NASA is accelerating its chase of advanced nuclear power systems that could allow spacecraft to travel deeper into space faster and cheaper. NASA Administrator Sean O’Keefe and other agency officials say the White House has approved a substantial budget increase for the $1 billion Nuclear Systems Initiative introduced last year. In about a week, when President Bush unveils his 2004 budget, the dollars invested in the renamed Project Prometheus will be more, though NASA won’t say how much. “We are looking to significantly enhance that effort, so stay tuned,” O’Keefe said. “We are looking to very specific mission objectives.”