BILLION DOLLARS TO TRACK DEADLY ASTEROIDS

The U.S. National Research Council (NRC) wants an international asteroid defense agency that can organize a proper mission to counter possible asteroid threats.

The NRC says the planet's current lack of readiness to deal with giant space rocks flying at it is a major concern.

Current sky surveys will not be able to find 90 percent of near-Earth objects that are 460 feet (140 m) or larger by 2020, as the U.S. Congress instructed NASA in 2005 to ensure they could due to a lack of funding.

An asteroid-hunting space telescope could go a long way toward playing catch-up and reaching the survey goal by 2022, but at the hefty cost of more than $1 billion.

Even if scientists spot a looming asteroid threat, few immediate solutions exist. The NRC runs down past proposals that range from "slow push" or "slow pull" gravity tractors to small kinetic collisions by spacecraft that could nudge a space rock off course -- assuming that there's decades to spare. But only nuclear explosions stand ready as the current practical means for dealing with the biggest threats in the form of space rocks greater than 1 km in diameter.

Several planned missions offer hope of not only studying asteroids for weaknesses, but even using them as a sort of "Plymouth Rock" stepping stone to colonize Mars. Such missions could represent small yet crucial steps toward generating interest in funding more asteroid detection and deflection methods.

The NRC's plans primarily cover large asteroid threats. Plenty of smaller meteorites still fall to Earth every year.

One plan is to send a manned space mission to land on an asteroid is gaining traction within both NASA and the aerospace industry as experts look to bridge the feasibility gap between lunar missions and an eventual rendezvous with Mars. Of course, no party is ruling out the possibility of an Armageddon-esque trip to a Near Earth Object (NEO) on a harmful trajectory, should the need arise in the future.

While neither NASA or the White House has signed off on - or even offered funding to study - such a mission, briefing charts put together by Lockheed Martin, maker of the space agency's next-gen passenger spacecraft, detail how a mission might work.

In Lockheed's scenario, aptly titled "Plymouth Rock," a two-person Orion craft would hook up with an unpiloted sister craft loaded with extra water, oxygen and other supplies. Orion would not land on the NEO itself, but would post up nearby while astronauts use jet backpacks to reach the object's surface. Once there, scientists could gather compositions samples of the rock and set up other scientific equipment that could be left behind on the NEO. That information would be extremely valuable to science, not to mention give scientists the upper hand should a worrisome rock ever come hurtling directly toward earth.

Right now it's only an idea on a briefing board, but both NASA and aerospace industry consider the mission is not only feasible, but could offer invaluable experience as a stepping stone between current low earth orbit excursions and forays deeper into space.

The consequences of a sufficiently large asteroid or comet strike would be catastrophic for most species.

Depending on size, an amount of energy equivalent to tens of thousands and even many millions of nuclear bombs would be released on impact. Such a strike could be disastrous not just for civilization, but for the planet's entire web of life.

If it landed in the ocean, the impact would send walls of water in all directions, inundating continental margins. If it struck land, it could ignite continent-wide fires.

And while the destruction would be immediate around the strike zone, the problems would likely become global in the aftermath: Dust injected into the atmosphere could block sunlight. Photosynthetic organisms would stop growing. Everything else that depended on them would suffer the consequences of a reduced food supply. Mass starvation would ensue.

The last asteroid strike on this scale is widely thought to have contributed to the dinosaurs' end 65 million years ago. The asteroid, which left a 110-mile-wide crater off Mexico's Yucatan Peninsula, was only six miles in diameter, roughly the size of Manhattan Island. But three-quarters of life on Earth disappeared.

Scientists generally agree that asteroid impacts in the future are a near-certainty ? smaller ones more often, larger and much more catastrophic ones less often. Scientists think that asteroids like the one that ended the dinosaurs' reign hit Earth every 100 million years or so.

That's why, in 2005, Congress mandated that NASA should try to detect 90 percent of near earth objects (NEOs) with a diameter of more 140 meters or more by 2020. Asteroids of this size hit earth roughly every 30,000 years.

Before that, in 1998, Congress asked that NASA find 90 percent of all NEOs measuring more than 1 kilometer in diameter within 10 years. These hit with less regularity, but could cause substantially more damage.

Late last week, the National Research Council released a progress report that found that NASA has been quite good at locating and tracking objects larger than 1 km in diameter. But, due to insufficient funding - only $4 million yearly for tracking NEOs - NASA wouldn't meet the goals set out by Congress in 2005.

"The current near-Earth object surveys cannot meet the goals of the 2005 George E. Brown, Jr. Near-Earth Object Survey Act directing NASA to discover 90 percent of all near-Earth objects 140 meters in diameter or greater by 2020," the report states. Then the authors lay out a few options for getting the job done:

If completion of the survey as close to the original 2020 deadline as possible is considered most important, a space mission conducted in concert with observations using a suitable ground-based telescope and selected by peer-reviewed competition is the best approach. This combination could complete the survey well before 2030, perhaps as early as 2022 if funding were appropriated quickly.

And cost conservation is deemed most important, the use of a large ground-based telescope is the best approach. Under this option, the survey could not be completed by the original 2020 deadline, but could be completed before 2030. To achieve the intended cost effectiveness, the funding to construct the telescope must come largely on the basis of non-NEO programs.

The report also calls on the US to lead the formation of an international body to monitor and deal with NEO threats.

NASA needs an additional $1 billion in funding over the next 15 years to attain its goal of cataloguing all potentially threatening asteroids. Today NASA's Near Earth Object Program is aware of and tracking 6,691 objects.