American astronauts could be camping on Mars within seven years if the White House — and Congress — decide to plant the flag. That was the timetable set yesterday at Otterbein College by Robert Zubrin, lead drumbeater for manned exploration of the red planet. He spoke at the college’s 2001 Science Lecture Series. For a decade, Zubrin has promoted his “Mars Direct” plan, which he maintains could put astronauts on Mars in fewer than 10 years — and at an affordable cost. The plan uses current rocket technology and fuel manufactured on the planet itself.