Elon Musk's rocket company SpaceX has landed another blow in its battle with a satellite launch company that employs more than 600 north Alabama workers.

On June 6, the U.S. Air Force announced SpaceX will launch the Air Force x-37B spaceplane in August aboard its Falcon 9 rocket. All four earlier launches of the craft, which looks like a mini space shuttle, had been atop United Launch Alliance rockets built in Decatur by those workers.

The August launch is the third Air Force contract SpaceX has won in the last year. The other two are for global positioning system (GPS) satellites, and they are also launches ULA would have made in the past.

At reported launch prices $83 million and $96 million for the GPS launches, that's a lot of money out of ULA's pocket. Because the x-37B is secret technology, the cost of its launch wasn't available. ULA CEO Tory Bruno has said his company wasn't allowed to bid on the X-37B contract.

SpaceX was certified to launch military satellites in 2015, making it ULA's only competitor in the market. The questions now are what that market will look like with two competitors and what the two competitors will look like after the competition.

Speculation is that Musk might be willing to launch rockets for a time at "little or no profit" to win business, and ULA has embarked on its own plan to trim costs and increase revenue. ULA itself is a joint venture of Boeing Corp. and Lockheed Martin Corp. formed because there wasn't enough launch business for two companies in the past.

The government has paid ULA incentives to assure the ability to launch sensitive military satellites, and ULA has responded with a perfect launch record. If it loses some of those incentives in a newly competitive market, that would be another financial hit.

ULA assembles its rockets at a sprawling plant on the Tennessee River west of downtown Decatur. The company has acknowledged layoffs.

"United Launch Alliance continues to transform our company to provide cost-effective solutions for our customers," spokeswoman Jessica Fry said this month. "while we maintain our focus on mission success.

"As we announced last year, ULA would have two workforce reshapings, one in 2016, which was completed, and one in 2017 to accomplish our business goals," Fry said. "We accomplished more than 65 percent of the 2016 and 2017 reductions through voluntary layoffs. We appreciate all of our team members' contributions and understand the difficulty and stress that reductions place on the impacted employees and their families."

Another company spokesperson said Tuesday that ULA now employs between 600 and 700 workers at the Decatur plant.

The SpaceX bidding competition isn't ULA's only challenge. Last week, the company had to rally its supporters in the U.S. Senate to amend a sanctions bill against Russia that would have blocked the Russian RD-180 rocket engine's continued access to the American market. ULA uses RD-180 engines in its Atlas V rocket, but is working hard on an alternative.