Posted on by Evan Gough

Watch the Sun to Know When We’re Going to Have Killer Auroras

The darker area on this image of the Sun's surface is the southern extension of the northern hemisphere polar corona. The coronal hole is a source of fast-moving streams of particles from the Sun, which can cause auroras here on Earth. Image: NASA/SDO

To the naked eye, the Sun puts out energy in a continual, steady state, unchanged through human history. (Don’t look at the sun with your naked eye!) But telescopes tuned to different parts of the electromagnetic spectrum reveal the Sun’s true nature: A shifting, dynamic ball of plasma with a turbulent life. And that dynamic, magnetic turbulence creates space weather.

Space weather is mostly invisible to us, but the part we can see is one of nature’s most stunning displays, the auroras. The aurora’s are triggered when energetic material from the Sun slams into the Earth’s magnetic field. The result is the shimmering, shifting bands of color seen at northern and southern latitudes, also known as the northern and southern lights.

This image of the northern lights over Canada was taken by a crew member on board the ISS in Sept. 2017. Image: NASA

There are two things that can cause auroras, but both start with the Sun. The first involves solar flares. Highly-active regions on the Sun’s surface produce more solar flares, which are sudden, localized increase in the Sun’s brightness. Often, but not always, a solar flare is coupled with a coronal mass ejection (CME).

A coronal mass ejection is a discharge of matter and electromagnetic radiation into space. This magnetized plasma is mostly protons and electrons. The CME ejection often just disperses into space, but not always. If it’s aimed in the direction of the Earth, chances are we get increased auroral activity.

The second cause of auroras are coronal holes on the Sun’s surface. A coronal hole is a region on the surface of the Sun that is cooler and less dense than surrounding areas. Coronal holes are the source of fast-moving streams of material from the Sun.

Whether it’s from an active region on the Sun full of solar flares, or whether it’s from a coronal hole, the result is the same. When the discharge from the Sun strikes the charged particles in our own magnetosphere with enough force, both can be forced into our upper atmosphere. As they reach the atmosphere, they give up their energy. This causes constituents in our atmosphere to emit light. Anyone who has witnessed an aurora knows just how striking that light can be. The shifting and shimmering patterns of light are mesmerizing.

The auroras occur in a region called the auroral oval, which is biased towards the night side of the Earth. This oval is expanded by stronger solar emissions. So when we watch the surface of the Sun for increased activity, we can often predict brighter auroras which will be more visible in southern latitudes, due to the expansion of the auroral oval.

This photo is of the aurora australis over New Zealand. Image: Paul Stewart, Public Domain, CC 1.0 Universal.

Something happening on the surface of the Sun in the last couple days could signal increased auroras on Earth, tonight and tomorrow (March 28th, 29th). A feature called a trans-equatorial coronal hole is facing Earth, which could mean that a strong solar wind is about to hit us. If it does, look north or south at night, depending on where your live, to see the auroras.

Of course, auroras are only one aspect of space weather. They’re like rainbows, because they’re very pretty, and they’re harmless. But space weather can be much more powerful, and can produce much greater effects than mere auroras. That’s why there’s a growing effort to be able to predict space weather by watching the Sun.

A powerful enough solar storm can produce a CME strong enough to damage things like power systems, navigation systems, communications systems, and satellites. The Carrington Event in 1859 was one such event. It produced one of the largest solar storms on record.

That storm occurred on September 1st and 2nd, 1859. It was preceded by an increase in sun spots, and the flare that accompanied the CME was observed by astronomers. The auroras caused by this storm were seen as far south as the Caribbean.

Sunspots are dark areas on the surface of the Sun that are cooler than the surrounding areas. They form where magnetic fields are particularly strong. The highly active magnetic fields near sunspots often cause solar flares. Image: NASA/SDO/AIA/HMI/Goddard Space Flight Center

The same storm today, in our modern technological world, would wreak havoc. In 2012, we almost found out exactly how damaging a storm of that magnitude could be. A pair of CMEs as powerful as the Carrington Event came barreling towards Earth, but narrowly missed us.

We’ve learned a lot about the Sun and solar storms since 1859. We now know that the Sun’s activity is cyclical. Every 11 years, the Sun goes through its cycle, from solar maximum to solar minimum. The maximum and minimum correspond to periods of maximum sunspot activity and minimum sunspot activity. The 11 year cycle goes from minimum to minimum. When the Sun’s activity is at its minimum in the cycle, most CMEs come from coronal holes.

NASA’s Solar Dynamics Observatory (SDO), and the combined ESA/NASA Solar and Heliospheric Observatory (SOHO) are space observatories tasked with studying the Sun. The SDO focuses on the Sun and its magnetic field, and how changes influence life on Earth and our technological systems. SOHO studies the structure and behavior of the solar interior, and also how the solar wind is produced.

Several different websites allow anyone to check in on the behavior of the Sun, and to see what space weather might be coming our way. The NOAA’s Space Weather Prediction Center has an array of data and visualizations to help understand what’s going on with the Sun. Scroll down to the Aurora forecast to watch a visualization of expected auroral activity.

NASA’s Space Weather site contains all kinds of news about NASA missions and discoveries around space weather. SpaceWeatherLive.com is a volunteer run site that provides real-time info on space weather. You can even sign up to receive alerts for upcoming auroras and other solar activity.

Posted on by Evan Gough

70,000 Years Ago a Nearby Star Messed With the Orbits Of Comets and Asteroids in our Solar System

70,000 years ago, Scholz's star, a red dwarf, came as close as 1 light-year to our Solar System. It could have perturbed the Oort Cloud. At that time, Neanderthals were still around. Image: Credit: José A. Peñas/SINC
70,000 years ago, Scholz's star, a red dwarf, came as close as 1 light year to our Solar System. At that time, neanderthals were still around. Image: Credit: José A. Peñas/SINC

70,000 years ago, our keen-eyed ancestors may have noticed something in the sky: a red dwarf star that came as close as 1 light year to our Sun. They would’ve missed the red dwarf’s small, dim companion—a brown dwarf—and in any case they would’ve quickly returned to their hunting and gathering. But that star’s visit to our Solar System had an impact astronomers can still see today.

The star in question is called Scholz’s star, after astronomer Ralf-Dieter Scholz, the man who discovered it in 2013. A new study published in the Monthly Notices of the Royal Astronomical Society by astronomers at the Complutense University of Madrid, and at the University of Cambridge, shows the impact Scholz’s star had. Though the star is now almost 20 light years away, its close approach to our Sun changed the orbits of some comets and asteroids in our Solar System.

When it came to our Solar System 70,000 years ago, Scholz’s star entered the Oort Cloud. The Oort Cloud is a reservoir of mostly-icy objects that spans the range from about 0.8 to 3.2 light years from the Sun. Its visit to the Oort Cloud was first explained in a paper in 2015. This new paper follows up on that work, and shows what impact the visit had.

“Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come.” – Carlos de la Fuente Marcos, Complutense University of Madrid.

In this new paper, the astronomers studied almost 340 objects in our Solar System with hyperbolic orbits, which are V-shaped rather than elliptical. Their conclusion is that a significant number of these objects had their trajectories shaped by the visit from Scholz’s star. “Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come,” explains Carlos de la Fuente Marcos, a co-author of the study now published in Monthly Notices of the Royal Astronomical Society. They found that there’s a cluster of these objects in the direction of the Gemini Constellation.

A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz’s Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester)

“In principle,” he adds, “one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud. However, what we find is very different—a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz’s star.”

There are four ways that objects like those in the study can gain hyperbolic orbits. They might be interstellar, like the asteroid Oumuamua, meaning they gained those orbits from some cause outside our Solar System. Or, they could be natives of our Solar System, originally bound to an elliptical orbit, but cast into a hyperbolic orbit by a close encounter with one of the planets, or the Sun. For objects originally from the Oort Cloud, they could start on a hyperbolic orbit because of interactions with the galactic disc. Finally, again for objects from the Oort Cloud, they could be cast into a hyperbolic orbit by interactions with a passing star. In this study, the passing star is Scholz’s star.

In this image the blue is a hyperbolic orbit while the green is a parabolic orbit. Image: By ScottAlanHill [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons
The timing of Scholz’s star’s visit to the Oort Cloud and our Solar System strongly coincides with the data in this study. It’s very unlikely to be coincidental. “It could be a coincidence, but it is unlikely that both location and time are compatible,” says De la Fuente Marcos. In fact, De la Fuente Marcos points out that their simulations suggest that Scholz’s star approached even closer than the 0.6 light-years pointed out in the 2015 study.

The one potentially weak area of this study is pointed out by the authors themselves. As they say in their summary, “…due to their unique nature, the orbital solutions of hyperbolic minor bodies are based on relatively brief arcs of observation and this fact has an impact on their reliability. Out of 339 objects in the sample, 232 have reported uncertainties and 212 have eccentricity with statistical significance.” Translated, it means that some of the computed orbits of individual objects may have errors. But the team expects the overall conclusions of their study to be correct.

The study of minor objects with hyperbolic orbits has heated up since the interstellar asteroid Oumuamua made its visit. This new study successfully connects one population of hyperbolic objects with a pre-historic visit to our Solar System by another star. The team behind the study expects that follow up studies will confirm their results.

Posted on by Evan Gough

Scientists Propose An Asteroid Nuke Mission To Save Earth From Potential Destruction

Mining asteroids might be necessary for humanity to expand into the Solar System. But what effect would asteroid mining have on the world's economy? Credit: ESA.

Some might say it’s paranoid to think about an asteroid hitting Earth and wiping us out. But the history of life on Earth shows at least 5 major extinctions. And at least one of them, about 65 million years ago, was caused by an asteroid.

Preparing for an asteroid strike, or rather preparing to prevent one, is rational thinking at its finest. Especially now that we can see all the Near Earth Asteroids (NEAs) out there. The chances of any single asteroid striking Earth may be small, but collectively, with over 15,000 NEAs catalogued by NASA, it may be only a matter of time until one comes for us. In fact, space rocks strike Earth every day, but they’re too small to cause any harm. It’s the ones large enough to do serious damage that concern NASA.

NASA has been thinking about the potential for an asteroid strike on Earth for a long time. They even have an office dedicated to it, called the Office of Planetary Defense, and minds there have been putting a lot of thought into detecting hazardous asteroids, and deflecting or destroying any that pose a threat to Earth.

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

One of NASA’s proposals for dealing with an incoming asteroid is getting a lot of attention right now. It’s called the Hyper-velocity Asteroid Mitigation Mission for Emergency Response, or HAMMER. HAMMER is just a concept right now, but it’s worth talking about. It involves the use of a nuclear weapon to destroy any asteroid heading our way.

The use of a nuclear weapon to destroy or deflect an asteroid seems a little risky at first glance. They’re really a weapon of last resort here on Earth, because of their potential to wreck the biosphere. But out in space, there is no biosphere. If scientists sound a little glib when talking about HAMMER, the reality is they’re not. It makes perfect sense. In fact, it may be the only sensible use for a nuclear weapon.

The idea behind HAMMER is pretty simple; it’s a spacecraft with an 8.8 ton tip. The tip is either a nuclear weapon, or an 8.8 ton kinetic impactor. Once we detect an asteroid on a collision course with Earth, we use space-based and ground-based systems to ascertain its size. If its small enough, then HAMMER will not require the nuclear option. Just striking a small asteroid with sufficient mass will divert it away from Earth.

If the incoming asteroid is larger, or if we don’t detect it early enough, then the nuclear option is chosen. HAMMER would be launched with an atomic warhead on it, and the incoming offender would be destroyed. It sounds like a pretty tidy solution, but it’s a little more complicated than that.

A lot depends on the size of the object and when it’s detected. If we’re threatened by an object we’ve been aware of for a long time, then we might have a pretty good idea of its size, and of its trajectory. In that case, we can likely divert it with a kinetic impactor.

Artist’s impression of the first interstellar asteroid, “Oumuamua”. This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO/M. Kornmesser

But for larger objects, we might require a fleet of impactors already in space, ready to be sent on a collision course. Or we might use the nuclear option. The ER in HAMMER stands for Emergency Response for a reason. If we don’t have enough time to plan or respond, then a system like HAMMER could be built and launched relatively quickly. (In this scenario, relatively quickly means years, not months.)

One of the problems is with the asteroids themselves. They have different orbits and trajectories, and the time to travel to different NEO‘s can vary widely. And things in space aren’t static. We share a region of space with a lot of moving rocks, and their trajectories can change as a result of gravitational interactions with other bodies. Also, as we learned from the arrival of Oumuamua last year, not all threats will be from our own Solar System. Some will take us by surprise. How will we deal with those? Could we deploy HAMMER quickly enough?

Another cautionary factor around using nukes to destroy asteroids is the risk of fracturing them into multiple pieces without destroying them. If an object larger than 1 km in diameter threatened Earth, and we aimed a nuclear warhead at it but didn’t destroy it, what would we do? How would we deal with one or more fragments heading towards Earth?

HAMMER and the whole issue of dealing with threatening asteroids is a complicated business. We’ll have to prepare somehow, and have a plan and systems in place for preventing collisions. But our best bet might lie in better detection.

We’ve gotten a lot better at detecting Near Earth Objects,(NEOs), Potentially Hazardous Objects (PHOs), and Near Earth Asteroids (NEAs) lately. We have telescopes and projects dedicated to cataloguing them, like Pan-STARRS, which discovered Oumuamua. And in the next few years, the Large Synoptic Survey Telescope (LSST) will come online, boosting our detection capabilities even further.

It’s not just extinctions that we need to worry about. Asteroids also have the potential to cause massive climate change, disrupt our geopolitical order, and generally de-stabilize everything going on down here on Earth. At some point in time, an object capable of causing massive damage will speed toward us, and we’ll either need HAMMER, or another system like it, to protect ourselves and the planet.

Posted on by Evan Gough

Gaze in Wonder at Jupiter’s Mysterious Geometric Polar Storms

This wondrous image of Jupiter's south pole shows the arrangement of cyclones that is unique in our Solar System: five circumpolar cyclones perfectly arranged around a single polar cyclone. Image: NASA/SWRI/JPL/ASI/INAF/IAPS

When the Juno spacecraft arrived at Jupiter in July 2016, it quickly got to work. Among the multitude of stunning images of the planet were our first ever images of Jupiter’s poles. And what we saw there was a huge surprise: geometric arrangements of cyclones in persistent patterns.

Jupiter’s polar regions have always been a mystery to Earth-bound observers. The planet isn’t tilted much, which means the poles are always tantalizingly out of view. Other spacecraft visiting Jupiter have focused on the equatorial regions, but Juno’s circumpolar orbit is giving us good, close-up views of Jupiter’s poles.

“They are extraordinarily stable arrangements of such chaotic elements. We’d never seen anything like it.” – Morgan O’Neill, University of Chicago

Juno has a whole suite of instruments designed to unlock some of the mysteries surrounding Jupiter, including an infrared imager and a visible light camera. The polar regions are a particular focus for the mission, and astronomers were looking forward to their first views of Jupiter’s hidden poles. They were not disappointed when they got them.

Each of Jupiter’s poles is a geometric array of large cyclones arranged in persistent, polygonal patterns. At the north pole, eight storms are arranged around a single polar cyclone. In the south, one storm is encircled by five others.

Jupiter’s north pole is an arrangement of 8 cyclones around one central cyclone. Image: NASA/SWRI/JPL/ASI/INAF/IAPS

This was a stunning discovery, and quickly led to questions around the why and the how of these storm arrangements. Jupiter’s atmosphere is dominated by storm activity, including the well-known horizontal storm bands in the equatorial regions, and the famous Great Red Spot. But these almost artful arrangements of polar storms were something else.

The persistent arrangement of the storms is a puzzle. Our current understanding tells us that the storms should drift around and merge, but these storms do neither. They just turn in place.

A new paper published in Nature is looking deeper into these peculiar arrangements of storms. The paper is by scientists from an international group of institutions including the University of Chicago. It’s one of four papers dedicated to new observations from the Juno spacecraft.

One of the paper’s co-authors is Morgan O’Neill, a University of Chicago postdoctoral scholar. Remarking on the storms, she had this to say: “They are extraordinarily stable arrangements of such chaotic elements. We’d never seen anything like it.”

This image from Juno’s JunoCam captured the south pole in visible light only. It’s a puzzle why the north and south poles are so similar, yet have a different number of cyclones. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

The strange geometrical arrangement of Jupiter’s polar storms reminded O’Neill of something from the library of strange physical phenomena only observed under laboratory conditions. Back in the ’90s, scientists had used electrons to simulate a frictionless, turbulent 2-D fluid as it cools. In those conditions, they observed similar behaviour. Rather than merging like expected, small vortices clumped together and formed equally spaced arrays around a center. They called these arrays “vortex crystals.”

This could help explain what’s happening at Jupiter’s poles, but it’s too soon to be certain. “The next step is: Can you create a model that builds a virtual planet and predicts these flows?” O’Neill said. That’ll be the next step in understanding the phenomenon.

Maybe it’s not surprising that these delicate-looking storms at the poles are so persistent. After all, the Great Red Spot on Jupiter has been visible for over 200 years. Maybe Jupiter is just huge and stable.

But the polar cyclones still require an explanation. And whatever that explanation is, understanding what’s happening on Jupiter will help us understand other planets better.

Posted on by Evan Gough

Hubble Sees a Huge Dust Cloud Around a Newly Forming Star

Astronomers have used NASA's Hubble Space Telescope to uncover a vast, complex dust structure, about 150 billion miles across, enveloping the young star HR 4796A. Image:NASA/ESA/G. Schneider (Univ. of Arizona)

Younger stars have a cloud of dusty debris encircling them, called a circumstellar disk. This disk is material left over from the star’s formation, and it’s out of this material that planets form. But scientists using the Hubble have been studying an enormous dust structure some 150 billion miles across. Called an exo-ring, this newly imaged structure is much larger than a circumstellar disk, and the vast structure envelops the young star HR 4796A and its inner circumstellar disk.

Discovering a dust structure around a young star is not new, and the star in this new paper from Glenn Schneider of the University of Arizona is probably our most (and best) studied exoplanetary debris system. But Schneider’s paper, along with capturing this new enormous dust structure, seems to have uncovered some of the interplay between the bodies in the system that has previously been hidden.

Schneider used the Space Telescope Imaging Spectrograph (STIS) on the Hubble to study the system. The system’s inner disk was already well-known, but studying the larger structure has revealed more complexity.

The Hubble Space Telescope has imaged a vast, complex dust structure surrounding the star HR 4769A. The bright, inner ring is well-known to astronomers, but the huge dust structure surrounding the whole system is a new discovery. Image: NASA/ESA/G. Schneider (Univ. of Arizona)

The origin of this vast structure of dusty debris is likely collisions between newly forming planets within the smaller inner ring. Outward pressure from the star HR 4769A then propelled the dust outward into space. The star is 23 times more luminous than our Sun, so it has the necessary energy to send the dust such a great distance.

A press release from NASA describes this vast exo-ring structure as a “donut-shaped inner tube that got hit by a truck.” It extends much further in one direction than the other, and looks squashed on one side. The paper presents a couple possible causes for this asymmetric extension.

It could be a bow wave caused by the host star travelling through the interstellar medium. Or it could be under the gravitational influence of the star’s binary companion (HR 4796B), a red dwarf star located 54 billion miles from the primary star.

“The dust distribution is a telltale sign of how dynamically interactive the inner system containing the ring is'” – Glenn Schneider, University of Arizona, Tucson.

The asymmetrical nature of the vast exo-structure points to complex interactions between all of the stars and planets in the system. We’re accustomed to seeing the radiation pressure from the host star shape the gas and dust in a circumstellar disk, but this study presents us with a new level of complexity to account for. And studying this system may open a new window into how solar systems form over time.

Artist’s impression of circumstellar disk of debris around a distant star. These disk are common around younger stars, but the star in this study has a massive dust cloud that envelops and dwarfs the smaller, inner ring. Credit: NASA/JPL

“We cannot treat exoplanetary debris systems as simply being in isolation. Environmental effects, such as interactions with the interstellar medium and forces due to stellar companions, may have long-term implications for the evolution of such systems. The gross asymmetries of the outer dust field are telling us there are a lot of forces in play (beyond just host-star radiation pressure) that are moving the material around. We’ve seen effects like this in a few other systems, but here’s a case where we see a bunch of things going on at once,” Schneider further explained.

The paper suggests that the location and brightness of smaller rings within the larger dust structure places constraints on the masses and orbits of planets within the system, even when the planets themselves can’t be seen. But that will require more work to determine with any specificity.

This paper represents a refinement and advancement of the Hubble’s imaging capabilities. The paper’s author is hopeful that the same methods using in this study can be used on other similar systems to better understand these larger dust structures, how they form, and what role they play.

As he says in the paper’s conclusion, “With many, if not most, technical challenges now understood and addressed, this capability should be used to its fullest, prior to the end of the HST mission, to establish a legacy of the most robust images of high-priority exoplanetary debris systems as an enabling foundation for future investigations in exoplanetary systems science.”

Posted on by Evan Gough

Rosetta’s 67P Is The Result Of A Collision Of Two Comets

The comet 67P/Churyumov-Gerasimenko, which was visited by Rosetta in 2014-15, certainly appears to be the result of a collision between two comets. A new study explains how and when the collision occurred. By ESA/Rosetta/OSIRIS - http://www.esa.int/spaceinimages/Images/2014/12/Colour_image_of_comet, CC BY-SA 3.0,

Ever since we’ve been able to get closer looks at comets in our Solar System, we’ve noticed something a little puzzling. Rather than being round, they’re mostly elongated or multi-lobed. This is certainly true of Comet 67P/Churyumov-Gerasimenko (67P or Chury for short.) A new paper from an international team coordinated by Patrick Michel at France’s CNRS explains how they form this way.

The European Space Agency (ESA) spacecraft Rosetta visited 67P in 2014, end even placed its lander Philae on the surface. Rosetta spent 17 months orbiting 67P, and at its closest approach, Rosetta was only 10 km (6 mi) from 67P’s surface. Rosetta’s mission ended with its guided impact into 67P’s surface in September, 2016, but the attempt to understand the comet and its brethren didn’t end then.

An artist’s illustration of the spacecraft Rosetta and the Philae lander at comet 67P C-G. Image: By European Space Agency – Rosetta and Philae at comet, CC BY-SA 3.0-igo,

Though Rosetta’s pictures of 67P are the most detailed comet pictures we have, other spacecraft have visited other comets. And most of those other comets appear elongated or multi-lobed, too. Scientists explain these shapes with a “comet merger theory.” Two comets collide, creating the multi-lobed appearance of comets like 67P. But there’s been a problem with that theory.

In order for comets to merge and come out looking the way they do, they would have to merge very slowly, or else they would explode. They would also have to be very low-density, and be very rich in volatile elements. The “comet merger theory” also says that these types of gentle mergers between comets would have to have happened billions of years ago, in the early days of the Solar System.

The problem with this theory is, how could bodies like 67P have survived for so long? 67P is fragile, and subjected to repeated collisions in its part of the Solar System. How could it have retained its volatiles?

Geysers of dust and gas shooting off the comet’s nucleus are called jets. The volatile material they deliver outside the nucleus builds the comet’s coma. Credit: ESA/Rostta/NAVCAM

In the new paper, the research team ran a simulation that answers these questions.

The simulation showed that when two comets meet in a destructive collision, only a small portion of their material is pulverized and reduced to dust. On the sides of the comets opposite from the impact point, materials rich in volatiles withstand the collision. They’re still ejected into space, but their relative speed is low enough for them to join together in accretion. This process forms many smaller bodies, which keep clumping up until they form just one, larger body.

The most surprising part of this simulation is that this entire process may only take a few days, or even a few hours. The whole process explains how comets like 67P can keep their low density, and their abundant volatiles. And why they appear multi-lobed.

This image from the simulation shows how the ejected material from two bodies colliding re-accretes into a bilobal comet. Image: ESA/Rosetta/Navcam – CC BY-SA IGO 3.0

The simulation also answered another question: how can comets like 67P survive for so long?

The team behind the simulation thinks that the process can take place at speeds of 1 km/second. These speeds are typical in the Kuiper Belt, which is the disc of comets where 67P has its origins. In this belt, collisions between comets are a regular occurrence, which means that 67P didn’t have to form in the early days of the Solar System as previously thought. It could have formed at any time.

The team’s work also explains the surface appearance of 67P and other comets. They often have holes and stratified layers, and these features could have formed during re-accretion, or sometime after its formation.

Smooth terrain in the Imhotep region on 67P C-G, showing layering (B) and circular structures or pits (circled). Credit: ESA/Rosetta

One final point from the study concerns the composition of comets. One reason they’re a focus of such intense interest is their age. Scientists have always thought of them as ancient objects, and that studying them would allow us to look back into the primordial Solar System.

Though 67P—and other comets—may have formed much more recently than we used to believe, this process shows that there is no significant amount of heating or compaction during the collision. As a result, their original composition from the the early days of the Solar System is retained intact. No matter when 67P formed, it’s still a messenger from the formative days.

You can watch a video from the simulation here: http://www.dropbox.com/s/u7643hanvva57rp/Catastrophic%20disruptions.mp4?dl=0

Posted on by Evan Gough

Astronomers See A Dead Star Come Back To Life Thanks To A Donor Star

The ESA INTEGRA observatory has witnessed a "zombie" neutron star being re-energized by the solar wind of its companion red giant star, and coming back to life in a burst of x-rays. Image: ESA

It’s not exactly an organ donor, but a star in the direction of the hyper-populated core of the Milky Way donating some of its mass to a dormant neighbor. The result? The dormant neighbor sprung back to life with an X-ray burst captured by the ESA‘s INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) space observatory.

“INTEGRAL caught a unique moment in the birth of a rare binary system” – Enrico Bozzo, University of Geneva.

The neighbors have likely been paired together for billions of years, which is not in itself noteworthy: stars often live in binary pairs. But the pair spotted by INTEGRAL on August 13th 2017 is very unusual. The donor star is a red giant, and the recipient is a neutron star. So far, astronomers only know of 10 of these pairs, called ‘symbiotic X-ray binaries’.

To understand what’s happening between these neighbors, we have to look at stellar evolution.

The donor star is in its red giant phase. That’s when a star in the same mass range as our star reaches the later stage of its life. As its mass is depleted, gravity can’t hold the star together in the same way it has for the early part of its life. The star expands outwards by millions of kilometers. As it does so, it sheds stellar material from its outer layers in a solar wind that travels several hundreds of km/sec.

The red giant and the neutron star may have traveled different evolutionary pathways, but proximity made them partners. Image: ESA

Its neighbor is in a different state. It’s a star that had an initial mass of about 25 to 30 times the Sun. When a star this big approaches the end of its life, it suffers a different fate. Stars this large live fast, and burn through their fuel quickly. Then, they explode as supernovae, in this case leaving a corpse behind. In the binary system captured by INTEGRAL, the corpse is a spinning neutron star with a magnetic field.

Neutron stars are dense. In fact, they’re some of the densest stellar objects we know of, packing as much mass as one-and-a-half of our Suns into an object that’s only about 10 km across.
When the red giant’s stellar wind met the neutron star, the neutron star slowed its rate of spin, and burst into life, emitting high-energy x-rays.

“INTEGRAL caught a unique moment in the birth of a rare binary system,” says Enrico Bozzo from University of Geneva and lead author of the paper that describes the discovery. “The red giant released a sufficiently dense slow wind to feed its neutron star companion, giving rise to high-energy emission from the dead stellar core for the first time.”

After INTEGRAL spotted the x-ray burst from the binary, other observations quickly followed. The ESA’s XMM Newton and NASA’s NuSTAR and Swift space telescopes got to work, along with ground-based telescopes. These observations confirmed what initial observations showed: this is a very peculiar pair of stars.

“…we believe we saw the X-rays turning on for the first time.” – Erik Kuulkers, ESA INTEGRAL Project Scientist.

The neutron star spins very slowly, taking about 2 hours to revolve, which is remarkable since other neutron stars can spin many times per second. The magnetic field of the neutron star was also much stronger than expected. But the magnetic field around a neutron star is thought to weaken over time, making this a relatively young neutron star. And a red giant is old, so this is a very odd pairing of old red giant with young neutron star.

One possible explanation is that the neutron star didn’t form from a supernova, but from a white dwarf. In that scenario, the white dwarf would’ve collapsed into a neutron star after a very long period of feeding on material from the red giant. That would explain the disparity in ages of the two stars in the system.

An artist’s illustration of ESA’s INTEGRAL space observatory. INTEGRAL was launched in 2002 to study some of the most energetic phenomena in the universe. Image: ESA.

“These objects are puzzling,” says Enrico. “It might be that either the neutron star magnetic field does not decay substantially with time after all, or the neutron star actually formed later in the history of the binary system. That would mean it collapsed from a white dwarf into a neutron star as a result of feeding off the red giant over a long time, rather than becoming a neutron star as a result of a more traditional supernova explosion of a short-lived massive star.”

The next question is how long will this process go on? Is it short-lived, or the beginning of a long-term relationship?

“We haven’t seen this object before in the past 15 years of our observations with INTEGRAL, so we believe we saw the X-rays turning on for the first time,” says Erik Kuulkers, ESA’s INTEGRAL project scientist. “We’ll continue to watch how it behaves in case it is just a long ‘burp’ of winds, but so far we haven’t seen any significant changes.”

The INTEGRAL space observatory was launched in 2002 to study some of the most energetic phenomena in the universe. It focuses on things like black holes, neutron stars, active galactic nuclei and supernovae. INTEGRAL is a European Space Agency mission in cooperation with the United States and Russia. Its projected end date is December, 2018.

Posted on by Evan Gough

Astronaut Scott Tingle Was Able To Control A Ground-Based Robot… From Space.

The artificially intelligent robot Justin cleans the solar panels in the simulated Martian landscape after being instructed to do so by American astronaut Scott Tingle aboard the ISS. Image: (DLR) German Aerospace Center (CC-BY 3.0)

If something called “Project METERON” sounds to you like a sinister project involving astronauts, robots, the International Space Station, and artificial intelligence, I don’t blame you. Because that’s what it is (except for the sinister part.) In fact, the Meteron Project (Multi-Purpose End-to-End Robotic Operation Network) is not sinister at all, but a friendly collaboration between the European Space Agency (ESA) and the German Aerospace Center (DLR.)

The idea behind the project is to place an artificially intelligent robot here on Earth under the direct control of an astronaut 400 km above the Earth, and to get the two to work together.

“Artificial intelligence allows the robot to perform many tasks independently, making us less susceptible to communication delays that would make continuous control more difficult at such a great distance.” – Neil Lii, DLR Project Manager.

On March 2nd, engineers at the DLR Institute of Robotics and Mechatronics set up the robot called Justin in a simulated Martian environment. Justin was given a simulated task to carry out, with as few instructions as necessary. The maintenance of solar panels was the chosen task, since they’re common on landers and rovers, and since Mars can get kind of dusty.

Justin is a pretty cool looking robot. Image: (DLR) German Aerospace Center (CC-BY 3.0)

The first test of the METERON Project was done in August. But this latest test was more demanding for both the robot and the astronaut issuing the commands. The pair had worked together before, but since then, Justin was programmed with more abstract commands that the operator could choose from.

American astronaut Scott Tingle issued commands to Justin from a tablet aboard the ISS, and the same tablet also displayed what Justin was seeing. The human-robot team had practiced together before, but this test was designed to push the pair into more challenging tasks. Tingle had no advance knowledge of the tasks in the test, and he also had no advance knowledge of Justin’s new capabilities. On-board the ISS, Tingle quickly realized that the panels in the simulation down here were dusty. They were also not pointed in the optimal direction.

This was a new situation for Tingle and for Justin, and Tingle had to choose from a range of commands on the tablet. The team on the ground monitored his choices. The level of complexity meant that Justin couldn’t just perform the task and report it completed, it meant that Tingle and the robot also had to estimate how clean the panels were after being cleaned.

“Our team closely observed how the astronaut accomplished these tasks, without being aware of these problems in advance and without any knowledge of the robot’s new capabilities,” says DLR engineer Daniel Leidner.

Streaks of dust or sand on NASA’s Mars rover Opportunity show what can happen to solar panels on the red planet. For any more permanent structures that we may put on Mars, an artificially intelligent maintenance robot under the control of an astronaut in orbit could be the perfect solution to the maintenance of solar panels. Credits: NASA/JPL-Caltech

The next test will take place in Summer 2018 and will push the system even further. Justin will have an even more complex task before him, in this case selecting a component on behalf of the astronaut and installing it on the solar panels. The German ESA astronaut Alexander Gerst will be the operator.

If the whole point of this is not immediately clear to you, think Mars exploration. We have rovers and landers working on the surface of Mars to study the planet in increasing detail. And one day, humans will visit the planet. But right now, we’re restricted to surface craft being controlled from Earth.

What METERON and other endeavours like it are doing, is developing robots that can do our work for us. But they’ll be smart robots that don’t need to be told every little thing. They are just given a task and they go about doing it. And the humans issuing the commands could be in orbit around Mars, rather than being exposed to all the risks on the surface.

“Artificial intelligence allows the robot to perform many tasks independently, making us less susceptible to communication delays that would make continuous control more difficult at such a great distance,” explained Neil Lii, DLR Project Manager. “And we also reduce the workload of the astronaut, who can transfer tasks to the robot.” To do this, however, astronauts and robots must cooperate seamlessly and also complement one another.

These two images from the camera on NASA’s Mars Global Surveyor show the effect that a global dust storm has on Mars. On the left is a normal view of Mars, on the right is Mars obscured by the haze from a dust storm. Image: NASA/JPL/MSSS

That’s why these tests are important. Getting the astronaut and the robot to perform well together is critical.

“This is a significant step closer to a manned planetary mission with robotic support,” says Alin Albu-Schäffer, head of the DLR Institute of Robotics and Mechatronics. It’s expensive and risky to maintain a human presence on the surface of Mars. Why risk human life to perform tasks like cleaning solar panels?

“The astronaut would therefore not be exposed to the risk of landing, and we could use more robotic assistants to build and maintain infrastructure, for example, with limited human resources.” In this scenario, the robot would no longer simply be the extended arm of the astronaut: “It would be more like a partner on the ground.”

Posted on by Evan Gough

Bacteria Surviving On Musk’s Tesla Are Either A Bio-threat Or A Backup Copy Of Life On Earth

The Tesla Roadster sent into space aboard the Falcon Heavy Rocket in early February. Is it teeming with Earthly bacteria? Image: SpaceX

A great celebratory eruption accompanied the successful launch of SpaceX’s Falcon Heavy rocket in early February. That launch was a big moment for people who are thoughtful about the long arc of humanity’s future. But the Tesla Roadster that was sent on a long voyage in space aboard that rocket is likely carrying some bacterial hitch-hikers.

The Falcon Heavy’s first flight. Image: SpaceX

A report from Purdue University suggests that, though unlikely, the Roadster may be carrying an unwelcome cargo of Earthly bacteria to any destination it reaches. But we’re talking science here, and science doesn’t necessarily shy away from the unlikely.

“The load of bacteria on the Tesla could be considered a biothreat, or a backup copy of life on Earth.” – Alina Alexeenko, Professor of Aeronautics and Astronautics at Purdue University.

NASA takes spacecraft microbial contamination very seriously. The Office of Planetary Protection monitors and enforces spacecraft sterilization. Spreading Terran bacteria to other worlds is a no-no, for obvious reasons, so spacecraft are routinely sterilized to prevent any bacterial hitch-hikers. NASA uses the term “biological burden” to quantify how rigorously a spacecraft needs to be sterilized. Depending on a spacecraft’s mission and destination, the craft is subjected to increasingly stringent sterilization procedures.

If a craft is not likely to ever contact another body, then sterilization isn’t as strict. If the target is a place like Mars, where the presence of Martian life is undetermined, then the craft is prepared differently. When required, spacecraft and spacecraft components are treated in clean rooms like the one at Goddard Space Flight Center.

The clean room at Goddard Space Flight Center where spacecraft are sterilized. Image: NASA

The clean rooms are strictly controlled environments, where staff wear protective suits, boots, hoodies, and surgical gloves. The air is filtered and the spacecraft are exposed to various types of sterilization. After sterilization, the spacecraft is handled carefully before launch to ensure it remains sterile. But the Tesla Roadster never visited such a place, since it’s destination is not another body.

The Tesla Roadster in space was certainly manufactured in a clean place, but there’s a big difference between clean and sterile. To use NASA’s terminology, the bacterial load of the Roadster is probably very high. But would those bacteria survive?

The atmosphere in space is most definitely hostile to life. The temperature extremes, the low pressure, and the radiation are all hazardous. But, some bacteria could survive by going dormant, and there are nooks and crannies in the Tesla where life could cling.

This images shows the Orion capsule wrapped in plastic after sterilization, and being moved to a workstand. These types of precautions are mandated by NASA’s Office of Planetary Protection. Image: NASA.

The Tesla is not predicted to come into contact with any other body, and certainly not Mars, which is definitely a destination in our Solar System that we want to protect from contamination. In fact, a more likely eventual destination for the Roadster is Earth, albeit millions of years from now. And in that case, according to Alina Alexeenko, a Professor of Aeronautics and Astronautics at Purdue University, any bacteria on the red Roadster is more like a back-up for life on Earth, in case we do something stupid before the car returns. “The load of bacteria on the Tesla could be considered a biothreat, or a backup copy of life on Earth,” she said.

But even if some bacteria survived for a while in some hidden recess somewhere on the Tesla Roadster, could it realistically survive for millions of years in space?

As far as NASA is concerned, length of time in space is one component of sterilization. Some missions are designed with the craft placed in a long-term orbit at the end of its mission, so that the space environment can eventually destroy any lingering bacterial life secreted away somewhere. Surely, if the Roadster does ever collide with Earth, and if it takes millions of years for that to happen, and if it’s not destroyed on re-entry, the car would be sterilized by its long-duration journey?

That seems to be the far more likely outcome. You never know for sure, but the space-faring Roadster is probably not a hazardous bio-threat, nor a back-up for life on Earth; those are pretty fanciful ideas.

Musk’s pretty red car is likely just a harmless, attention-grabbing bauble.

Posted on by Evan Gough

22 Years Of The Sun From Soho

The magnetic field of the Sun operates on a 22 year cycle. It takes 11 years for the orientation of the field to flip between the northern and southern hemisphere, and another 11 years to flip back to its original orientation. This composite image is made up of snapshots of the Sun taken with the Extreme ultraviolet Imaging Telescope on SOHO. Image: SOHO (ESA & NASA)

The Solar and Heliospheric Observatory (SOHO) is celebrating 22 years of observing the Sun, marking one complete solar magnetic cycle in the life of our star. SOHO is a joint project between NASA and the ESA and its mission is to study the internal structure of the sun, its extensive outer atmosphere, and the origin of the solar wind.

The activity cycle in the life of the Sun is based on the increase and decrease of sunspots. We’ve been watching this activity for about 250 years, but SOHO has taken that observing to a whole new level.

Though sunspot cycles work on an 11-year period, they’re caused by deeper magnetic changes in the Sun. Over the course of 22 years, the Sun’s polarity gradually shifts. At the 11 year mark, the orientation of the Sun’s magnetic field flips between the northern and southern hemispheres. At the end of the 22 year cycle, the field has shifted back to its original orientation. SOHO has now watched that cycle in its entirety.

The magnetic field of the Sun operates on a 22 year cycle. It takes 11 years for the orientation of the field to flip between the northern and southern hemisphere, and another 11 years to flip back to its original orientation. This composite image is made up of snapshots of the Sun taken with the Extreme ultraviolet Imaging Telescope on SOHO. Image: SOHO (ESA & NASA)

SOHO is a real success story. It was launched in 1995 and was designed to operate until 1998. But it’s been so successful that its mission has been prolonged and extended several times.

An artist’s illustration of the SOHO spacecraft. Image: NASA

SOHO’s 22 years of observation has turbo-charged our space weather forecasting ability. Space weather is heavily influenced by solar activity, mostly in the form of Coronal Mass Ejections (CMEs). SOHO has observed well over 20,000 of these CMEs.

Space weather affects key aspects of our modern technological world. Space-based telecommunications, broadcasting, weather services and navigation are all affected by space weather. So are things like power distribution and terrestrial communications, especially at northern latitudes. Solar weather can also degrade not only the performance, but the lifespan, of communication satellites.

Besides improving our ability to forecast space weather, SOHO has made other important discoveries. After 40 years of searching, it was SOHO that finally found evidence of seismic waves in the Sun. Called g-modes, these waves revealed that the core of the Sun is rotating 4 times faster than the surface. When this discovery came to light, Bernhard Fleck, ESA SOHO project scientist said, “This is certainly the biggest result of SOHO in the last decade, and one of SOHO’s all-time top discoveries.”

Data from SOHO revealed that the core of the Sun rotates 4 times faster than the surface. Image: ESA

SOHO also has a front row seat for comet viewing. The observatory has witnessed over 3,000 comets as they’ve sped past the Sun. Though this was never part of SOHO’s mandate, its exceptional view of the Sun and its surroundings allows it to excel at comet-finding. It’s especially good at finding sun-grazer comets because it’s so close to the Sun.

“But nobody dreamed we’d approach 200 (comets) a year.” – Joe Gurman, mission scientist for SOHO.

“SOHO has a view of about 12-and-a-half million miles beyond the sun,” said Joe Gurman in 2015, mission scientist for SOHO at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “So we expected it might from time to time see a bright comet near the sun. But nobody dreamed we’d approach 200 a year.”

A front-row seat for sun-grazing comets allows SOHO to observe other aspects of the Sun’s surface. Comets are primitive relics of the early Solar System, and observing them with SOHO can tell scientists quite a bit about where they formed. If a comet has made other trips around the Sun, then scientists can learn something about the far-flung regions of the Solar System that they’ve traveled through.

Watching these sun-grazers as they pass close to the Sun also teaches scientists about the Sun. The ionized gas in their tails can illuminate the magnetic fields around the Sun. They’re like tracers that help observers watch these invisible magnetic fields. Sometimes, the magnetic fields have torn off these tails of ionized gas, and scientists have been able to watch these tails get blown around in the solar wind. This gives them an unprecedented view of the details in the movement of the wind itself.

It’s hard to make out, but the dot in the cross-hairs is a comet streaming toward the Sun. This image is from 2015, and the comet is the 3,000th one discovered by SOHO since it was launched. Image: SOHO/ESA/NASA

SOHO is still going strong, and keeping an eye on the Sun from its location about 1.5 million km from Earth. There, it travels in a halo orbit around LaGrange point 1. (It’s orbit is adjusted so that it can communicate clearly with Earth without interference from the Sun.)

Beyond the important science that SOHO provides, it’s also a source of amazing images. There’s a whole gallery of images here, and a selection of videos here.

In 2003, SOHO captured this image of a massive solar flare, the third most powerful ever observed in X-ray wavelengths. Very spooky. Image: NASA/ESA/SOHO

You can also check out daily views of the Sun from SOHO here.