Europe's Mars sample return orbiter moving ahead despite NASA budget uncertainty

a cube-shaped spacecraft with two large wing-like solar panels in orbit above a reddish-orange planet
Artist impression of the Earth Return Orbiter (ERO). (Image credit: Airbus/ESA)

While NASA's portion of the Mars Sample Return mission sits in budgetary limbo, the European Space Agency (ESA) continues to move forward with its piece of the Red Planet sampling puzzle: the Earth Return Orbiter (ERO).

ERO will provide the crucial transport of Mars samples collected by NASA's Perseverance rover from the Red Planet to Earth. In order to do so, it will rendezvous with the sample in Martian orbit, catch a basketball-sized capsule whizzing around the planet and finally bring that capsule back to Earth.

The spacecraft has just passed its design review, which validated its technical details and moves the project onto manufacturing and testing. "A robust design is the foundation for building, testing and assembling the hardware into a complete spacecraft," Tiago Loureiro, ERO’s project team leader, said in a statement.

Engineering qualification model of the Remote Interface Unit (RIU) for the Earth Return Orbiter. The RIU connects most of the spacecraft's equipment, such as sensors and actuators including the chemical propulsion valves, reaction wheels, relay commanding and temperature sensors, to the main computer. This is a replica of the flight model and it is used to test it conditions which are supposed to be harsher than what engineers expect to see in an interplanetary flight to Mars. (Image credit: Airbus/ESA)

"From a staggering distance of up to several hundred million kilometers, Earth-based teams will choreograph a complex orbital dance around Mars," said Orson Sutherland, ESA's Mars program manager.

Though ESA's ERO program is moving forward, NASA's side of the mission — which comprises transporting the sample on the Martian surface and using a rocket called the Mars Ascent Vehicle to launch it into Martian orbit —  is still undergoing review after its $11 billion budget was deemed too expensive

As such, it may face numerous design changes in the near future. In fact, NASA has recently commissioned ten studies to reduce the scale (and therefore the cost) of the mission.

But ESA affirms that ERO will be able to adapt to any changes to Mars Sample Return mission. "The configuration of the spacecraft is robust enough to be flexible with the cargo and to help find solutions for a new architecture. ESA and our industrial partners adapted to a new scenario, staying inventive and resourceful while remaining a reliable partner for NASA," Tiago said. "We have confirmed that the Earth Return Orbiter works for what was planned to do and more, whatever the alternatives are."

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Stefanie Waldek
Contributing writer contributing writer Stefanie Waldek is a self-taught space nerd and aviation geek who is passionate about all things spaceflight and astronomy. With a background in travel and design journalism, as well as a Bachelor of Arts degree from New York University, she specializes in the budding space tourism industry and Earth-based astrotourism. In her free time, you can find her watching rocket launches or looking up at the stars, wondering what is out there. Learn more about her work at

  • vadertime
    So, of course this begs the question: What if NASA cannot accomplish their part of the exercise - building a vehicle to launch the samples into orbit for the Europeans. Think about it. We are not talking about 1 space craft. We are talking about a minimum of two if not more. Something has to transport the Mars surface return rocket to Mars. Then the return rocket has to descend to Mars, collect the samples, which I understand are scattered over a large area, and then stow them into the return container and take off with it into Mars Orbit. So, we are talking: 1) Big ship to carry small surface ship to Mars, 2) Surface ship, either 1 or 2 piece, that also carries 3) surface vehicle to collect the samples. We are talking about a minimum of 3 vehicles. It would have been easier if Perseverance came with a collection container in which to put all the samples, but I guess those rocket engineers weren't thinking that far ahead. Good luck and thanks for all the fish. Cheers.
  • Rob77
    Depending how Starship goes and how ambitious Musk is - I think we might get people to Mars before NASA builds ships to collect the samples.
  • EJD1984
    How can the ESA fully continue with their ERO design since the main component, CCRS is a NASA GSFC design that is currently on pause?
    *Though the CCRS design is also nearly 100% complete.