Asteroids Archives

May 23, 2018May 23, 2018 by Matt Williams

Oumuamua was Just the Beginning. Astronomers Find an Interstellar Asteroid Orbiting Retrograde near Jupiter.

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

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) telescope in Hawaii announced the first-ever detection of an interstellar asteroid – I/2017 U1 (aka. ‘Oumuamua). Originally mistaken for a comet, follow-up observations conducted by the European Southern Observatory (ESO) and others confirmed that ‘Oumuamua was actually a rocky body that had originated outside of our Solar System.

News of this interstellar asteroids, the first to ever be detected by astronomers, raised a lot of excitement. And according to a new study by an international pair of astronomers, ‘Oumuamua was not the Solar System’s first interstellar visitor. Whereas ‘Oumuamua was an interloper on its way to another star system, this latest object – known as Asteroid (514107) 2015 BZ509 – appears to be a long-term resident.

The study, titled “An interstellar origin for Jupiter’s retrograde co-orbital asteroid“, recently appeared in the Monthly Notices of Royal Astronomical Society: Letters. The study team consisted of Fathi Namouni, a researcher at Université Côte d’Azur and the Observatoire de la Côte d’Azur; and Maria Helena Moreira Morais, a researcher from the Instituto de Geociências e Ciências Exatas at the Universidade Estadual Paulista (UNESP).

Images of 2015 BZ509 obtained at the Large Binocular Telescope Observatory (LBTO) that established its retrograde co-orbital nature (click on the image to see the animation). Credit: C. Veillet / Large Binocular Telescope Observatory.

After locating this asteroid, the team noticed something very interesting about it. All planets in our Solar System, and the vast majority of objects as well, orbit the Sun in the same direction. However, upon observing 2015 BZ509, the team concluded that it had a retrograde orbit – i.e. it rotated in the opposite direction as the other planets and objects. As Dr. Fathi Namouni, the lead author of the study, explained:

“How the asteroid came to move in this way while sharing Jupiter’s orbit has until now been a mystery. If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them.”

Using a high-resolution statistical search for stable orbits, the team found that 2015 BZ509 has been in its current orbital state since the formation of the Solar System – ca. 4.5 billion years ago. From this, they determined that the asteroid could not be indigenous to the Solar System since it would not have been able to assume its current large-inclination orbit – not when the nearby planets had early coplanar orbits and interacted with coplanar debris.

The only conclusion they could reach from these results was that this asteroid was captured from the interstellar medium 4.5 billion years ago. As Dr. Maria Helena Moreira Morais, the second author on the paper, added:

“Asteroid immigration from other star systems occurs because the Sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids. The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another.”

*Based on their study, the team determined that 2015 BZ509 was acquired by our Solar System early in its history. Credit: NASA*

The discovery of the first interstellar asteroid was certainly excited and led to multiple proposals for sending a mission to study it up close. The discovery of an interstellar asteroid that became a permanent resident in our system, however, has important implications for the study of planet formation, the evolution of the Solar System, and maybe even the origin of life itself – all of which remain open questions at this point.

Looking ahead, Dr. Namouni and Dr. Moraiswant hope to obtain more information on 2015 BZ509 so they might be able to determine exactly when it how it settled in the Solar System. In so doing, they will be able to provide clues about the Sun’s original star nursery, and about how our Early Solar System might have been enriched with components necessary for the appearance of life on Earth.

And who knows? We may soon discovery many more asteroid interlopers and long-term residents in the future. The study of these could provide even more information on the early history of our Solar System, how it interacted with neighboring systems, and how the basic ingredients for life (as we know it) came to be distributed. Perhaps the Rama enthusiasts had a point when they reminded us that the Ramans “do everything in threes”!

Further Reading: RAS, MNRAS

May 14, 2018May 15, 2018 by David Dickinson

Recovered Asteroid 2010 WC9 Set to Buzz the Earth Tomorrow

The orbit of asteroid 2010 WC9. Credit: NASA/JPL

Incoming: The Earth-Moon system has company tonight.

The Asteroid: Near Earth Asteroid 2010 WC9 is back. Discovered by the Catalina Sky Survey outside Tucson, Arizona on November 30^th, 2010, this asteroid was lost after a brief 10 day observation window and was not recovered until just earlier this month. About 71 meters in size, 2010 WC9 is one of the largest asteroids to pass us closer than the Earth-Moon distance.

A closeup of the passage of asteroid 2010 WC9 through the Earth-Moon system on May 15th. Credit: NASA-JPL

2010 WC9 poses no threat to the Earth. About the size of the Statue of Liberty from the ground level to her crown, the asteroid is over three times bigger than the one that exploded over Chelyabinsk, Russia on the morning of February 15th, 2013.

The view from asteroid 2010 WC9 on closest approach. Credit: Starry Night

The Pass: 2010 WC9 passes just 0.5 times the Earth-Moon distance (126,500 miles or 203,500 kilometers) on Tuesday, May 15^th at 22:05 UT/6:05 PM EDT. That’s only roughly five times the distance of satellites in geosynchronous orbit. The asteroid is also a relative fast mover, whizzing by at over 12 kilometers per second. An Apollo-type asteroid, 2010 WC9 orbits the Sun once every 409 days, ranging from a perihelion of 0.78 astronomical units (AU) outside the orbit of Venus out to 1.38 AU, just inside the orbit of Mars. This is the closest passage of the asteroid by the Earth for this century.

The passage of asteroid 2010 WC9 through the constellation Ophiuchus on May 15th from 00:00 to 16:00 UT. Credit Starry Night.

Observing: This one grabbed our attention when it cropped up on the Space Weather page for close asteroid passes this past weekend: a large, fast mover passing close to the Earth is a true rarity. At closest approach, 2010 WC9 will be moving at 0.22 degrees (that’s 13 arcminutes, about half the span of a Full Moon) per minute through the constellation Pavo the Peacock shining at magnitude +10, making it a good telescopic object for observers based in South Africa as it heads over the South Pole.

The southern hemisphere passage of asteroid 2010 WC9 on May 15th from 19:00 to 23:00 UT.

North American and European observers get their best look at the asteroid tonight into early tomorrow morning while it’s still twice the distance of the Moon, shining at 13th magnitude and moving southward through the constellation Ophiuchus and across the ecliptic plane.

The best strategy to ambush the space rock is to simply aim a low power field of view at the right coordinates at the right time (see below), and watch. You should be able to see the asteroid moving slowly against the starry background, in real time.

Asteroid 2010 WC9 (non-streaking dot in the center) on May 15th while it was still 730,000 km out. Credit: Gianluca Masi/Virtual Telescope Project 2.0.

Keep in mind, the charts we made here are geocentric, assuming you’re observing from the center of the Earth. Parallax comes into play on a close asteroid pass, and the Earth’s gravity will deflect 2010 WC9’s orbit considerably. Your best bet for generating a refined track for the asteroid is to use NASA JPL’s Horizons web interface to generate Right Ascension/Declination coordinates for the 2010 WC9 for your location.

How do you ‘lose an asteroid?” Often, an initial observation arc for a distant asteroid is too short to pin down a refined orbit. We have a blind spot sunward, for example, and fast moving asteroids can also be difficult to track across rich star fields and movement from one celestial hemisphere to the next. Recovery of 2010 WC9 earlier this month now gives us a solid seven year observation arc to peg its orbit down to a high accuracy.

Clouded out, or live in the wrong hemisphere? Slooh will carry an observing session for 2010 WC9 starting tonight at 24:00 UT/ 8:00 PM EDT. The Northholt Branch Observatories in London, England will also stream the pass live via Facebook tonight. Check their page for a start time.

Go, little asteroid… the speedy passage of 2010 WC9. Credit: Northolt Branch Observatories.

There’s no word yet if Arecibo radar plans to ping 2010 WC9 over the coming days, but if they do, so expect to see an animation soon.

Don’t miss tonight’s passage of 2010 WC9 near the Earth, either in person or online.

March 24, 2018March 25, 2018 by Matt Williams

That Interstellar Asteroid ‘Oumuamua Probably Came From a Binary Star System

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) telescope in Hawaii announced the first-ever detection of an interstellar asteroid – I/2017 U1 (aka. ‘Oumuamua). Since that time, no effort has been spared to study this object before it leaves our Solar System. These include listening to it for signs of communications, determining its true nature and shape, and determining where it came from.

In fact, the question of this interstellar object’s origins has been mystery since it was first discovered. While astronomers are sure that it came from the direction of Vega and some details have been learned about its past, where it originated from remains unknown. But according to a new study by a team of astronomers from the University of Toronto, Scarborough, ‘Oumuamua may have originally come from a binary star system.

The study, titled “Ejection of rocky and icy material from binary star systems: Implications for the origin and composition of 1I/‘Oumuamua “, recently appeared in the Monthly Notices of the Royal Astronomical Society. The study was led by Alan P. Jackson, a research fellow at the Center for Planetary Sciences (CPS) at the University of Scarborough, and included members from both the CPS and the Canadian Institute for Theoretical Astrophysics (CITA).

*Oumuamua as it appeared using the William Herschel Telescope on the night of October 29. Credit: Queen’s University Belfast/William Herschel Telescope*

For the sake of their study, Jackson and his co-authors considered how in single star systems (like our own), asteroids do not get ejected very often. For the most part, it is comets that become interstellar objects, mainly because they orbit the Sun at a greater distance and are less tightly bound by its gravity. And while ‘Oumuamua was initially mistaken for a comet, follow-up observations by the European Southern Observatory (ESO) indicated that it is likely an asteroid.

With the help of other astronomers, it soon became apparent that ‘Oumuamua was likely an oddly-shaped rocky object that measured about 400 meters (1312 ft) long and was tube-shaped. These findings were rather surprising to astronomers. As Jackson explained in a recent Royal Astronomical Society press release:

“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the Solar System ejects many more comets than asteroids.”

As such, Jackson and his team hypothesized that interstellar objects like ‘Oumuamau are more likely to be ejected from a binary system. To test this theory, they constructed a population synthesis model that considered just how common binary star systems are in the Galaxy. They also conducted 2000 N-body simulations to see just how efficient such systems would be at ejecting objects like ‘Oumuamua.

*Diagram showing the orbit of the interstellar asteroid ‘Oumuamua as it passes through the Solar System. Credit: ESO/K. Meech et al.*

What they found was that binary stars are produced at a rate of about 30% by number and 41% by mass, and that rocky objects like ‘Oumuamua are far more likely to be ejected from binary than single star systems. Based on ‘Oumuamua’s rocky composition, they also determined that the asteroid was likely ejected from the inner part of its solar system (i.e. inside the “Ice Line”) while the system was still in the process of formation.

Lastly, they determined that rocky objects are ejected from binary systems in comparable numbers to icy objects. This is based on the fact that the presence of a companion star would mean that more material would become unstable due to stellar encounters. In the end, this material would be more likely to be ejected rather than accreted to form planets, or take up residence in the outer reaches of the star system.

While there are still many unanswered questions about ‘Oumuamua, it remains the first interstellar asteroid that scientists have ever known. As such, its continued study can tell us a great deal about what lies beyond our Solar System. As Jackson put it:

“The same way we use comets to better understand planet formation in our own Solar System, maybe this curious object can tell us more about how planets form in other systems.”

The team’s findings were also the subject of a presentation that took place at the 49th Lunar and Planetary Science Conference, which took place this week at The Woodlands, Texas.

Further Reading: Royal Astronomical Society, MNRAS

March 12, 2018March 13, 2018 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.

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.

February 21, 2018 by Matt Williams

OSIRIS-REx Sends Home an Image of the Earth and Moon

Image of the Earth-Moon system, taken by the OSIRIS-REx spacecraft on Jan. 17th 2018. Credit: NASA/Goddard/University of Arizona/Lockheed Martin

On September 8th. 2016, NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) launched from Earth to rendezvous with the asteroid 101955 Bennu. This mission will be the first American robotic spacecraft to rendezvous with an asteroid, which it will reach by December of 2018, and return samples to Earth for analysis (by September 24th, 2023).

Since that time, NASA has been keeping the public apprised of the mission’s progress, mainly by sending back images taken by the spacecraft. The latest image was one of the Earth and Moon, which the spacecraft took using its NavCam 1 imager on January 17th, 2018. As part of an engineering test, this image shows just how far the probe has ventured from Earth.

The image was taken when the spacecraft was at a distance of 63.6 million km (39.5 million mi) from the Earth and Moon. When the camera acquired the image, the spacecraft was moving at a speed of 8.5 km per second (19,000 mph) away from Earth. Earth can be seen in the center of the image as the brightest of the two spots while the smaller, dimmer Moon appears to the right.

Several constellations are also visible in the surrounding space, including the Pleiades cluster in the upper left corner. Hamal, the brightest star in Aries, is also visible in the upper right corner of the image. Meanwhile, the Earth-Moon system is nestled between the five stars that make up the head of Cetus the Whale.

This is merely the latest in a string of photographs that show how far OSIRIS-REx has ventured from Earth. On October 2nd, 2017, the probe’s MapCam instrument took a series of images of the Earth and Moon while the probe was at a distance of 5 million km (3 million mi) – about 13 times the distance between the Earth and the Moon. NASA then created a composite image to create a lovely view of the Earth-Moon system (see below).

On September 22nd, 2017, the probe also snapped a “Blue Marble” image of Earth (seen below) while it was at a distance of just 170,000 km (106,000 mi). The image was captured just a few hours after OSIRIS-REx had completed its critical Earth Gravity Assist (EGA) maneuver, which slung it around the Earth and on its way towards the asteroid Bennu for its scheduled rendezvous in December of 2018.

On both of these occasions, the images were taken by the probe’s MapCam instrument, a medium-range camera designed to capture images of outgassing around Bennu and help map its surface in color. The NavCam 1 instrument, by contrast, is a grayscale imager that is part of Touch-And-Go Camera System (TAGCAMS) navigation camera suite.

A color composite image of Earth taken on Sept. 22, 2017 by the MapCam camera on NASA’s OSIRIS-REx spacecraft just hours after the spacecraft completed its Earth Gravity Assist at a range of approximately 106,000 miles (170,000 kilometers). Credit: NASA/Goddard/University of Arizona

The design, construction and testing of this instrument was carried out by Malin Space Science Systems, and Lockheed Martin is responsible for its operation. By the time OSIRIS-REx begins to approach asteroid Bennu in December of 2018, we can expect that the probes cameras will once again be busy.

However, by this time, they will be turned towards its destination. As it nears Bennu, its cameras will need to be calibrated yet again by snapping images of the asteroid on approach. And we, the public, can expect that more beautiful composite images will be shared as a result.

Further Reading: NASA

February 16, 2018February 16, 2018 by Matt Williams

Interstellar Asteroid ‘Oumuamua Had a Violent Past

Since that time, multiple investigations have been conducted to determine ‘Oumuamua’s structure, composition, and just how common such visitors are. At the same time, a considerable amount of attention has been dedicated to determining the asteroid’s origins. According to a new study by a team of international researchers, this asteroid had a chaotic past that causes it to tumble around chaotically.

The study, titled “The tumbling rotational state of 1I/‘Oumuamua“, recently appeared in the scientific journal Nature Astronomy. The study was led by Wesley C. Fraser, a research fellow at the University of Queens Belfast’s Astrophysics Research Center, and included members from the Academy of Sciences of the Czech Republic, the The Open University and the University of Belgrade.

As they indicate, the discovery of ‘Oumuamua has provided scientists with the first opportunity to study a planetesimal born in another planetary system. In much the same way that research into Near-Earth Asteroids, Main Belt Asteroids, or Jupiter’s Trojans can teach astronomers about the history and evolution of our Solar System, the study of a ‘Oumuamua would provide hints as to what was going on when and where it formed.

For the sake of their study, Dr. Fraser and his international team of colleagues have been measuring ‘Oumuamua brightness since it was first discovered. What they found was that ‘Oumuamua wasn’t spinning periodically (like most small asteroids and planetesimals in our Solar System), but chaotically. What this means is that the asteroid has likely been tumbling through space for billions of years, an indication of a violent past.

While it is unclear why this is, Dr. Fraser and his colleagues suspect that it might be due to an impact. In other words, when ‘Oumuamua was thrown from its own system and into interstellar space, it is possible it collided violently with another rock. As Dr. Fraser explained in a Queen’s University Belfast press release:

“Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again. While we don’t know the cause of the tumbling, we predict that it was most likely sent tumbling by an impact with another planetesimal in its system, before it was ejected into interstellar space.”

These latest findings mirror what other studies have been able to determine about ‘Oumuamua based on its object changes in its brightness. For example, brightness measurements conducted by the Institute for Astronomy in Hawaii – and using data from the ESO’s Very Large Telescope (VLT) – confirmed that the asteroid was indeed interstellar in origin, and that its shape is highly elongated (i.e. very long and thin).

However, measurements of its color have produced little up until now other than confusion. This was due to the fact that the color appeared to vary between measurements. When the long face of the object is facing telescopes on Earth, it appears largely red, while the rest of the body has appeared neutral in color (like dirty snow). Based on their analysis, Dr. Fraser and his team resolved this mystery by indicating that the surface is “spotty”.

In essence, most of the surface reflects neutrally, but one of its long faces has a large red region – indicating the presence of tholins on its long surface. A common feature of bodies in the outer Solar System, tholins are organic compounds (i.e. methane and ethane) that have turned a deep shade of reddish-brown thanks to their exposure to ultra-violet radiation.

What this indicates, according to Dr. Fraser, is broad compositional variations on ‘Oumuamua, which is unusual for such a small body:

“We now know that beyond its unusual elongated shape, this space cucumber had origins around another star, has had a violent past, and tumbles chaotically because of it. Our results are really helping to paint a more complete picture of this strange interstellar interloper. It is quite unusual compared to most asteroids and comets we see in our own solar system,” comments Dr Fraser.

*Oumuamua as it appeared using the William Herschel Telescope on the night of October 29. Queen’s University Belfast/William Herschel Telescope*

To break it down succinctly, ‘Oumuamua may have originated closer to its parent star (hence its rocky composition) and was booted out by strong resonances. In the course of leaving its system, it collided with another asteroid, which sent it tumbling towards interstellar space. It’s current chaotic spin and its unusual color are both testaments to this turbulent past, and indicate that its home system and the Solar System have a few things in common.

Since its arrival in our system, ‘Oumuamua has set off a flurry of scientific research. All over the world, astronomers are hoping to get a glimpse of it before it leaves our Solar System, and there are even those who hope to mount a robotic mission to rendezvous with it before its beyond our reach (Project Lyra). In any event, we can expect that this interstellar visitor will be the basis of scientific revelations for years to come!

This study is the third to be published by their team, which has been monitoring ‘Oumuamua since it was first observed in October. All studies were conducted with support provided by the Science and Technology Facilities Council.

Further Reading: Queen’s University Belfast

February 7, 2018February 7, 2018 by Matt Williams

The Solar System Probably has Thousands of Captured Interstellar Asteroids

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar asteroid, named 1I/2017 U1 (aka. ‘Oumuamua). Originally thought to be a comet, this interstellar visitor quickly became the focus of follow-up studies that sought to determine its origin, structure, composition, and rule out the possibility that it was an alien spacecraft!

While ‘Oumuamua is the first known example of an interstellar asteroid reaching our Solar System, scientists have long suspected that such visitors are a regular occurrence. Aiming to determine just how common, a team of researchers from Harvard University conducted a study to measure the capture rate of interstellar asteroids and comets, and what role they may play in the spread of life throughout the Universe.

The study, titled “Implications of Captured Interstellar Objects for Panspermia and Extraterrestrial Life“, recently appeared online and is being considered for publication in The Astrophysical Journal. The study was conducted by Manasavi Lingam, a postdoc at the Harvard Institute for Theory and Computation (ITC), and Abraham Loeb, the chairman of the ITC and a researcher at the Harvard-Smithsonian Center for Astrophysics (CfA).

For the sake of their study, Lingam and Loeb constructed a three-body gravitational model, where the physics of three bodies are used to compute their respective trajectories and interactions with one another. In Lingam and Loeb’s model, Jupiter and the Sun served as the two massive bodies while a far less massive interstellar object served as the third. As Dr. Loeb explained to Universe Today via email:

“The combined gravity of the Sun and Jupiter acts as a ‘fishing net’. We suggest a new approach to searching for life, which is to examine the interstellar objects captured by this fishing net instead of the traditional approach of looking through telescope or traveling with spacecrafts to distant environments to do the same.”

Using this model, the pair then began calculating the rate at which objects comparable in size to ‘Oumuamua would be captured by the Solar System, and how often such objects would collide with the Earth over the course of its entire history. They also considered the Alpha Centauri system as a separate case for the sake of comparison. In this binary system, Alpha Centauri A and B serve as the two massive bodies and an interstellar asteroid as the third.

As Dr. Lingam indicated:

“The frequency of these objects is determined from the number density of such objects, which has been recently updated based on the discovery of ‘Oumuamua. The size distribution of these objects is unknown (and serves as a free parameter in our model), but for the sake of obtaining quantitative results, we assumed that it was similar to that of comets within our Solar System.”

*The theory of Lithopanspermia states that life can be shared between planets within a planetary system. Credit: NASA*

In the end, they determined that a few thousands captured objects might be found within the Solar system at any time – the largest of which would be tens of km in radius. For the Alpha Centauri system, the results were even more interesting. Based on the likely rate of capture, and the maximum size of a captured object, they determined that even Earth-sized objects could have been captured in the course of the system’s history.

In other words, Alpha Centauri may have picked up some rogue planets over time, which would have had drastic impact on the evolution of the system. In this vein, the authors also explored how objects like ‘Oumuamua could have played a role in the distribution of life throughout the Universe via rocky bodies. This is a variation on the theory of lithopanspermia, where microbial life is shared between planets thanks to asteroids, comets and meteors.

In this scenario, interstellar asteroids, which originate in distant star systems, would be the be carriers of microbial life from one system to another. If such asteroids collided with Earth in the past, they could be responsible for seeding our planet and leading to the emergence of life as we know it. As Lingam explained:

“These interstellar objects could either crash directly into a planet and thus seed it with life, or be captured into the planetary system and undergo further collisions within that system to yield interplanetary panspermia (the second scenario is more likely when the captured object is large, for e.g. a fraction of the Earth’s radius).”

In addition, Lingam and Loeb offered suggestions on how future visitors to our Solar System could be studied. As Lingam summarized, the key would be to look for specific kinds of spectra from objects in our Solar Systems:

“It may be possible to look for interstellar objects (captured/unbound) in our Solar system by looking at their trajectories in detail. Alternatively, since many objects within the Solar system have similar ratios of oxygen isotopes, finding objects with very different isotopic ratios could indicate their interstellar origin. The isotope ratios can be determined through high-resolution spectroscopy if and when interstellar comets approach close to the Sun.”

“The simplest way to single out the objects who originated outside the Solar System, is to examine the abundance ratio of oxygen isotopes in the water vapor that makes their cometary tails,” added Loeb. “This can be done through high resolution spectroscopy. After identifying a trapped interstellar object, we could launch a probe that will search on its surface for signatures of primitive life or artifacts of a technological civilization.”

It would be no exaggeration to say that the discovery of ‘Oumuamua has set off something of a revolution in astronomy. In addition to validating something astronomers have long suspected, it has also provided new opportunities for research and the testing of scientific theories (such as lithopanspermia).

In the future, with any luck, robotic missions will be dispatched to these bodies to conduct direct studies and maybe even sample return missions. What these reveal about our Universe, and maybe even the spread of life throughout, is sure to be very illuminating!

Further Reading: arXiv

January 17, 2018 by Matt Williams

Asteroid Mining is Getting Closer to Reality. Planetary Resources Arkyd-6 Satellite Just Launched

The launch of the PSLV-C40 rocket from the First Launch Pad at the Satish Dhawan Space Centre. Credit: ISRO

In 2009, Arkyd Aeronautics was formed with the intention of becoming the first commercial deep-space exploration program. In 2012, the company was renamed Planetary Resources, and began exploring the ambitious idea of asteroid prospecting and mining. By harnessing Near-Earth Objects (NEOs) for their water and minerals, the company hopes to substantially reduce the costs of space exploration.

A key step in this vision is the deployment of the Arkyd 6, a CubeSat that will begin testing key technologies that will go into asteroid prospecting. Last week (on Friday, January 12th), the Arkyd-6 was one of 31 satellites that were launched into orbit aboard an Indian-built PSLV rocket. The CubeSat has since been deployed into orbit and is already delivering telemetry data to its team of operators on the ground.

The launch was not only a milestone for the asteroid prospecting company, but for commercial aerospace in general. For the purposes of creating the Arkyd 6, the company modified commercial-available technology to be used in space. This includes the mid-wave infrared (MWIR) sensor the spacecraft will use to detect water on Earth, as well as its avionics, power systems, communications, attitude determination and control systems.

*The Arkyd-6 deploying from the PSLV rocket that carried it into orbit. Credit: ISRO*

This process is central to the new era of commercial aerospace, where the ability to adapt readily-available technology will allow companies to have control over every stage of the development process, as well as significantly reducing costs. As Chris Lewicki, the President and CEO Planetary Resources, said in a recent company statement:

“The success of the Arykd-6 will validate and inform the design and engineering philosophies we have embraced since the beginning of this innovative project. We will continue to employ these methods through the development of the Arkyd-301 and beyond as we progress toward our Space Resource Exploration Mission.”

The company hopes to mount the Space Resource Exploration Mission by 2020, which will involve multiple spacecraft being deployed as part of a single rocket launch. These will be carried beyond Earth’s orbit and will use low-thrust ion propulsion systems to travel to asteroids that have been prospected by Arkyd-301. Once there, they will collect data and collect samples for analysis.

During the course of the Arkyd-6’s flight, 17 elements will be tested in total, the most important of which is the MWIR imager. This instrument will be the first commercial infrared imager to be used in space and relies on custom optics to collect pixel-level data. With this high-level of precision, the imager will conduct hydration studies of Earth to determine how effective the instrument is at sniffing out sources of water on other bodies.

*Planetary Resources onfographic, showing the process of asteroid prospecting. Credit: Planetary Resources*

Based on the findings from this initial flight, the company plans to further develop the sensor technology, which will be incorporated into their next mission – the Arkyd-301. This spacecraft will be the first step in Planetary Resources plan to make asteroid mining a reality. Using the same technology as the Arkyd-6 (with some refinements), the spacecraft will be responsible for identifying sources of water on Near-Earth Asteroids.

These asteroids will be the target of future missions, where commercial spacecraft attempt to rendezvous and mine them for water ice. As Chris Voorhees, the Chief Engineer at Planetary Resources, said:

“If all of the experimental systems operate successfully, Planetary Resources intends to use the Arkyd-6 satellite to capture MWIR images of targets on Earth’s surface, including agricultural land, resource exploration regions, and infrastructure for mining and energy. In addition, we will also have the opportunity to perform specific celestial observations from our vantage point in low Earth orbit. Lessons learned from Arkyd-6 will inform the company’s approach as it builds on this technology to enable the scientific and economic evaluation of asteroids during its future Space Resource Exploration Mission.”

All told, there are over 1600 asteroids in Near-Earth space. According to Planetary Resources own estimates, these contain a total of 2 trillion metric tons (2.2 US tons) of water, which can be used for the sake of life support and manufacturing fuel for space missions. By tapping this abundant off-world resource, they estimate that the associated costs of mounting missions to space can be reduced by 95%.

Much like SpaceX’s ongoing development of reusable rockets and attempts to create reusable space planes (such as the Dream Chaser and the Sabre Engine), the goal here is to make space exploration not only affordable, but lucrative. Once that is achieved, the size and shape of space exploration will be limited only by our imaginations.

And be sure to check out this video from Planetary Resources that outlines their Exploration Program:

“The success of the Arykd-6 will validate and inform the design and engineering philosophies we have embraced since the beginning of this innovative project,” said Chris Lewicki, President and CEO, Planetary Resources. “We will continue to employ these methods through the development of the Arkyd-301 and beyond as we progress toward our Space Resource Exploration Mission.”

Further Reading: Planetary Resources

January 4, 2018January 4, 2018 by Matt Williams

Here’s the Earth and Moon Seen from OSIRIS-REx

On September 8th, 2016, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission was launched into space. In the coming months, this space probe will approach and then rendezvous with the asteroid 101955 Bennu – a Near-Earth Object (NEO) – for the sake of studying it. The mission will also acquire samples of the asteroid, which will be returned to Earth by 2023.

The OSIRIS-REx mission is an historic one, since it will be the first US spacecraft to conduct a sample-return mission with an asteroid. In the meantime, as the probe has makes its way further into space, it has been providing some truly breathtaking images of the journey. Consider the recently-released composite image of the Earth-Moon system, which NASA created using images that were taken by the probe on October 2nd, 2017.

The images were all taken by the probe’s MapCam instrument, a medium-range camera designed to capture images of outgassing around Bennu and help map its surface in color. On this occasion, it snapped three beautiful pictures of Earth and the Moon. These images were all taken when the spacecraft was at a distance of approximately 5 million km (3 million mi) from Earth – about 13 times the distance between the Earth and the Moon.

*Black and white image of Earth taken by the OSIRIS-REx’s NavCam 1 instrument. Credit: NASA/OSIRIS-REx team and the University of Arizona*

As part of the OSIRIS-REx Camera Suite (OCAMS), which is operated by researchers at the University of Arizona, the CapCam has four color filters. To produce the image, three of them (b, v and w) were used as a blue, green and red filters and then stacked on top of each other. The Earth and Moon were each color-corrected, and the Moon was brightened to make it more easily visible.

A second image of planet Earth (shown above), was taken on September 22nd, 2017, by one of the probe’s navigational cameras (NavCam 1). As the name suggests, this instrument is intended to help OSIRIS-REx orient itself while making its journey to Bennu and while it studies the asteroid. This is done by tracking starfields in space (while in transit) and landmarks on Bennu’s surface once it has arrived.

The image was taken when OSIRIS-REx was at a distance of 110,000 km (69,000 mi) from Earth. This was just after the probe had completed an Earth gravity-assist maneuver, where it used Earth’s gravitational force to slingshot around its equator and pick up more speed. The original image (shown below) was rotated so that the North Pole would be pointed up and the entire image was enlarged to provide more detail.

As you can see in the altered image, North America is visible on the upper right portion, while Hurricane Maria and the remnants of Hurricane Jose are visible in the far upper-right. The acquisition of these images was the result of painstaking calculations and planning, which were performed in advance by engineers and navigation specialists on the mission team using software called Systems Tool Kit (STK).

*Original image taken by the OSIRIS-REx NavCam 1 of Earth. Credit: NASA/Goddard/University of Arizona/Lockheed Martin*

These plans were developed to ensure that the probe would be able to snap pictures with precise timing, which were then uploaded to the spacecraft’s computer weeks ahead of time. Within hours of the probe executing its gravity-assist maneuver, crews on the ground were treated to the first images from the spacecraft’s navigational cameras, which confirmed that the probe was following the right path.

The probe is scheduled to reach Bennu in December of 2018, with approach operations commencing this coming August. Bennu is also expected to make a close pass with Earth several centuries from now, and could even collide with us by then. But for the time being, it represents a major opportunity to study the history and evolution of the Solar System, since it is essentially a remnant left over from its formation.

By studying this asteroid up close, and bringing samples back to Earth for further study, the OSRIS-REx mission could help us understand how life began on Earth and where the Solar System as a whole is headed. But in the meantime, the probe has been able to provide us with some beautiful snapshots of Earth, which serve to remind us all of certain things.

Much like Voyager 1‘s “Pale Blue Dot” photo, seeing Earth from space helps to drive home the fact that life is rare and precious. It also reminds us that we, as a species, are all in this together and completely and utterly dependent on our planet and its ecosystems. Once in awhile, we need to be reminded of these things. Otherwise, we might do some stupid – like ruin it!

Further Reading: NASA

December 19, 2017February 7, 2018 by Matt Williams

Updates on ‘Oumuamua. Maybe it’s a Comet, Actually. Oh, and no Word From Aliens.

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar object, named 1I/2017 U1 (aka. ‘Oumuamua). After originally hypothesizing that it was a comet, observations performed by the European Southern Observatory (ESO) and other astronomers indicated that it was likely a strange-looking asteroid measuring about 400 meters (1312 ft) long.

Since that time, multiple surveys have been conducted to determine the true nature of this asteroid, which have included studies of its composition to Breakthrough Listen‘s proposal to listen to it for signs of radio transmissions. And according to the latest findings, it seems that ‘Oumuamua may actually be more icy than previously thought (thus indicated that it is a comet) and is not an alien spacecraft as some had hoped.

The first set of findings were presented in a study that was recently published in the scientific journal Nature, titled “Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 ‘Oumuamua“. The study was led by Alan Fitzsimmons of Queen’s University Belfast, and included members from The Open University in Milton Keynes, the Institute for Astronomy (IfA) at the University of Hawaii, and the European Southern Observatory (ESO).

*‘Oumuamua, as imaged by the William Herschel Telescope on October 29th, 2017. Credit: Queen’s University Belfast/William Herschel Telescope*

As they indicate in their study, the team relied on information from the ESO’s Very Large Telescope in Chile and the William Herschel Telescope in La Palma. Using these instruments, they were able to obtain spectra from sunlight reflected off of ‘Oumuamua within 48 hours of the discovery. This revealed vital information about the composition of the object, and pointed towards it being icy rather than rocky. As Fitzsimmons explained in op-ed piece in The Conversation:

“Our data revealed its surface was red in visible light but appeared more neutral or grey in infra-red light. Previous laboratory experiments have shown this is the kind of reading you’d expect from a surface made of comet ices and dust that had been exposed to interstellar space for millions or billions of years. High-energy particles called cosmic rays dry out the surface by removing the ices. These particles also drive chemical reactions in the remaining material to form a crust of chemically organic (carbon-based) compounds.”

These findings not only addressed a long-standing question about ‘Oumuamua true nature, it also addresses the mystery of why the object did not experience outgassing as it neared our Sun. Typically, comets experience sublimation as they get closer to a star, which results in the formation of a gaseous envelope (aka. “halo”). The presence of an outer layer of carbon-rich material would explain why this didn’t happen ‘Oumuamua.

They further conclude that the red layer of material could be the result of its interstellar journey. As Fitzsommons explained, “another study using the Gemini North telescope in Hawaii showed its color is similar to some ‘trans-Neptunian objects’ orbiting in the outskirts of our solar system, whose surfaces may have been similarly transformed.” This red coloring is due to the presence of tholins, which form when organic molecules like methane are exposed to ultra-violet radiation.

Similarly, another enduring mystery about this object was resolved thanks to the recent efforts of Breakthrough Listen. As part of Breakthrough Initiatives’ attempts to explore the Universe and search for signs of Extra-Terrestrial Intelligence (ETI), this project recently conducted a survey of ‘Oumuamua to determine if there were any signs of radio communications coming from it.

While previous studies had all indicated that the object was natural in origin, this survey was more about validating the sophisticated instruments that Listen relies upon. The observation campaign began on Wednesday, December 13th, at 3:00 pm EST (12:00 PST) using the Robert C. Byrd Greenbank Radio Telescope, the world’s premiere single-dish radio telescope located in West Virginia.

The observations period was divided into four “epochs” (based on the object’s rotational period), the first of which ran from 3:45 pm to 9:45 pm ET (12:45 pm to 6:45 pm PST) on Dec 13th, and last for ten hours. During this time, the observation team monitored ‘Oumuamua across four radio bands, ranging from the 1 to 12 GHz bands. In addition to calibrating the instrument, the survey accumulated 90 terabytes of raw data over after observing ‘Oumuamua itself for two hours.

The initial results and data were released last week (Dec. 13th) and are available through the Breakthrough Listen archive. As Andrew Siemion – the Director of Berkeley SETI Research Center who took part in the survey – indicated in a Breakthrough Initiatives press release:

“It is great to see data pouring in from observations of this novel and interesting source. Our team is excited to see what additional observations and analyses will reveal”.

So far, no signals have been detected, but the analysis is far from complete. This is being conducted by Listen’s “turboSETI” pipeline, which combs the data for narrow bandwidth signals that are drifting in frequency. This consists of filtering out interference signals from human sources, then matching the rate at which signals drift relative to the expected drift caused by ‘Oumuamua’s own motion.

In so doing, the software attempts to identify any signals that might be coming from ‘Oumuamua itself. So far, data from the S-band receiver (frequencies ranging from 1.7 to 2.6 GHz) has been processed, and analysis of the remaining three bands – which corresponds to receivers L, X, and C is ongoing. But at the moment, the results seem to indicate that ‘Oumuamua is indeed a natural object – and an interstellar comet to boot.

This is certainly bad news for those who were hoping that ‘Oumuamua might be a massive cylinder-shaped generation ship or some alien space probe sent to communicate with the whales! I guess first contact – and hence, proof we are NOT alone in the Universe – is something we’ll have to wait a little longer for.

Further Reading: The Conversation, Nature, Breakthrough Initiatives