This story was updated at 7:50 a.m. ET.
Space shuttle Discovery and its crew of seven astronauts are headed for a morning landing in Florida today, now that rain and fog have cleared up enough to allow their return to Earth.
Fog and rain delayed NASA's first attempt to land the shuttle at its Kennedy Space Center in Cape Canaveral, Fla., but conditions have improved greatly. Discovery is due to land at the space center — its home port and launch site — at 9:08 a.m. EDT (1308 GMT).
Mission Control radioed the good news to Discovery's crew and ordered the astronauts to fire their shuttle's rocket engines at 8:02 a.m. EDT (1202 GMT) in order to leave Earth orbit and begin the descent home.
"Roger, Houston, we are go for the deorbit burn," Discovery commander Alan Poindexter replied.
Discovery is flying a rare re-entry and landing approach that will carry it over much of North America.
The shuttle should be visible (weather permitting) to observers on the ground as it streaks from the northwestern United States to the southeast, passing over parts of western Canada, Washington, Wyoming, Colorado, Kansas, Nebraska, Oklahoma, Arkansas, Mississippi, Alabama and Georgia and then finally into Florida for a landing at Cape Canaveral. The last time a shuttle made such an approach was in 2007.
NASA typically tries to have space shuttles re-enter from the southwest — an approach that is mostly over the southern Pacific Ocean, parts of Central America and the Gulf of Mexico — to avoid flying over populated areas since the tragic loss of the shuttle Columbia, which broke apart over Texas during re-entry.
NASA had several options to land Discovery in Florida and at a backup runway in California today. But the space agency preferred to land Discovery in Florida since it saves about a week of time and $1.8 million in transport costs to ferry the spacecraft home from California atop a modified Boeing 747 jumbo jet.
Discovery is returning home to wrap up a 15-day mission to the International Space Station, where the astronauts delivered nearly 8 tons of supplies, science equipment and spare parts, and performed three maintenance spacewalks. The shuttle launched into space on April 5.
This mission is the second-to-last mission for Discovery, which is NASA's oldest space shuttle. The spaceflight is also one of NASA's few remaining shuttle missions before the space plane fleet is retired in the September.
After Discovery lands, NASA plans to launch just three more shuttle missions.
The next to fly is shuttle Atlantis, which is due to roll out to its seaside launch pad at the Kennedy Space Center tonight. That launch pad trek — the last planned one for Atlantis — was also delayed a day because of bad weather.
SPACE.com is providing complete coverage of Discovery's STS-131 mission to the International Space Station with Managing Editor Tariq Malik and Staff Writer Clara Moskowitz based in New York. Click here for shuttle mission updates and a link to NASA TV.