An Afghan cosmonaut and two Soviet crewmates blasted off from the Baikonur launch pad on Monday to join two Soviet cosmonauts aboard the Mir orbiting station. The launch of their Soyuz TM-6 spacecraft was televised live from Soviet Central Asia. Capt. Abdol Ahad Mohmand, 29, is the first Afghan in space. Mohmand and Soviet pilot Vladimir Lyakhov, 47, will return to Earth Sept. 6. Physician Valery Polyakov, 46, will remain aboard Mir to observe the health of cosmonauts Vladimir Titov and Musa Manarov, in space since last December. "Our joint flight is a step forward in international cooperation in space and demonstrates Soviet-Afghan friendship," Lyakhov said. During their week aboard Mir, Mohmand and Lyakhov will join Titov and Manarov in space research including photographic studies of Afghanistan aimed at bolstering the economy of the war-ravaged country.