Two mini-probes fade into the sunset beyond Mars: Is Opportunity rover next?

Mars view from MarCO
This image of Mars was captured by one of NASA’s MarCO satellites from a distance of about 4,700 miles, about 10 minutes after the descent of NASA’s Mars InSight lander on Nov. 26, 2018. The grid seen on the right edge of the image is the spacecraft’s high-gain antenna. (NASA / JPL-Caltech Photo)

Farewell, WALL-E and EVE: NASA says it’s lost contact with two briefcase-sized MarCO nanosatellites, more than two months after their history-making Mars flyby.

And yet another robotic explorer, NASA’s Opportunity rover, has been mute on Mars for eight months, heightening suspicions that its 15-year watch could be at an end.

There’s still hope for Oppy: Mission managers at NASA’s Jet Propulsion Laboratory say they haven’t been able to rouse the golf-cart-sized robot since a global dust storm wiped kept it from recharging its solar-powered battery system last June. But with Martian winter closing in, they’ve just begun a new set of wakeup strategies.

There’s less hope for the two MarCO satellites, whose nicknames come from a couple of robotic characters in the Disney/Pixar animated film “WALL-E.”

WALL-E and EVE were launched as secondary payloads with NASA’s Mars InSight lander last May, to test low-cost technologies for generating power and relaying data back to Earth from deep space. Their $18.5 million MarCO mission made history as the first interplanetary voyage taken on by a class of miniaturized satellites known as CubeSats. (MarCO is short for “Mars Cube One.”)

MarCO was a huge success, sending back not only data but also a crowd-pleasing series of images captured before and after the Nov. 26 flyby.

There had been rumblings about a follow-on mission, but NASA lost contact with WALL-E on Dec. 29, a little more than a month after the flyby. EVE was last heard from on Jan. 4. In this week’s status update, NASA says WALL-E is currently more than a million miles beyond Mars, and EVE is almost a million miles farther out.

The mission team has several theories for why they haven’t been able to contact the pair. Their thrusters may no longer be able to keep the spacecraft steady enough to send and receive commands. Or maybe the probes’ brightness sensors aren’t working well enough to keep the solar-powered spacecraft properly pointed at the sun. The farther out the probes get, the harder it is to maintain precise aim.

WALL-E and EVE are continuing outward in their orbit and won’t start coming back toward Earth and the sun until this summer. The mission team will try to re-establish contact at that time, but it’s unclear whether their batteries and other components will last that long.

Andy Klesh, the mission’s chief engineer at JPL, paid tribute to WALL-E and EVE for blazing a trail that future CubeSats will surely follow.

“This mission was always about pushing the limits of miniaturized technology and seeing just how far it could take us,” Klesh said in the NASA update. “We’ve put a stake in the ground. Future CubeSats might go even farther.”

Going forward, NASA plans to invest roughly $100 million a year in small satellites, including CubeSats. And thanks to the small-satellite revolution, even students from middle schools and elementary schools can build probes for space exploration.

“There’s big potential in these small packages,” said John Baker, the MarCO program manager at JPL. “CubeSats — part of a larger group of spacecraft called SmallSats — are a new platform for space exploration that is affordable to more than just government agencies.”

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