WASHINGTON Cake, gifts and a low-key family celebration may be how many senior citizens picture their 70th birthday. But NASA 's oldest serving astronaut Don Pettit became a septuagenarian while hurtling towards the Earth in a spacecraft to wrap up a seven-month mission aboard the International Space Station ( ISS ). A Soyuz capsule carrying the American and two Russian cosmonauts landed in Kazakhstan on April 20, the day of Pettit's milestone birthday. "Today at 4:20 Moscow time (1:20 GMT),