Nasa has said it will send a new rover to Mars in 2020 as the next stepping-stone to a manned mission.
The new robot will be partially based on the same technology that built and successfully landed the $2.5 billion Mars rover Curiosity earlier this year.
It will be launched in 2020, and will reuse the 'Sky Crane' landing system which saw Curiosity lowered on wires safely to the surface, from a levitating platform.
Nasa said basing the new, $1.5 billion robot on Curiosity's "architecture" would help keep costs low.
"The Obama administration is committed to a robust Mars exploration program," NASA Administrator Charles Bolden said. "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."
In total Nasa said it is participating in seven Mars missions.
- The Curiosity and Opportunity rovers
- The 2013 launch of the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter to study the Martian upper atmosphere
- The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) Participation in ESA's 2016 and 2018 ExoMars missions
- The new rover to launch in 2020
It is currently thought that humans might be sent to orbit Mars in the 2030s, but that manned exploration of the surface might be decades further away.
"The challenge to restructure the Mars Exploration Program has turned from the seven minutes of terror for the Curiosity landing to the start of seven years of innovation," NASA's associate administrator for science, and astronaut John Grunsfeld said in a statement.
"This mission concept fits within the current and projected Mars exploration budget, builds on the exciting discoveries of Curiosity, and takes advantage of a favourable launch opportunity."
Nasa has come under strict budget pressure in recent years, and is increasingly turning to private companies to supply its International Space Station and other key mission requirements.
This image taken by the Mast Camera on NASA's Curiosity rover highlights the geology of Mount Sharp, a mountain inside Gale Crater, where the rover landed.
Base Of Mount Sharp
South/Southwest Of Landing Site
This photo is from a test series of the 100-millimeter Mast Camera on NASA's Curiosity rover. It is looking south-southwest of the landing site and taken on Aug. 23, 2012.
More From Mast Cam
Another test photo from the Mast Camera on NASA's Curiosity Rover. Again, it's looking south-southwest on Aug. 23, 2012. The gravelly area of the landing site is visible in the foreground.
The landing site is visibile here in this portion of a 360-degree color panorama along the heights of Mount Sharp.
Big Wheels Rolling
This photo was taken by a front Hazard-Avoidance camera on NASA's Curiosity and shows track marks from the rover's first Martian drives.
Curiosity's Second Drive
Track marks are seen here after the NASA Curiosity rover completes a successful drive to an area of bedrock.
The donut-shaped tracks shown here make an infinity symbol, following the first two drives from NASA's curiosity rover. The drives took place on Aug. 22 and Aug. 27, respectively.
Heights Of Mount Sharp
The highest point of Mount Sharp visible from NASA's Curiosity rover is seen here in a high-resolution image taken on Aug. 18.
Traces Of The Landing
This mosaic image was created from images taken by the rover's Navigation cameras on Aug. 7 Pacific Time / Aug. 8 Eastern Time.
Curiosity's Extended Arm
This photo taken on Aug. 20 shows the many tools on Curiosity's extended arm.
NASA's Curiosity rover tests its wheels at its landing site on Aug. 21. Photo taken by the rover's Navigation cameras.
NASA's Curiosity rover fired its laser 50 times against these rocks at a mark called "Goulburn."
Rover Takes First 'Steps'
This overhead view shows NASA's Curiosity rover after its first successful test drive on Aug. 22, 2012.
Another Look At Rover's First Steps
Here's another view of the first track marks Rover left in the Martian surface on Aug. 22, 2012.