November 4, 2013
The newly discovered asteroid 2013 TV135 is one of those rare space objects assigned a number on the Torino scale. Discovered last month by astronomers working at the Crimean Astrophysical Observatory in Ukraine, the rock came within about 6.7 million kilometers of Earth on this pass.
The asteroid is about 400 meters in diameter, and based on what we know today, has a 1-in-63,000 chance of colliding with Earth in 2032. That’s enough to give it a value of “1” on the Torino scale, which ranks threats to Earth from asteroids. The only other object currently assigned a number other than zero is 2007 VK184, about 130 meters in diameter, which has a 1-in-1820 chance of impacting Earth in 2048, giving it a Torino score of 1. Both objects are likely to be downgraded to zero as astronomers learn more about their orbits.
The highest Torino rating in recent years went to the asteroid 99942 Apophis, which was briefly assigned a 4 when early observations indicated a 2.7 percent probability that it would collide with Earth in 2029. With a diameter of 350 meters, it would have enough energy on impact to kill millions and devastate several countries. But as usual, further observations ruled out a collision altogether.
Any Torino score of less than 5 should not concern us very much. However, the Chelyabinsk meteor that entered Earth atmosphere over Russia last February without any warning reminds us that our detection system is far from perfect. The many impact craters found on Earth — Meteor Crater in Arizona is a stark example – not to mention the far more numerous impact scars seen on the Moon, Mars, and other rocky planets, vividly show us the devastating effects asteroid impacts can have. Even a relatively small asteroid like 2013 TV135 would hit with a force 50 times greater than the biggest nuclear bomb. That’s why near-earth object observation programs like Spaceguard are so important.
Bear in mind, though, that we partly owe our existence to a past impact. Without the huge asteroid slamming into Earth at the end of the Cretaceous period about 66 million years ago, dinosaurs might still be roaming the Earth. That catastrophe drastically changed environmental conditions on the planet. While the dinosaurs were unable to adapt, our rodent-like ancestors were. And this wasn’t the only time an impact changed the trajectory of terrestrial life – another reason why, now that we’re on top, we want to keep an eye (or two) on the skies.
Dirk Schulze-Makuch is a professor of astrobiology at Washington State University and has published seven books related to the field of astrobiology. He is also adjunct professor at the Beyond Center at Arizona State University.
April 12, 2013
This week NASA announced plans to capture a small asteroid in 2019 and bring it back to the vicinity of the Moon for later study by astronauts. It’s a good idea, for several reasons.
It’s of real importance to society.
The asteroid threat is sometimes overhyped, and it’s no wonder politicians don’t consider it an emergency when the last Extinction Level Event (to borrow a term from Deep Impact) happened 64 million years ago. Still, the fireball over Chelyabinsk in February demonstrated that even a small space rock can do damage, and hinted at even scarier scenarios. The rock that NASA plans to retrieve would be just half the size of the 60-foot Chelyabinsk object, small enough to burn up harmlessly if it entered our atmosphere. But learning to deflect or move even a mini-asteroid should give us valuable experience.
Public support for asteroid research is a no-brainer, yet NASA has had trouble allocating even a few million dollars a year (in an $18 billion budget) for a comprehensive search using a modest, space-based telescope. This new mission would help get the hunt started, because it requires an inventory of even smaller objects than we’ve tracked in the past.
Meanwhile, NASA still struggles to find a compelling destination for future astronauts that will sell with the general public. Expeditions to Mars or setting up an outpost on the Moon are fascinating projects, but hardly essential, and many taxpayers still consider them frivolous. Understanding asteroids and learning how to alter their course, on the other hand, are critical to humanity’s ultimate survival.
It advances space technology.
A mission that sounds straightforward, and is expected to cost no more than NASA’s latest Mars rover, would nonetheless require several new technologies that could also be applied to other projects. Solar electric engines for the unmanned tug that retrieves the asteroid can be used on future planetary spacecraft. Robotic tools for snagging an “uncooperative” target like a tumbling asteroid might also be used to clean up space debris or refuel satellites in orbit. After the rock is retrieved, astronauts will have to learn to live and work in what’s called cislunar space, something they’ve never done. In short, there’s plenty of cool and useful technology in an asteroid retrieval mission.
It sends astronauts farther than they’ve ever gone.
Does human spaceflight have a future? In 2013, the answer is not obvious. The technologies of robotics and telepresence are advancing far faster than rockets and space capsules, which are still spinning off ideas developed in the 1950s. Those who doubt that humans will ever be content to explore deep space virtually, as opposed to going there in person, should consider Skype and Oculus Rift. Behaviors deeply embedded in human culture are changing before our eyes. Military forces are rapidly evolving from a centuries-old model of flesh-and-blood warriors facing off on battlefields to drones fighting drones. Why should space exploration be any different?
This may not, in fact, be the last hurrah for old-school (human) astronauts. But choosing a just-over-the-horizon destination like the lunar far side, while reviving some of the old Apollo mojo, will help us decide whether to continue sending people farther out into the solar system.
It encourages cooperation.
Groups including the B612 Foundation already are working to characterize the threat of larger incoming asteroids (“city killers” upwards of 100 feet in size), while others have announced plans to mine smaller rocks. NASA might be able to leverage these private ventures to keep its own costs down and encourage more players in the space business.
Within the agency itself, an asteroid retrieval mission would demand closer collaboration between the astronaut program and the science side of the house than at any time since Apollo. Meanwhile, partners in the International Space Station, who’ve shown only polite interest in the Moon or Mars, might be more willing to join in a smaller-scale mission with obvious benefit to all nations.
Maybe the biggest advantage of all.
Every so often, a U.S. President (Bushes 41 and 43 most recently) proposes a grandiose go-to-the-Moon or –Mars scheme, which quickly peters out when everyone realizes, once again, that it costs way too much. Space advocates with long memories might be forgiven if they no longer expect Charlie Brown to kick the football.
Today the economic situation is worse than at any time in the space age. With millions unemployed and uninsured, and with public and private debt skyrocketing, no politician is about to suggest an expensive mission to the moon or Mars. Sorry, that’s not strictly true. Those representing districts with NASA centers will. But don’t expect many others to join them.
That leaves NASA building a new rocket (the Space Launch System) and new vehicle (Orion), with no obvious place to go. Space agency managers rightly asked themselves what they could realistically do with the tools and money on hand, in a relatively short time. And the asteroid retrieval mission is what they came up with.
Some will say that grabbing a space rock – a tiny one at that – is not ambitious enough, not worthy of the nation that launched Apollo. “A man’s reach should exceed his grasp,” so this argument goes. Maybe. But while Robert Browning’s advice may be good for an artist, it can lead to frustration and failure for engineers and accountants.
So here’s a more pertinent line from the same poem: “Less is more.”
Let’s do something we can actually accomplish. And let’s get on with it.
February 14, 2013
Asteroids asteroids asteroids. Forget exoplanets. If you want to keep up with your space nerd coworkers at the water cooler, you better be up on your rocks-in-space facts. Some people want to mine them. Some people want to visit them. One or two want to smash spaceships full of paintballs into them. (Why not, really?) And then there’s the asteroid we’re all going to watch skim the treetops tomorrow.
But to mine, visit, or save ourselves from them, we have to actually find them first. There are pint-sized telescope networks hard at work and infrared space telescopes gearing up, but there’s still one small group out there plugging away, monitoring the skies, that don’t often make headlines. That’s why the Minor Planet Center at the Smithsonian Astrophysical Observatory gives out the annual Edgar Wilson Awards. The recipients, who get plaques and cash awards, are amateur astronomers who discover comets during the previous year. There were five winning discoverers in 2012, announced in late January: three from Russia, one from Australia, and one hometown skywatcher from Warrenburg, Missouri.
We asked Tim Spahr, the director of the Minor Planet Center, about the motivation for the award, which has been given out since 1999. Spahr thinks the most likely reason was that the widespread use of electronic surveys (the recent discovery of Comet ISON was made with an automated program) was “killing off some of the amateur contributions, and Mr. Wilson wanted to spur them back to their scopes.” If the surveys are making quick work of object discovery, why the need to encourage individuals with their backyard ‘scope and single pair of eyes? Spahr answered:
Right now only 5% of near-Earth asteroid discoveries (and a larger percentage–perhaps 10% of comet discoveries) are made by amateurs. It is very hard to compete with the huge telescopes and software engineers that work at these projects. Still, amateurs do contribute, and they also contribute to follow-up and observing of these objects for orbit refinement.
As the observatory noted in their announcement, “the historical naming of the comet for [the discoverer] has more meaning than any award,” but they wanted to recognize the long, unpaid hours these individuals contribute to our knowledge of what’s in the sky.
January 9, 2013
A tweet from science fiction writer David Brin alerted me to some of the fun and innovative things people are doing with space-y graphics and visualizations—everything from a weightless Google page to an animation of the Sun and planets moving together through the Milky Way.
My favorite is this simulation, created by software engineer Ian Webster, of all the asteroids orbiting the Sun in Earth’s vicinity. The simulation is designed for Chrome, but works in some other browsers, too. (If you don’t see a giant swarm of asteroids, you’re not getting the full effect.)
Webster even lets you sort the rocks by their accessibility and economic value. Watching all these would-be impactors crossing Earth’s orbit makes me glad that asteroids are small and space is big.
January 27, 2012
At a little after 10:00 EST this morning, a “bus-size” asteroid will give us a little buzz. It isn’t big enough to do damage, even if it were to hit our atmosphere, but its a reminder that there are objects out there that we might want to be worried about, if only we knew where they were.
Now an innovative new telescope is getting into the asteroid hunting game. DARPA’s Space Surveillance Telescope (SST) had its first light early in 2011, and is now officially online and going through its first demonstration, seeking out potentially Earth-threatening asteroids.
It’s not the first asteroid hunter. Among others, NASA’s WISE (Wide-field Infrared Survey Explorer) space telescope found over 33,000 new asteroids during its all-sky survey in 2010 (the team will be publishing their official results this March). There’s also the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) on top of Mount Haleakala in Maui, Hawaii. The team’s goal since they started operations in 2010 is to complete a survey of all asteroids over 1 km wide.
DARPA hopes the SST will fill out that catalog further by seeing even smaller, but still potentially dangerous, asteroids. Commissioned in 2002, the SST is unique in that its “mirrors are some of the steepest aspherical curvatures ever to be polished, and allow the telescope to have the fastest optics of this aperture class.” It’s short focal length and wide field-of-view allow it to be moved rapidly. By seeing smaller objects, it can help protect not just Earth, but satellites in orbit — military satellites, that is, as SST is primarily run by the U.S. Air Force at the White Sands Missile Base in New Mexico.
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