【Watch Black Water: Abyss Online】

Just call it an interplanetary postcard.

On May 5,Watch Black Water: Abyss Online NASA launched two, tiny, briefcase-sized satellites (called cubesats) to Mars, but at least one of them still has an eye for Earth. One of the Mars Cube One (MarCO) cubesats, nicknamed Wall-E, snapped a photo of Earth from more than half a million miles away.

Earth appears as a pale blue speck, and to its left is an even fainter speck: our moon.

NASA scientists weren't doing this for sport, but to see if the cubesat's antenna had unfolded -- and worked.

The cubesats are following NASA's InSight lander to the red planet.

NASA wants to see if these small satellites can relay information from the lander -- a car-sized spacecraft that will study Mars' geology -- back to Earth as the probe lands on the Martian surface.

For NASA scientists, Earth's appearance as just a minuscule blue dot was reminiscent of an image the Voyager spacecraft sent back to Earth in 1990, from several billion miles away.

"Consider it our homage to Voyager," Andy Klesh, Mars Cube One's chief engineer said in a statement.

"Cubesats have never gone this far into space before, so it's a big milestone," Klesh added. "Both our Cubesats are healthy and functioning properly. We're looking forward to seeing them travel even farther."

The cubesats -- formally called MarCO-A and MarCO-B -- have a ways to go.

They'll be subjected to the intense cold and radiation of deep space for six months, and it's unknown if the miniaturized satellites will be able to bear the extreme conditions.

If they do make it to Mars and successfully relay information back to Earth, they will have demonstrated that perhaps small satellites may have a place in deep space as a part of a NASA mission after all.

Rather than building and launching bulky satellites into space, these small, cheaper spacecraft can accompany missions to land on other planets and moons, making hugely expensive space exploration considerably more affordable.

The two Mars Cube One satellites and InSight should arrive at Mars in November.