Twin small spacecraft in space.

An artist's rendering of NASA's twin Mars Cube One (MarCO) spacecraft as they fly through deep space. Credit: NASA/JPL-Caltech

What was MarCO (Mars Cube One)?

On May 5, 2018, NASA launched a spacecraft called InSight that landed on Mars on Nov. 26, 2018. Riding along with InSight were two CubeSats—the first of this kind of spacecraft to fly to deep space. The CubeSats were part of a technology demonstration mission called Mars Cube One (MarCO).

  • The MarCO twins were nicknamed EVE and WALL-E after characters from Pixar's "WALL-E" movie.
  • The spacecraft provided an experimental communications relay to let scientists on Earth know quickly about InSight's landing.
  • MarCO A and B successfully completed their missions on Nov. 26, 2018. WALL-E was last heard from on Dec. 29, 2018; EVE on Jan. 4, 2019.

Nation United States of America (USA)
Objective(s) Mars Flyby
Spacecraft MarCO (Mars Cube One)
Spacecraft Mass 30 pounds (13.5 kilograms) (each)
Mission Design and Management NASA / JPL
Launch Vehicle Atlas V-401
Launch Date and Time May 5, 2018 | 11:05 UTC
Launch Site Vandenberg Air Force Base, Calif. (USA)
Scientific Instruments 1. UHF Radio Receiver
2. X Band Radio Transmitter
View of Mars from MarCO spacecraft.
MarCO-B, one of the experimental Mars Cube One (MarCO) CubeSats, took this image of Mars from about 4,700 miles (6,000 kilometers) away during its flyby of the Red Planet on Nov. 26, 2018. Credit: NASA/JPL-Caltech


  • MarCO was the first mission to test CubeSats in deep space

Key Dates

May 5, 2018: Launch (with NASA's InSight lander)

Nov. 26, 2018: Mars flyby / Relay operations

Dec. 29, 2018: Last contact with WALL-E

Jan. 4, 2019: Last contact with EVE

A 3D model of MarCO, a twin pair of spacecraft that proved cubesats could work in deep space. Credit: NASA Visualization Technology Applications and Development (VTAD) › Download Options

In Depth: MarCO (Mars Cube One)

MarCO, short for Mars Cube One, was the first interplanetary mission to use a class of mini-spacecraft called CubeSats. All previous CubeSats have orbited the Earth.

The MarCOs were nicknamed EVE and WALL-E for characters in the Pixar film "WALL-E." They 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.

The MarCOs sent back InSight's first image and WALL-E sent back stunning images of Mars as well. 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, 2018; EVE, on Jan. 4, 2019.

The mission team has several theories for why they haven't 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.

Man working on small spacecraft.
Engineer Joel Steinkraus uses sunlight to test the solar arrays on one of the Mars Cube One (MarCO) spacecraft.

The MarCOs are in orbit around the Sun and will only get farther away. Even if they're never revived, the team considers MarCO a spectacular success.

"This mission was always about pushing the limits of miniaturized 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."

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.

More small spacecraft are on the way. NASA is set to launch a variety of new CubeSats in the coming years.

"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."

Key Resources

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