The Omega-Tango Missions

The Omega-Tango Missions is the thrilling conclusion to the Battle For Mars Technothriller series. The Omega site on Mars seems to show some kind of semi-transparent tunnel exposed above ground for a short distance. NASA and the Chinese space agency both send people to investigate. But the tunnel hides a deadly secret and the trail will lead to another site and another mission, the Tango Mission, where humans will finally discover the last and ultimate Martian secret. Will they find a way to get back to Earth, or will that secret die with them?