(Reuters) - In what may be the ultimate in long-distance telephone service, NASA on Wednesday put out a call for a commercially owned and operated satellite network on Mars.

The U.S. space agency needs to keep in touch with its rovers, landers and orbiters that have been chipping away at studies and experiments to learn if the planet most like Earth in the solar system ever supported life.

The robotic probes, however, are useless if they cannot relay their results, and the two communication satellites currently in orbit are getting old. The Mars Odyssey spacecraft was launched in 2001. Mars Reconnaissance Orbiter followed in 2005.

The aging of NASA’s Mars communications system comes as the United States, Europe, Russia and India mount a fresh wave of science campaigns, including two atmospheric probes slated to arrive at Mars in September and two life-hunting rovers due to launch in 2018 and 2020.

“There is a potential communications gap in the 2020s,” NASA wrote in its solicitation, which was posted on the agency’s procurement website.

“With that in mind, NASA is interested in exploring alternative models to sustain and evolve the Mars relay infrastructure,” the solicitation said.

A commercially operated communications service could be less expensive and more capable than what NASA could build and operate on its own, while providing “appropriate return-on-investment,” to the service provider, NASA Mars exploration program executive Lisa May said in a statement.

For now, NASA is just seeking ideas, with no firm plans or funding to purchase commercial communication services on Mars. Proposals are due by Aug. 25.

The solicitation is open to all organizations, including U.S. industry, universities, nonprofit groups, NASA and other government centers, as well as international organizations.

(Reporting by Irene Klotz; Editing by Ken Wills)