Heavy Stellar Traffic Sends Dangerous Comets Our Way

New image of comet ISON
Comet C/2012 S1 (ISON) as imaged by TRAPPIST–South national telescope at ESO’s La Silla Observatory in 2013 (TRAPPIST/E. Jehin/ESO)

Sixty-six million years ago Earth underwent a cataclysmic change. Back then, our planet was dominated by dinosaurs, but a mass extinction event hastened the demise of these huge reptiles and paved the way for the mammalian takeover. Though there is some debate as to whether the extinction of the dinosaurs was triggered by an isolated disaster or a series of disasters, one event is clear — Earth was hit by a massive comet or asteroid and its impact had global ramifications.

The leading theory is that a massive comet slammed into our planet, creating the vast Chicxulub Crater buried under the Yucatán Peninsula in Mexico, enshrouding the atmosphere in fine debris, blotting out the sun for years.

Although there is strong evidence of comet impacts on Earth, these deep space vagabonds are notoriously hard to track, let alone predict when or how often they may appear. All we know is that they are out there, there are more than we thought, they are known to hit planets in the solar system and they can wreak damage of apocalyptic proportions.

Now, using fresh observations from the European Space Agency’s Gaia mission, astronomer Coryn Bailer-Jones, who works at the Max Planck Institute for Astronomy in Munich, Germany, has added an interesting component to our understanding of cometary behavior.

Stellar Traffic

Long-period comets are the most mysterious — and troubling — class of comet. They will often appear from nowhere, after falling from their distant gravitational perches, zoom through the inner solar system and disappear once more — often to be never seen again. Or they hit something on their way through. These icy bodies are the pristine left-overs of our solar system’s formation five billion years ago, hurled far beyond the orbits of the planets and into a region called the Oort Cloud.

In the Oort Cloud these ancient masses have remained in relative calm far from the gravitational instabilities close to the sun. But over the eons, countless close approaches by other stars in our galactic neighborhood have occurred, causing very slight gravitational nudges to the Oort Cloud. Astronomers believe that such stellar encounters are responsible for knocking comets from this region, sending them on a roller-coaster ride to the inner solar system.

The Gaia mission is a space telescope tasked with precisely mapping the distribution and motion of stars in our galaxy, so Bailer-Jones has investigated the rate of stellar encounters with our solar system. Using information in Gaia’s first data release (DR1), Bailer-Jones has published the first systematic estimate of stellar encounters — in other words, he’s estimated the flow of stellar traffic in the solar system’s neighborhood. And the traffic was found to be surprisingly heavy.

In his study, to be published in the journal Astronomy & Astrophysics, Bailer-Jones estimates that, on average, between 490 and 600 stars will come within 16.3 light-years (5 parsecs) of our sun and 19-24 of them will come within 3.26 light-years (1 parsec) every million years.

According to a press release, all of these stars will have some gravitational effect on the solar system’s Oort Cloud, though the closest encounters will have a greater influence.

This first Gaia data release is valid for five million years into the past and into the future, but astronomers hope the next data release (DR2) will be able to estimate stellar traffic up to 25 million years into the past and future. To begin studying the stellar traffic that may have been responsible for destabilizing the dinosaur-killing comet that hit Earth 66 million years ago will require a better understanding of the mass distribution of our galaxy (and how it influences the motion of stars) — a long-term goal of the Gaia project.

An Early Warning?

Spinning this idea into the future, could this project be used to act as an early warning system? Or could it be used to predict when and where a long-period comet may appear in the sky?

In short: “No,” Bailer-Jones told Astroengine via email. “Some close stellar encounters will for sure shake up the Oort cloud and fling comets into the inner solar system, but which comets on which orbits get flung in we cannot observe.”

He argues that the probability of comets being gravitationally nudged can be modeled statistically, but this would require a lot of assumptions to be made about the Oort Cloud, a region of space that we know very little about.

Also, the Oort Cloud is located well beyond the sun’s heliosphere and is thought to be between 50,000 and 200,000 AU (astronomical units, where 1 AU is the average distance between the sun and the Earth) away, so it would take a long time for comets to travel from this region, creating a long lag-time between stellar close approach and the comet making an appearance.

“Typically it takes a few million years for a comet to reach the inner solar system,” he added, also pointing out that other factors can complicate calculations, such as Jupiter’s enormous gravity that can deflect the passage of comets, or even fling them back out of the solar system again.

This is a fascinating study that goes to show that gravitational perturbations in the Oort Cloud are far from being rare events. A surprisingly strong flow of stellar traffic will constantly rattle otherwise inert comets, but how many are dislodged and sent on the long journey to the solar system’s core remains a matter for statistics and probability.


Astroengine Roundup: Time Machines, Stealth Solar Eruptions, Comet Oxygen

As I freelance for other websites, I thought I’d begin posting links and summaries here on a quasi-regular basis so you can keep up with the other space stuff I write about. So, to kick off the Astroengine Roundup, here you go:

Using TARDIS to Mathematically Travel Through Time (HowStuffWorks.com)


Ever since H. G. Wells wrote “The Time Machine” in 1895, we’ve been fascinated with the possibility of magically bouncing around through history. But it wasn’t until Einstein published his historic theory of general relativity that scientists (and science fiction writers) realized that time wasn’t necessarily as ridged as classical theories predicted. After a thought-provoking chat with general relativity expert Ben Tippett, of the University of British Columbia, I was able to get the lowdown on his mathematical model of a time machine called… TARDIS.

Comets Are Oxygen Factories (HowStuffWorks.com)


When Europe’s Rosetta mission discovered molecular oxygen venting from comet 67P/Churyumov-Gerasimenko in 2015, scientists were weirded out. In space, molecular oxygen (O2, i.e. the stuff we breathe) is highly reactive and will break down very quickly. The working theory was that the O2 had been locked in the comet’s ices for billions of years since the solar system’s earliest moments, but new research suggests that 67P is actually producing its own O2 right this moment from a complex interplay between the venting water molecules and chemicals on the comet’s surface. Yes, comets are therefore molecular oxygen factories.

Not So Fast: Magnetic Mystery of Sun’s ‘Stealth’ Eruptions Uncovered (SPACE.com)

NASA’s Goddard Space Flight Center/ARMS/Joy Ng

Coronal mass ejections, or CMEs, are the most dramatic eruptions that our sun can produce. If they are Earth-directed, these magnetized bubbles of superheated plasma can cause all kinds of issues for our high-technology civilization. Usually, space weather forecasters do a great job of at least predicting when these eruptions might be triggered in the sun’s lower corona, but there’s a different type of CME — the so-called “stealth” CME — that appears to come out of nowhere, created by the complex interplay of magnetic fields high in the sun’s atmosphere.

NASA Competitions (SPACE.com: 1, 2)


There’s been a couple of updates from NASA challenges and competitions these last few days. The first was the announcement of the High Performance Fast Computing Challenge (HPFCC), which challenges coders with some time on their hands to better optimize supercomputer software for NASA’s simulations of aeronautics models. The second was the announcement of the first winners of Phase 2 of NASA’s 3D-Printed Habitat Challenge — a competition that hopes to pull in talent from a range of backgrounds to ultimately develop the technology to 3D print habitats on Mars and beyond.

~Ad astra

The British (Astronauts) Are Coming!

Lucky sod: Major Tim Peake, training British astronaut (BNSC)
Lucky sod: Major Tim Peake, British astronaut (BNSC)

Really, we are. But for the love of god old chap, make sure the first 2015 space station cargo run is packed to the brim with tea bags!

Ever since I heard the first UK government-funded astronaut was being trained to join the European Space Agency in 2009, I nearly wet myself. You see, when you’re a kid growing up in the UK, you can say: “I want to be a fireman,” “I want to be a policeman,” or “I want to be a doctor,” (I said the latter, which, as it turned out, wasn’t too far off.) You can’t say, for example: “I want to be an astronaut!” — to do that you’d have to emigrate, something my mum would never have endorsed to a starry-eyed 10-year-old.

Ever since Margaret Thatcher’s government deemed human spaceflight too expensive for our little island nation to shoulder in the 1980s, we Brits have been relegated to spectators in the human spaceflight arena (robotic spaceflight, however, is a whole different matter). But now, that’s beginning to change with the announcement that Major Tim Peake has been selected as a 2015 space station crew member.

Luvly jubbly.

Read more: UK to Send First Astronaut to Space Station

No Matter How You Spin It, A Hole is Still a Hole

Mars Express to Beagle 2: But you forgot your... ah, never mind.
Mars Express to Beagle 2: "But you forgot your... ah, never mind." (ESA)

Over Christmas in 2003, I was watching the BBC news with my grandfather, hoping to hear that ESA or NASA had picked up a signal from the Martian surface. We waited.

We waited a bit more. However, it wasn’t until some weeks later (if I remember correctly) that the UK’s Beagle 2 Mars lander was officially declared dead (although I suspected as much in the 30 minutes of silence after the time it was supposed to touch down). The little lander’s taxi ride across millions of miles of space, the Mars Express, was working just fine, but Beagle 2? Not so much.

This was incredibly sad on so many levels. From a patriotic viewpoint, I was shattered. The chance to have a British presence on the Red Planet would not only have been inspiring, it may have given funding a small boost for the UK science community. Also, personally, only the week before, I’d been defending the mission to some friends who were convinced that the crazy idea of sending a British probe to Mars was pointless, as it was never going to make it.

What ever came before that December in 2003, it was all academic. Beagle 2, for whatever reason, didn’t phone home. Game over.

Of course, that wouldn’t be it. For months after, Martian satellites hunted for any evidence for a mini Beagle-shaped divot in the red dirt. Eventually, they found it, two years later.

So what happened to the little robot? Why did it turn into a meteorite and not a lander? Well, back in 2008, Madhat Abdel-Jawad and his engineer team at the University of Queensland thought they’d worked it all out. Apparently, Beagle 2’s gyroscopic spin was too fast, causing it to become unstable during re-entry. This may have caused it to tumble as it entered the Mars atmosphere. Obviously, tumbling isn’t good, so it hit the ground like scrap metal.

As it turns out, the Beagle 2 team are far from convinced this happened at all. Arthur Smith of Fluid Gravity Engineering in Emsworth, Hampshire, points out that Abdel-Jawad’s team did not simulate re-entry in a gravity field, and they failed to realize the lander had an offset centre of gravity. This means the simulation wasn’t complete, indicating the “tumbling Beagle” may not be the final explanation.

Now, Smith and his team will be publishing a paper with their findings

All our assumptions were valid over the time of flight we analysed,” Abdel-Jawad said in response to this news. “We would be delighted to accept the findings of the Beagle team’s new study if it were found to be valid after we review their analysis.”

Whether the Australian team is correct or not seems rather academic. Something went terribly wrong during re-entry, this is true, but there are so many variables that I’m not sure if we’ll ever hit on the real reason why Beagle 2 dropped from the sky that 2003 winter. Sure, it might aid future development of future landers, but unless they find a gaping design flaw or construction mistake (like the NASA Genesis “woops, I installed the accelerometer backwards” mission mishap), Beagle 2 made a crater in the Martian surface, and there won’t be a crash recovery team to pick up the bits for a long while yet…

Source: New Scientist

British Astronauts? Yey! British Astronauts!

Our last astronauts were these guys (from a Cambridge University project).
Our last astronauts were these guys (from a Cambridge University project).

For an island of explorers, you may be confused by the fact there’s never been a British astronaut. Poppycock! What about that Michael Foale bloke? He’s British, and he spent a hell of a lot of time in space for a guy who shouldn’t be up there! Actually, Foale wasn’t a ‘British astronaut,’ he was a ‘British-born astronaut’ who is dual-nationality, lives in the US and works for NASA; being from the UK wasn’t a factor. Other British-born astronauts have either changed nationality or had to take the private route into space. The UK didn’t invest any money in their aspirations for rocketry.

And that’s what it came down to in 1986 when UK Prime Minister Maggie Thatcher decreed that there would be no British astronauts. We were ‘banned’ from space. Bummer. Basically, the expense of supporting a British manned space effort was sidelined, thereby removing the UK from any involvement in any manned space program. This included the International Space Station (just in case you haven’t noticed, there’s no British flag on the ISS, and there’s no 30-minute tea breaks or roast dinners served on Sundays in low-Earth orbit).

However, in a bloody fantastic turn of events, it’s been announced (right at the time of the 40th anniversary of the Apollo 11 moon landing) by Lord Drayson, UK Science Minister, that British astronauts will feature in the future of the UK’s space ambitions.

Britain should be playing a full role in space exploration. There was a special fund for training astronauts and we did not contribute, but that is now changed. There are important benefits that come from manned space-flight and we have dropped our opposition. We have an astronaut entering training soon and I hope he will be the first of many. —Lord Drayson

Lucky sod: Major Tim Peake, training British astronaut (BNSC)
Lucky sod: Major Tim Peake, training British astronaut (BNSC)

This news comes after the European Space Agency (ESA) selected lucky Tim Peake for their astronaut training program. Up until now, the annal £180 million ($290 million) the UK pays ESA could only be invested in robotic space exploration programs. Therefore, Peake can now be supported by the UK government, making him the first British astronaut to train in Europe.

I hope Tim Peake will be the first of many Britons selected to train as European astronauts,” Lord Drayson added.

This increased interest in British manned spaceflight could have some serious ramifications for the future of the nation, but the first thing that will need an upgrade is the British National Space Centre (yes, we really do have one) which is currently run by a part-time crew of civil servants pulled from other government departments, two research councils and the Met Office.

I can’t begin to put into words of how many shades of awesomeness this is, but I’m very excited that the United Kingdom will once again be involved with manned spaceflight… rather than just being known for making small craters with unfortunate Mars robots…

Special thanks to the ever-vigilant Dr Lucy Rogers

Source: Times

Mars Chaos

Of all the places I’d want to visit on Mars, this would be high on my list. After travelling to the bottom of Hellas Planitia (for the thick atmosphere and possibly finding liquid water) and the summit of Olympus Mons (for the view), I’d be sure to have a scout around Ariadnes Colles, in the southern hemisphere (pictured above).

The Ariadnes Colles region may not be a household name, but looking at these new high resolution images coming from the Mars Express orbiter, I can’t help but be impressed…
Continue reading “Mars Chaos”

Sci-Fi Space Robots: Top Five

Update (Nov 18th): OK, it looks like this article just hit the front page of Digg. Whilst cool, I’ve made a very quick deduction that people from Digg must not read the text of an article before commenting. Please read the opening paragraph before shouting “OMFG! This guy should really understand what sci-fi means!.” Perhaps the title could be improved (read: “Top 5 Space Robots that Look Like Science Fiction“), but I think all this can be remedied by simply reading the text and not just looking at the pictures. Thanks!

I love science fiction, I always have. In fact, it was the main motivational factor for me to begin to study science in the early 90’s. Although sci-fi is outlandish, futuristic and seemingly impossible, there is actually a high degree of science fact behind the TV shows, movies and video games. So when I was young, sci-fi fuelled my enthusiasm for physics; more specifically, astrophysics.

Many years after these first forays into trying to understand how the Universe really worked, I now find myself drawn to real space missions doing real science only to find the divide between sci-fi and sci-fact is getting smaller and smaller. However, to ignite the imagination and build an enthusiasm for the “futuristic” science being carried out right now, it helps if the robotic embodiment of the satellite, rover, probe or lander looks futuristic itself (possibly even a bit “sci-fi”). This way we not only do great science, but we ignite the imaginations of men, women and children who would have otherwise ignored the science behind space exploration.

So, here are my top five missions to ignite the imagination, past and future…
Continue reading “Sci-Fi Space Robots: Top Five”

CryoSat-2, a Satellite that Looks Like a Shed, Doing Science in the Freezer

Cryosat-2. Resembles something Da Vinci would design (ESA)
Cryosat-2. Resembles something Da Vinci would have designed (ESA)

ESA Cryosat-2 is set for launch in 2009 and it is the second attempt at getting the technology into orbit. Back in 2005, the original CryoSat was lost after a rocket malfunction caused it to fall short of the desired orbit, but much like the Phoenix Mars Lander story (i.e. it rose from the ashes of the lost Mars Polar Lander mission, recycled spare parts and reassembled the robot), Cryosat will fly once more. So what makes this mission so important? Well, it will carry out an essential three-year survey, measuring the thickness of global ice sheets.

But why am I really mentioning it? Like many ESA missions, the designs of their satellites and robots are so cool, and Cryosat-2 is no different. From some angles it looks like a sturdy intergalactic battleship, from others it looks like it was painstakingly designed by Da Vinci. Sometimes it even looks like a flying shed. In my books, that’s one interesting satellite. The science isn’t bad either…
Continue reading “CryoSat-2, a Satellite that Looks Like a Shed, Doing Science in the Freezer”