We'll keep the lights on for you. (MAS)

For the past nine years, two gigantic beams of light have shown over Lower Manhattan—a beacon of loss and hope, a searchlight for something that would never be found and yet would stay with all New Yorkers forever.

Known as the Tribute in Light, it was a public art project created by the Municipal Art Society and Creative Time to commemorate the fallen Twin Towers. Beginning six months after 9/11, and relit every anniversary thereafter, the temporary, luminous memorial will return this year for the 10th anniversary of the attacks. It could be for the last time ever.While it seems as simple as flipping a switch, Tribute in Light actually costs hundreds of thousands of dollars to produce each year. Here is how the MAS describes the process:

It takes more than a week to produce Tribute in Light. The process starts Friday, September 2, and continues through dusk on September 11, when a switch is flipped and the powerful beams shoot four miles across the sky, visible for 60 miles around.

Everything is done by hand by the crew of 30 electricians, lighting technicians, stagehands and production assistants. From September 2 to 11 they’re at the projection site, the roof of the Battery Parking Garage in Lower Manhattan, installing, arranging, calibrating and testing 88 refrigerator-sized, 7,000-watt xenon searchlight bulbs so powerful that everyone handling them must wear eye protectors and special gloves.

And it's not just labor and expensive light bulbs that drive up the cost. There is also storage costs and site fees, plus one heck of a Con-Ed bill. Still, it's worth it, and the Municipal Art Society is hoping New Yorkers and other will help keep the Tribute in Light on. The Lower Manhattan Development Corporation and other donors have spent millions of dollars to produce the project over the years, but that funding does not extend beyond this year.

The MAS is launching a Tribute in Light fundraiser to make the project permanent, including finding it a new home.

"Tribute has become a world-renowned icon of remembrance, honoring those who were lost, as well as those who worked so hard to get our city through that terrible trial," according to the MAS. What will it take to ensure the tribute itself is not lost?

mchaban [at] observer.com | @MC_NYC