Asteroids Archives

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 16, 2018February 16, 2018 by Matt Williams

Interstellar Asteroid ‘Oumuamua Had a Violent Past

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.

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

October 20, 2017October 21, 2017 by Matt Williams

Good News Everyone! There are Fewer Deadly Undiscovered Asteroids than we Thought

An artist's impression of a Nearth-Earth Asteroid (NEA) breaking up. Credit: NASA/JPL-Caltech

Beyond Earth’s orbit, there are innumerable comets and asteroids that are collectively known as Near-Earth Objects. On occasion, some of these objects will cross Earth’s orbit; and every so often, one will pass too close to Earth and impact on its surface. While most of these objects have been too small to cause serious damage, some have been large enough to trigger Extinction Level Events (ELEs).

For this reason, NASA and other space agencies have spent decades cataloging and monitoring the larger NEAs in order to determine if they might collide with Earth at some point in the future. The only question has been, how many remain to be found? According to a recent analysis performed by Alan W. Harris of MoreData! – a California-based research company – only a handful of NEAs haven’t been catalogued yet.

These findings were the subject of a presentation made this week at the 49th annual meeting of the American Astronomical Society’s Division for Planetary Sciences in Provo, Utah. As Harris indicated during the presentation, titled “The Population of Near-Earth Asteroids Revisited”, previous estimates of the remaining NEAs have been plagued by a consequential round-off error that have skewed the results.

*Artist’s concept of the Wide-field Infrared Survey Explorer as its orbit around Earth. Credit: NASA/JPL*

The source of this error has to do with how organizations that monitor NEOs determine “size-frequency distribution”. Basically, estimates are given in terms of number versus brightness, since most discovery surveys were conducted in the visible spectrum. This is not a reliable way of determining size though, since asteroids don’t all have the same albedo (aka. reflectivity).

As such, NEA brightness is expressed in units of absolute magnitude (H), where lower numbers indicate brighter objects. The IAU Minor Planet Center – which is responsible for maintaining information on asteroid and other small-body measurements – rounds off the reported values of H to the nearest 0.1 magnitude. As Harris explained during the course of his presentation:

“So, for example, a bin from H of 17.5 to 18.0 is really from 17.55 to 18.05, or 17.45 to 17.95, depending on which side of the bin you take “less than or equal to” rather than ‘less than’.”

While this has not caused much in the way of problems in the past, it has become significant as far as assessments of how many larger objects remain to be found are concerned. Harris first became aware of the potential for problems this past year after Dr. Pasqual Tricario – a Senior Scientist at the Planetary Science Institute – conducted a study that produced estimates different from those obtained by Harris and Italian astronomer Germano D’Abramo two years before.

*This graphic shows asteroids and comets observed by NASA’s Near-Earth Object Wide-field Survey Explorer (NEOWISE) mission. Credit: NASA/JPL-Caltech/UCLA/JHU*

The 2015 study conducted by Harris and D’Abramo – which appeared in Icarus under the title “The population of near-Earth asteroids” – yielded an estimate of 990 NEAs that were larger than 1 km in diameter. However, Tricario’s study (“The near-Earth asteroid population from two decades of observations“, also published in Icarus), which was based on the opposite “less than or equal to” assumption, produced estimates that were 10% lower.

As Harris explained, this prompted D’Adramo and him to considered a different approach. “We corrected the problem for the current analysis by choosing bin boundaries at .05 magnitudes, e.g. 17.25 to 17.75, so the 0.1 round-off thresholds naturally put objects in the right bin,” he said. “When Tricarico and I each made these corrections, our population estimates fell into almost perfect agreement.”

After applying the correction, Harris and D’Abramo’s overall estimate of undiscovered NEAs dropped from 990 to 921 ± 20. Beyond allowing for consistency between different studies, these corrected estimates also reduced the total number of undiscovered objects that remain undiscovered. According to the latest tallies from NASA’s Jet Propulsion Laboratory, 884 NEAs that are about 1 km in diameter have been discovered so far.

Based on the previous population estimate of 990 objects, this implied that the current surveys are 89% complete and 106 were yet to be found. When the corrections were applied to these numbers, JPL’s surveys now appears to be 96% complete, and only 37 objects remain to be found (almost three times less). Naturally, these new estimates depends on their own sets of assumptions, and different results can be obtained based on different criteria.

*NASA is getting much better at discovering and detecting NEOs. Credit: NASA/NEO Program.*

Still, a reduced estimate of undiscovered asteroids is definitely encouraging news. Especially when one considers how hazardous large asteroids are to the safety and well-being of life here on Earth. As of October 3rd, 2017, NASA’s Center for Near-Earth Object Studies (CNEOS) announced that there are a total of 157 potentially hazardous asteroids out there. Knowing that only a few more need to be found is bound to help some of us sleep at night!

Future studies are also expected to benefit from the deployment of next-generation missions. Thanks to the efforts of NASA’s Near-Earth-Object WISE (NEOWISE) mission, which looks for NEOs in the infrared band (rather than visible light), that number of known NEOs has increased substantially. With the deployment of the James Webb Space Telescope, those numbers are expected to reach even higher.

Between improvements in technology and methodology, a day may yet come when all Near-Earth Objects – be they big or small, potentially hazardous or harmless – are accounted for. Combined with asteroid defenses, like directed-energy beams or robots spacecraft capable of attaching themselves to asteroids and redirecting them, Extinction Level Events might very well become a thing of the past.

Further Reading: The Spaceguard Center

October 11, 2017October 11, 2017 by Nancy Atkinson

Watch a House-Sized Asteroid Pass Close to Earth Tonight (October 11/12)

Asteroid 2012 TC4 captured remotely on October 11, 2017 from the iTelescope SRO Observatory. Credit and copyright: Ernesto Guido/Remanzacco Observatory.

On Oct. 12, a house-size asteroid will pass quite close to Earth – only 26,000 miles (42,000 kilometers) away. This is just above the orbital altitude of communications satellites and a little over one-tenth the distance to the Moon. But not to fear, it has no chance of hitting Earth.

Artists concept of Asteroid 2012 TC4’s close pass of Earth on Oct. 12, 2017. Based on continuing observations, scientists have determined that it will pass the Earth at a distance of about 26,000 miles (42,000 kilometers). Credits: NASA/JPL-Caltech

Asteroid 2012 TC4 was discovered almost 4 years ago to the day, on October 4, 2012, just a week before it made another close pass by Earth.

With a little more advance notice this time around, NASA and asteroid trackers around the world are using the close pass to test their ability to operate as a coordinated International Asteroid Warning Network. This is a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.

“Asteroid trackers are using this flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid-impact threat,” said Michael Kelley, program scientist and NASA lead for the TC4 observation campaign. You can read more details about the observing campaign in our previous article.

You can watch it pass by too, if you have a at least an 8 inch telescope, according to our David Dickinson, who has a very informative post about 2012 TC4 at Sky & Telescope.

Closest approach will be at on October 12, 2017, at 5:41 Universal Time (1:41 a.m. EDT).

You can also watch a couple of webcasts of the pass:

Virtual Telescope will have a live feed, and the Slooh Telescope crew will also host a live feed starting tonight at 8 pm EDT on Oct. 11.

2012 TC4 is estimated to be 45 to 100 feet (15 to 30 meters) in size.

NASA’s Asteroid Watch says that no asteroid currently known is predicted to impact Earth for at least the next 100 years.

More info at NASA’s website.

September 21, 2017September 22, 2017 by Ken Kremer

NASA’s OSIRIS-REx Asteroid Sampler Slingshots Around Earth Friday, Sept. 22 – Catch It If You Can!

Artist's concept shows the OSIRIS-REx spacecraft passing by Earth on Sept. 22, 2017. Credits: NASA's Goddard Space Flight Center/University of Arizona

KENNEDY SPACE CENTER, FL – Barely a year after NASA’s OSIRIS-REx robotic asteroid sampler launched on a trailblazing mission to snatch a soil sample from a pristine asteroid and return it to Earth for research analysis, the probe is speeding back home for a swift slingshot around our home planet on Friday Sept. 22 to gain a gravity assist speed boost required to complete its journey to the carbon rich asteroid Bennu and back.

As it swings by Earth NASA’s first ever asteroid sample return mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer), will pass only 11,000 miles (17,000 kilometers) above Earth just before 12:52 p.m. EDT on Friday.

And NASA is asking the public to try and ‘Catch It If You Can’ – by waving hello and/or taking snapshots during and after the probes high speed flyby.

Plus you can watch NASA Facebook Live event at Noon Friday: https://www.facebook.com/NASAGoddard/

OSIRIS-REx will be approaching Earth at a velocity of about 19,000 mph on Friday as it begins flying over Australia during the Earth Gravity Assist (EGA) maneuver.

Since blastoff from the Florida Space Coast on Sept. 8, 2016 the probe has already racked up almost 600 million miles on its round trip journey from Earth and back to set up Friday’s critical gravity assist maneuver to Bennu and back.

As OSIRIS-REx continues along its flight path the spacecraft will reach its closest point to Earth over Antarctica, just south of Cape Horn, Chile. It will gain a velocity boost of about 8400 mph.

The spacecraft will also conduct a post flyby science campaign by collecting images and science observations of Earth and the Moon four hours after closest approach to calibrate its five science instruments.

NASA’s OSIRIS-REx asteroid sampling spacecraft, return capsule and payload fairings inside the Payloads Hazardous Servicing Facility high bay at NASA’s Kennedy Space Center is being processed for Sep. 8, 2016 launch to asteroid Bennu from Cape Canaveral, FL. Credit: Ken Kremer/kenkremer.com

The allure of Bennu is that it is a carbon rich asteroid – thus OSIRIS-REx could potentially bring back samples infused with the organic chemicals like amino acids that are the building blocks of life as we know it.

“We are interested in that material because it is a time capsule from the earliest stages of solar system formation,” OSIRIS-Rex Principal Investigator Dante Lauretta told Universe Today in a prelaunch interview with the spacecraft in the cleanroom at NASA’s Kennedy Space Center.

The do or die gravity assist plunge is absolutely essential to set OSIRIS-REx on course to match the asteroid’s path and speed when it reaches the vicinity of asteroid Bennu a year from now in October 2018.

“The Earth Gravity Assist is a clever way to move the spacecraft onto Bennu’s orbital plane using Earth’s own gravity instead of expending fuel,” says Lauretta, of the University of Arizona, Tucson.

Just how close to Earth will OSIRIS-REx be during its flyby on Friday? The spacecraft will come within 11,000 miles (17,000 km) of the Earth’s surface as it passes over Antarctica at 12:52 a.m. EDT. on Sept. 22, 2017. Credits: NASA’s Goddard Space Flight Center/University of Arizona

Bennu’s orbit around the Sun is tilted at a six-degree inclination with respect to Earth’s orbital plane.

The asteroid is 1,614-foot (500 m) in diameter and crosses Earth’s orbit around the sun every six years.

Numerous NASA spacecraft – including NASA’s just completed Cassini mission to Saturn – utilize gravity assists around a variety of celestial bodies to gain speed and change course to save vast amounts of propellant and time in order to accomplish science missions and visit additional target objects that would otherwise be impossible.

The flyby will be a nail-biting time for NASA and the science team because right afterwards the refrigerator sized probe will be out of contact with engineers – unable to receive telemetry for about an hour.

“For about an hour, NASA will be out of contact with the spacecraft as it passes over Antarctica,” said Mike Moreau, the flight dynamics system lead at Goddard, in a statement.

“OSIRIS-REx uses the Deep Space Network to communicate with Earth, and the spacecraft will be too low relative to the southern horizon to be in view with either the Deep Space tracking station at Canberra, Australia, or Goldstone, California.”

NASA says the team will regain communication with OSIRIS-REx roughly 50 minutes after closest approach over Antarctica at about 1:40 p.m. EDT.

The post flyby science campaign is set to begin at 4:52 p.m. EDT, Friday, Sept. 22.

United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft on the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. Liftoff was at 7:05 p.m. EDT on September 8, 2016 in this remote camera view taken from inside the launch pad perimeter. Note the newly install crew access arm and white room for astronaut flights atop Atlas starting in early 2018. Credit: Ken Kremer/kenkremer.com

The OSIRIS-Rex spacecraft originally departed Earth atop a United Launch Alliance Atlas V rocket under crystal clear skies on September 8, 2016 at 7:05 p.m. EDT from Space Launch Complex 41 at Cape Canaveral Air Force Station, Florida.

Everything with the launch went exactly according to plan for the daring mission boldly seeking to gather rocks and soil from carbon rich Bennu.

View of science instrument suite and TAGSAM robotic sample return arm on NASA’s OSIRIS-REx asteroid sampling spacecraft inside the Payloads Hazardous Servicing Facility at NASA’s Kennedy Space Center. Probe is slated for Sep. 8, 2016 launch to asteroid Bennu from Cape Canaveral Air Force Station, FL. Credit: Ken Kremer/kenkremer.com

OSIRIS-Rex is equipped with an ingenious robotic arm named TAGSAM designed to collect at least a 60-gram (2.1-ounce) sample and bring it back to Earth in 2023 for study by scientists using the world’s most advanced research instruments.

“The primary objective of the OSIRIS-Rex mission is to bring back pristine material from the surface of the carbonaceous asteroid Bennu,” OSIRIS-Rex Principal Investigator Dante Lauretta told me in the prelaunch interview in the KSC cleanroom with the spacecraft as the probe was undergoing final launch preparations.

“We are interested in that material because it is a time capsule from the earliest stages of solar system formation.”

“It records the very first material that formed from the earliest stages of solar system formation. And we are really interested in the evolution of carbon during that phase. Particularly the key prebiotic molecules like amino acids, nucleic acids, phosphates and sugars that build up. These are basically the biomolecules for all of life.”

NASA and the mission team is also inviting the public to get engaged by participating in the Wave to OSIRIS-REx social media campaign.

“Individuals and groups from anywhere in the world are encouraged to take photos of themselves waving to OSIRIS-REx, share them using the hashtag #HelloOSIRISREx and tag the mission account in their posts on Twitter (@OSIRISREx) or Instagram (@OSIRIS_REx).

Participants may begin taking and sharing photos at any time—or wait until the OSIRIS-REx spacecraft makes its closest approach to Earth at 12:52p.m. EDT on Friday, Sept. 22.”

The probe’s flight path during the flyby will pass through the ring of numerous satellites orbiting in geosynchronous orbit, but none are expected to be within close range.

Members of the OSIRIS-REx mission team celebrate the successful spacecraft launch on Sept. 8, 2016 atop ULA Atlas V at the post-launch briefing at the Kennedy Space Center, FL. Principal Investigator Dante Lauretta is 4th from right, NASA Planetary Science Director Jim Green is center, 5th from left. Credit: Ken Kremer/kenkremer.com

Watch for Ken’s continuing onsite NASA mission and launch reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

September 20, 2017September 20, 2017 by Fraser Cain

300 Asteroids to be Explored by a Fleet of Nanosatellites

Artist’s concept of the spacecraft. Credit: FMI

The more that planetary astronomers study asteroids, they more they’re realizing just how varied and different they can be. Some, like 16 Psyche are made of solid nickel and iron, while others are made of rock. Some asteroids have been found with moons, rings, and some icy objects really blur the line between comet and asteroid. In order to truly understand their nature, it would take dozens or maybe hundreds of individual missions on the scale of Rosetta or New Horizons.

Or maybe not.

A team of researchers with the Finnish Meteorological Institute announced today that the best way to explore the varied objects in the asteroid belt would be with a fleet of tiny nanosatellites – 50 ought to do the trick to explore 300 separate asteroids, bringing the individual costs down to a few hundred thousand dollars per asteroid. During a presentation they made at the European Planetary Science Congress (EPSC) 2017 in Riga on Tuesday, the researchers showed how these tiny satellites could travel out to the asteroid belt, gather data on individual asteroids, and return to Earth to download their data.

The 50 satellites could be launched together in a single vehicle, and then separate once in space, or they could fill extra space in existing launches. The exact launch orbit doesn’t matter, as long as the spacecraft can get outside the Earth’s protective magnetosphere, where they can catch a ride on the solar wind.

Once in space, 5-kg spacecraft would deploy a 20 km-long wire tether that would catch the solar wind; the constantly flowing particles coming off the Sun, imparting a tiny thrust. This is known as an “E-sail” or electric sail. Unlike a solar sail, which depends on the momentum of photons coming from the Sun, electric sails harvest the momentum of charged protons.

Artist's illustration of the Heliopause Electrostatic Rapid Transit System. — Artist’s illustration of the Heliopause Electrostatic Rapid Transit System.

Researchers are still figuring out if this is an effective propulsion system for spacecraft. An Estonian prototype satellite was launched back in 2015, but its onboard motor failed to reel out its tether. The Finnish Aalto-1 satellite launched in June, 2017, and will test out a prototype electric sail in addition to several other experiments over the course of the next year. Even more advanced versions have been proposed, such as Heliopause Electrostatic Rapid Transit System (or HERTS), a mission which could reach 100 astronomical units in 10-15 years by deploying a huge electrified net in space.

In the case of this asteroid mission, each satellite’s electric sail would only give it a change in velocity of only one millimeter per second, but over the course of a 3.2 year mission, it would allow the spacecraft to reach the asteroid belt and return to Earth.

Mission trajectory. The spacecraft would take 3.2 years to reach the asteroid belt and return.

In fact, the spacecraft would use their tethers to maneuver within the asteroid belt, flying past as many targets as they can with this minuscule thrust. Each satellite should be able to reach at least 6-7 numbers asteroids, and maybe even more smaller ones.

Each satellite would be equipped with a telescope with only a 40 mm aperture. That’s the size of a small spotting scope or half a pair of binoculars, but it would be enough to resolve features on the surface of an asteroid as large as 100 meters across from 1,000 km away. In addition to taking visual images of the asteroid targets, the spacecraft would be equipped with an infrared spectrometer to determine its meteorology.

Because the spacecraft are so small, they won’t be capable of carrying a transmitter to send their data back to Earth. Instead, they’d store all their scientific findings on a memory card, and then dump their data when their orbit brings them back close to Earth.

The researchers estimate that development of the mission would probably cost about 60 million Euros, or $70 million dollars, bringing the cost per asteroid down to about 200,000 Euros or $240,000.

Further Reading: Europlanet, Science Daily

August 18, 2017August 18, 2017 by Matt Williams

Large Near-Earth Asteroid Will Pass Earth by This September

Artist's impression of a Near-Earth Asteroid passing by Earth. Credit: ESA

Within Earth’s orbit, there are literally thousands of what are known as Near-Earth Objects (NEOs), more than fourteen thousands of which are asteroids that periodically pass close to Earth. Since the 1980s, these objects have become a growing source of interest to astronomers, due to the threat they sometimes represent. But as ongoing studies and decades of tracking the larger asteroids has shown, they usually just pass Earth by.

More importantly, it is only on very rare occasions (i.e. over the course of millions of years) that a larger asteroid will come close to colliding with Earth. For example, this September 1st, the Near-Earth Asteroid (NEA) known as 3122 Florence, will pass by Earth, but poses no danger of hitting us. Good thing too, since this Near-Earth Asteroid is one of the largest yet to be discovered, measuring about 4.4 km (2.7 mi) in diameter!

To put that in perspective, the asteroid which is thought to have killed the dinosaurs roughly 65 million years ago (aka. the Cretaceous–Paleogene extinction event) is believed to have measured 10 km (6 mi) in diameter. This impact also destroyed three-quarters of the plant and animal species on Earth, hence why organizations like NASA’s Center for Near-Earth Object Studies (CNEOS) is in he habit of tracking the larger NEAs.

Asteroid Florence, a large near-Earth asteroid, will pass safely by Earth on Sept. 1, 2017, at a distance of about 7 million km (4.4 million mi). Credits: NASA/JPL-Caltech

Once again, NASA has determined that this particular asteroid will sail harmlessly by, passing Earth at a minimum distance of over 7 million km (4.4 million mi), or about 18 times the distance between the Earth and the Moon. As Paul Chodas – NASA’s manager of CNEOS at the Jet Propulsion Laboratory in Pasadena, California – said in a NASA press statement:

“While many known asteroids have passed by closer to Earth than Florence will on September 1, all of those were estimated to be smaller. Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began.”

Rather than being a threat, the flyby of this asteroid will be an opportunity for scientists to study it up close. NASA is planning on conducting radar studies of Florence using the Goldstone Solar System Radar in California, and the National Science Foundation’s (NSF) Arecibo Observatory in Peurto Rico. These studies are expected to yield more accurate data on its size, and reveal surface details at resolutions of up to 10 m (30 feet).

This asteroid was originally discovered on March 2nd, 1981, by American astronomer Schelte Bus at the Siding Spring Observatory in southwestern Australia. It was named in honor of Florence Nightingale (1820-1910) the founder of modern nursing. Measurements obtained by NASA’s Spitzer Space Telescope and the NEOWISE mission are what led to the current estimates on its size – about 4.4 km (2.7 mi) in diameter.

Artist’s rendition of how far Florence will pass by Earth. Credits: NASA/JPL-Caltech

The upcoming flyby will be the closest this asteroid has passed to Earth since August 31st, 1890, where it passed at a distance of 6.7 million km (4.16 million mi). Between now and then, it also flew by Earth on August 29th, 1930, passing Earth at a distance of about 7.8 million km (4.87 million mi). While it will pass Earth another seven times over the course of the next 500 years, it will not be as close as it will be this September until after 2500.

For those interesting into doing a little sky watching, Florence will be brightening substantially by late August and early September. During this time, it will be visible to those using small telescopes for several nights as it moves through the constellations of Piscis Austrinus, Capricornus, Aquarius and Delphinus.

Be sure to check out these animations of Florence’s orbit and its close flyby to Earth:

https://echo.jpl.nasa.gov/asteroids/Florence/Florence_orbit.mov

https://echo.jpl.nasa.gov/asteroids/Florence/Florence_Earth_flyby.mov

Further Reading: NASA

June 29, 2017June 29, 2017 by Nancy Atkinson

Watch Live 24-Hour Webcast for International Asteroid Day

Picture of the asteroid that exploded over Cherlyabinsk on Feb 15, 2013. Credit: Tuvix/Youtube

Every day, Earth is hit by 60 to 300 metric tons of space dust and smaller meteoroids. But sometimes, larger and more dangerous space rocks plummet to Earth, such as on June 30, 1908 when an estimated 40 meter-wide meteoroid exploded over the Tunguska, Siberia region in Russia, devastating 2000 sq. kilometers (770 square miles) of forest. As the 2013 Chelyabinsk meteor event attests, the likelihood of a similar event happening again is not an “if” but a “when.”

To raise public awareness about asteroid impact hazards and to urge political leaders to work together to be prepared, the United Nations proclaimed June 30 as International Asteroid Day.

A first-ever 24-hour Asteroid Day program will be feature nearly 1,000 events around the world. It starts at 9 p.m. EDT on June 29 (1 a.m. June 30 GMT), streaming online at the Asteroid Day webcast.

The events start in Tucson, Arizona with an event hosted by our friend, Meteorite Man and Action Scientist Geoff Notkin speaking with Dante Lauretta and Heather Enos from the OSIRIS-REx mission to asteroid Bennu, Eric Christensen, director, Catalina Sky Survey for Near-Earth Objects and many more.

Other events around the world feature Brian Cox, Neil deGrasse Tyson, Brian May, Peter Gabriel, as well as dozens of expert scientists, technologists and researchers in planetary science, NASA astronauts Rusty Schweickart, Ed Lu and Nicole Stott, ESA astronauts Michel Tognini, Jean-François Clervoy; and Romanian astronaut Dorin Prunariu.

NASA and ESA are both hosting events as well. You can see the entire lineup of events here (Google document) and find additional information at the Asteroid Day Live website.

In addition, the Discovery Channel, has produced two specials about asteroids and Asteroid Day to air June 30 around the world: “How to Survive an Asteroid Impact” and a three-minute Virtual Reality video that re-enacts the Tunguska event, provides viewers with an insight into the risks of asteroids, how scientists are trying to protect our planet, and what viewers should do if an asteroid is about to impact their city.

There is also a seven-part series called “Scientists Rock” that introduces you to the people working to protect us from Asteroids.

According to a press release from Asteroid Day, central to Asteroid Day is the 100x Declaration, calling for the 100-fold increase in the detection and monitoring of asteroids. Signed to date by more than 60,000 people around the world, the Declaration resolves to “solve humanity’s greatest challenges to safeguard our families and quality of life on Earth in the future. The Declaration is available online for the signature of anyone concerned about advancing asteroid research and technology.

June 12, 2017June 16, 2017 by Fraser Cain

Astronomy Cast Ep. 452: Summer Observing Challenges

Summer is almost here, and for the northern hemisphere, that means warm nights for observing. But what to observe? We’re here with a list of events and targets for you to enjoy over the summer. Get your calendars handy, and start organizing some events with your friends, and then get out there!

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We usually record Astronomy Cast as a live Google+ Hangout on Air every Friday at 1:30 pm Pacific / 4:30 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

May 18, 2017 by Evan Gough

Dinosaur Killing Asteroid Hit in Exactly the Wrong Place

When an asteroid struck the Yucatan region about 66 million years ago, it triggered the extinction of the dinosaurs. ESA's Hera mission is visiting the smallest spacerock ever as part of our effort to not get creamed by an asteroid. Credit: NASA/Don Davis

The asteroid that struck Earth about 66 million years ago and led to the mass extinction of dinosaurs may have hit one of the worst places possible as far as life on Earth was concerned. When it struck, the resulting cataclysm choked the atmosphere with sulphur, which blocked out the Sun. Without the Sun, the food chain collapsed, and it was bye-bye dinosaurs, and bye-bye most of the other life on Earth, too.

But, as it turns out, if it had struck a few moments earlier or later, it would not have hit the Yucatan, and things may have turned out differently. Why? Because of the concentration of the mineral gypsum in that area.

The place where the asteroid hit Earth is called the Chicxulub Crater, and scientists have been studying that area to try to learn more about the impact event that altered the course of life on Earth. An upcoming BBC documentary called “The Day The Dinosaurs Died,” focuses on what happened when the asteroid struck. Drill-core samples from the Yucatan area help explain the events that followed the impact.

The drilling rig off the coast of the Yucatan. The rig was there in the Spring of 2016 obtaining samples from the seafloor. Image: BBC/Barcroft Productions.

The core samples, which are from as deep as 1300 m beneath the Gulf of Mexico, are from a feature called the peak ring.

When the asteroid struck Earth, it excavated a crater 100 km across and 30 km deep. This crater collapsed into a wider but shallower crater 200 km across and a few km deep. Then the center of the crater rebounded, and collapsed again, leaving the peak ring feature. The Chicxulub crater is now partly under water, and that’s where a drilling rig was set up to take samples.

The peak ring is at the center of the crater, offshore of the Yucatan Peninsula. Image: NASA/BBC

The core samples revealed rock that has been heavily fractured and altered by immense pressures. The same impact that altered those rocks would have generated an enormous amount of heat, and that heat created an enormous cloud of sulphur from the vaporized gypsum. That cloud persisted, which led to a global winter. Temperatures dropped, plant growth came to a standstill, and the course of events on Earth were altered forever.

“Had the asteroid struck a few moments earlier or later, rather than hitting shallow coastal waters it might have hit deep ocean,” documentary co-presenter Ben Garrod told the BBC.

“This is where we get to the great irony of the story – because in the end it wasn’t the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct – it was where the impact happened,” said Ben Garrod, who presents “The Day The Dinosaurs Died” with Alice Roberts.

“An impact in the nearby Atlantic or Pacific oceans would have meant much less vaporised rock – including the deadly gypsum. The cloud would have been less dense and sunlight could still have reached the planet’s surface, meaning what happened next might have been avoided,” said Garrod.

In the documentary, host Alice Roberts will also visit a quarry in New Jersey, where fossil evidence shows a massive die-off in a very short period of time. In fact, these creatures could have died on the very day that the asteroid struck.

The core samples from the drilling rig show rocks that were subjected to immense heat and pressure at the time of the impact. Image: Barcroft Productions/BBC

“All these fossils occur in a layer no more than 10cm thick,” palaeontologist Ken Lacovara tells Alice. “They died suddenly and were buried quickly. It tells us this is a moment in geological time. That’s days, weeks, maybe months. But this is not thousands of years; it’s not hundreds of thousands of years. This is essentially an instantaneous event.”

There’s lots of evidence showing that an asteroid struck Earth about 66 million years ago, causing widespread extinction. NASA satellite images clearly show crater features, now obscured by 66 million years of geological activity, but still visible.

There’s also what’s called the K-T Boundary, or Cretaceous-Tertiary Boundary. It’s a geological signature dating to 66 million years ago, which marks the end of the Cretaceous Period. In that boundary is a layer of iridium at very high concentrations, much higher than is normally present in the Earth’s crust. Since iridium is much more abundant in asteroids, the conclusion is that it was probably deposited by an asteroid.

But this is the first evidence that shows how critical the actual location of the event may have been. If it had not struck where it had, dinosaurs may never have gone extinct, you and I would not be here, and things on Earth could look much different.

It might sound like the stuff of science fiction, but who knows? Maybe a race of intelligent lizards might already have mastered interstellar travel.