NASA has just announced new plans for additional Mars missions, building on its ongoing Curiosity rover expedition. The US space agency will send a new "robotic science rover" to the Red Planet in 2020, which it says will cap a decade of new missions. NASA Administrator Charles Bolden said of the plans that "with this next mission, we're ensuring America remains the world leader in the exploration of the Red Planet, while taking another significant step toward sending humans there in the 2030s."

"Another step toward being responsive to high-priority science goals and the president's challenge of sending humans to Mars orbit in the 2030s."

The announcement adds to a growing list of Mars missions for NASA; the agency recently announced that it will return to Mars in 2016 for geologic discovery with its InSight lander. Through the remainder of the decade, NASA will study Mars at various levels: on the surface, in the atmosphere, and into Mars' interior. NASA says the new rover mission will be based on the Mars Science Laboratory, but it doesn't have a specific purpose yet; the agency plans to form a team to outline the mission's scientific objectives, and then use a competitive process to determine scientific instrument selection.

On August 6th, 2012, NASA successfully landed the Curiosity rover on Mars as humans around the world looked on in excitement. As NASA streamed live coverage of the rover's approach to Mars, anticipation climaxed in "seven minutes of terror:" Curiosity's descent from Mars' atmosphere to the planet's surface. Since its celebrated landing on the planet's surface, the rover has been returning regular dispatches to Earth, including intriguing instrument data, breathtaking panoramas, and one self-portrait.

NASA will provide a formal announcement tonight at 7PM ET on Ustream — and we'll be watching.