WASHINGTON (CNN) -- The U.S. military may try within days to shoot down a failed satellite using a missile launched from a Navy ship, officials announced Thursday.
A Delta II rocket lifts off in December, carrying a reconnaissance satellite that failed hours later.
Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, told reporters at the Pentagon that the window to accomplish the mission could begin in three to four days, and remain open for seven to eight.
While much space trash and debris have safely crashed to Earth after burning up in the atmosphere on re-entry, authorities said what makes this 5,000-pound satellite different is the approximately 1,000 pounds of frozen toxic hydrazine propellant it carries.
Without any intervention, officials believe the satellite would come down on its own in early March.
If it came down in one piece, nearly half the spacecraft would survive re-entry and the hydrazine -- heated to a gas -- could spread a toxic cloud roughly the size of two football fields, Cartwright said. Learn more about the shoot-down mission »
Hydrazine is similar to chlorine or ammonia in that it affects the lungs and breathing tissue, the general said.
The option of striking the satellite with a missile launched from an Aegis cruiser was decided upon by President Bush after consultation with several government and military officials and aerospace experts, said Deputy National Security Adviser James Jeffrey.
"After further review of this option and, in particular, consideration of the question of saving or reducing injury to human life, the president, on the recommendation of his national and homeland teams, directed the Department of Defense to carry out the intercept," Jeffrey said.
The goal is to hit the satellite just before it enters Earth's atmosphere and blast it apart so that the hydrazine tank explodes. The smaller debris would be more likely to burn up in the atmosphere.
NASA Administrator Michael Griffin said there's nothing the military can do to make the outcome worse.
"If we miss, nothing changes. If we shoot and barely touch it, the satellite is just barely in orbit" and would still burn up somewhat in the atmosphere, Griffin said.
"If we shoot and get a direct hit, that's a clean kill and we're in good shape," he added.
Experts said that with three-quarters of Earth covered in water, there's a 25 percent chance the satellite's remnants will hit land -- and a 1 percent chance they will hit a populated area.
There will be three Navy ships involved in the operation. The USS Lake Erie, an Aegis cruiser, will fire the missile, while trajectory information comes from a second ship. The third ship will be used as a backup, U.S. Navy officials said.
The Lake Erie has long been used as the platform for the sea-based missile defense program.
Cartwright said the satellite stopped working within hours of its launch in December and has not responded to attempts to communicate with it. He brushed off blog theories that the military wants to shoot down the satellite with a missile to destroy any classified data it may have accumulated in its short life, or to prevent other countries from acquiring the technology.
In January 2007, China used a land-based missile to destroy a 2,200-pound satellite that was orbiting 528 miles above Earth.
But the impact left more than 150,000 pieces of debris floating above Earth, NASA estimates. The space agency characterizes nearly 2,600 pieces as "large," meaning greater than 4 inches across, which pose a potential threat to satellites and spacecraft.
China is responsible for 42 percent of all satellite debris in orbit as of January 1, most of it from that Fengyun-C meteorological satellite.
NASA has called it the worst satellite breakup in history. E-mail to a friend
CNN's Mike Mount and Kate Tobin contributed to this report.