Help NASA Hunt For Killer Asteroids

It is time for the private sector to aid in the search for potentially city-destroying asteroids and meteors, lawmakers said during a hearing Wednesday (April 10).

The House Committee on Science, Space and Technology made the call while hearing from NASA scientists and private-sector asteroid hunters during a hearing entitled “Threats from Space,” with both groups agreeing that something more needs to be done.

“Detecting asteroids should not be the primary mission of NASA,” Rep. Lamar Smith (R-Texas), chairman of the House Committee on Science, Space and Technology, said at the hearing. “No doubt the private sector will play an important role as well. We must better recognize what the private sector can do to aid our efforts to protect the world.” [Meteor Streaks over Russia, Explodes (Photos)]

The meeting Wednesday was the second of three aimed at understanding the threat to Earth posed by asteroids in space. The first hearing took place in late March, and addressed the ways governmental entities, like NASA and the Air Force, are mitigating the risks posed by close-flying space rocks. The meetings were scheduled in response to a surprise meteor explosion over Russia and the close flyby of asteroid 2012 DA14 — both of which occurred on Feb. 15.

Astronomers have mapped the orbits of more than 90 percent of the potentially world-ending asteroids in close proximity to the Earth; however, tracking anything smaller than 0.6 miles (1 kilometer) in diameter is more difficult, said Ed Lu, the CEO of the B612 Foundation, a nonprofit organization in the early stages of building a near-Earth-object-hunting space telescope scheduled for launch in 2018.

“NASA has not even come close to finding and tracking the 1 million smaller asteroids that might only just wipe out a city, or perhaps collapse the world economy if they hit in the wrong place,” Lu said at the hearing.

B612′s space telescope, dubbed Sentinel, will be built to aid in the search for smaller asteroids near Earth. Less than 10 percent of asteroids measuring around 459 feet (140 meters) in diameter have been found, while only 1 percent of all asteroids measuring around 131 feet (40 meters) —  or “city killer” range — have been tracked, Lu said.

These city-destroying asteroids are notoriously difficult to track with the ground-based methods used by NASA today because the space rocks are relatively small and dark, said Don Yeomans, the head of NASA’s Near-Earth Object Program.

“A dramatic increase in near-Earth asteroid-discovery efficiencies is achievable using space-based infrared telescopes,” Yeomans said at the hearing.

Searching for space rocks in infrared light — as the $240 million Sentinel is expected to do — could allow astronomers to find a larger number of smaller objects that are too dark to be seen in visible light, Yeomans said.

A space-based asteroid hunter is also helpful because it can seek out space rocks at all hours of the day, as opposed to just at night, Yeomans added.

All of these hunting efforts should be put in place to find near-Earth objects well before they could hit the Earth, the panelists said.

At the moment, we have the technology to deflect an asteroid, but scientists won’t be able to use those methods without ample time to implement them, Michael A’Hearn, an astronomer working with the National Research Council, said at the hearing.

But first, the asteroids have to be found, Lu said.

“You can’t deflect an asteroid that you haven’t yet tracked,” Lu said. “Our technology is useless against something we haven’t yet found.”

Courtesy-Space

Can NASA Really Grab An Asteroid?

NASA’s bold plan to drag an asteroid into orbit around the moon may sound like science fiction, but it’s achievable with current technology, experts say.

President Barack Obama’s 2014 federal budget request, which will be unveiled today (April 10), likely includes about $100 million for NASA to jump-start an asteroid-capture mission, U.S. Senator Bill Nelson (D-FL) said last week.

The plan aims to place a roughly 23-foot-wide (7 meters) space rock into a stable lunar orbit, where astronauts could begin visiting it as soon as 2021 using NASA’s Space Launch System rocket and Orion capsule, Nelson said.

While challenging, the mission is definitely doable, said Chris Lewicki, president and chief engineer of billionaire-backed asteroid-mining firm Planetary Resources. [NASA's Asteroid-Capture Plan (Video)]

“Return of a near-Earth asteroid of this size would require today’s largest launch vehicles and today’s most efficient propulsion systems in order to achieve the mission,” Lewicki, who served as flight director for NASA’s Spirit and Opportunity Mars rovers and surface mission manager for the agency’s Phoenix Mars lander, wrote in a blog post Sunday (April 7).

“Even so, capturing and transporting a small asteroid should be a fairly straightforward affair,” Lewicki added. “Mission cost and complexity are likely on par with missions like the [$2.5 billion] Curiosity Mars rover.”

Spurring solar system exploration

NASA’s idea is similar to one proposed last year by scientists based at Caltech’s Keck Institute for Space Studies in Pasadena.

The Keck study estimated that a robotic spacecraft could drag a 23-foot near-Earth asteroid (NEA) — which would likely weigh about 500 tons — into a high lunar orbit for $2.6 billion. The returns on this initial investment are potentially huge, the researchers said.

“Experience gained via human expeditions to the small returned NEA would transfer directly to follow-on international expeditions beyond the Earth-moon system: to other near-Earth asteroids, [the Mars moons] Phobos and Deimos, Mars and potentially someday to the main asteroid belt,” the Keck team wrote in a feasibility study of their plan.

The mission would also help develop asteroid-mining technology, advocates say, and advance scientists’ understanding of how our solar system took shape more than 4.5 billion years ago.

Asteroids “probably represent samples of the earliest matter that was made available to form our solar system and our Earth,” Caltech’s Paul Dimotakis, a member of the Keck study team, told SPACE.com in February.

“We learned a lot about the moon by analyzing the moon rocks that Apollo astronauts brought back,” he added. [NASA's 17 Apollo Moon Missions in Pictures]

Asteroids are fascinating for lots of reasons. They contain a variety of valuable resources and slam into our planet on a regular basis, occasionally snuffing out most of Earth’s lifeforms. How much do you know about space rocks?

Unmanned probes have successfully rendezvoused with asteroids in deep space multiple times. Japan’s Hayabusa craft even snagged pieces of the near-Earth asteroid Itokawa in 2005, sending them back to our planet for study.

But bagging an entire asteroid and dragging it to our neck of the cosmic woods is unprecedented, and it presents several daunting challenges.

For example, the target asteroid will be spinning, which doesn’t make for a smooth ride to lunar orbit. After the spacecraft captures the asteroid and brings it into a hold of sorts, the space rock will have to be de-spun, likely with thrusters, Dimotakis said.

“You might use reaction jets to take out most of it [the spin],” he said. “You would give you yourself a lot of time to do this, because there’s no second chance in any of this.”

Further, bringing the asteroid onboard greatly increases the spacecraft’s mass, making propulsion and navigation much more difficult. And precise navigation will definitely be required to deliver the space rock to its desired orbit, Dimotakis said (though he also stressed that any asteroid chosen would pose no danger to humanity even if it somehow struck our planet).

But ion thrusters like the ones powering NASA’s Dawn mission to the huge asteroid Vesta and dwarf planet Ceres should be muscular enough to make the journey, likely taking a few years to reach the asteroid and somewhat longer to come back. And the asteroid-laden probe could probably still be guided with great care, he added.

“My guess is that all of these are not insurmountable challenges, and you would be able to calibrate yourself after you snagged it and adjust your controls,” Dimotakis said.

Choosing a target

Perhaps the biggest challenge of the entire mission is picking a suitable space rock to retrieve, Lewicki wrote in his blog post.

The Keck study recommends going after a carbonaceous asteroid packed full of water and other volatiles. Carbonaceous asteroids can be very dark, and it’s tough to spot and characterize a 23-foot asteroid in the vast depths of space whatever its color.

So both Lewicki and Dimotakis stressed the importance of searching for potential asteroid targets sooner rather than later. Planetary Resources plans to begin launching a line of small prospecting space telescopes in 2014 or 2015, and these “Arkyd-100″ craft could aid NASA’s mission, Lewicki wrote.

Dimotakis, for his part, is engaged in a follow-up to the Keck study that’s looking for potential targets in observations made by current telescopes.

“We are developing software in collaboration with JPL [NASA's Jet Propulsion Laboratory] that is going to exploit the observational digital record and essentially flag things that could be of interest and might be in this class,” he said. “This has never happened before.”

Still, mission scientists and engineers shouldn’t just sit on their hands until an asteroid selection is made, he added.

It’s important “to start developing the spacecraft before you even know where you’re going,” Dimotakis said. “If you do these things in parallel, then the mission timeline shrinks.”

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Will Manned Asteroid Missions Be Tougher Than Man Going To Mars?

Though asteroids are viewed as stepping stones in NASA’s manned march to Mars, sending humans to a space rock may actually be a bigger challenge than putting boots on the Red Planet.

Mars is farther away than any near-Earth asteroid that NASA would target, but this disadvantage may be outweighed by the greater knowledge scientists have gained of the Red Planet thanks to the many Mars missions that have launched over the years, experts say.

Further, mapping out an asteroid mission is nearly impossible at this point, since NASA does not yet know where it’s going.

“There are still no good asteroid targets for such a mission, a necessary prerequisite for determining mission length and details such as the astronauts’ exposure to radiation and the consumables required,” states a December 2012 report from the U.S. National Research Council (NRC). [How NASA Will Explore Asteroids (Gallery)]

The road to Mars

Landing astronauts on Mars has been the long-term goal of NASA’s human spaceflight program for decades, but the agency’s vision of how to get there was shaken up recently.

NASA had viewed the moon as a stepping stone, working to get humans to Earth’s natural satellite by 2020 under a program called Constellation, which was initiated during the presidency of George W. Bush. But President Barack Obama cancelled Constellation in 2010, after an independent review panel found it to be significantly under-funded and behind schedule.

instead directed NASA to send astronauts to a near-Earth asteroid by 2025, then on to the vicinity of Mars by the mid-2030s. The agency is developing a new crewed capsule called Orion and a huge rocket called the Space Launch System to make it all happen.

The new “asteroid-next” plan has not been enthusiastically embraced by NASA or the broader space community, the NRC report concluded.

“Despite isolated pockets of support for a human asteroid mission, the committee did not detect broad support for an asteroid mission inside NASA, in the nation as a whole or from the international community,” write the authors of the report, which is called “NASA’s Strategic Direction and the Need for a National Consensus.”

A tough proposition

The NRC report was based on research, interviews, site visits and analysis conducted by a 12-member independent committee over the course of about five months in 2012.

One of the people the study team met with was Bill Gerstenmaier, NASA’s associate administrator for human exploration and operations.

Gerstenmaier “talked about how NASA had discovered, in the two years that had elapsed by the time he was speaking to us, just how hard [a manned asteroid mission] was,” committee member and space policy expert Marcia Smith said during a presentation with NASA’s Future In-Space Operations working group on Jan. 30.

“He said in many respects, it’s easier to go to Mars, because we know a lot about Mars,” Smith added. “We know where it is, and we’ve done all these reconnaissance missions already, so we have a knowledge base from which to work in terms of sending humans, whereas no particular asteroid has been selected yet.”

While sending astronauts to an asteroid has never been done before, unmanned probes have successfully rendezvoused with the objects in deep space multiple times.

For example, NASA’s Dawn spacecraft orbited the protoplanet Vesta — the second-largest body in the main asteroid belt between Mars and Jupiter — for more than a year before departing to head to the belt’s largest denizen, Ceres, last September. And in 2005, Japan’s Hayabusa probe plucked some pieces off the near-Earth asteroid Itokawa, sending them back to Earth for analysis.

NASA plans to launch its own asteroid-sampling mission, called Osiris-Rex, in 2016. And two private companies — Planetary Resources and Deep Space Industries — intend to loft reconnaissance spacecraft over the next few years, kicking off an ambitious efforts to mine water, metals and other resources from asteroids.

Courtesy-Space.com

 

The Big Bang To Recreated By A Supercomputer

Scientists would love to be able to rewind the universe and watch what happened from the start. Since that’s not possible, researchers must create their own mini-universes inside computers and unleash the laws of physics on them, to study their evolution.

Now researchers are planning the most detailed, largest-scale simulation of this kind to date. One of the main mysteries they hope to solve with it is the origin of the dark energy that’s causing the universe to accelerate in its expansion.

The new simulation is a project led by physicists Salman Habib and Katrin Heitmann of Illinois’ Argonne National Laboratory, and will run on the lab’s Mira supercomputer, the third-fastest computer in the world, starting in the next month or two. The program will use hundreds of millions of “particles” — elements in the simulation that stand in for small bits of matter. The computer will let time run, and watch as the particles move through space in response to the forces acting on them.

As the simulation progresses, these bits of matter will clump together under gravity to form larger and larger blobs representing galaxies, galaxy clusters and superclusters. To evolve the universe from the Big Bang 13.7 billion years forward to today, the simulation will take up to two weeks. [Video: Simulation of the Universe from Big Bang to Now]

Testing the theory

The ultimate goal is to compare the best telescope observations of structure in the universe to the structure displayed in the computer model, to test the reigning theory of cosmology.

“We are trying to look for subtle ways in which it’s wrong,” Habib told SPACE.com. “That’s why you need these very high-resolution, very large-scale simulations to see if the observations don’t match the predictions.”

Dark energy is the name given to whatever is causing the expansion of the universe to accelerate. When this acceleration was first discovered in the 1990s, it shocked the science community, because theories predicted the universe’s expansion would be steady or slowing down, because of the inward pull of gravity.

The current reigning theory posits that dark energy is what’s called the cosmological constant, a term Einstein first thought to put into his equations of general relativity to represent the vacuum energy of the universe. Although Einstein ultimately decided not to include the term, scientists later realized that it could explain the current observations of the expansion of the universe.

However, cosmologists aren’t satisfied with this explanation, Habib said.

Another possibility

“It’s just a single number entered as an extra term in the equations,” he said. “The problem is that if you ask what its value should be, it’s enormous — many orders of magnitude bigger than what is actually observed.”

While simulations based on the cosmological constant so far appear to match what’s seen in large-scale observations of the universe, scientists think that next-generation observations may reveal discrepant details.

If a cosmological constant is not to blame for the accelerated expansion of the universe, another possibility is that space contains some other type of mass or energy, such as a field, that is pulling everything apart.

“It’s basically guesswork; it could be like this, or it could be like that,” Habib said. “Either way it’s very interesting.”

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Courtesy-Space.com

 

The Universe Captured In New 3D Map

The largest 3D map yet of the universe’s huge galaxies and bright black holes may serve as a springboard toward solving some of astronomy’s greatest mysteries, its creators say.

The map, which was released Wednesday (Aug. 8), uses new data to reveal the locations of more than a million galaxies over a total volume of 70 billion cubic light-years. (A light-year is the distance light travels in one year — about 6 trillion miles, or 10 trillion kilometers.)

David Schlegel of Lawrence Berkeley National Laboratory in California said this kind of atlas could help scientists get to the bottom of perplexing mysteries such as the invisible, untouchable dark matter and dark energy that seem to be rampant in space.

“Dark matter and dark energy are two of the greatest mysteries of our time,” Schlegel said in a statement issued with the map’s release. “We hope that our new map of the universe can help someone solve the mystery.”

The new data come from the Sloan Digital Sky Survey III (SDSS-III), and they include measurements from the ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which calculates the distances to galaxies as far as 6 billion light-years away and humongous black holes that lie up to 12 billion light-years from Earth.

The SDSS-III project publically released a large amount of its data, including the map, for use by astronomers around the world in their own studies.

“Our goal is to create a catalog that will be used long after we are done,” said Michael Blanton of New York University, who led the team that prepared the data release.

The release contains photos of 200 million galaxies and spectra (measurements where an object’s light is split into its constituent wavelengths) of 1.35 million galaxies.

“We want to map the largest volume of the universe yet, and to use that map to understand how the expansion of the universe is accelerating,” said Daniel Eisenstein of the Harvard-Smithsonian Center for Astrophysics, the director of SDSS-III.

Scientists think the prevalence of dark energy in the universe is the force causing space to accelerate in its expansion to a greater and greater volume.

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Astronomers Capture Best Shot Of Quasar

Scientists using three telescopes spaced thousands of miles apart have caught the best look ever of the center of a distant quasar, an ultra-bright galaxy with a giant black hole at its core.

By linking powerful radio telescopes in Chile, Arizona and Hawaii together, astronomers created a deep-space observing system with 2 million times sharper vision than the human eye, which gave them the most detailed direct view ever of a supermassive black hole inside a galaxy 5 billion light-years from Earth.

The telescopes revealed a fresh look at the quasar 3C 279, a galaxy in the constellation Virgo that scientists classify as a quasar because it shines ultra-bright as massive amounts of material falls into the giant black hole at its core. The black hole is about 1 billion times the mass of the sun, with the linked-up telescopes providing details down to a resolution of 1 light-year or less, researchers said in an announcement today (July 18).

The new view used an astronomy technique called interferometry and marked “a remarkable achievement for a target that is billions of light-years away,” researchers with the European Southern Observatory explained in a statement.”The observations represent a new milestone towards imaging supermassive black holes and the regions around them.”

The European Southern Observatory (ESO) in Chile is home to the Atacama Pathfinder Experiment telescope used in the quasar study. The other two instruments included the Submillimeter Array in Hawaii, and the Submillimeter Telescope in Arizona. [What Does Quasar 3C 279 Really Look Like (Video)]

By linking the three telescopes together, astronomers with ESO, the Onsala Space Observatory and the Max Planck Institute for Radio Astronomy used an observation method called Very Long Baseline Interferometry.

Here’s how the interferometry method works:

In astronomy, larger telescopes can take sharper pictures or measurements of the universe. The interferometry technique allows astronomers to use multiple telescopes perform as if they were a single telescope, one that is as large as the distance between the different instruments. In Very Long Baseline Interferometry, astronomers seek to maximize the distance between telescopes to create the sharpest views possible.

For the new quasar study, astronomers created a huge triangle of telescopes on Earth using the three different instruments. The distance between the Chile and Hawaii telescopes is 5,870 miles (9,447 kilometers), with the baseline from Chile to Arizona extending across 4,458 miles (7,174 km). The baseline from Arizona back to Hawaii was 2,875 miles (4,627 km).

The telescopes also observed the quasar at extremely short wavelength, making it the shortest wavelength ever observed using such a large baseline array, researchers said.

Altogether, the telescope array was reached a resolution of just 8 billionths of a degree arc in the night sky. For comparison, your closed fist held out at arm’s length covers about 10 full degrees in the sky.

ESO officials said the new look at quasar 3C 279 marks a major step forward for an even more ambitious interferometry-based project called the Event Horizon Telescope. That project aims to combine more telescopes to create an even more powerful very long baseline array, one that could ultimately reveal the shadow of the supermassive black hole at the center of our own Milky Way galaxy.

“The shadow — a dark region seen against a brighter background — is caused by the bending of light by the black hole, and would be the first direct observational evidence for the existence of a black hole’s event horizon, the boundary from within which not even light can escape,” ESO officials said.

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Astronomers Find Dark Galaxies

A telescope in South America has found tantalizing evidence of primitive galaxies born in the early universe, a find that, if confirmed, would mark the first-ever view of the so-called “dark galaxies.”

Dark galaxies are small, gas-rich objects from the early universe. The existence of such galaxies, which are devoid of stars, but packed with gas, has long been predicted in galaxy formation theories, but direct proof of them has so far remained elusive.

Now, an international team of astronomers may have found dark galaxies by using the light from quasars, the brightest and most energetic objects in the universe, as a guide.

Quasars are powered by enormous black holes that give off huge amounts of energy and light as gas, dust and other material falls into their cores. The astronomers pinpointed the dark galaxies by their glow from the quasars’ light.

“Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it,” study co-author Simon Lilly, of ETH Zurich, an engineering and science university in Switzerland, said in a statement. “We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club.”

In the new study, the scientists were able to glean some preliminary characteristics of the dark galaxies. They estimate that the mass of the gas in such galaxies is roughly 1 billion times that of the sun, which is expected for gas-rich, low-mass galaxies in the early universe. [7 Surprising Things About the Universe]

The astronomers also estimate that star formation in the dark galaxies is suppressed by a factor of more than 100 compared with typical star-forming galaxies at similar stages in their cosmic histories.

In theories of galaxy formation, dark galaxies are thought to be the building blocks of the bright, star-filled galaxies we see today. Some theories state that dark galaxies may have also funneled gas to larger galaxies to form the stars that currently exist.

But dark galaxies are inherently challenging to spot, the researchers said. Since dark galaxies have no stars, they do not emit much light. Astronomers have long attempted to confirm their existence using new techniques that could reveal dark galaxies in the cosmos.

Previous studies of small absorption dips in the spectra of background light sources were thought to have hinted at dark galaxies, but this new study may be the first time that these mysterious objects have been directly detected.

Chasing dark galaxies

Using the European Southern Observatory’s Very Large Telescope (VLT) in northern Chile, the researchers saw the extremely faint fluorescent glow of the dark galaxies. They used the telescope’s FORS2 instrument to map a region of the sky around the bright quasar HE 0109-3518, searching for ultraviolet light that is released by hydrogen gas when it is bombarded with intense radiation.

“After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects,” study lead author Sebastiano Cantalupo, from the University of California, Santa Cruz, said in a statement.

The astronomers found almost 100 gaseous objects within a few million light-years of the brilliant quasar. They eventually narrowed the list to 12, after weeding out objects where the emission might be a product of star formation in the galaxies, rather than from the quasar’s light.

According to the researchers, these objects represent the most convincing detections of dark galaxies in the early universe to date.

“Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds,” Cantalupo said. “With this study, we’ve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas.”

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Courtesy-Space.com

Private Telescope to Hunt Dangerous Asteroids

The hunt is on. A group of scientists has banded together to build the world’s first privately funded deep-space telescope, to hunt for asteroids that could pose a major threat to Earth.

The private space telescope forms the heart of Project Sentinel, a deep-space mission being unveiled today (June 28) in Mountain View, Calif., by the B612 Foundation, a nonprofit group of scientists and explorers that has long advocated the exploration of asteroids and better space rock monitoring.

Project Sentinel involves the development of a super-snooper telescope that would be placed in orbit around the sun. The goal, foundation officials say, is to create the first comprehensive dynamic map of our inner solar system.

That map would yield a lively look at the present and future locations and trajectories of near-Earth asteroids, paving the way to protecting the Earth from future impacts and opening the solar system to future exploration. [Sentinel Space Telescope's Asteroid Mission (Pictures)]

An asteroid sentinel in space

Ed Lu is B612 chairman and CEO, a former NASA astronaut who has flown on the space shuttle and Russia’s Soyuz capsule and lived aboard the International Space Station.

“The reason we’re doing this is because we can!”Lu told SPACE.com

Private organizations can now carry out awe-inspiring and audacious projects that previously only governments could accomplish, Lu said.

“So it isn’t crazy to think of a large telescope being funded privately. In fact, historically, that has been the way large, private telescopes here on Earth have been funded. The exception here is that rather than being on the Earth, this one is orbiting the sun,” Lu said.

A lot of work has gone into shaping Project Sentinel over the last year, Lu said. Akin to the architectural plans for a building, he said, a preliminary spacecraft and mission design is complete.

“This isn’t a viewgraph,” Lu added.”What we’ve built is the best technical team on this planet.”

A firm fixed-price proposal to carry out Project Sentinel has been submitted by Ball Aerospace of Boulder, Colo., enabled in part by early infrared-detector work funded by B612.

No stranger to big space scopes, Ball Aerospace is the technical sparkplug behind such NASA-sponsored spacecraft as theplanet-hunting Kepler mission and the infrared Spitzer Space Telescope.

Under a NASA Space Act Agreement signed with B612, the space agency will provide Deep Space Network communications and tracking as well as technical support.

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Return To PollHunting asteroids for all mankind

Project Sentinel would complete its near-Earth object (NEO) survey work in 5.5 years.

“The line in the sand is for the spacecraft to find 90 percent of near-Earth objects larger than 140 meters [459 feet] in size. That translates into approximately a 100-megaton explosion should one hit the Earth,” Lu said. “If we go as long as we think we’re going to go, we’re also going to find the vast majority of Tunguskas, too.” [7 Strangest Asteroids in the Solar System]

The Tunguska River in remote Siberia was the site directly under a huge explosion in 1908, an air burst of a large meteoroid or comet fragment estimated to have flattened more than 80 million trees over 830 square miles (2,150 square kilometers).

According to B612, only about 10,000 of the more than half million asteroids larger than the 1908 Tunguska asteroidwhose orbits cross Earth’s orbit have been discovered and tracked.

Project Sentinel would find and road-map Earth-bound asteroids with sufficient warning time – years to decades – to enable deflection missions.

This all adds up to an awe-inspiring project for the global good, the B612 NEO team said.

Space telescope price tag

What’s the cost to build the Project Sentinel telescope?

“We can’t disclose the final price, but I can give you a ballpark of a few hundred million dollars. Which is, I think, a factor of several less than what NASA could do this for,” Lu said.

To foot the bill for Project Sentinel, a worldwide fundraising campaign is being implemented, including outreach to citizens around the globe.

“Our constituency is everybody,” said B612 spokeswoman Diane Murphy.

“If you think about it, what we are is a small capital campaign,” Lu said. “At any given time in the United States, there’s probably a hundred fundraising campaigns larger than this … for symphony halls, museums, performing arts centers.”

Data pipeline set

As now forecast, Project Sentinel would be launched in 2016 aboard a SpaceX Falcon 9 rocket, Lu said. The spacecraft operations center is to be based at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado, Boulder.

Project Sentinel would require a gravity slingshot off Venus to enter solar orbit. Data relay would be carried out through the NASA Deep Space Network. Data analysis — identification of NEO threats — is to be handled through an existing data pipeline at the Minor Planet Center in Cambridge, Mass., and the NASA Jet Propulsion Laboratory in Pasadena, Calif.

“When you stand back from this, … this is like the whole issue of mapping the U.S, and almost everything else that precedes real development and exploration,” said former astronaut Rusty Schweickart, B612 chairman emeritus, who was the lunar module pilot on the Apollo 9 mission.

“The meta-view of what we’re doing … is mapping the Earth, sun, the inner solar system … the Earth Territory, if you will,” Schweickart said. That, he said, would pave the way toward protecting the Earth from impacts and opening the solar system to exploration.

Legacy space systems

“An exciting aspect of Ball’s role on Sentinel is leveraging sophisticated technology developed under the Deep Impact, Spitzer, and Kepler missions for the B612 Foundation,” said John Troeltzsch, the company’s Sentinel Program manager.

Troeltzsch told SPACE.com the aerospace firm will reuse deep-space elements the company helped pioneer. For the privately funded mission, that could include the science-downlink technology flown on Kepler and the cryogenic thermal-isolation system from the Spitzer Space Telescope.

The Sentinel ground system will build on the system in daily use by the Kepler mission, which is supplied to Ball by the LASP at Colorado-Boulder.

“Ball has been working on the mission concept for a NEO survey mission like Sentinel since 2005. This has allowed us to refine and iterate the design to a state of maturity that supports a commercial offering to B612,” Troeltzsch said. “Although there are challenges in front of us, like the development of the focal plane detectors, the overall system is based on proven, high-heritage systems.”

Troeltzsch said it’s not every day you can have fun working on a powerful space telescope and help protect the planet at the same time.

“Sooner or later one of the NEOs that Sentinel will discover will end up on a collision course with the Earth. I am sure that my kids and grandkids will appreciate the foresight B612 has shown in sponsoring this mission to help protect us all,” Troeltzsch concluded.

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Courtesy-Space.com

 

Do Cosmologist Understand The Echos Of The Big Bang?

Seeing is believing, except when you don’t believe what you see.

This is according to veteran radio astronomer Gerrit Verschuur, of the University of Memphis, who has an outrageously unorthodox theory that if true, would turn modern cosmology upside down.

He proposes that at least some of the fine structure seen in the all-sky plot of the universe’s cosmic microwave background is really the imprint of our local interstellar neighborhood. It has nothing to do with how the universe looked 380,000 years after the Big Bang, but how nearby clouds of cold hydrogen looked a few hundred years ago.

The idea is so unbelievable that it’s little wonder that cosmologists have largely ignored his work that has been published over the last few years.

“Science is supposed to be about the excitement of making new discoveries. But this discovery terrifies me,” he told reporters at the recent meeting of the American Astronomical Society in Anchorage, Alaska.

Verschuur’s radio maps of hydrogen surrounding our local stellar neighborhood out to a few hundred light-years appear to have an uncanny match-up to the mottled structure of the cosmic microwave background that is 13.7 billion light-years away.

NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) mapped the CMB in exquisite detail in 2003. The data show the slight temperature fluctuations in the early universe that are believed to be the seeds of galaxy formation. It is a landmark observation that is considered the “blueprint” for the subsequent evolution of the universe.

Verschuur is quick to applaud the WMAP team for a “brilliant experiment” to attempt to resolve the structure of the primeval universe as encoded in ancient microwave radiation. But he suggests that the team failed to subtract all the foreground radio phenomena that may have contaminated the data.

In a moment of serendipity, Verschuur found that his contour radio maps of cold hydrogen in interstellar space seem to fit the false-color speckled microwave background pattern (shown above). It’s like a child putting a puzzle piece into a pre-shaped slot.

Peaks in the foreground radio emission appear to overlay the peaks in the warmest region of the background, or appeared slightly offset.

In 2007 and 2010, Verschuur published a list of over 100 apparent matches between the CMB pattern and his interstellar hydrogen pattern.

Verschuur would have dismissed this as an odd coincidence until he realized that small interstellar clouds of hydrogen collide and jostle electrons to generate high-frequency radio emissions.

Like other foreground sources this would overlay the CMB. Because the WMAP team didn’t consider or know about the contribution of such a phenomenon they didn’t try and subtract it as they did numerous other electromagnetic “contaminants” in their data reduction, says Verschuur.

If Verschuur’s theory is correct, the consequences would send seismic waves through the cosmology community. It implies that at least some of the small-scale structure in the CMB map doesn’t exist at all.

But hold on. Detailed analysis of the angular diameter of CMB blobs yield a power spectrum that exactly fits theoretical predictions. The first peak in the spectrum shows a geometrically flat universe. The next peak determines the density of normal matter. The third peak provides information about the density of dark matter. And it all fits together beautifully.

Verschuur shrugs off the interpretation, saying that astronomers can analyzed the data and then stop when, “they find what they are looking for.

Cosmologists have also said that Verschuur’s claim needs a detailed statistical analysis. But Verschuur is equally dismissive: “astronomers who study interstellar structure do not use statistics to show associations between different forms of matter … they go by what the data look like.”

Astrophysicists Kate Land and Anze Slosar conducted an analysis of Verschuur’s study that was published in the Dec. 10, 2007, edition of The Astrophysical Journal. In an email to Wired, they concluded that Verschuur’s correlation of the radio emissions from nearby hydrogen and the WMAP data was nothing more than a coincidence.

“Notoriously, by eye, one can often think they see correlations between patterns,” Land told Wired. “But one doesn’t really see the anti-correlations. So two maps (of the sky) that just fluctuate randomly can appear correlated.”

This wouldn’t be the first time that random fluctuations in the CMB have led researchers to claim that they have seen patterns, only for their claims to be refuted and found flawed.

Observations from the European Space Agency’s Planck mission that is now measuring the CMB promises to yield a more detailed all-sky map than WMAP. Assuming the datasets between the missions agree at some level, this would rule out Verschuur’s claim as simply being an over-interpretation of his radio observations — agreeing with Land’s 2007 rebuttal.

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Did NASA Spot Bing Bang Objects?

New observations from a NASA space telescope have spotted what may be the very first objects created in the universe in unprecedented detail, scientists say.

The faint objects, imaged in infrared light by NASA’s Spitzer space telescope, might be hugely massive stars or black holes, but are too distant to see individually.

The Big Bang is thought to have kick-started the universe about 13.7 billion years ago. At first, the universe was too hot and dense for particles to be stable, but then the first quarks formed, which then grouped together to make protons and neutrons, and eventually the first atoms were created. After about 500 million years, the first stars, galaxies and black holes began to take shape.

The scientists can’t confirm for sure that the objects they see date from the early universe, but say that’s the most likely explanation.

“These objects would have been tremendously bright,” Alexander “Sasha” Kashlinsky of NASA’s Goddard Space Flight Center in Greenbelt, Md., said in a statement Thursday (June 7). “We can’t yet directly rule out mysterious sources for this light that could be coming from our nearby universe, but it is now becoming increasingly likely that we are catching a glimpse of an ancient epoch.”

Spitzer spotted these ancient structures after observing two patches of sky for more than 400 hours each. The telescope sees in infrared light, the long-wavelength range of the electromagnetic spectrum that’s less energetic than optical light. [Infrared Pictures from the Spitzer Space Telescope]

The researchers first removed all known stars and galaxies from the images. What was left over showed lumps of structure in a pattern consistent with how very distant objects are thought to cluster together.

The light spied by Spitzer has probably traveled for billions of years to reach us. It would have started out as optical or ultraviolet light, but over time stretched until it became infrared.

While Spitzer, which launched in 2003 and orbits the sun in an unusual Earth-trailing path, has made inroads in observing these objects, scientists are waiting for the James Webb Space Telescope to make major progress in understanding them.

James Webb, billed as the successor to the Hubble telescope, is an $8.8 billion infrared observatory due to launch in 2018.

“This is one of the reasons we are building the James Webb Space Telescope,” said Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington, D.C. “Spitzer is giving us tantalizing clues, but James Webb will tell us what really lies at the era where stars first ignited.”

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Is Dark Matter’s Existence Being Questioned?

A sprawling collection of galaxies and star clusters surrounding our own Milky Way is challenging long-standing theories on the existence of dark matter, the mysterious substance thought to pervade the universe.

The structure of satellite galaxies and star clusters around the Milky Way is so vast that it reaches across a million light-years – 10 times as wide as the Milky Way itself, according to astronomers at the University of Bonn in Germany, who made the discovery.

Existing dark matter theories fail to explain the arrangement of these cosmic objects, the scientists say.

“Our model appears to rule out the presence of dark matter in the universe, threatening a central pillar of current cosmological theory,” said study team member Pavel Kroupa, a professor of astronomy at the University of Bonn. “We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit.”

Dark matter is an invisible substance that is thought to make up roughly 23 percent of the universe. While dark matter has never been directly detected, it is inferred based on its gravitational effects.

Astronomers estimate that the Milky Way contains 300,000 million stars in addition to extensive “arms” of gas and dust that reach out in a flat disk extending from the galaxy’s central bar. The main part of the Milky Way is roughly 100,000 light-years across, which means that a beam of light would take 100,000 years to travel across it.

A number of smaller satellite galaxies and tight spherical bundles of ancient stars, called globular clusters, orbit at different distances from the main part of the Milky Way. [Stunning Photos of Our Milky Way Galaxy]

A picture of the cosmos

In the new study, researchers noted that the different objects are distributed in a plane at right angles to the Milky Way’s galactic disk. The massive, newly discovered structure stretches from as close as 33,000 light-years away from the center of the Milky Way to as far as 1 million light-years away from the center.

By merging data from a range of sources to compile a census of our galaxy’s surroundings, the scientists found that the area around the Milky Way includes bright “classical” satellite galaxies, plus fainter galaxies that were more recently detected, and globular clusters.

“Once we had completed our analysis, a new picture of our cosmic neighborhood emerged,” the study’s lead author Marcel Pawlowski, a Ph.D. student at the University of Bonn, said in a statement.

The astronomers were also surprised by the arrangement of the cosmic objects. “We were baffled by how well the distributions of the different types of objects agreed with each other,” Kroupa said

As the different companions orbit around the Milky Way, they shed material, stars and sometimes gas, which leaves long streams along their path, the researchers explained. The results of the new study show that this lost material is also aligned with the plane of the galaxies and globular clusters.

“This illustrates that the objects are not only situated within this plane right now, but that they move within it,” Pawlowski said. “The structure is stable.”

Existing theories of dark matter cannot adequately explain this galactic configuration, the researchers said.

“In the standard theories, the satellite galaxies would have formed as individual objects before being captured by the Milky Way,” Kroupa said. “As they would have come from many directions, it is next to impossible for them to end up distributed in such a thin plane structure.”

Signs of an ancient galaxy crash?

The observations by Pawlowski and his colleagues suggest that other forces caused the unexpected arrangement of satellite galaxies around the Milky Way.

“The satellite galaxies and clusters must have formed together in one major event, a collision of two galaxies,” study team member Jan Pflamm-Altenburg, a postdoctoral researcher, said in a statement.

Such galaxy collisions are relatively common, and typically result in large chunks of galaxies being torn out by strong gravitational and tidal forces. These violent interactions sometimes form tails that become the birthplaces of new objects such as star clusters and dwarf galaxies, according to the researchers.

“We think that the Milky Way collided with another galaxy in the distant past,” Pawlowski said. “The other galaxy lost part of its material, material that then formed our galaxy’s satellite galaxies and the younger globular clusters and the bulge at the galactic center. The companions we see today are the debris of this 11-billion-year-old collision.”

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Will Mining Asteroids Be Profitable?

Science fiction dreams of mining riches from asteroids only make sense if humans can make it worth their time and effort. The new Planetary Resources group backed by Silicon Valley billionaires and Hollywood moguls is now betting on the fact that there is big money in mining space rocks.

Nobody knows exactly how much asteroid wealth exists, but early estimates point to riches beyond Earth’s wildest dreams. Just the mineral wealth of the asteroid belt between the orbits of Mars and Jupiter could be equivalent to about $100 billion for every person on Earth, according to “Mining the Sky: Untold Riches from the Asteroid, Comets, and Planets” (Addison-Wesley, 1996) — perhaps slightly less now after accounting for the Earth’s population growth over the past 15 years. [Does Asteroid Mining Violate Space Law?]

“The near-Earth asteroid population could easily support 10 to 40 times the population of Earth, with all the necessary resources to do that,” said John Lewis, a professor emeritus at the Lunar and Planetary Laboratory of the University of Arizona and author of “Mining the Sky.”

Even smaller space rocks can have mineral prizes worth tens of trillions of dollars. The smallest known metallic asteroid that is an accessible near-Earth object has 40 times as much metal as all the metal in Earth’s history, Lewis pointed out. He has joined Planetary Resources as perhaps the most recognized expert on asteroid wealth.

There’s platinum in thar rocks

Knowing what asteroid wealth consists of depends on incomplete but enticing scientific surveys. Scientists sitting on Earth can detect chemical signatures of asteroids based on reflected light, or directly sample space rocks fallen to Earth as meteoroids. Japan has carried out the only successful space mission to retrieve asteroid samples in space, but the U.S. is planning its own asteroid sample and retrieval missions.

An M-class asteroid about 79-feet (24-meter) long could have as much as 33,000 tons of extractable metal and possibly one ton of platinum group metals. The platinum alone could be easily worth about $50 million dollars in Earth’s commodity markets, according to studies cited by the paper “Assessment on the feasibility of future shepherding of asteroid resources” in the April-May issue of the journal Acta Astronautica.

Such platinum-group metals represent the main prize for Earth markets, said Joan-Pau Sanchez, a researcher in the Advanced Space Concepts Laboratory at the University of Strathclyde in the UK. He coauthored the Acta Astronautica paper.

“Platinum-group metals (PGMs) are likely to be the only material from asteroids that will prove economically viable to be transported back to Earth’s commodity markets,” Sanchez told InnovationnewsDaily. “PGMs are in high demand, and will be even more in the future.”

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Turning space rocks into riches

But the Planetary Resources group has its eyes on more than just platinum to strike it rich, Lewis said. He described using asteroid metals to build huge space stations or even space solar power stations for beaming energy down to Earth.

That could come from the abundant S-class asteroids — about 40 percent of the near-Earth objects — which hold metals, semiconductors, and even oxygen or water. One 79-foot (24-meter) asteroid of the S-class could provide 1,100 to 4,400 tons of iron for building the structural support for a huge solar array capable of making a gigawatt of power (as much as a large power plant) for either space stations or Earth, according to the Acta Astronautica paper.

A similar-size hydrated carbonaceous asteroid could hold a million liters of water (enough to fill half a million soft drink bottles). That would fall under the second big market envisioned by Planetary Resources — harvesting asteroid resources for use as rocket propellants, drinking water and oxygen to support space exploration missions.

“The billionaires who are standing behind this right now are not doing this for fun and recreation,” Lewis said. “They see it as a great economic value in the long run, and I’m not surprised if more than one wants to make a dime out of it.”

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Gamma-Ray Objects Puzzles Astronomers

The universe is filled with high-energy radiation, much of which is made of gamma rays belched out by strange pulsing stars and the remnants of supernova explosions. But a new study of some of most extreme objects has turned up a mystery: nearly one-third of all gamma-ray emitting objects seen to date defy identification.

The objects were spotted by NASA’s Fermi Gamma-ray Space Telescope, which scans the entire sky over the course of three hours, mapping the powerful spectrum. When stacked together, the surveys create an extremely precise view of the gamma-ray universe.

Scientists then match these images to other observations to identify each source. But the identities of some gamma-ray sources in space still continue to elude the astronomers.

“There’s some that, despite all our efforts, we really do not know what they are,” David Thompson, Fermi’s deputy project scientist, told SPACE.com. “They do not seem to be any of the usual suspects.” [Video: Mystery of Fermi's Gamma-Ray Objects]

The cosmic detective

The Fermi space telescope has spotted nearly 500 powerful gamma-ray sources in deep space over the last three years. Before its launch in 2008, scientists only knew of four such objects.

“We’re not looking for the ordinary things,” Thompson said. “We’re looking for the extraordinary; powerful things that might produce gamma rays.”

Of the newly discovered bodies, more than half are active galaxies. Pulsars and supernova remnants each make up about 5 percent of the sources, with high-mass binary stars and other galaxies contributing just a smidge more, the researchers said.

Yet a large collection of objects remains unidentified, they added.

In some cases, the readings themselves helped scientists to classify the sources. By looking for changes in energy levels or studying the objects’ shapes, astronomers could identify pulsars and galaxies.

But gamma-ray targets without these distinctions remain a mystery. In many cases, the problem may simply be one of not enough data.

“Deeper observations at other wavelengths could find counterparts to some Fermi sources in the future,” Pascal Fortin, at the Ecole Polytechnique’s Laboratoire Leprince-Ringuet in France, told SPACE.com in an email. Fortin was one of the leaders of the international team that produced Fermi’s hard-source list.

A tantalizing mystery

Despite their mysterious origins, the sheer number of unidentified sources is promising.

“The fact that there are so many of these suggests to us — maybe this is wishful thinking — that there may indeed be something new out there,” Thompson said. “What we’d really like to find is something new and exotic.”

One potential cause of the baffling readings could be black holes that are interacting in a new and unexpected way, he added.

If the strange objects reveal nothing else, they highlight how much of space is still a mystery.

“We still have a lot to learn about high-energy processes in the universe,” Fortin said.

Over its decade-long mission, Fermi will continue to gather information about the gamma-ray emitters, and may help answer some of the questions it is creating.

“It’s an exciting field to work in,” Thompson said. “The fact that we have so many of these, I think is very promising in terms of future discoveries.”

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Vesta Shows Its Spots

A NASA spacecraft orbiting the huge asteroid Vesta has snapped amazing new photos of the colossal space rock, images that reveal strange features never-before-seen on an asteroid, scientists say.

The new photos of Vesta from NASA’s Dawn spacecraft highlight odd, shiny spots that are nearly twice as bright as other parts of the asteroid — suggesting it is original material left over from the space rock’s birth 4 billion years ago, NASA officials said today (March 21).

With a width of about 330 miles (530 km), asteroid Vesta is one of the largest and brightest objects in the main asteroid belt between the orbits of Mars and Jupiter. NASA’s Dawn probe has been orbiting Vesta since 2011 to study the space rock in unprecedented detail.

“Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago,” said Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park, in a statement. “We’re eager to learn more about what minerals make up this material and how the present Vesta surface came to be.”

Asteroid Vesta unveiled

Li and his colleagues unveiled Dawn’s new views of Vesta today at the 43rd Lunar and Planetary Science Conference in The Woodlands, Texas.

The photos show surprisingly bright spots all over Vesta, with the most predominant ones located inside or around the asteroid’s many craters. The bright areas range from large spots (around several hundred feet across) to simply huge, with some stretching across 10 miles (16 kilometers) of terrain. [Video: Vesta — Asteroid or Dwarf Planet?]

“Dawn’s ambitious exploration of Vesta has been going beautifully,” said Marc Rayman, Dawn chief engineer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., which oversees the mission. “As we continue to gather a bounty of data, it is thrilling to reveal fascinating alien landscapes.”

Dawn mission scientists suspect the bright patches on Vesta were exposed during violent collisions with other space rocks. These impacts may have spread the bright material across the asteroid and mixed it together with darker material on Vesta’s surface, researchers said.

Astronomers have known about variations in Vesta’s brightness for some time. Photos taken by the Hubble Space Telescope before Dawn arrived at the asteroid also revealed the bright patches.

Never-before seen asteroid melt

But only the close-up photos from the Dawn probe have revealed the surprising variety of dark blotches on Vesta, which appear as dark gray, brown or reddish blemishes, NASA officials said.

In some views, these darker spots are small deposits near impact craters, while in other photos they appear in larger concentrations. These darker spots on Vesta may also be the result of collisions on the asteroid, researchers said.

Slow carbon-rich asteroids may have created some of the smaller dark material deposits without carving out a big crater. Meanwhile, faster objects may have potentially slammed into Vesta so hard they melted the big asteroid’s crust, which could have also created the dark spots.

“Some of these past collisions were so intense they melted the surface,” said Brett Denevi, a Dawn participating scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Dawn’s ability to image the melt marks a unique find. Melting events like these were suspected, but never before seen on an asteroid.”

NASA launched the $466 million Dawn spacecraft in 2007 and Vesta is only the first stop of the spacecraft’s two-asteroid tour. Dawn arrived at Vesta in July 2011 and is expected to spend about a year there before heading off to its next target — the even larger asteroid Ceres, which is also classified as a dwarf planet.

Dawn is expected to arrive at Ceres in February 2015.

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Can A Nuke Save Earth From A Gigantic Asteroid?

A well-placed nuclear explosion could actually save humanity from a big asteroid hurtling toward Earth, just like in the movies, a new study suggests.

Scientists at Los Alamos National Laboratory, a United States Department of Energy facility in New Mexico, used a supercomputer to model nukes’ anti-asteroid effectiveness. They attacked a 1,650-foot-long (500-meter) space rock with a 1-megaton nuclear weapon — about 50 times more powerful than the U.S. blast inflicted on Nagasaki, Japan, to help end World War II.

The results were encouraging.

“Ultimately this 1-megaton blast will disrupt all of the rocks in the rockpile of this asteroid, and if this were an Earth-crossing asteroid, would fully mitigate the hazard represented by the initial asteroid itself,” Los Alamos scientist Bob Weaver said in a recent video released by the lab. [Video: Nuclear bomb takes out asteroid]

In the 3-D modeling study, run on 32,000 processors of the Cielo supercomputer, the blast went off at the asteroid’s surface. So the nuke likely wouldn’t have to be deposited deep into a threatening space rock, a dangerous job Bruce Willis and his astronaut crew tackled in the 1998 film “Armageddon.”

Weaver stressed that nuclear bombs would likely be deployed only as a last resort, if an impact loomed just months away. And other researchers caution that a nuclear blast might have negative side effects, such as sending a hail of many small space rocks toward Earth instead of a single big one.

If humanity had more notice of an impending impact, there are several other asteroid defense strategies we might be able to employ, scientists have said.

For example, we could send a robotic probe out to rendezvous and ride along with the potentially dangerous asteroid. The spacecraft’s modest gravity would exert a tug on the space rock as the two cruise through space together. Over months or years, this “gravity tractor” method would pull the asteroid into a different, more benign orbit.

We have the know-how to pull off such a mission. Multiple probes have met up with rocks in deep space, including NASA’s Dawn spacecraft, which is currently orbiting the huge asteroid Vesta. And in 2005, Japan’s Hayabusa probe plucked some pieces off the asteroid Itokawa, sending them back to Earth for analysis.

Humanity could also simply slam the rendezvous craft into the asteroid, relying on brute force rather than a gentle gravitational tug to push it off course. This impactor approach would not be as precise as the gravity tractor technique, researchers say, but it could still do the job under certain circumstances.

We’ve demonstrated the ability to accomplish this more aggressive mission as well. In 2005, for example, NASA sent an impactor barreling into the comet Tempel 1 to determine the icy object’s composition.

Discussions about asteroid deflection aren’t just academic exercises. Huge impacts are a part of our planet’s history; one wiped out the dinosaurs 65 million years ago, and it’s just a matter of time before another big space rock lines Earth up in its sights, astronomers say.

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