(CNN) When NASA's InSight lander was on its seven-month trip to Mars, it wasn't alone. Two suitcase-size spacecraft, called MarCO, followed InSight on its journey. They were the first cube satellites to fly into deep space. And now, they've fallen silent.

During InSight's entry, descent and landing on November 26 , the MarCO satellites received and transmittedcommunication from the lander to let NASA know that InSight was safely on the surface of the Red Planet. They were nicknamed EVE and WALL-E, for the robots from the 2008 Pixar film.

They were the great experiment accompanying the InSight mission, and their success was measured by survival, according to NASA. The fact that the tiny satellites made it to Mars, flying behind InSight through space, excited engineers.

But the experiment has come to an end.

After InSight was safely on Mars, MarCO kept on flying. At the time, the MarCO team collected data from each satellite to determine how much fuel they had left and took a deeper look at how they performed.

Engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the MarCO spacecraft.

"WALL-E and EVE performed just as we expected them to," MarCO chief engineer Andy Klesh at NASA's Jet Propulsion Laboratory said at the time. "They were an excellent test of how CubeSats can serve as 'tag-alongs' on future missions, giving engineers up-to-the-minute feedback during a landing."

Engineers last heard from WALL-E on December 29 and EVE on January 4, the agency said. They estimate that EVE is now 2 million miles past Mars, and WALL-E is more than 1 million miles past Mars.

The loss of communication isn't entirely a surprise. The team believes that WALL-E's leaky thruster, wobble-causing control issues, the lack of being able to send and receive commands or even battery issues could be at play. The satellites have sensors to point them toward the sun and recharge.

The satellites are orbiting the sun and will only gain more distance from Earth. If there is any hope of future communication, the satellites will have to keep pointing their antennas to be able to transmit to mission scientists. The team believes there is another chance to try to contact the satellites this summer, when they're moving toward the sun, but they don't know whether the batteries or other components will last that long in deep space.

Little satellites have a big future

But MarCO was still a successful experiment, they said.

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

MarCO is a demonstration of potential future capability, said Jim Green, director of NASA's Planetary Sciences Division.

In addition to assisting with communication about the landing, MarCO-B took an image of Mars from 4,700 miles away during its flyby.

"WALL-E sent some great postcards from Mars!" said Cody Colley of JPL, MarCO's mission manager. "It's been exciting to see the view from almost 1,000 miles (1,600 kilometers) above the surface."

MarCO-B took this image as it approached Mars just before NASA's InSight spacecraft landed.

And also during the flyby, MarCO-A transmitted signals through the edge of the Martian atmosphere. That atmosphere causes interference to change the signal when it's received on Earth, a way for scientists to detect how much atmosphere is present and even its composition.

"CubeSats have incredible potential to carry cameras and science instruments out to deep space," said John Baker, JPL's program manager for small spacecraft. "They'll never replace the more capable spacecraft NASA is best known for developing. But they're low-cost ride-alongs that can allow us to explore in new ways."

And for the team that worked on MarCO, the success of the mission is just the beginning.

"MarCO is mostly made up of early-career engineers and, for many, MarCO is their first experience out of college on a NASA mission," said Joel Krajewski of JPL, MarCO's project manager. "We are proud of their accomplishment. It's given them valuable experience on every facet of building, testing and operating a spacecraft in deep space."

This paves the way for new CubeSats that NASA will launch.

"There's big potential in these small packages," Baker said. "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."

So how is InSight doing?

The stationary lander has been quietly toiling away and sending back selfies to assure everyone that it's doing just fine, even as MarCO disappears into the void.

InSight placed its seismometer, which can detect quakes on Mars and provide mission scientists with a sense of the planet's deep interior, on the surface in December. It's been making adjustments to that for the past few weeks.

NASA's InSight lander deployed its Wind and Thermal Shield to cover InSight's seismometer.

This week, InSight placed a protective domed shield over the seismometer to make sure the data it collects is accurate, since factors like wind can create disruptions. The shield will keep the instrument, which is incredibly sensitive, from being affected by wind. It was designed with aerodynamics in mind so the wind wouldn't flip it off the instrument and instead would help press it down.

Because InSight's location includes a few rocks, the shield has a chain mail skirt around the bottom to help it settle over the surface. The shield was also designed to help stabilize temperature. The temperature here can fluctuate by about 170 degrees Fahrenheit over the day, the agency said.

"Temperature is one of our biggest bugaboos," InSight Principal Investigator Bruce Banerdt said. "Think of the shield as putting a cozy over your food on a table. It keeps SEIS from warming up too much during the day or cooling off too much at night. In general, we want to keep the temperature as steady as possible."

Next week, InSight will deploy more instruments on the Martian surface.</s>The first two tiny satellites to ever go interplanetary have fallen silent in deep space for some unknown reason, and it’s likely we may never hear from them again. But for NASA, which launched the probes last year, this loss of communication isn’t considered a failure. Before the pair went quiet, these vehicles demonstrated that tiny satellites could become critical tools for exploring other worlds deep within our Solar System.

The silent satellites are the two MarCO probes — nicknamed EVE and WALL-E from Pixar’s sci-fi movie — which flew to Mars along with NASA’s InSight lander last year. Both MarCOs are modified CubeSats, a type of standardized small satellite about the size of a cereal box used for space research. Before the InSight mission, CubeSats had only ever orbited around Earth, but NASA wanted to know if these types of satellites could be useful on deep-space missions, too.

small satellites about the size of a cereal box

The MarCO satellites demonstrated just that and more, exceeding everyone’s expectations. They launched along with the InSight lander on May 5th, and flew in formation with the spacecraft all the way to the Red Planet. Once InSight got to Mars and started its descent to the surface on November 26th, the MarCO satellites observed the landing sequence from overhead and sent real-time status updates back to Earth. That way, NASA knew how each step of the landing process went just minutes after it happened. “We got the data much earlier than we would have — in near real-time as the landing was happening — adding to the excitement of the event,” Joel Krajewski, the project manager of the MarCO spacecraft at NASA’s Jet Propulsion Laboratory, tells The Verge.

These quick notifications were a luxury that NASA wouldn’t have had without the MarCO satellites. Other, larger spacecraft in orbit around Mars were gathering data of InSight’s landing, too. But because of their locations and the positions of the planets, it took a while for these vehicles to send that info back to Earth. For instance, NASA’s Mars Reconnaissance Orbiter, which has been in orbit around the Red Planet since 2006, observed the InSight landing from the Martian skies but then quickly dipped below the horizon. It wasn’t able to send back the data until three hours after the landing.

If something had gone wrong during InSight’s landing, it might have taken some time for NASA to diagnose and work the problem without the MarCO satellites. “We always want to get data from a landing while it’s happening, in case the unfortunate happens and we lose a lander,” Krajewski says. “We want the equivalent of the airline black box to understand as much as possible.” Fortunately, InSight’s landing was flawless, and so were the MarCO satellites’. The satellites even sent back the first picture that InSight’s camera took on Mars, showing a flat red surface through a dirty camera lens.

“We want the equivalent of the airline black box to understand as much as possible.”

But while the MarCOs were a resounding success, they weren’t really designed to last beyond the InSight landing. “This mission was experimental from day one, where much of the objective of MarCO was simply to survive as we traveled out to Mars,” Andy Klesh, the MarCO chief engineer at NASA JPL, tells The Verge, adding that, “two months into the mission, we had proven every piece of our technology.” After observing the InSight landing, the satellites ended up in orbit around the Sun, and for about a month, they sent signals back to Earth. But in late December and early January, NASA lost communication with WALL-E and EVE within just one week of each other. The space agency hasn’t been able to regain contact since, leading engineers to think the twins might be gone for good.

The MarCO team isn’t exactly sure why the satellites have gone silent. It’s possible that deep-space cosmic rays hit the probes’ electronics, knocking both of the spacecraft out. But engineers also knew that WALL-E had a leaky thruster. Both MarCOs were equipped with thrusters that expel cold gas to maneuver through space (just like the fictional WALL-E). The satellites need this hardware to point their radio antennas back towards Earth — and the farther away these satellites get from Earth, the more precisely they need to point to be heard. A leak may mean that WALL-E has run out of fuel, and the satellite can’t precisely point anymore.

Another theory is that both of them are just getting too far from the Sun, and that’s making it harder for them to get power. Each MarCO satellite has sensors designed to detect the location of the Sun, so they can both properly orient their solar panels. But as the satellites get farther away from the Sun, these sensors may be having a hard time figuring out where the star is. As a result, the MarCOs aren’t pointing properly and aren’t getting enough light on their panels.

If it’s the latter problem, then there may be some hope to recover the satellites. Right now, their orbit is taking them farther and farther away from the Sun, but they’ll be coming back around again in the months ahead. In August, they’ll be at the same distance from the Sun as they were during the flyby. It’s possible the sensors will be able to locate the Sun again and the MarCOs can power back up. “We might talk to them again,” says Krajewski. “We’ll schedule a few more attempts to find them.”

Even if the MarCOs stay silent forever, the mission team is still incredibly pleased with what they’ve accomplished. The MarCOs were made with a budget of just $18.5 million, a bargain compared to InSight’s budget of nearly $830 million. And the satellites did fulfill what they had been set out to do. “We’re deep into extra credit territory here,” Krajewski says.

The team has also shown that CubeSat technologies can fare well in a deep-space environment. Each MarCO was equipped with a specialized radio about the size of a fist that can communicate up to millions of miles away. The satellites also had systems for adjusting the spacecraft’s orientation, solar panels, and thrusters. These technologies were made specifically to fit each CubeSat, and they had never operated together on such a small vehicle bound for deep space before. Future CubeSat missions are already adopting this new technology. One such mission, known as Lunar Flashlight, will send a CubeSat to the space near the Moon to look for ice inside lunar craters. And it’s going to need some of the same basic tech that the MarCOs just demonstrated.

Additionally, CubeSats could accompany future larger missions to deep space, serving as communication relays to Earth. This would be especially helpful in places like Venus, for instance, which doesn’t have a vast network of communication satellites like Mars does. Or it’s possible that engineers might want to send tiny spacecraft to explore inhospitable areas of space, like the turbulent tail of a comet or the plumes of water bursting forth from Saturn’s moon Enceladus. That way if they get destroyed, it’s not as much of a financial loss.

Ultimately, MarCO proved that such ideas aren’t so far-fetched. “Small spacecraft not only allow us to do relay communications, but further our scientific interests as well,” says Klesh.</s>The two robots have been lost for more than a month and have flown so deep into space that NASA will be unable to reach them. Nicknamed 'EVE' and 'WALL-E' it is thought the spacecraft are now millions of miles beyond Mars. Despite losing contact with the two spacecraft, NASA still considers the mission a complete success as they could still talk to them despite being so deep in space.

The mission’s chief engineer, Andy Flesh said: “This mission was always about pushing the limits of miniaturised technology and seeing just how far it could take us. “We've put a stake in the ground. Future CubeSats might go even farther." NASA also insisted that the mission had helped improve concepts that would allow others missions to go further deeper into space. Collectively known as MarCO, the pair launched last year and were purely a speculative mission to see if they were able to operate in deep space.

The two followed NASA’s previous Mars aircraft, InSight which touched down on the red planet around the New Year. EVE and WALL-E were used to ferry communications from InSight and helped beam data back from the rover. WALL-E also sent back the first incredible images of Mars while EVE also collected radio data. After their work around Mars, the two spacecraft continued into deep space. READ MORE: NASA COVER-UP: Shock after ‘fossil found on MARS’ - bombshell claim

The last message received from either robot was on January 4 and NASA believe that the two are a million to two million miles from Mars. It is unknown what caused why the pair have lost touch with NASA. They will continue to fly away from Earth as February goes on which means receiving data even more difficult. NASA now hope to use the technology for further projects with John Baker, MarCO programme manager concluding that there is “big potential” in the small packages.</s>NASA has confirmed this week a pair of brief-case sized satellites dubbed MarCO have gone missing in the void of space behind Mars. The two Mars satellites have been silent for more than a month as NASA’s engineers attempted to re-establish contact. The US space agency now fears the odds of hearing from the missing satellites again are slim. NASA MarCO probes, or Mars Cube One, were the world’s first pair of interplanetary mini-satellites dubbed CubeSats.

The tiny spacecraft named WALL-E and EVE after charters from the beloved Pixar film were sent to Mars as part of the NASA InSight mission. Bizarre theories and conspiracy claims quickly flooded social media in the wake of the disappearance. Twitter user @MotownJones said: “Not to worry when the superior alien intelligence is done reprogramming they’ll send it back to annihilate Earth.” Carl Badder, @carlbadder, tweeted: “I’m not saying it’s aliens, but… It’s definitely aliens!” READ MORE: Life on Mars BOMBSHELL: Physicist Brian Cox admits 'alien life must exist' in space

And Edward Preston jokingly tweeted at NASA: “So that is where the Borg will have gotten the idea for their ship design.”

But what exactly was the role of the two cube-shaped mini-satellites and could they have collected evidence of alien life on Mars? The MarCO mission accompanied NASA InSight and served as a communication relay during the spacecraft’s landing. WALL-E and EVE collected and beamed back to Earth data from each stage of InSight’s descent to Mars in real-time. READ MORE: Physicist 'discovers proof' of something that should NOT be on Mars

WALL-E was also responsible for snapping some of the most stunning images of the Red Planet while EVE performed radio scans of Mars. It is, however, extremely unlikely the miniature satellites made any groundbreaking discovery of life on Mars. The two satellites were last heard from by NASA on December 29, 2018, and January 4, 2019, respectively. WALL-E was last tracked more than one million miles (1.6 million km) past Mars and EVE disappeared some two million miles (3.2 million km) past the planet. READ MORE: NASA plan to save Earth by derailing 2,600FT asteroid system REVEALED

NASA’s experts have a number of theories about the disappearance – none of which include contact with alien UFOs. One possible scenario is WALL-E suffered a leaky thruster or attitude-control problems have caused the CubeSats to wobble and lose contact with Eart. NASA has also considered the possibility WALL-E and EVE are unable to charge their solar batteries. Andy Klesh, the mission's chief engineer, said: “This mission was always about pushing the limits of miniaturized technology and seeing just how far it could take us.</s>Unlike most interplanetary missions, NASA’s InSight lander didn’t make the journey to Mars alone. The MarCO (Mars Cube One) satellites headed into space on the same rocket, and the shadowed InSight all the way to its encounter with Mars. These tiny satellites were not essential to InSight, but they performed their intended functions perfectly. Now, these robotic pioneers have winked out, but that doesn’t equate to failure.

The Mars Cube One satellites, MarCO-A and MarCO-B, coasted along near the InSight lander as it headed for Mars. As the name implies, these were low-cost CubeSats seen most often in low-Earth orbit research. They’re called “CubeSats” because a single unit (or 1U) is a 10-centimeter cube. For more complex experiments, engineers can work with 2U, 3U, and larger designs. The MarCO satellites, nicknamed Eve and Wall-E after the characters in the Pixel film, were 6U designs.

NASA spent a mere $18 million on the two satellites, which is a bargain for something you’re sending into deep space. That was exactly the point — CubeSats have only operated in Earth orbit, but the MarCO mission showed they could also perform at greater distances for many months. The probes had experimental high-gain antennas, but most of the parts were off-the-shelf.

MarCO-A and MarCO-B snapped some photos and relayed communication data for InSight as it landed on Mars late last year. NASA had contingency plans in place in case the MarCO probes failed, but the little satellites came through. Unfortunately, the simple cold-gas propulsion in the CubeSats lacked the power to maneuver them into orbit of Mars. They continued to drift along, pinging NASA on occasion to confirm they were still operational despite having already completed their mission. Now, Eve and Wall-E are silent.

NASA says MarCO-B last made contact on December 29th, and MarCO-A checked in a few days later on January 4th. The agency doubts either probe will phone home again, but this mission could already reshape unmanned exploration of the solar system. Most deep space probes cost hundreds of millions of dollars, but CubeSats are comparatively cheap. The Mars Cube One mission proved that these devices can complete basic tasks in deep space without breaking the bank. We might see many more missions to other planets based on CubeSat designs in the future.
• On Its Way to Mars, Cubesat Snaps Photo of Earth and the Moon
• Scientists Measure the Total Brightness of the Universe: 4 x 10⁸⁴ Photons
• China’s First Space Station Has Broken Up, Landed in Pacific Ocean [Update]</s>Twin tiny satellites launched with NASA’s Mars InSight lander in May 2018 have been out of touch with mission controllers on Earth for slightly over a month.

Called Mars Cube One or MarCO for short, the mini-satellites, each approximately the size of a briefcase and nicknamed WALL-E and EVE after characters in a Pixar film, were the first tiny satellites launched into deep space.

Small satellites represent a new technology that is less expensive than standard-sized satellites and could potentially be used for very distant missions, including a possible robotic visit to the exoplanet orbiting Proxima Centauri, the star closest to the Solar System.

Placed into an elliptical solar orbit, both CubeSats, whose $18.5-million cost was funded by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, are now well past Mars.

WALL-E, which last communicated with Earth on Dec. 29, is slightly more than one million miles (1.6 million kilometers) beyond the Red Planet while EVE, which last contacted Earth on Jan. 4, is close to two million miles (3.2 million kilometers) past Mars.

Both WALL-E and EVE were built at JPL. NASA plans to repurpose some of the spare parts used in their construction, such as antennas, experimental radios, and propulsion systems, to build additional CubeSats scheduled to launch in the near future.

One important benefit of CubeSats is that each one carries its own navigation and communication systems.

In several months, the CubeSats’ elliptical orbits will bring them closer to the Sun. Mission scientists will then attempt to regain contact with them, but even if that fails, the MarCO mission is viewed as a success and a milestone in the use of this new, still-experimental technology.

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

Mission scientists have several theories as to why the CubeSats lost contact. Both recharge their batteries by pointing their solar panels at the Sun. If the brightness sensors that keep them pointing at the Sun have malfunctioned, the batteries may be unable to recharge. The satellites are still receding from the Sun, and their greater distance requires more precision in aiming their antennas toward Earth.

Problems with attitude control, which involves the orientation of spacecraft in three-dimensional space so they directly point toward their targets, such as the Sun or Earth, could be causing both CubeSats to wobble, leaving them unable to receive commands or communicate. Additionally, one of WALL-E’s thrusters is known to be leaking.

The systems used for the MarCOs are produced by commercial companies and are likely compatible with various other types of CubeSats.

Jim Green, director of NASA’s Planetary Sciences Division, described the MarCo mission as “a demonstration of future potential capability” while MarCO program manager John Baker of JPL praised them as a technology affordable to private companies as well as to governments.

Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.</s>NASA has lost touch with the first mini-spacecraft that ventured into deep space, according to the US space agency which said that it is unlikely the twin CubeSats will be heard from again. The MarCO CubeSats were launched last year to test if such low-cost technology can operate in deep space. The twins, nicknamed EVE and WALL-E after characters from a Pixar film, served as communications relays during the InSight’s Mars 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. Having travelled well past Mars, the twin CubeSats seem to have reached their limit, NASA said in a statement. It has 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 will be heard from again.

The experimental technology cost a fraction of what most space missions do — USD 18.5 million. WALL-E was last heard from on December 29 and EVE, on January 4. Based on trajectory calculations, WALL-E is currently more than 1.6 million kilometers past Mars; EVE is farther, almost 3.2 million kilometres past Mars. The mission team has several theories for why they have not been able to contact the pair. WALL-E has a leaky thruster.

Attitude-control issues could be causing them to wobble and lose the ability to send and receive commands. The brightness sensors that allow the CubeSats to stay pointed at the Sun and recharge their batteries could be another factor. The MarCOs are in orbit around the Sun and will only get farther away as February wears on. The farther they are, the more precisely they need to point their antennas to communicate with Earth.

The MarCOs will not start moving toward the Sun again until this summer. The team will reattempt to contact the CubeSats at that time, though whether their batteries and other parts will last that long can not be predicted. Even if they are never revived, the team considers MarCO a spectacular success.

“This mission was always about pushing the limits of miniaturised technology and seeing just how far it could take us,” said Andy Klesh, the mission’s chief engineer at JPL. “We’ve put a stake in the ground. Future CubeSats might go even farther,” Klesh said. A number of the critical spare parts for each MarCO will be used in other CubeSat missions. That includes their experimental radios, antennas and propulsion systems. Several of these systems were provided by commercial vendors, making it easier for other CubeSats to use them as well.</s>The robotic duo — dubbed “EVE” and “WALL-E” in a nod to the Pixar movie — have not been heard from for more than a month.

But the pair will start moving toward the Sun this summer, giving NASA a chance to recover them.

NASA lost contact with the bots after they travelled millions of miles away after a successful mission to Mars.

The agency had been experimenting with the mini satellites, known as CubeSats, to see if they could operate in deep space.</s>NASA’s Mars InSight mission is moving along nicely, with the robotic lander preparing for many months of research that will tell scientists more about the interior of the planet than ever. Unfortunately, two of the machines that helped NASA track InSight’s perfect landing now refuse to answer calls from the space agency, and nobody knows exactly why.

The success of the MarCO mini satellites — named WALL-E and EVE in honor of the futuristic Pixar flick (which isn’t as good as A Bug’s Life) — was a long shot for NASA from the start. The tiny CubeSat spacecraft were designed to track InSight’s position so that NASA could keep a close eye on its progress as it made its way to the surface. They performed better than anyone could have expected, but we may never hear from them again.

Put simply, nobody really knew if the tiny spacecraft were going to be able to make the tough journey to Mars and do the jobs they were tasked with. Nobody had ever tried it before, and the tiny (and inexpensive) CubeSats had never been pushed in such a way.

Despite all that, both WALL-E and EVE performed incredibly well, relaying communications and even snapping images which were then sent back to Earth. It was a remarkable success, but the tiny machines weren’t designed to last forever.

In a new post by NASA, scientists reveal that it’s now been over a month since either of the MarCO CubeSats made contact with Earth, and nobody knows if we’ll ever hear from them again. Both of the machines will begin heading back towards the Sun in a few months, at which point NASA will once again attempt to wake them up, but whether they’ll be up for a chat is anyone’s guess.

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

NASA doesn’t know exactly why the twins stopped responding, and there could be a number of explanations and a combination of factors. On top of that, the CubeSats’ batteries may be long dead and fail to recharge by the time they are bathed in full sunlight once more. But even so, they performed admirably in their short stint in space.</s>Washington: NASA`s first interplanetary mission to use a class of mini-spacecraft has fallen silent in deep space and it is unlikely that they will be heard again, the US space agency has said.

Launched last year, the pair of briefcase-sized spacecraft known collectively as MarCO (Mars Cube One) -- 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.

However, "it`s been over a month since engineers have heard from MarCO," NASA said in a statement. "At this time, the mission team considers it unlikely they`ll be heard from again.

"WALL-E was last heard from on December 29, EVE, on January 4. Based on trajectory calculations, WALL-E is currently more than 1.6 million km past Mars. EVE is farther, almost 3.2 million km past Mars," NASA noted.

The team is not exactly sure why the satellites have gone silent.

"WALL-E has a leaky thruster. Attitude-control issues could be causing them to wobble and lose the ability to send and receive commands. The brightness sensors that allow the CubeSats to stay pointed at the Sun and recharge their batteries could be another factor," NASA said.

The MarCOs are in orbit around the Sun and would not start moving again until this summer.

Although the team will re-attempt to contact the CubeSats at that time, it is doubtful whether their batteries and other parts will last that long, as the farther they are, the more precisely they need to point their antennas to communicate with Earth.

Even if they are never revived, the MarCO mission was a spectacular success, NASA said. WALL-E sent back stunning images of Mars as well, while EVE performed some simple radio science.

"This mission was always about pushing the limits of miniaturised technology and seeing just how far it could take us," said Andy Klesh, the mission`s chief engineer at NASA`s Jet Propulsion Laboratory in California, which built the CubeSats.

"We`ve put a stake in the ground. Future CubeSats might go even farther," Klesh added.
NASA scientists report the MarCO satellites, two CubeSats in deep space, have lost contact with Planet Earth.