and again in their plans). This telescope will be used both to look for and observe known Near-Earth asteroids, and can also be pointed down to Earth for remote sensing operations.

I’ll note Lewicki said they expect to launch the first of these telescopes by the end of next year, 2013. They’re already building them (what’s referred to as “cutting metal”). They could launch on already-existing rockets — an Atlas or Delta, for example, Europe’s Ariane, India’s GSLV, or Space X’s Falcon 9.

After that, once they’re flight-tested, more of these small spacecraft can be launched equipped with rocket motors. If they hitch a ride with a satellite destined for a 40,000 km (24,000 mile) geosynchronous orbit, the motor can be used to take the telescope — now a space probe — out of Earth orbit and set on course for a pre-determined asteroid destination. Technical bit: orbital velocity at geosync is about 3 km/sec, so only about an additional 1 km/sec is needed to send a probe away from Earth, easily within the capability of a small motor attached to a light-weight probe.

Many asteroids pass close to the Earth with a low enough velocity that one of these probes could reach them. Heck, some are easier to reach in that sense than the Moon! Any asteroid-directed probe can be equipped with sensors to make detailed observations, including composition. It could even be designed to land on the asteroid and return samples back to Earth, or leave when the observations are complete and head off to observe more asteroids up close and personal.

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Step 2

Once a suitable asteroid is found, the idea is not to mine it right away for precious metals to return to Earth, Lewicki told me, but instead to tap it for volatiles — materials with low boiling points such as water, oxygen, nitrogen, and so on, which also happen to be critical supplies for use in space.

The idea behind this is to gather these materials up and create in situ space supply depots. Water is very heavy and incompressible, so it’s very difficult to launch from Earth into space (Lewicki quoted a current price of roughly $20,000 per liter to get water into space). But water should be abundant on some asteroids, locked up in minerals or even as ice, and in theory it shouldn’t be difficult to collect it and create a depot. Future astronauts can then use these supplies to enable longer stays in space — the depots could be put in Earthbound trajectories for astronauts, or could be placed in strategic orbits for future crewed missions to asteroids. Lewicki didn’t say specifically, but these supplies could be sold to NASA — Planetary Resources would make quite a bit money while saving NASA quite a bit. Win-win.

The details of exactly how they’ll collect these resources and store them may be revealed in the press conference Tuesday. If I can, I’ll ask.

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Step 3

The last step is to actually get the precious minerals from the asteroids and bring them to Earth. The exact setup for this isn’t clear at this time — again, the press conference should reveal that — but for the moment it may not really need to be. There are several options. One way would be to launch equipment to a distant asteroid already explored previously by a souped-up Arkyd. Another might be to use the small spacecraft to bring a smallish asteroid near the Earth — a study of this was just released, in fact [Note: two of the authors on that study were from Planetary Resources, including Lewicki]. A rock could be brought into an orbit around the Moon (that’s easiest to do in terms of fuel) where it could then be mined. Or it could be both: a small operation could start work while the asteroid is being towed to Earth, getting a few years head start.

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Step 4: Profit???

I asked Lewicki specifically about how this will make money. Some asteroids may be rich in precious metals — some may hold tens or even hundreds of billions of dollars in platinum-group metals — but it will cost billions and take many years, most likely, to mine them before any samples can be returned. Why not just do it here on Earth? In other words, what’s the incentive for profit for the investors? This is probably the idea over which most people are skeptical, including several people I know active in the asteroid science community.

I have to admit, Lewicki’s answer surprised me. “The investors aren’t making decisions based on a business plan or a return on investment,” he told me. “They’re basing their decisions on our vision.”

On further reflection, I realized this made sense. Not every wealthy investor pumps money into a project in order to make more… at least right away. Elon Musk, for example, has spent hundreds of millions of his own fortune on his company Space X. Amazon’s founder Jeff Bezos is doing likewise for his own space company, Blue Origin. Examples abound. And it’ll be years before either turns a respectable profit, but that’s not what motivates Musk and Bezos to do this. They want to explore space.

The vision of Planetary Resources is in their name: they want to make sure there are available resources in place to ensure a permanent future in space. And it’s not just physical resources with which they’re concerned. Their missions will support not just mining asteroids for volatiles and metals, but also to extend our understanding of asteroids and hopefully increase our ability to deflect one should it be headed our way.

This again was a topic I discussed with Lewicki specifically. He agreed with my proposition that all three topics — science, deflection, and resource use — are tied together. After all, we need to understand asteroids scientifically if we want to use them or prevent them from hitting us. We can use them for depots to establish better exploration of them, and sometime in the future we may need to deflect one to prevent all this from being a moot point anyway.

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My opinion on all this

The beauty of being me (among other things) is that I don’t always have to be objective. So I’ll say this: I love this idea. Love it.

Mind you, that’s different than saying I think they can do it. But, in theory at least, I think they can. Their step-wise plan makes sense to me, and they don’t need huge rockets and huge money to get things started. By the time operations ramp up to something truly ambitious they should already have in place the pieces necessary for it, including the track record. In other words, by the time they’re ready to mine an asteroid, they’ll have in place all the infrastructure needed to actually do it. I still want to see some engineering plans and a timeline, but in general what I’ve heard sounds good.

My biggest initial skepticism would be the investors — with no hope of profit for years, would they really stick with it?

But look at the investors: Film maker James Cameron. Google executives Larry Page & Eric Schmidt, and Google investor K. Ram Shriram. Software pioneer Charles Simonyi. Ross Perot, Jr. These are all billionaires, some of them adventurers, and all of them have proven to have patience in developing new ventures. I don’t think they’ll turn tail and run at the first setback.

Lewicki said much the same thing. “I was a harsh skeptic at first, but [when the company founders Peter Diamandis and Eric Anderson] approached me we talked about a plan on how to create a company and pursue this.” Soon after, he came to the conclusion this was a logical plan and the group was capable of doing it. In the press release, he said, “Not only is our mission to expand the world’s resource base, but we want to expand people’s access to, and understanding of, our planet and solar system by developing capable and cost-efficient systems.”

That sounds like a great idea to me. And I am strongly of the opinion that private industry is the way to make that happen. The Saturn V was incredible, but not terribly cost effective; that wasn’t its point. And when NASA tried to make a cost-effective machine, they came up with the Space Shuttle, which was terribly expensive, inefficient, and — let’s face it — dangerous. The government is good for a lot of things, but political machinations can really impede innovation when it comes to making things easier and less costly. As many people involved with NASA used to joke: “Faster, better, cheaper: pick two.”

I still strongly support NASA, of course; don’t get me wrong. It should still do what it does best: the things private industry can’t, like breaking new ground. That’s what NASA has been doing in space for 50 years, and now that paved way is being taken up by private companies. I think it’s just that combination of government support and private innovation that will get us to the stars. And for now, just for now, you know what?

Getting to the asteroids will do just fine.

Stunning vortex appears on Saturn’s moon, puzzles scientists

By Mike Wehner, Tecca

NASA’s Cassini orbiter has already taken some stunning photos of Saturn and its moons, but the latest snapshot from the multi-billion-dollar mission might be its most impressive yet. After swinging down to the southern hemisphere of Titan — Saturn’s largest moon — the high-powered orbiter captured images of a massive vortex forming at its pole, and scientists can only guess as to why it’s suddenly appeared.

The massive collection of swirling gas has gathered at Titan’s south pole, which measures approximately 3,200 miles across. The whirlwind has never before been spotted, and it remains unclear how long it has been forming. Cassini — which first arrived near Saturn in 2004 (and shot the stunning images below) — had been orbiting the moon too far north to have captured it, until now.

Photo of Titan against backdrop of Saturn

Prior to this discovery, the probe spotted images of a large “hood” on Titan’s north pole, which researchers believe is the result of cell convection — a process where dense air sinks towards the surface, pushing air at its edges upwards to create clouds. As Titan’s seasons change, scientists believe that the same mechanism may be at work at the moon’s southern pole, but they can’t be sure.

Cassini photo of Saturn

A single year on Titan lasts approximately 30 Earth years, making the study of each season a lengthy endeavor. The planet is composed of rock, water ice, and methane, making for some weather formations not typically seen here on Earth. The gigantic, swirling anomaly — which is spinning at four times the speed of the rest of the moon — appears to be yet another interesting characteristic of Saturn’s most interesting satellite.

High-contrast photo of Saturn from Cassini probe

Battered Tharsis Tholus Volcano On Mars

ScienceDaily (Nov. 8, 2011) — The latest image released from Mars Express reveals a large extinct volcano that has been battered and deformed over the aeons.

Tharsis Tholus Volcano - Mars

By Earthly standards, Tharsis Tholus is a giant, towering 8 km above the surrounding terrain, with a base stretching over 155 x 125 km. Yet on Mars, it is just an average-sized volcano. What marks it out as unusual is its battered condition.

Shown in images taken by the HRSC high-resolution stereo camera on the European Space Agency’s Mars Express spacecraft, the volcanic edifice has been marked by dramatic events.

At least two large sections have collapsed around its eastern and western flanks during its four-billion-year history and these catastrophes are now visible as scarps up to several kilometres high.

The main feature of Tharsis Tholus is, however, the caldera in its centre.

It has an almost circular outline, about 32 x 34 km, and is ringed by faults that have allowed the caldera floor to subside by as much as 2.7 km.

It is thought that the volcano emptied its magma chamber during eruptions and, as the lava ran out onto the surface, the chamber roof was no longer able to support its own weight.

So, the volcano collapsed, forming the large caldera.

November is a busy month for Mars exploration: Russia and NASA both plan launches this month.

Russia’s Phobos-Soil (formerly known as Phobos-Grunt) is designed to land on Phobos, the larger of Mars’ two moons, to collect samples, and return them to Earth in 2014. It also carries the first Chinese spacecraft to Mars, Yinghuo-1.

Mars Express HRSC digital elevation models of Phobos were used by Russian scientists to assess the mission’s potential landing sites and ESA is also providing telecommunications support for both Phobos-Soil and Yinghuo-1.

In return, the European scientific community will have access to data obtained by both spacecraft.

NASA’s mission is the Mars Science Laboratory, a large rover known as Curiosity, with experiments designed to detect organic molecules — past or present — on the Red Planet.

Also worth noting is the simulated Mars mission, Mars500, which ended on Friday when the hatch was opened for the first time since June 2010. For 520 days, the international crew had been working in a simulated spacecraft in Moscow.

Slideshow
http://news.yahoo.com/photos/mars-volcano-1320955000-slideshow/