Spaceway F1, at 13,376 lb. the heaviest commercial satellite ever orbited , was set to begin providing local high definition television (HDTV) service to major cities across the U.S. after a Sea Launch Zenit-3SL delivered it to its proper geostationary transfer orbit Apr. 26. Liftoff from the Sea Launch Odyssey oceangoing platform, operating on the Equator at 154 deg. W. Long., came at 3:31 a.m. EDT, and a ground station in South Africa acquired the spacecraft as planned about 1 hr. later, according to Sea Launch Co. Spaceway F1 is the first of four Ka-band spacecraft DirecTV plans to launch by 2007 to deliver local and national HDTV programming. Based on the Boeing 702 bus, the satellite and a follow-on set for launch in June will begin delivering digital and high-definition local channels in 12 U.S. markets that together represent 36 million homes--32.8% of the U.S. television market, DirecTV said.