The US and European space agencies are edging towards a joint mission to bring back rock and soil samples from Mars.
Nasa and Esa have signed a letter of intent that could lead to the first "round trip" to another planet.
The move was announced as a meeting in Berlin, Germany, discussed the science goals and feasibility of a Mars Sample Return (MSR) mission.
The venture would allow scientists to answer key questions about Martian history, reports BBC.
Those questions include whether the Red Planet once hosted life.
Scientists at the Mars meeting said that there was only so much they could learn from Martian meteorites and from the various rovers and static landers sent to the Red Planet.
The next step had to be a mission that would retrieve samples from the Martian surface, blast them into space in a capsule and land them safely on Earth.
They could then be subjected to detailed analysis in laboratories, using instruments that are currently too large and power-hungry to carry as part of a robotic rover's payload and techniques that are difficult to perform from 55 million kilometres away.
Making the announcement at the ILA Berlin Air and Space Show, which is taking place at the same time as the Mars meeting, Dr Thomas Zurbuchen, Nasa's associate administrator for science, said: "We want to partner with the European Space Agency, but also with other partners."
He said this included potential link-ups with the commercial space sector, adding: "We will at every point look at what is available in the commercial market. Nasa has no interest whatsoever in developing things that we can buy."
Dave Parker, director of human and robotic exploration at Esa, commented: "It's very important that every mission we send to Mars discovers something slightly unusual. It's on the basis of that that we tend to plan the next mission or next missions."