Orbit diagram of Asteroid 2013 LR6. Credit: JPL Small Body Database.
A truck-sized asteroid just discovered yesterday (Thursday, June 6) will give Earth a relatively close shave later today/early tomorrow, depending on your time zone. Asteroid 2013 LR6 is somewhere between 5- 16 meters (16 to 54 feet) in diameter and will be flying by at only about 111,000 kilometers (69,000 mi, 0.29x Lunar Distances) from Earth at 4:43UTC/12:43AM EDT on June 8, 2013.
This is similar in size to the space rock that exploded over Russia back in February of this year. The Russian asteroid was about 15 meters (50 feet) in diameter before it exploded in an airburst event about 20-25 km (12-15 miles) above Earth’s surface.
Find out how you can watch the flyby live online, below.
This flyby is not at close as February’s 2012 DA14 flyby, but it indeed is quite close by Solar System standards. It will be speeding by 9.8 km a second (6.14 mi/s). The asteroid was first spotted by the Catalina Sky Survey and now several other observatories have made follow-up observations to verify and help determine its size and orbit.
According to the Minor Planet Center’s Twitter feed, 2013 LR6 is the 167th minor planetary object discovered so far in the month of June 2013! That is incredible, and as astronomer Nick Howes said via Twitter, “That number should give people a good heads up as to why searching is important.”
According to our David Dickinson, 2013 LR6 will be plunging thru the constellation Vela at closest approach tonight, but it will be a faint one, as it won’t break +13 magnitude.
Since this discovery is so new, Gianluca Masi and the Virtual Telescope Project in Italy has put together a last-minute opportunity to watch the flyby live, online via their telescopes.
The dust tail on Asteroid P/2010 A2 (LINEAR) has grown to over 1 million kilometers long. Image taken with the new One Degree Imager (ODI), a wide field optical camera at the WIYN telescope on Kitt Peak.
A strange comet-like object discovered in 2010 ended up being an asteroid that had been the victim of a head-on collision from another space rock. The object created a bit of buzz because of its mysterious X-shaped debris pattern and long, trailing streamers of dust. Named P/2010 A2 (LINEAR), the object is located in the asteroid belt between Mars and Jupiter, and has been the focus of much study, including images taken by the Hubble Space Telescope and many ground-based observatories. But over time, the asteroid’s long dust tail has grown to be so long that the entire object can’t fit into the field of view of most observatories.
“Here, we are watching the death of an asteroid,” said Jayadev Rajagopal, a scientist at the WIYN (Wisconsin Indiana at Yale NOAO) Telescope, speaking today at the American Astronomical Society meeting in Indianapolis, Indiana. “We know of dozens of asteroids this has happened to in the past, but this is the only one showing us the event as it is happening.”
A graphic showing the orbit of Asteroid P/2010 A2. Credit: WIYN telescope.
Using the new wide-field camera at the WIYN 3.5 meter telescope, Rajagopal and his team have found that the peculiar asteroid P/2010 A2’s tail is much longer than was previously supposed. The tail is about a million kilometers long, roughly three times the distance from the Earth to the Moon. The new One Degree Imager (ODI) can currently image an area of the sky about the size of the full moon: a future upgrade will increase the size of the field to about four times as large.
“Three and a half years after the initial disruption, and almost a full orbit around the Sun, the tail is still visible and growing,” said Rajagopal. “One of the reasons it is so long is that radiation pressure and gravity are stretching out the tail. It will progressively grow and sweep out into the ecliptic.”
He added that imaging the full extent of the tail will help pin down the total mass in the dust tail, as well as helping to determine the size of dust particles.
Hubble Views of Comet-like Asteroid P/2010 A2. Credit: NASA, ESA, and D. Jewitt (UCLA)
Asteroid collisions are thought to be a commonplace occurrence, and are responsible for kicking up dust in our Solar System and probably other planetary systems, too. Just how much dust is produced, and how frequent the collisions happen is still a hazy topic. But the observations of P/2010 A2 are helping astronomers to better model this phenomenon. By figuring out how much dust is produced by the process of ‘collisional grinding,’ astronomers can better model the dusty debris disks of other planetary systems, as well as our own.
“This object is giving us insight into the interplay between asteroids and debris disks,” Rajagopal said. “How much dust do objects like this contribute to our zodiacal dust disk to keep it replenished? This dust must be constantly replenished because it is constantly being destroyed by radiation. The very unusual tail of this active asteroid will help us pin down the mass of the tail, and in a broader context, help us understand how asteroids brought organics and other materials into the inner planets.”
Rajagopal also said this the tail of Asteroid P/2010 A2 is a meteor stream in the making. “It will eventually sweep into the Earth’s orbit and give us a meteorite stream, sending some meteorites our way, maybe a million years from now.”
Since Asteroid 1998 QE2 has a name which evokes cruise ships, astrophysicist Rhys Taylor has created this wonderful video comparing the two QE2s. He also has more information on his great blog, Physicists of the Caribbean.
An artist's conception of an asteroid collision, in the belt between Mars and Jupiter. Credit: NASA/JPL-Caltech
In perhaps the neatest astronomical application of geneology yet, astronomers found 28 “hidden” families of asteroids that could eventually show them how some rocks get into orbits that skirt the Earth’s path in space.
From scanning millions of snapshots of asteroid heat signatures in the infrared, these groups popped out in an all-sky survey of asteroids undertaken by NASA’s orbiting Wide-Field Infrared Survey Explorer. This survey took place in the belt of asteroids between Mars and Jupiter, where most near-Earth objects (NEOs) come from.
NEOs, to back up for a second, are asteroids and comets that approach Earth’s orbit from within 28 million miles (45 million kilometers). Sometimes, a gravitational push can send a previously unthreatening rock closer to the planet’s direction. The dinosaurs’ extinction roughly 65 million years ago, for example, is widely attributed to a massive rock collision on Earth.
Artist concept of the asteroid belt between Mars and Jupiter. Credit: NASA
There are about 600,000 known asteroids between Mars and Jupiter, and the survey looked at about 120,000 of them. Astronomers then attempted to group some of them into “families”, which are best determined by the mineral composition of an asteroid and how much light it reflects.
While it’s hard to measure reflectivity in visible light — a big, dark asteroid reflects a similar amount of light as a small shiny one — infrared observations are harder to fool. Bigger objects give off more heat.
This allowed astronomers to reclassify some previously studied asteroids (which were previously grouped by their orbits), and come up with 28 new families.
“This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth,” stated Lindley Johnson, NASA’s program executive for the Near-Earth Object Observation Program.
This diagram illustrates the differences between orbits of a typical near-Earth asteroid (blue) and a potentially hazardous asteroid, or PHA (orange). Image credit: NASA/JPL-Caltech
The astronomers next hope to study these different families to figure out their parent bodies. Astronomers believe that many asteroids we see today broke off from something much larger, most likely through a collision at some point in the past.
While Earthlings will be most interested in how NEOs came from these larger bodies and threaten the planet today, astronomers are also interested in learning how the asteroid belt formed and why the rocks did not coalesce into a planet.
The prevailing theory today says that was due to influences from giant Jupiter’s strong gravity, which to this day pulls many incoming comets and asteroids into different orbits if they swing too close. (Just look at what happened to Shoemaker-Levy 9 in 1994, for example.)
Asteroid 1998 QE2, taken on May 31, 2013 when it was 5.8 million km (3.6 million miles) from Earth and moving at around 21 arc mins per hour. The asteroid was quite bright at around magnitude 11. Credit and copyright: Damian Peach.
Will the flyby of Near Earth Asteroid 285263 (1998 QE2) reveal more surprises? NASA announced yesterday that radar images uncovered a previously unknown small moon orbiting the big asteroid. Now, observatories and amateurs around the world are taking a look at this big, dark space rock, which is about 2.7 kilometers (1.7 miles) in diameter. Here are some of the “early returns” just in!
This asteroid will pass 5.86 million km (3.64 million miles) from the Earth on Friday, May 31st at 20:59 Universal Time (UT) or 4:59PM EDT. That is about 15 times the distance between Earth and the Moon, so no worries. But it is not often an asteroid this big comes by within viewing range of observatories on Earth.
Asteroid (285263) 1998 QE2, on May 31, 2013, taken remotely from the H06 iTelescope Observatory in New Mexico. Credit and copyright: Ernesto Guido and Nick Howes, Remanzacco Observatory.
The Remanzacco Observatory team of Ernesto Guido and Nick Howes provided this image, above, and a great animation of the asteroid, as well:
Animation of (285263) 1998 QE2 on May 31, 2013 by E. Guido & N. Howes
Asteroid 1998 QE2 on May 28, 2013. Credit and copyright: Gianluca Masi, Ceccano, Italy; Virtual Telescope Project.
Masi also provided a video from his May 30 observations:
Animation of Asteroid 1998 QE2, May 31, 2013 taken remotely with iTelescope T9. Credit and copyright: Ian Musgrave.
Here’s one from Ian Musgrave. If the animation isn’t working in your browser, click on the image to animate. Ian also has provided this graphic made from Celestia software to show Asteroid 1998 QE2’s orbit:
Orbit of 1998 QE2 simulated in Celestia at closest approach on May 31 20:59 UT. Via Ian Musgrave.
Want to try and see this asteroid for yourself? Our very own David Dickinson has written a great “how-to” for this object, but you are going to need a fairly large backyard telescope, since it will be about 100 times fainter than what can be seen with the naked eye, even at closest approach.
The Slooh online telescope will have views of online tomorrow, which you can watch at their website. The webcast will start at 20:30 UTC (4:30 p.m. EDT) on Friday, May 31.
Also, starting at 20:00 UTC (4:00 p.m. EDT), astrophysicist Gianluca Masi will have a webcast from the Virtual Telescope Project in Italy.
Also, if you want more asteroids, on Friday May 31, the White House is hosting an asteroid-themed “We the Geeks” Google+ Hangout starting at 2 p.m. EDT.
The live video conference will feature Bill Nye the Science Guy, JL Galache from the Minor Planet Center, former astronaut Ed Lu, NASA Deputy Administrator Lori Garver, and Peter Diamandis, co-founder of asteroid mining company Planetary Resources. They will discuss identification, resource potential and threat of asteroids. Here’s the link the White House’s Google+ page.
A relatively new cluster of impact craters on Mars as seen by the HiRISE camera on the Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/MSSS/Univ. of Arizona
One of the benefits of having a spacecraft in orbit around another planet for several years is the ability to make long-term observations and interpretations. The Mars Reconnaissance Orbiter has been orbiting Mars for over seven years now, and by studying before-and-after images from the High Resolution Imaging Science Experiment (HiRISE) camera, scientists have been able to estimate that the Red Planet gets womped by more than 200 small asteroids or bits of comets per year, forming craters at least 3.9 meters (12.8 feet) across.
“It’s exciting to find these new craters right after they form,” said Ingrid Daubar of the University of Arizona, Tucson, lead author of the paper published online this month by the journal Icarus. “It reminds you Mars is an active planet, and we can study processes that are happening today.”
New impact site on Mars formed between November 2005 and October 2010. Credit: NASA/JPL-Caltech/MSSS/Univ. of Arizona
Over the last decade, researchers have identified 248 new impact sites on parts of the Martian surface in the past decade from spacecraft images, determining when the craters appeared. The 200-per-year planetwide estimate is a calculation based on the number found in a systematic survey of a portion of the planet.
The orbiters took pictures of the fresh craters at sites where before-and-after images by other cameras helped figure out when the impacts occurred. This combination provided a new way to make direct measurements of the impact rate on Mars. This will lead to better age estimates of recent features on Mars.
Daubar and co-authors calculated a rate for how frequently new craters at least 3.9 meters in diameter are excavated. The rate is equivalent to an average of one each year on each area of the Martian surface roughly the size of the U.S. state of Texas. Earlier estimates pegged the cratering rate at three to 10 times more craters per year. They were based on studies of craters on the moon and the ages of lunar rocks collected during NASA’s Apollo missions in the late 1960s and early 1970s.
“Mars now has the best-known current rate of cratering in the solar system,” said HiRISE Principal Investigator Alfred McEwen of the University of Arizona, a co-author on the paper.
Examples of craters listed in the paper ‘The Current Martian Cratering Rate.’ Credit: NASA/JPL/Univ. of Arizona.
These asteroids, or comet fragments, typically are no more than 3 to 6 feet (1 to 2 meters) in diameter. Space rocks too small to reach the ground on Earth cause craters on Mars because the Red Planet has a much thinner atmosphere.
For comparison, the meteor over Chelyabinsk, Russia, in February was about 10 times bigger than the objects that dug the fresh Martian craters.
HiRISE targeted places where dark spots had appeared during the time between images taken by the spacecraft’s Context Camera (CTX) or cameras on other orbiters. The new estimate of cratering rate is based on a portion of the 248 new craters detected. It comes from a systematic check of a dusty fraction of the planet with CTX since late 2006. The impacts disturb the dust, creating noticeable blast zones. In this part of the research, 44 fresh impact sites were identified.
Estimates of the rate at which new craters appear serve as scientists’ best yardstick for estimating the ages of exposed landscape surfaces on Mars and other worlds.
One of many fresh impact craters spotted by the UA-led HiRISE camera, orbiting the Red Planet on board NASA’s Mars Reconnaissance Orbiter since 2006. (Photo: NASA/JPL-Caltech/MSSS/UA).
A crane lifts the Orion EFT-1 crew module from its birdcage processing stand for transfer it to a dolly for continued assembly inside the Operations and Checkout Building high bay at NASA’s Kennedy Space Center in Florida as workers monitor progress. Orion’s first unpiloted test flight is scheduled to launch in 2014. Credit: NASA/Frankie Martin
NASA is picking up the construction pace on the inaugural space-bound Orion crew capsule at the Kennedy Space Center (KSC) in Florida – and accelerating towards blastoff on the unmanned Exploration Flight Test-1 mission (EFT-1) slated for September 2014 atop a mammoth Delta 4 Heavy Booster which will one day lead to deep space human forays to Asteroids and Mars.
Orion was at the center of an impressive and loud beehive of action packed assembly activities by technicians during my recent exclusive tour of the spacecraft to inspect ongoing progress inside the renovated Orion manufacturing assembly facility in the Operations and Checkout Building (O & C) at KSC.
“We plan to power up Orion for the first time this summer,” said Scott Wilson in an exclusive interview with Universe Today beside the Orion vehicle. Wilson is Orion’s Production Operations manager for NASA at KSC.
The Orion EFT-1 flight is a critical first step towards achieving NASA’s new goal of capturing and retrieving a Near Earth Asteroid for eventual visit by astronauts flying aboard an Orion vehicle by 2021 – if NASA’s budget request is approved.
An artist concept shows Orion as it will appear in space for the Exploration Flight Test-1 attached to a Delta IV second stage. Credit: NASA
KSC will have a leading role in NASA’s asteroid retrieval project that could occur some four years earlier than President Obama’s targeted goal of 2025 for a human journey to an asteroid.
Capturing an asteroid and dispatching astronauts aboard Orion to collect precious rock samples will aid our scientific understanding of the formation of the Solar System as well as bolster Planetary Defense strategies – the importance of which is gathering steam following the unforeseen Russian meteor strike in February which injured over 1200 people and damaged over 3000 buildings.
Dozens of highly skilled workers were busily cutting metal, drilling holes, bolting screws and attaching a wide range of mechanical and electrical components and bracketry to the Orion pressure vessel’s primary structure as Universe Today conducted a walk around of the EFT-1 capsule, Service Module and assorted assembly gear inside the O&C.
Orion EFT-1 crew cabin and full scale mural showing Orion Crew Module atop Service Module inside the O & C Building at the Kennedy Space Center, Florida. Credit: Ken Kremer/kenkremer.com
Lockheed Martin is the primary contractor for Orion. A growing number of employees hired by Lockheed and United Space Alliance (USA) are “working 2 shifts per day 7 days a week to complete the assembly work by year’s end,” said Jules Schneider, Orion Project manager for Lockheed Martin at KSC, during an exclusive interview with Universe Today.
I watched as the workers were boring hundreds of precision holes and carefully tightening the high strength steel bolts to attach the top to bottom ring segments made of titanium to the main load paths on the pressure vessel.
“We are installing lots of wiring to support ground test instrumentation for the strain gauges as well as microphones and accelerometers.”
“The simulated back shell panels are being installed now as guides,” said Wilson. “The real back shell panels and heat shield will be installed onto the structure later this year.”
“The heat shield is the biggest one ever built, 5 meters in diameter. Its bigger than Apollo and Mars Science Lab. It varies in thickness from about 1 to 3 inches depending on the expected heating.”
“We are making good progress on the Orion Service module too. The outer panels will be installed soon,” Wilson explained.
The olive green colored crew module was clamped inside the birdcage-like Structural Assembly Jig during my visit. The Jig has multiple degrees of freedom to maneuver the capsule and more easily enable the detailed assembly work.
“The technicians are installing strain gauges and secondary structure components to get it ready for the upcoming structural loads test,” said Schneider.
“After that we need to finish installing all the remaining parts of the primary structure and a significant portion of the secondary structure.”
For the next stage of processing, the EFT-1 crew module has been lifted out of the birdcage Jig and moved onto an adjacent dedicated work station for loads testing at the Operations and Checkout building.
As reported in my earlier article the Orion pressure vessel sustained three ‘hairline” cracks in the lower half of the aft bulkhead during proof pressure testing of the vessel and welds at the O & C.
I was observing as the technicians were carefully milling out the miniscule bulkhead fractures.
Workers have now installed custom built replacement brackets and reinforcing doublers on the aft bulkhead.
“We will do the protocol loads test with pressure using about 9 different load cases the vehicle will see during the EFT-1 flight. Chute deployment and jettison motor deployment is a driving load case,” said Schneider.
“We will also squeeze the capsule,” said Wilson.
“That structural loads testing of the integrated structure will take about 6 to 8 weeks. There are thousands of gauges on the vehicle to collect data,” Schneider elaborated.
“The test data will be compared to the analytical modeling to see where we are at and how well it matched the predictions – it’s like acceptance testing.”
“After we finish the structural loads tests we can than start the assembly and integration of all the other subsystems.”
“When we are done with the ground testing program then we remove all the ground test instrumentation and start installing all the actual flight systems including harnesses and instrumentation, the plumbing and everything else,” Schneider explained.
Orion hardware built by contractors and subcontractors from virtually every state all across the U.S is being delivered to KSC for installation onto EFT-1. Orion is a nationwide human spaceflight project.
Concept of Spacecraft with Asteroid Capture Mechanism Deployed. Credit: NASA.
During the unmanned Orion EFT-1 mission, the capsule will fly on a two orbit test flight to an altitude of 3,600 miles above Earth’s surface, farther than any human spacecraft has gone in 40 years.
It will then fire braking rockets to plunge back to Earth, re-enter the atmosphere at about 20,000 MPH and test numerous spacecrafts systems, the heat shield and all three parachutes for an ocean splashdown.
Meanwhile other Orion EFT-1 components such as the emergency Launch Abort System (LAS) and Service Module are coming together – read my Orion follow-up reports.
Humans have not ventured beyond low Earth orbit since the Apollo Moon landings ended in 1972. Orion will change that.
Learn more about Orion, Antares, SpaceX, Curiosity and NASA robotic and human spaceflight missions at Ken’s upcoming lecture presentations:
April 20/21 : “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus “The Space Shuttle Finale and the Future of NASA – Orion, SpaceX, Antares and more!” NEAF Astronomy Forum, Rockland Community College, Suffern, NY. 3-4 PM Sat & Sunday. Display table all day.
April 28: “Curiosity and the Search for Life on Mars – (in 3-D)”. Plus the Space Shuttle, SpaceX, Antares, Orion and more. Washington Crossing State Park, Titusville, NJ, 130 PM
Orion EFT-1 crew cabin construction ongoing at the Kennedy Space Center which is due to blastoff in September 2014 atop a Delta 4 Heavy rocket. Credit: Ken Kremer
Concept of asteroid capture in progress. Credit: NASA.
NASA’s FY2014 budget proposal includes a plan to robotically capture a small near-Earth asteroid and redirect it safely to a stable orbit in the Earth-moon system where astronauts can visit and explore it. A spacecraft would capture an asteroid — which hasn’t been chosen yet, but would be about 7 meters (25 feet) wide — in 2019. Then using an Orion space capsule, a crew of about four astronauts would station-keep with the space rock in 2021 to allow for EVAs for exploration.
NASA has released new images, a video and more information about the mission.
They say that performing all the elements for the proposed asteroid initiative “integrates the best of NASA’s science, technology and human exploration capabilities and draws on the innovation of America’s brightest scientists and engineers.” The mission will combine existing technology along with capabilities being developed to find both large asteroids that pose a hazard to Earth and small asteroids that could be candidates for the proposed mission. NASA says this initiative will help accelerate technology development activities in high-powered solar electric propulsion and take advantage the Space Launch System rocket and Orion spacecraft currently being built, “helping to keep NASA on target to reach the President’s goal of sending humans to Mars in the 2030s.”
Here’s more of NASA’s info:
When astronauts don their spacesuits and venture out for a spacewalk on the surface of an asteroid, how they move and take samples of it will be based on years of knowledge built by NASA scientists and engineers who have assembled and operated the International Space Station, evaluated exploration mission concepts, sent scientific spacecraft to characterize near-Earth objects and performed ground-based analog missions.
As early as the 1970s, NASA examined potential ways to use existing hardware to visit an asteroid to understand better its characteristics. On the International Space Station, scientific investigations and technology demonstrations are improving knowledge of how humans can live and work in space. The agency also has examined many possible mission concepts to help define what capabilities are needed to push the boundaries of space exploration.
During the early space shuttle flights and through assembly of the space station, NASA has relied on testing both in space and on Earth to try out ideas through a host of analog missions, or field tests, that simulate the complexity of endeavors in space.
Concept of Spacecraft with Asteroid Capture Mechanism Deployed. Credit: NASA.
Through 16 missions in the National Oceanic and Atmospheric Administration’s underwater Aquarius Reef Base off the coast of Key Largo, Fla., aquanauts have tested techniques for human space exploration. These underwater tests have been built upon the experience gained by training astronauts in the Neutral Buoyancy Laboratory at NASA’s Johnson Space Center in Houston to assemble and maintain the space station. The NASA Extreme Environment Mission Operations (NEEMO) 15 and 16 missions in 2011 and 2012, respectively, simulated several challenges explorers will face when visiting an asteroid, including how to anchor to and move around the surface of a near-Earth object and how to collect samples of it.
NASA also has simulated an asteroid mission as part of its 2012 Research and Technology Studies ground test at Johnson. During the simulation, a team evaluated how astronauts might do a spacewalk on an asteroid and accomplish other goals. While performing a spacewalk on a captured asteroid will involve different techniques than the activities performed during recent analog exercises, decisions made about ways to best sample an asteroid will be informed by the agency’s on-going concept development and past work.
Artist’s Concept of a Solar Electric Propulsion System. Credit: NASA.
Scientific missions also have investigated the nature of asteroids to provide a glimpse of the origins of the solar system. From the Pioneer 10 spacecraft, which in 1972 was the first to venture into the Main Asteroid Belt, to the Dawn mission, which recently concluded its investigations of asteroid Vesta and is on its way to the dwarf planet Ceres, NASA’s forays help us understand the origins of the solar system and inform decisions about how to conduct missions to distant planetary bodies. Scientists both at NASA and across the world also continue to study asteroids to shed light on their unique characteristics.
As NASA ventures farther into the solar system, the agency continues to simulate and evaluate operations and technical concepts for visiting an asteroid.
It was an event that took the world by surprise: On the morning of February 15, 2013 a 7,000-ton asteroid crashed into the Earth’s atmosphere. According to NASA, the Siberian meteor exploded with the power of 30 Hiroshima bombs and was the largest object to burst in the atmosphere since the Tunguska event of 1908. This video from PBS’s science show NOVA aired last night on television and is now available to watch online. (Note: the video may not yet be available to watch in all areas of the world.)
The show reveals what scientists have gleaned so far about this object from the numerous dashcam videos in Russia and other data, and how this event could have been much worse.
It features interviews with several scientists, including Peter Brown and Margaret Campbell-Brown from the University of Western Ontario, Mark Boslough from the University of New Mexico, Dan Durda from the Southwest Research Institute and Apollo 9 astronaut Rusty Schweickart, who is now Chair Emeritus of the B612 Foundation, the organization that is building the “Sentinel” telescope to search for asteroids heading for Earth.
In this new video from Big Think, astrophysicist Neil deGrasse Tyson says he’s almost embarrassed for our species that it takes a warning shot across our bow before legislators take seriously the advice they’ve been receiving from astronomers about getting serious about asteroid detection and deflection; that it’s a matter of when not if Earth will get smacked by an asteroid. “But it took an actual meteor over Russia exploding with 25 times the power of the atom bomb in Hiroshima to convince people that maybe we should start doing something about it.”
