Jupiter Not the Planetary Protector We Thought it Was?

Jupiter takes a beating from Comet Shoemaker-Levy 9. Credit: NASA/Hubble Space Telescope team.
Jupiter takes a beating from Comet Shoemaker-Levy 9. Credit: NASA/Hubble Space Telescope team.

I’ve always liked the idea that Jupiter has acted like a protector to its little brother, Earth. That it has used its massive gravitational pull to divert asteroids and comets from a collision course with Earth. Maybe Jupiter even felt bad when one got through, and doomed the dinosaurs to extinction. But a new study has cast this idea into doubt.

The idea of Jupiter as a protector has been around for a while. The images of comet Shoemaker-Levy 9 breaking apart and crashing into Jupiter in 1994 reinforced the idea. But according to Kevin Grazier, at the Jet Propulstion Laboratory (JPL), rather than acting solely as a shield, re-directing comets and other objects away from the inner solar system, Jupiter may have actually directed planetesimals into the inner solar system.

Illustration of a rocky planet being bombarded by comets. (Image credit: NASA/JPL-Caltech)
Illustration of a rocky planet being bombarded by comets. (Image credit: NASA/JPL-Caltech)

In the early days of the Solar System, there was much more debris around than there is now. The early days would have been a race between planetesimals to gather enough mass to form the planets we see today. After planets were formed, there would still have been plenty of planetesimals left. This new study shows that, rather than clearing the inner solar system from all this debris that could collide with Earth, Jupiter nudged many of these planetesimals towards Earth, helping to create Earth as we know it.

As reported in January 2016 in Astrobiology, Glazier created a simulator of the solar system, and ran 30,000 particles through this simulation. All of the particles began in “non life-threatening” trajectories, but a significant number of them ended the simulation in orbits that crossed the orbit of the Earth.

So not only did Jupiter—and Saturn—re-direct material into the inner Solar System, but the simulation also showed that Jupiter slowed that material to a speed which allowed it to contribute mass to Earth.

But these planetesimals would have contributed more than just mass to Earth. They would have carried volatiles with them. Volatiles are chemical elements and molecules with low boiling points. They are associated with the atmosphere and the crust. These volatiles, which include nitrogen, hydrogen, carbon dioxide, and others, make up a large portion of the Earth’s crust. Without them, Earth would be a very different place. It may never have developed the atmosphere that has allowed life to flourish.

It’s clear that Jupiter has contributed to the evolution of Earth and the Solar System as we know it. As the largest planet by far, its influence is undeniable. As a result of this study, we better understand the dual-role Jupiter has played. While it no doubt has played the role of protector, by changing the direction of some objects on a collision course with Earth, Jupiter’s presence has also been responsible for slowing and diverting planetesimals—and their life-friendly volatiles—directly into Earth.

Earth From Afar Would Look Only 82% Right For Life

From Lunar orbit, Earth is obviously habitable. But from a distant point in the galaxy, not so much. Image: NASA/LRO.
From Lunar orbit, Earth is obviously habitable. But from a distant point in the galaxy, not so much. Image: NASA/LRO.

Right now, we’re staring hard at a small section of the sky, to see if we can detect any planets that may be habitable. The Kepler Spacecraft is focused on a tiny patch of sky in our Milky Way galaxy, hoping to detect planets as they transit in front of their stars. But if alien astronomers are doing the same, and detect Earth transiting in front of the Sun, how habitable would Earth appear?

You might think, because, well, here we are, that the Earth would look 100% habitable from a distant location. But that’s not the case. According to a paper from Rory Barnes and his colleagues at the University of Washington-based Virtual Planetary Laboratory, from a distant point in the galaxy, the probability of Earth being habitable might be only 82%.

Illustration of the Kepler spacecraft.(NASA/Kepler mission/Wendy Stenzel)
Illustration of the Kepler spacecraft.(NASA/Kepler mission/Wendy Stenzel)

Barnes and his team came up with the 82% number when they worked to create a “habitability index for transiting planets,” that seeks to rank the habitability of planets based on factors like the distance from its star, the size of the planet, the nature of the star, and the behaviour of other planets in the system.

The search for habitable exo-planets is dominated by the idea of the circumstellar habitable zone—or Goldilocks Zone—a region of space where an orbiting planet is not too close to its star to boil away all the water, and not so far away that the water is all frozen. This isn’t a fixed distance; it depends on the type and size of the star. With an enormous, hot star, the Goldilocks Zone would be much further away than Earth is from the Sun, and vice-versa for a smaller, cooler star. “That was a great first step, but it doesn’t make any distinctions within the habitable zone,” says Barnes.

Comparing a star's habitable zone based on its size. Credit: Fine Art America/Detlev Van Ravenswaay
Comparing a star’s habitable zone based on its size. Credit: Fine Art America/Detlev Van Ravenswaay.

Kepler has already confirmed the existence of over 1,000 exo-planets, with over 4,700 total candidate planets. And Kepler is still in operation. When it comes time to examine these planets more closely, with the James Webb Space Telescope and other instruments, where  do we start? We needed a way to rank planets for further study. Enter Barnes and his team, and their habitability index.

To rank candidates for further study, Barnes focused on not just the distance between the planet and the host star, but on the overall energy equilibrium. That takes into account not just the energy received by the planet, but the planet’s albedo—how much energy it reflects back into space. In terms of  being warm enough for life, a high-albedo planet can tolerate being closer to its star, whereas a low-albedo planet can tolerate a greater distance. This equilibrium is affected in turn by the eccentricity of the planet’s orbit.

The habitability index created by Barnes—and his colleagues Victoria Meadows and Nicole Evans—is a way to enter data, including a planet’s albedo and its distance from its host star, and get a number representing the planet’s probability of being habitable. “Basically, we’ve devised a way to take all the observational data that are available and develop a prioritization scheme,” said Barnes, “so that as we move into a time when there are hundreds of targets available, we might be able to say, ‘OK, that’s the one we want to start with.’”

So where does the Earth fit into all this? If alien astronomers are creating their own probability index, at 82%, Earth is a good candidate. Maybe they’re already studying us more closely.

 

The Highest-Resolution Image Ever Seen in Astronomy

A jet of material being ejected out of a black hole at the centre of the galaxy BL Lacertae. Image: Dr. Jose L. Gomez
A jet of material being ejected out of a black hole at the centre of the galaxy BL Lacertae. Image: Dr. Jose L. Gomez

What do you get when you combine 15 radio telescopes on Earth and one in space? You get an enormous “virtual telescope” that is 63,000 miles across. And when you point it at a distant black hole, you get the highest resolution image every seen in astronomy.

Although it looks just like a big green blob, it’s actually an enormously energetic jet of matter streaming out of a black hole. And this black hole is 900 million light years away.

As reported at Popular Science, it required an array of 15 radio telescopes on Earth, and the Russian space telescope Spektr-R, to capture the image. This technique—called interferometry—is like creating a telescope that is 63,000 miles across. The detail it provides is like seeing a 50 cent coin on the Moon.

For perspective, the object in the image is 186 billion miles long, at minimum, and would just barely fit in the Oort Cloud.

The jet at the heart of BL Lacertae, with the Oort Cloud and Alpha Centauri for comparison. Image: Gomez et. al., A Lobanov, NRAO.
The jet at the heart of BL Lacertae, with the Oort Cloud and Alpha Centauri for comparison. Image: Gomez et. al., A Lobanov, NRAO.

China Shares Stunning New Moon Photos With the World

This image shows the Yutu rover leaving the lander area and making its way on the lunar surface. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
This image shows the Yutu rover leaving the lander area and making its way on the lunar surface. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.

China has released hundreds of images of the Moon, taken by its Chang’e 3 lander and its companion rover, Yutu. It’s been 50 years since the first lunar photos were taken by astronauts on NASA’s Apollo 11 mission. China is the third nation to land on the Moon, with the USA and the USSR preceding them.

Even though the Yutu rover’s engine failed after a short time on the lunar surface, the mission’s camera systems have captured hundreds of images.

Thanks to the hard work of Emily Lakdawalla at The Planetary Society, who wrestled with a somewhat cumbersome Chinese website, and stitched some of these images together, we can get a first-hand look at what Chang’e 3 and Yutu were up to.

Here are some of our favourites.

Pyramid Rock, as named by the Chinese. This rock was ejected when the crater immediately behind it was created. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
Pyramid Rock, as named by the Chinese. This rock was ejected when the crater immediately behind it was created. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.

 

This is a 360 degree panoramic image of the rover and part of the lander. Bright white rocks litter the rim of the crater on the left. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
This is a 360 degree panoramic image of the rover and part of the lander. Bright white rocks litter the rim of the crater on the left. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
The Yutu lander looks at its tracks in the lunar soil. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
The Yutu lander looks at its tracks in the lunar soil. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
This image shows a lot of detail of the Yutu rover. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.
This image shows a lot of detail of the Yutu rover. Image: Chinese Academy of Sciences/China National Space Administration/The Science and Application Centre for Moon and Deep Space Exploration/Emily Lakdawalla.

Emily Lakdawalla talks more about the camera systems here, and talks about what other images might be coming soon.

Universe Today reported on the Chinese Moon mission here.

A Cataclysmic Collision Formed the Moon, but Killed Theia

Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone
Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone

The Moon is the first object in space that fascinates we Earthlings. The Sun might be more prominent, but you can’t stare at the Sun without ocular damage. Anyone can gaze at the Moon, with or without binoculars or a telescope, and wonder where it came from and what it all means.

New evidence from a team at UCLA is clarifying the story of the Moon’s origins. According to this research, the Moon was formed as a result of a massive collision between Earth and a “planet embryo” about the size of Mars called Theia. This collision happened about 100 million years after the Earth was formed. Published on January 29th in the journal Science, this new geological evidence strengthens the case for the collision model.

The researchers compared Earth rocks with rocks retrieved from the Moon over the years. (Over 380kg of rocks have been brought back to Earth.) They found that these samples—collected on Apollo missions 12, 15, and 17—had the same chemical composition as seven rocks collected from Earth’s mantle, in Hawaii and Arizona. The key to the comparison lies in the nature of the oxygen atoms in the rocks.

Oxygen is a highly reactive element. It is easily combined with other elements, and is the most common element in the Earth’s crust. There are several different oxygen isotopes present in the Earth’s crust, and on other bodies in the solar system. The amount of each isotope present on each body is the “fingerprint” that makes the formation of each body different.

But the team at UCLA has shown that Earth and the Moon share the same cocktail of oxygen isotopes. They have the same fingerprint. This means that somehow, someway, their formation is linked. It can’t be pure coincidence. Says Edward Young, lead author of the new study, “We don’t see any difference between the Earth’s and the Moon’s oxygen isotopes; they’re indistinguishable.”

So how did this happen? How do Earth and the Moon share the same oxygen fingerprint? Enter Theia, an embryonic planet that got in the way of Earth’s orbit around the Sun. And as the research shows, this collision had to be more than a glancing blow. The collision had to be direct and cataclysmic.

This video shows how the collision would have played out.

A glancing blow would mean that the Moon would be mostly made of Theia, and would therefore have a different oxygen isotope fingerprint than Earth. But the fact that the Earth and Moon are indistinguishable from each other means that Theia had to have been destroyed, or rather, had to become part of both the Earth and the Moon.

“Theia was thoroughly mixed into the Earth and the Moon, and evenly dispersed between them. This explains why we don’t see a different signature of Theia in the Moon versus Earth,” said Young.

If this collision had not taken place, our Solar System would look very different, with an additional rocky planet in the inner regions. We also would have no Moon, which would have changed the evolution of life on Earth.

This collision theory, called the Theia Impact, or the Big Splash, has been around since 2012. But in 2014, a team of German researchers reported in Science that the Earth and Moon have different oxygen isotope ratios, which threw the collision formation theory into doubt. These new results confirm that it was a cataclysmic collision that gave birth to the Moon, and changed our Solar System forever.

Massive Ariane 5 To Launch Giant NextGen Telescope In Dynamic Deployment To L2

The Ariane5 lifting off from Kourou in French Guiana. Image: ESA/Arianespace.
The Ariane5 lifting off from Kourou in French Guiana. Image: ESA/Arianespace.

The Ariane 5 rocket is a workhorse for delivering satellites and other payloads into orbit, but fitting the James Webb Space Telescope (JWST) inside one is pushing the boundaries of the Ariane 5’s capabilities, and advancing our design of space observatories at the same time.

The Ariane 5 is the most modern design in the ESA’s Ariane rocket series. It’s responsible for delivering things like Rosetta, the Herschel Space Observatory, and the Planck Observatory into space. The ESA is supplying an Ariane 5 to the JWST mission, and with the planned launch date for that mission less than three years away, it’s a good time to check in with the Ariane 5 and the JWST.

The Ariane 5 has a long track record of success, often carrying multiple satellites into orbit in a single launch. Here’s its most recent launch, on January 27th from the ESA’s spaceport in French Guiana. This is Ariane 5’s 70th successful launch in a row.

But launching satellites into orbit, though still an amazing achievement, is becoming old hat for rockets. 70 successful launches in a row tells us that. The Ariane 5 can even launch multiple satellites in one mission. But launching the James Webb will be Ariane’s biggest challenge.

The thing about satellites is, they’re actually getting smaller, in many cases. But the JWST is huge, at least in terms of dimensions. The mass of the JWST—6,500 kg (14,300 lb)—is just within the limits of the Ariane 5. The real trick was designing and building the JWST so that it could fit into the cylindrical space atop an Ariane 5, and then “unfold” into its final shape after separation from the rocket. This video shows how the JWST will deploy itself.

The JWST is like a big, weird looking beetle. Its gold-coated, segmented mirror system looks like multi-faceted insect eyes. Its tennis-court sized heat shield is like an insect’s shell. Or something. Cramming all those pieces, folded up, into the nose of the Ariane 5 rocket is a real challenge.

Because the JWST will live out its 10-year (hopefully) mission at L2, rather than in orbit around Earth, it requires this huge shield to protect itself from the sun. The instruments on the James Webb have to be kept cool in order to function properly. The only way to achieve this is to have its heat shield folded up inside the rocket for launch, then unfolded later. That’s a very tricky maneuver.

But there’s more.

The heart of the James Webb is its segmented mirror system. This group of 18 gold-coated, beryllium mirrors also has to be folded up to fit into the Ariane 5, and then unfolded once it’s separated from the rocket. This is a lot trickier than launching things like the Hubble, which was deployed from the space shuttle.

Something else makes all this folding and unfolding very tricky. The Hubble, which was James Webb’s predecessor, is in orbit around Earth. That means that astronauts on Shuttle missions have been able to repair and service the Hubble. But the James Webb will be way out there at L2, so it can’t be serviced in any way. We have one chance to get it right.

Right now, the James Webb is still under construction in the “Clean Room” at NASA’s Goddard Space Flight Centre. A precision robotic arm system is carefully mounting Webb’s 18 mirrors.

A robotic arm positions one of James Webb's 18 mirrors. Image: NASA/Chris Gunn
A robotic arm positions one of James Webb’s 18 mirrors. Image: NASA/Chris Gunn

There’s still over two years until the October 2018 launch date, and there’s a lot of testing and assembly work going on until then. We’ll be paying close attention not only to see if the launch goes as planned, but also to see if the James Webb—the weird looking beetle—can successfully complete its metamorphosis.

Our Place in the Universe: The Most Detailed Map Yet

Astronomy and the other space sciences are the best branches of science for pure eye candy. Biology is great, but who wants to watch videos of a cell dividing? Over and over again. Not me, and not you either, I’ll bet.

This new video from Futurism.com shows our place in the Laniakea Supercluster. Superclusters are the largest-scale structures in the universe, and next to them, we are indeed puny creatures. Our Milky Way galaxy is but a tiny dot in an unremarkable corner of Laniakea.

Thanks to Futurism.com, Nature.com, and R. Brent Tully at the University of Hawaii, we can see better than ever how we Milky Way inhabitants fit into the larger structure of the Universe.

This video is actually a spiffy new edit of an older video, with explanatory voice-over. Check it out.

Blue Origin Reaches Another Milestone: Reusable Rocket Launches and Lands Safely

Blue Origin's New Shepard rocket has successfully launched and landed a second time. Image: Blue Origin
Blue Origin's New Shepard rocket has successfully launched and landed a second time. Image: Blue Origin

On Friday, January 22nd, commercial space company Blue Origin successfully launched and landed its reusable rocket, New Shepard, at their launch facility in Texas. This is the second flight for New Shepard, showing that reusable rockets are on their way to becoming the launch system of choice. New Shepard launched, travelled to apogee at 101.7 kilometres, (63.19 miles) and then descended to land safely at their site in West Texas. This is the first successful reuse of a rocket in history.

Reusable rockets are an important development for space travel. Rockets are enormously expensive, and having to trash each rocket after a single use makes commercial space flight a real challenge. Blue Origin—and other companies like SpaceX—are blazing a trail to cheaper space flight with their reusable designs. This is great, not only for all the good sciencey reasons that we love so much, but because eventually civilian space enthusiasts may be able to travel past the Karman Line without having to sell all their possessions to do so. (Reserve your ticket here.) Continue reading “Blue Origin Reaches Another Milestone: Reusable Rocket Launches and Lands Safely”

Lonely But Not Alone: A Planet Orbits its Star at 1 Trillion Kilometres

A false-colour image of the planet 2MASS J2126 and star TYC 9486-927-1 moving through space. The white arrow indicates 1,000 years of movement. Image: 2MASS/S. Murphy/ANU
A false-colour image of the planet 2MASS J2126 and star TYC 9486-927-1 moving through space. The white arrow indicates 1,000 years of movement. Image: 2MASS/S. Murphy/ANU

The Royal Astronomical Society (RSA) has announced the discovery of a planet that orbits its star at a distance of 1 trillion kilometres. This is easily the furthest distance between a star and a planet ever found. For comparison, that’s 7,000 times further than the Earth is from the Sun. At that distance, a single orbit takes about 900,000 years, meaning that the planet has orbited its star less than 50 times.

Continue reading “Lonely But Not Alone: A Planet Orbits its Star at 1 Trillion Kilometres”

Extinction Alert: Stephen Hawking Says Our Technology Might Wipe Us Out

Professor Stephen Hawking enjoying a lighter moment. Image credit: Zero G
Professor Stephen Hawking enjoying a lighter moment, and not contemplating the end of humanity. Image credit: Zero G

If you’re thinking of having yourself cryogenically suspended and awakened in some future paradise, you might want to set your alarm clock for no later than 1,000 years from now. According to the BBC, Stephen Hawking will be saying this much in the 2016 Reith Lectures – a series of lectures organized by the BBC that explore the big challenges faced by humanity.

In Hawking’s first lecture, which will be broadcast on February 26th on the BBC, Hawking covers the topic of black holes, whether or not they have hair, and other concepts about these baffling objects.

But at the end of the lecture, he responded to audience questions about humanity’s capacity for self destruction. Hawking said that 1,000 years might be all we have until we meet our demise at the hands of our own scientific and technological advances.

As we have become increasingly advanced both scientifically and technologically, Hawking says, we will be creating “new ways that things can go wrong.” Hawking mentioned nuclear war, global warming, and genetically engineered viruses as things that could cause our extinction.

Nuclear War

Through the Cold War, annihilation at the hands of our own nuclear weapons was a real danger. The threat of a nuclear launch in response to a real or perceived threat was real. The resulting retaliation and counter-retaliation was a risk faced by everyone on the planet. And the two superpowers had enough warheads between them to potentially wipe out life on Earth.

One nuclear explosion can ruin your whole day. Image: Andrew Kuznetsov, CC by 2.0
One nuclear explosion can ruin your whole day. Image: Andrew Kuznetsov, CC by 2.0

The USA and the USSR have reduced their stockpiles of nuclear weapons in recent decades, but there are still enough warheads around to wipe us out. The possibility of a rogue state like North Korea setting off a nuclear confrontation is still very real. By the time Hawking’s 1,000 year time-frame has passed, we’ll either have solved this problem, or we won’t be here.

Global Warming

Earth is getting warmer, and though the Earth has warmed and cooled many times in its history, this time we only have ourselves to blame. We’ve been inadvertently enriching our atmosphere with carbon since the Industrial Revolution. All that carbon is creating a nice insulating layer around Earth, as it traps heat that would normally radiate into space. If we reach some of the “tipping points” that scientists talk about, like the melting of permafrost and the subsequent release of methane, we could be in real trouble.

Global Mean Surface Temperature. Image: NASA, Goddard Institute for Space Studies
Global Mean Surface Temperature. Image: NASA, Goddard Institute for Space Studies

Different climate engineering schemes have been thought up to counteract global warming, like seeding the upper atmosphere with reflective molecules, and having fleets of ships around the equator spraying sea mist into the air to partially block out the sun. Or even extracting carbon from the atmosphere. But how realistic or effective those counter-measures might be is not clear.

Genetically Engineered Viruses

As a weapon, a virus can be cheap and effective. There’ve been programs in the past to develop biological weapons. The temptation to use genetic science to create extremely deadly viruses may prove too great.

Smallpox and Viral Hemorrhagic Fevers have been weaponized, and as our genetic manipulation abilities grow, it’s possible, or even likely, that somebody somewhere will attempt develop even more dangerous viral weapons. They may be doing it right now.

There’s a ban on viral weapons, called the Biological and Toxin Weapons Convention signed in 1972. But, not everybody has signed it.

Artificial Intelligence

Hawking never mentioned AI in his talk, but it fits in with the discussion. As our machines get smarter and smarter, will they deduce that the only chance for survival is to remove or reduce the human population? Who knows. But Hawking himself, as well as other thinkers, have been warning us that there may be a catastrophic downside to our achievements in AI.

A Google driverless car: Looks harmless, doesn't it? Image: Michael Shick http://creativecommons.org/licenses/by-sa/4.0
A Google driverless car: Looks harmless, doesn’t it? Image: Michael Shick http://creativecommons.org/licenses/by-sa/4.0

We may love the idea of driverless cars, and computer assistants like SIRI. But as numerous science fiction stories have warned us (Skynet in the Terminator series being my favorite,) it may be a small step from very helpful AI that protects us and makes our lives easier, to AI that decides existence would be a whole lot better without us pesky humans around.

The Technological Singularity is the point at which artificially intelligent systems “wake up” and become—more or less—conscious. These AI machines would start to improve themselves recursively, or build better and smarter machines. At this point, they would be a serious danger to humanity.

Drones are super popular right now. They flew off the shelves at Christmas, and they’re great toys. But once we start seeing drones with primitive but effective AI, patrolling the property of the wealthy, it’ll be time to start getting nervous.

Extinction May Have To Wait

As our scientific and technological prowess grows, we’ll definitely face new threats, just like Hawking says. But, that same progress may also protect us, or make us more resilient. Hawking says, “We are not going to stop making progress, or reverse it, so we have to recognise the dangers and control them. I’m an optimist, and I believe we can.” So do we.

Maybe you’ll be able to hit the snooze button after all.

Original Source: BBC News