WASHINGTON -- Has your mailbox recently been invaded by a census form? Take heart. You're not alone.

Nearly 100 million U.S. Census 2000 questionnaires were sent out as part of a massive mailout/mailback campaign. But by 2010, when the next decennial census is slated, remote sensing spacecraft will likely sweep the landscape for a more accurate tally.

"We're looking at the possibility of that kind of technology for the future as higher resolution birds get up there," said Bob Marx, chief of the geography division of the Census Bureau in Suitland, Maryland. High-powered spacecraft cameras can pick up roads and individual housing units, he said.

According to the Bureau of the Census, data now being collected helps communities obtain federal and state funds, aids municipalities to better plan for schools and hospitals, and even helps discern which neighborhoods need greater services for the elderly.

Marx said the idea of using satellites to snag census data is not new.

"We started looking at this technology back in the mid-1970s. But back then you couldn't even see a road, let alone individual buildings. Things have gotten a lot better since then. The odds of being able to see what we need to see are getting pretty high now," he said.

The Bureau of the Census has contracted Booz Allen & Hamilton, a private consulting group, to review how remote sensing satellites might help modernize census taking. "We're assessing what's possible. This is a 'What if?…Will it work?…Can it save them money?…' proof of concept study," said Mike Keister, a program manager for Booz Allen in Camp Springs, Maryland. The analysis has been underway since October of last year and the findings will drop on Census Bureau desks this June, he said.

At the heart of the Booz Allen study is to see if the Census Bureau's Topologically Integrated Geographic Encoding and Referencing (TIGER) system can be made more accurate by using photo-snapping spacecraft, as well as navigation-aiding Global Positioning Satellites (GPS). TIGER files are a digital database of geographic features, such as roads, railroads, rivers, lakes, political boundaries and census statistical boundaries that cover the entire United States.

Keister said that using satellites looks promising to "ensure that every structure or every home in America is accounted for." Each structure could be given 'x' and 'y' coordinates. Doing so would mean no computer confusion in pinning addresses to homes and buildings seen in satellite pictures. Even a 'z' coordinate could be assigned, yielding information on a building's height. That's ideal for those canyons of tightly packed skyscrapers found in places like New York City, he said.

"It's not possible to conduct the census by flying a satellite over the country and counting all the people. That is science fiction and only works in movies."
     

People who don’t turn in their census forms could be better identified by the melding of satellite shots with GPS data, Marx said. That would minimize accidental pestering of people by door-knocking census takers in search of tardy respondents, he said.

However, there are drawbacks to taking census by satellite.

For one, satellite imagery is not cheap, Keister said. "To do the entire United States, we're talking about hundreds of millions of dollars," he said.

Secondly, in order for data to be useful for the census, satellite imagery has to be specially processed to improve its accuracy. "But the processing to do that is even more expensive than the collection," Keister said.

However, more high-resolution satellites similar to the commercial Ikonos spacecraft, which Space Imaging sent up last year, are due to be launched. Ikonos and other satellites soon to follow can offer snapshots of Earth down to 3.3 feet (1 meter) across. Cameras with greater resolving power are now under discussion. With more and more privately launched high-resolution satellites up, competition is expected to drive pay-per-view costs of Earth down, Keister said. Furthermore, new ways to reduce satellite image processing times from many hours to minutes is near-at-hand, he said.

But as satellite-clicking cameras speed by overhead, should the public be concerned about Big Brother-like intrusions on daily life?

"It's not possible to conduct the census by flying a satellite over the country and counting all the people. That is science fiction and only works in movies," said Chris Roberts, CEO of PixSell Data Brokers, Inc. of Silver Spring, Maryland.

Where commercial imaging satellites can help, Roberts said, is in helping the Census Bureau know where people are, or are not, and to help contact all residences. Also, satellite-gleaned data, coupled with heat-signature data, can distinguish between occupied and abandoned buildings. "This information can be used to help create a list of all dwellings in the nation to which the Census Bureau should send forms to people," he said.

Roberts said that while imagery cannot directly see or count people, satellite photos can discern in some cases the impact that human habitation has on the environment. Using special software, the presence of human beings can be inferred, he said.

The technology now exists to perform census taking on a small scale with some accuracy. "The Census Bureau could use commercial satellite imagery now to spot-check its results and procedures," Roberts said. "However, we are years away from doing this on a nationwide scale. It might be possible to process and interpret this volume of data for the 2010 census, but it would be a formidable task," he said.

Keister of Booz Allen said that satellite-aided census taking appears to offer a cost reduction in doing the bureau's business. "It's very, very important to keep people informed and educated that the use of satellite imagery is another tool to reduce the cost of taking the census," he said.

Today, the U.S. Census Bureau proudly points out that Census 2000 is the first fully computerized census. The final results are to be released on the internet, providing millions of data users the tools they need to construct a digital picture of America, down to any one of 7 million census blocks.

In 2010, given the proliferation of camera-toting satellites, the second census of the new millennium will not only be more high-tech, but may be going sky-high as well.