By Andrea Shalal and Irene Klotz

April 13 (Reuters) - The company that launches most of America's satellites unveiled on Monday a reusable rocket named "Vulcan" that is slated to take off in 2019 and end U.S. dependence on Russian-built rocket engines.

United Launch Alliance (ULA), a joint venture of Lockheed Martin Corp and Boeing Co, said more than a million people voted in an online contest to name the rocket after the home planet of Spock from the television show "Star Trek."

The rocket's first stage will be powered by a pair of liquid-oxygen and liquefied methane engines under development by Blue Origin, a space company started by Amazon.com founder Jeff Bezos.

The design should save money and help ULA compete with upstart Space Exploration Technologies Corp, or SpaceX.

Russian-made RD-180 engines currently power ULA's Atlas rocket, but the U.S. Congress banned further imports as part of trade sanctions enacted after Russia invaded Ukraine last year.

ULA Chief Executive Officer Tory Bruno told a news conference at the annual Space Symposium in Colorado that the engines will be designed to return to Earth, so they can be refurbished and reflown.

ULA's plan is to skip returning the whole booster, an approach favored by rival SpaceX, and separate the engines after launch, inflate a heat shield around them and dispatch a helicopter to nab them mid-air.

Reusing the engines will enable ULA to cut launch costs to about $100 million for a medium-lift booster and about $200 million for heavy-lift variants - roughly half the cost of ULA's current Delta 4 Heavy rocket.

Initially, ULA will use its existing upper-stage Centaur engine but plans to introduce in 2023 an advanced motor that can recycle waste propellants, greatly extending its orbital lifetime and the number of missions it can perform.

"We can take multiple satellites into orbit. We can put them in different planes. When we get done with that, we can fly back to the space station. We can do all sorts of things," Bruno said. "This is truly a game-changer."

ULA plans to reduce its launch pads from five to two, and offer a standardized menu of fixed launch prices, much like SpaceX, which posts its Falcon rocket pricing on its website.

Bruno declined to say how much Vulcan's development will cost, but said such efforts typically run at least $2 billion. Bruno said ULA will use its own profits to bankroll the venture.

(Reporting by Andrea Shalal in Colorado Springs, Colorado; and Irene Klotz in Cape Canaveral, Florida)