Complex sentence: According to the 2001 "Guinness World Records", Apollo 10 set the record for the highest speed attained by a manned vehicle at 39,897 km/h (11.08 km/s or 24,791 mph) during the return from the Moon on May 26,1969.
Split into simpler sentences: According to the 2001 Guinness World Records Apollo 10 set the record for the highest speed attained by a manned vehicle at 39,897 km/h (11.08 km/s or 24,791 mph). The speed record was set during the return from the Moon on May 26,1969.