By Senior Space Writer
updated 3/22/2004 7:32:09 PM ET 2004-03-23T00:32:09

An asteroid flew past Earth last week so close that it nearly entered an orbital halo where weather satellites roam. Scientists spotted it March 15 and watched it zoom by just three days later. It posed no threat, but there are hundreds of thousands more where that one came from.

And while asteroid 2004 FH, as it is known, was watched calmly by astronomers, a more frightening scenario unfolded two months earlier:

An unprecedented asteroid scare in January had astronomers worried for a few hours over a rock that had a 1-in-4 chance of hitting Earth during the next few days. At the time, some of the scientists were unsure who should be notified. The event has prompted NASA to set up a formal process for notifying top officials in the future of any impending impacts, Space.com has learned.

The plan, which has existed on an informal basis for months but was not known to all the key scientists involved, could be put out for review this summer and finalized by the end of the year.

The blueprint will be limited to spelling out lines of communication within NASA, but it might spur other governmental officials to begin considering how to respond to a threat from beyond if NASA Administrator Sean O'Keefe were to be informed of one, said Lindley Johnson, the top official for Near Earth Object Observation at NASA Headquarters.

No emergency plan
For now, there is no established chain of command to the White House in relation to possible asteroid impacts, nor is there any plan for what government agencies should do regarding possible evacuations or emergency preparations.

Key NASA scientists who monitor potentially threatening space rocks already knew what to do on the night of Jan 13-14 when an apparent cosmic bogey was detected, Johnson said in a recent telephone interview. But there was concern and confusion, both among NASA scientists and between them and other astronomers who play vital roles in tracking newfound space rocks.

Few involved in the somewhat ad hoc global system of asteroid hunting knew exactly who should call whom as the situation unfolded.

How it started
It all began with a routine observation.

The Lincoln Near Earth Asteroid Research observatories in New Mexico had recorded four images of an object moving across the sky. LINEAR's measurements were sent as part of a daily batch to the Minor Planet Center in Cambridge, Mass, on that Tuesday in January.

Interactive: Below the belt At the Minor Planet Center, researcher Tim Spahr carried out a daily duty, using a computer program to generate trajectories for the newfound object. Spahr posted the results — along with paths for other newly detected objects — to a Web page monitored by professional and amateur astronomers. The amateurs do the bulk of the follow-up observations that help the Minor Planet Center pin down the paths of newfound asteroids.

The presumed asteroid was temporarily designated AL00667. Spahr left for the day.

Within an hour, European amateur astronomer Reiner Stoss saw the posting and realized that AL00667 would be six times closer to Earth within a day. He posted a message to the Minor Planet Mailing List, which other asteroid hunters and researchers monitor.

The object was thought to be relatively small. At the time, astronomers estimated it was 100 feet (30 meters) wide. Were a rock that size to target Earth, scientists aren't sure what would happen. Something slightly smaller would probably explode brilliantly but harmlessly in the atmosphere, theory predicts. Something slightly larger could explode closer to the ground and devastate an area the size of a small city.

What to do
Alan Harris, of the Space Science Institute in Boulder, Colo., saw Stoss' message and checked the orbital path posted on the Minor Planet Center Web site, which all the astronomers knew was preliminary and could have wide error margins. Harris realized that the orbital path posted would have the asteroid hitting Earth the next day.

At 7:09 p.m. ET, Harris alerted several colleagues, including Don Yeomans, head of the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory.

Yeomans called the Minor Planet Center to try to get access to the original data set. (The actual observations are not posted on the Minor Planet Center Web site until after an official announcement circular is published, usually in a couple of days.) Spahr, not realizing he'd posted an orbital path that went right through the Earth, had gone to dinner.

It took about 30 minutes before Yeomans and his colleagues heard back from Brian Marsden, director of the Minor Planet Center, who was working late that evening. After another 20 minutes, Yeomans and his JPL team had the observational data and calculated the rock had about a 25 percent chance of impact.

Meanwhile, other possible paths based on the sketchy data showed the rock could also miss Earth by a wide margin. More observations were needed.

'This must be a mistake'
Clark Chapman of the Southwest Research Institute, also in Boulder, had been apprised of the situation, too.

"As I was driving home, I was thinking that this must be a mistake," Chapman recalled last week. Asteroid experts have seen many threats of impacts, predicted for future years, come and go over the course of a day or two as new observations provided a more accurate picture of a space rock's path. Never, however, have they faced such an apparently imminent threat.

Chapman had begun keeping a narrative of the unusual situation. At one point early on, this log included musings over whether NASA or the White House should be alerted, but he says it was not something he seriously contemplated.

Many in the media reported that the astronomers had pondered calling the White House. Chapman says the media got it wrong.

During the critical period when JPL had calculated a 10 to 40 percent chance of impact, "there's nothing in the narrative that says a thing about the White House," Chapman said. He and NASA's David Morrison, who was also involved in the e-mail communications, both say there was never any serious consideration of calling the president.

"The real issue that we did discuss was when, if at all, it would be appropriate for any of us, especially Don Yeomans … to notify officials in the Office of Space Science at NASA Headquarters," Morrison said, adding that he did wonder who should be called if it became necessary.

Hours passed as cloudy skies prevented follow-up observations.

Finally, in the wee hours of Jan. 14, the spot where AL00667 would have been if it were heading earthward was found to be empty. (The object was later calculated to be larger, and computers showed it would come nowhere close to Earth. It was then given a permanent designation of 2004 AS1.)

Lack of preparation
In hindsight, astronomers say the episode reveals a system not prepared to properly find and evaluate small asteroids that could hit Earth within hours or days of being spotted.

"We were all surprised about what happened," Chapman told Space.com.

NASA spends a modest $3.5 million per year as part of the Spaceguard Survey search for large asteroids, the sort that could cause global damage, including a global "winter" that might last years, could kill off some species and possibly threaten civilization. Were one of these objects bigger than 0.6 miles (1 kilometer) found to be on an Earth-impact trajectory, scientists agree the warming time would almost certainly be years or decades.

But very little money is spent to catalog and process the observational data, which include the serendipitous discoveries of many small asteroids that could destroy a city or devastate a country. The smaller objects typically go unnoticed until they are very near the planet (and most of them pass by without incident — were it otherwise, you'd know).

Shoestring budget
Only about 3 or 4 percent of NASA's asteroid spending goes toward follow-up work. The Minor Planet Center, meanwhile, operates on a shoestring budget relying partly on subscriptions to its data mailings.

"For the most part, we had not previously contemplated the possibility of discovery by the Spaceguard Survey of a small asteroid on its final plunge toward Earth," said Morrison, an astrobiologist and asteroid expert at NASA's Ames Research Center. "Indeed, it is exceeding unlikely for such an event to occur."

But low odds don't mean it won't happen tomorrow, or next month.

"If we simply trusted the odds, we would probably pack up and go home, since no impact is likely within our lifetimes," he said. "But it is the possibility of an improbable impact that motivates us."

Within 48 hours of the January scare, Chapman says, the Minor Planet Center made changes to its software so that precisely this kind of situation can't happen again. In fact, he notes, a similar scenario arose two weeks later but did not cause alarm.

Clarifying roles
After the January AL00667 event, Lindley Johnson, the near-Earth object chief at NASA Headquarters, sent a memo to Yeomans, Chapman and other asteroid researchers clarifying that Yeomans should call Johnson if a serious and immediate threat were ever deemed real.

Yeomans has known this for months and has had Johnson's phone number, Johnson and Chapman say.

"I think the system worked the way it was supposed to," Johnson says of the winter scare.

He credits the Minor Planet Center for having quickly sought follow-up observations, as it routinely does for any potentially threatening object. And importantly, unlike a half-dozen or so other asteroid scares dating back to the late 1990s, this one did not play out in the media, but rather was resolved by astronomers before the any public false alarms were sounded.

Johnson allows that the chain of command was informal, "and still is, until we draft a formal plan. But we always kind of knew that if we got a call from the astronomers — in particular Don Yeomans — about how we'd handle it back here. There are only two to three layers of bureaucracy between me and the administrator [Sean O'Keefe]. So it's not like it would take much time to get the word up."

What O'Keefe would do with any such information is not spelled out anywhere.

"To my knowledge there's been no discussions at that level as to what would be done," said Johnson, a retired lieutenant colonel who served 23 years in the U.S. Air Force. "It's going to be up to him [O'Keefe] to take it from there."

Johnson said that the plan he's formalizing might "prompt O'Keefe to think, 'OK, now what do I do?'"

Johnson stressed that NASA's directive has been limited to conducting a scientific survey for the larger objects.

"We have not been authorized or appropriated funding to be operating a network capable of providing accurate and credible warning for near-term (hours to days) impacts, be they large or small objects," he said.

A busy future
Astronomers estimate there are about 1,100 asteroids larger than 0.6 miles (1 kilometer) that sometimes inhabit the same general space as Earth. These are the potential civilization-destroyers. More than half have been found, and 90 percent are expected to be cataloged by 2008. So far, none has been found to be heading our way anytime soon.

Asteroid hunters agree they need to figure out what to do beyond 2008.

NASA has studied the costly possibility of expanding the asteroid search to purposely include smaller objects, of which there are probably hundreds of thousands that cross the orbit of Earth. The effort would require new telescopes and more astronomers' time.

If such a search is ever undertaken, significant new funds would have to be devoted to follow-up observations and cataloging, too.

"When we start talking about the smaller objects … that's going to require some additional capability to handle orbits and observations," Johnson said. "We'd be dealing with thousands of objects a week instead of tens."

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