More than two months after they provided relay communications for the landing of InSight on Mars, and more than a month since any contact has been heard from them, engineers now consider the two MarCO cubesats to likely be dead.

Now well past Mars, the daring twins seem to have reached their limit. It’s been over a month since engineers have heard from MarCO, which followed NASA’s InSight to the Red Planet. At this time, the mission team considers it unlikely they’ll be heard from again.

MarCO, short for Mars Cube One, was the first interplanetary mission to use a class of mini-spacecraft called CubeSats. The MarCOs – nicknamed EVE and WALL-E, after characters from a Pixar film – served as communications relays during InSight’s landing, beaming back data at each stage of its descent to the Martian surface in near-real time, along with InSight’s first image. WALL-E sent back stunning images of Mars as well, while EVE performed some simple radio science.

All of this was achieved with experimental technology that cost a fraction of what most space missions do: $18.5 million provided by NASA’s Jet Propulsion Laboratory in Pasadena, California, which built the CubeSats.

WALL-E was last heard from on Dec. 29; EVE, on Jan. 4. Based on trajectory calculations, WALL-E is currently more than 1 million miles (1.6 million kilometers) past Mars; EVE is farther, almost 2 million miles (3.2 million kilometers) past Mars.

Their loss of contact more than a month after the November landing of InSight actually shows their incredible success. Both MarCO cubesats functions well past Mars, demonstrating that these tiny satellites can do much of the same things bigger satellites costing billions do.