Original sentence: However, recent financial analysis has shown that the Ares I would cost $1 billion or more to operate per flight only if the Ares I is flown once a year.If the Ares I system is flown multiple times a year the costs could fall to about $176 million per flight
Edited sentence: However, recent financial analysis has shown that the Ares I would cost $1 billion or more to operate per flight if the Ares I is flown just once a year.If the Ares I system is flown multiple times a year the costs could fall to as low as $138 million per launch