They hover above our heads, out of sight, zooming in and taking pictures.

They aren't interested in the latest celebrity wedding or covert military operation. And the images they take aren't going to make the front page of any magazine or website.

But maybe they should.

That's because the data collected by these powerful satellites have helped save countless lives by allowing meteorologists to warn people about dangerous storms -- sometimes a week before they strike -- with pinpoint accuracy.

Seven days before Superstorm Sandy hit the United States on October 29, computer models based on the data from these satellites predicted the storm would make landfall in New Jersey.

It landed just five miles from where the earliest forecasts said it would.

"It is unprecedented," said Chad Myers, CNN's severe weather expert and meteorologist. "(No) other storm in recent memory has been forecast that good for that long.

"We knew days in advance, much more in advance, 48 hours in advance more than we knew in Katrina (in 2005)."

It could have been a much different story.

A month before the 1,000-mile-wide storm struck the Northeast, at the height of the hurricane season, the geostationary satellite that monitors the Caribbean and Atlantic -- where Sandy gathered strength -- stopped working. While there are dozens of American weather satellites in orbit, these geostationary spacecraft are crucial to predicting dangerous weather patterns.

Luckily, the National Oceanic and Atmospheric Administration, or NOAA, had a backup satellite to scramble into place. Without it, the early warning for Sandy's impending strike on the northeast might not have been as accurate.

That close call has meteorologists worried that, in this era of shrinking budgets, aging satellites might not get the expensive repairs they need to operate, and NOAA might not be able to purchase backup satellites.

Satellites like these are expensive -- $1 billion each -- and they take five years to build and launch.

Compare that to the cost of major storms, like Sandy which is estimated to have inflicted nearly $80 billion in damage in New York and New Jersey alone. Not to mention the cost in human lives.

"If there's a major failure of the satellites, that would be a major disaster and indeed we would be blinded in many respects," explained Kevin Trenberth, who heads climate analysis at the National Center for Atmospheric Research.

"We would not be able to see what's going on in the Earth's system as well as we can now."

Scientists can only wonder how many lives this technology could have saved on September 8, 1900, when a Category 4 hurricane slammed into Galveston, Texas, with no warning, killing at least 8,000 people. It would be another 70 years before satellites were used in weather forecasting.

A major failure of these satellites could pose a serious threat as climatologists and meteorologists warn that storms like Sandy could become more frequent and more powerful in the near future.

Lessons from Katrina

Seven years ago, the only thing protecting the low-lying city of New Orleans from a massive storm surge was an inadequate and outdated system of levees and floodwalls.

After Hurricane Katrina slammed into the U.S. Gulf Coast in 2005 -- killing 1,800 people and inflicting $100 billion in damage -- Congress said never again.

Federal lawmakers spent $14.5 billion, mostly federal funds, to build a fortress around New Orleans.

Today the city is protected by 350 miles of stronger levees and higher flood walls that form a circle around New Orleans to keep any deadly storm surges at bay.

Among its most powerful new weapons: the largest storm-surge barrier in the world.

The massive barrier wall extends nearly 200 feet into the earth, and towers 26 feet above the water. It's reinforced by 350,000 tons of steel -- 50 times the amount in the Eiffel Tower.