Mercury's surface in "enhanced color," a color scheme created to emphasize color differences. This is not what Mercury would look like to the human eye, but by applying mathematical analysis to images, color differences can be accentuated beyond those visible to a person.
Mount Rushmore National Memorial under construction.
The workers had to endure conditions that varied from blazing hot to bitterly cold and windy. Each day they climbed 700 stairs to the top of the mountain to punch-in on the time clock. Then 3/8 inch thick steel cables lowered them over the front of the 500-foot face of the mountain in a "bosun chair." Despite the dangers, no one was killed during the project.
Otters in Glacier Bay National Park and Preserve, Alaska.
The sea otter population of Glacier Bay has increased dramatically in the past 20 years. Ecologists consider sea otters a keystone species here. Otters consume vast quantities of clams, urchins, crabs, and other invertebrates and their presence creates ripples through the ecosystem. NPS photo.
Every day someone like you becomes a wildland wildfire fighter, a teacher, a trail-builder, a museum curator, or a park ranger. Discover your opportunities in national parks. Come to play. Come to learn. Come to serve. Develop your environmental leadership skills. Find a job. Be the next generation to preserve and protect these great places.
With more than 80% of Americans living in urban areas, urban parks are more important than ever. The father of American landscape architecture, Frederick Law Olmsted, said of urban parks:
It is one great purpose of the Park to supply to the hundreds of thousands of tired workers, who have no opportunity to spend their summers in the country, a specimen of God's handiwork that shall be to them, inexpensively, what a month or two in the White Mountains or the Adirondacks is, at great cost, to those in easier circumstances.
AMERICA'S GREAT OUTDOORS: Salazar Announces Successful Renovation of Lincoln Memorial Reflecting Pool
National Park Service to begin filling Reflecting Pool in coming days; Sustainable, accessible design to re-open to public end of August
WASHINGTON DC -- Secretary of the Interior Ken Salazar today announced that the National Park Service will soon begin refilling the Lincoln Memorial Reflecting Pool after completing a historic renovation, including replacement of the pool's structure and installation of a sustainable, state-of-the-art circulation system that pulls water from the Tidal Basin. Nearly 25 million people visit the National Mall each year.
“The Reflecting Pool has served as the backdrop for important moments in our nation's history ranging from Marian Anderson's concert on Easter Sunday in 1939 to Martin Luther King's ‘I Have a Dream' speech in 1963,” Salazar said. “With this renovation, we have given the Reflecting Pool a much-needed overhaul and brought its engineering into the 21st century. The design is accessible and sustainable, significantly reducing water usage, improving water quality, and welcoming visitors from around the world who come to see this iconic landmark."
Built in the 1920's on marshland without pilings for support, the original pool sank significantly over the years, which caused cracks and leaks. Holding 6.75 million gallons of water, the reflecting pool lost an estimated 500,000 gallons a week to leaks and evaporation and required about 30 million gallons of municipal water annually to maintain it. Because it lacked a circulation system, it had to be emptied, cleaned and refilled twice a year.
The pool was closed in November, 2010 for reconstruction, which was made possible with $34 million in funding from the American Recovery and Reinvestment Act.
The new pool is supported underground by more than 2,100 50-foot timbers to prevent it from sinking. It is shallower than the original, holding about 4 million gallons of water and realizing significant water savings. Specially-designed tinted concrete will improve the appearance and reflectivity of the water. The design maintained the footprint of the original structure, and the 580 granite stones that had been placed along the edges of the pool in the 1920's were catalogued and put back into place to maintain the pool's cultural integrity.
The new pool uses the Tidal Basin as its primary water source, eliminating the reliance on the potable city water supply. The water will be treated and circulated in a closed loop. Water that is lost to evaporation will be addressed by capturing and treating the discharge from the adjacent World War II Memorial fountain.
“The extraordinary engineering of the new pool will enable the National Park Service to meet our long-term strategy for sustainable management of our parks,” said National Park Service Director Jonathan B. Jarvis. “The design enhances what is one of the most iconic vistas in the National Park System for the benefit of the 25 million visitors each year and for generations to come.”
The project also improved security for the Lincoln Memorial and enhanced the surrounding landscape. Dirt walkways were paved to improve access for visitors and will be wheelchair accessible. New energy-efficient lighting will reduce light pollution and cut maintenance costs.
Overall, the renovation required more than 19,000 cubic yards of concrete, 14,300 linear feet of pipe, 3 million pounds of epoxy coated rebar, and more than 350,000 square feet of copper wire mesh.
It will take the National Park Service approximately three to five days to fill the pool, which is scheduled to be reopened to the public at the end of the month.
“We know that the pool's closure during construction has been a disappointment to many of our visitors, so we're excited to be able to make it available once again,” said Bob Vogel, superintendant of the National Mall and Memorial Parks. “This is one of our nation's most important landmarks, and I think that our visitors will agree that the wait was well worth it when they see the quality of work and improved design.”