With a massive dead NASA satellite due to plunge back to Earth this week, the Federal Emergency Management Agency is laying the groundwork for a fast response in case the six-ton spacecraft falls over American soil.
The defunct spacecraft, called the Upper Atmosphere Research Satellite, or UARS), is projected to make an uncontrolled fiery fall on Friday, plus or minus a day, according to NASA.
Odds are that nobody will be beaned by any remaining chunks of the nearly $750 million spacecraft, with NASA experts forecasting a remote 1-in-3,200 chance of anyone being hit by any of the satellite debris. [That translates into a roughly 1-in-20 trillion chance for any particular person.]
But re-entry specialists do expect about 26 different components from UARS to survive the plunge — a total leftover mass of 1,170 pounds (532 kilograms) — components made of titanium, aluminum, steel and beryllium.
It is impossible to pinpoint just where UARS satellite debris will fall. With Earth being three-fourths ocean, the odds of a harmless splashdown are good. But NASA estimates the debris footprint will be about 500 miles (800 kilometers) long.
The word from NASA is direct: "If you find something you think may be a piece of UARS, do not touch it. Contact a local law enforcement official for assistance."
That's where FEMA comes in.
Consequence planning
Be it satellite re-entry, terrorist act or natural disaster, the U.S. Department of Homeland Security and its daughter agency FEMA would bring to bear the expertise and authorities of agencies across the federal government to support state and local governments.
These roles are outlined in the National Response Framework, a guide to how the nation conducts all-hazards response — from the smallest incident to the largest catastrophe.
FEMA's "consequence planning" stems from lessons learned after the 2003 Columbia shuttle disaster over Texas, an incident that provided that agency with critical insight toward planning, preparing and responding.
FEMA also revved up a satellite re-entry action plan in early 2008. The worry then focused on the out-of-control spy satellite USA-193 (also known as NROL-21) owned by the U.S. National Reconnaissance Office.
The classified USA-193 satellite tipped the scales at roughly 5,000 pounds (2.3 metric tons), and about 50 percent of it was predicted to survive re-entry. Of key concern was a tank that held about a half-ton of toxic hydrazine, a fuel source thought likely to survive re-entry and be intact when it struck the Earth, rupturing and releasing the hazardous material.
The U.S. military planned to shoot the spy satellite down.
"Please keep in mind that the probability that it will fall upon the United States is low, yet we must be ready," explained a FEMA communique to a network of first responders in 2008. "We will have six Federal Joint Interagency Task Forces located around the country ready to deploy the moment we know the impact area, responding to assist you in your role of immediate consequence management."
FEMA's on-call duties became moot when the errant NRO satellite was shattered by an interceptor missile on Feb. 21, 2008, rocketed spaceward from the USS Lake Erie, a U.S. Navy Aegis cruiser stationed west of Hawaii. Contents of the spacecraft's propellant tank were dispersed high above the Earth by the shootdown.
Chain of command
The UARS satellite due to fall from the sky this week does not have any fuel remaining onboard. NASA commanded the satellite to use it all in 2005, when it was decommissioned, to put it on its years-long disposal course.
Since the spacecraft isn't carrying any hazardous materials, there's little need to try and shoot it down, officials said.
"There doesn't appear to be a reason to do those same measures," confirmed U.S. Air Force Maj. Michael Duncan, deputy chief of space situational awareness for the U.S. Strategic Command at Vandenberg Air Force Base in California.
Duncan told Space.com during a Sept. 9 teleconference that his organization will notify FEMA "as part of our chain of command notifications for re-entries over North America."
On the actual day of the UARS re-entry, Duncan said, they will be providing 24-hour, 12-hour, six-hour, and two-hour predictions as estimates for the actual re-entry time are improved.
"Obviously FEMA is always prepared to assist … should any of these components land in the United States," said Nicholas Johnson, chief scientist for NASA's Orbital Debris Program at the Johnson Space Center in Houston. "It's, again, very, very unlikely when you look at the ratio of the land mass of the United States to the land mass of the world. We have had intergovernmental meetings on this issue and I feel very confident that they will rise to the occasion should the occasion arise."
Numerically speaking
UARS will re-enter the atmosphere somewhere between 57 degrees north and 57 degrees south. That means the six-ton, bus-sized craft will hit the Earth’s atmosphere anywhere from northern Canada to southern South America.
"And once you get 57 degrees plus or minus, you've pretty much encompassed all 7 billion people of the planet," Johnson said.
Numerically speaking, it comes out to a chance of 1 in 3,200 that one person anywhere in the world might be struck by a piece of debris. "So those are actually, obviously, very, very low odds that anything — anybody is going to be impacted by this debris," Johnson added.
According to Harro Zimmer, a devoted satellite tracker in Berlin, Germany, timing of the UARS nose-dive is being affected by a relatively high-level of solar activity lately.
Zimmer has been in the prediction business for more than 45 years. He's also authorized by the U.S. Strategic Command to use their data and issue the results of his independent analysis as an open source. He predicts the end of UARS on Friday, give or take eight hours.
"The earlier decay of UARS seems very realistic," Zimmer told Space.com.
[On Tuesday, NASA stuck with its forecast of a Friday fall, plus or minus a day, and promised that "predictions will become more refined over the next two days." The satellite's orbit had fallen to a level of 127 by 140 miles (205 by 225 kilometers) as of Tuesday, NASA said.]
Future fall
Another uncontrolled re-entry of a NASA satellite is on the distant horizon, but that plunge is several years away. The spacecraft, a joint project of NASA and the Japan Aerospace Exploration Agency, is the still-operational Tropical Rainfall Measuring Mission (TRMM). It is expected to continue its mission for up to another three years before plummeting back to Earth.
TRMM was launched in 1997 for what was intended to be a three-year mission. Moved into extended mission status, it consumed the onboard fuel needed to execute a controlled re-entry.
When TRMM gradually falls back to Earth in an uncontrolled manner, the risk of its debris to people on Earth, however, will be less than UARS, according to orbital debris experts.
Leonard David has been reporting on the space industry for more than five decades. He is a winner of this year's National Space Club Press Award and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for Space.com since 1999.