This story was updated on Jan. 4 to give the new planned launch date of Jan. 7.
The wait is almost over for the mysterious Zuma spacecraft.
A SpaceX Falcon 9 rocket is scheduled to launch Zuma, a top-secret U.S. government satellite, between 8 p.m. and 10 p.m. EDT Sunday (Jan. 7; 0100 to 0300 GMT Jan. 8) from Space Launch Complex 40 at the Cape Canaveral Air Force Station in Florida.
The liftoff was originally planned for mid-November, but SpaceX pushed the launch date back to study data from a recent payload-fairing test performed for another customer. (The payload fairing is the nose cone that protects a spacecraft during liftoff.) SpaceX had been targeting Friday evening (Jan. 5) but on Thursday (Jan. 4) announced an additional two-day delay.
It's unclear what Zuma will do once it's aloft; the satellite and its mission are shrouded in mystery. Pretty much all we know is Zuma's vague destination: somewhere in low-Earth orbit.
Sunday's action will also include a landing attempt by the first stage of the two-stage Falcon 9, which will come back to Earth at Landing Zone 1, a SpaceX facility at Cape Canaveral Air Force Station, which is next door to NASA's Kennedy Space Center.
To date, SpaceX has landed Falcon 9 boosters 20 times and reflown used first stages five times. Such activities are part of the company's push to develop fully reusable rockets and spacecraft, an advance that company founder and CEO Elon Musk has said will slash the cost of spaceflight.
Editor's note: This story was updated Jan. 5 to correct the launch site for SpaceX's Zuma mission. It will launch from Space Launch Complex 40 at the Cape Canaveral Air Force Station in Florida, not NASA's Kennedy Space Center.