NASA engineers weren’t sure what to expect when the MarCO mission launched last May. “I think it’s opened up so many doors and kind of shattered expectations,” said Anne Marinan, a systems engineer at the Jet Propulsion Laboratory in Pasadena, Calif. “The fact that we actually got as far as we did with both satellites working was huge.”

About a month after dropping InSight onto Mars, NASA lost contact with the MarCOs. The agency may attempt to wake them up someday, but for now Wall-E and EVE are silently roaming the solar system, proof of a new space exploration technology that almost never got to the launchpad.

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Uncanceling the cubesat program

The MarCO mission was canceled repeatedly. After all, the primary goal of NASA’s InSight mission was to land a stationary spacecraft on Mars and listen for marsquakes, giving scientists an improved picture of the red planet’s internal makeup.

And multiple spacecraft orbiting Mars already relay information from its surface back to Earth. The cubesats wouldn’t play a direct role in InSight’s success or failure, so it was a challenge to persuade NASA to support a nonessential program using unproven technology .

The MarCO team fought hard, prevailing at last with the argument that at a cost of only $18 million, the idea was worth taking a chance on. If these two tiny satellites worked well, it would not only mean that similar spacecraft could support big planetary missions in the future, but also that cubesats might carry instruments of their own.