NASA Administrator Jared Isaacman has stated "we simply will not fly it" if claims about the costs of the repurposed Mars rover engineering model prove anywhere near accurate.

Isaacman was responding to the Planetary Society's chief of space policy, Casey Dreier, who had run the numbers on his plan to send a robot to the Moon, built from parts of engineering models of the successful Mars rovers Perseverance and Curiosity.

Dreier estimated that the Polar Rover for Observation, Mapping, and In-Situ Exploration (PROMISE) mission, as discussed by Isaacman in a June presentation, would cost between $723 million and $1.33 billion.

Dreier's figures include a low-end launch and landing cost of $234 million and a high-end estimate of $320 million.

PROMISE is intended to put a rover on the Moon for a fraction of the usual cost. There are engineering testbeds for both Perseverance and Curiosity, dubbed OPTIMISM (Operational Perseverance Twin for Integration of Mechanisms and Instruments Sent to Mars) and MAGGIE (Mars Automated Giant Gizmo for Integrated Engineering) respectively.

While not 100 percent identical to what was sent to Mars, the pair are designed to be close enough to allow engineers to perform activities such as plotting drives on simulated Martian terrain and seeing how the hardware will react to commands sent from Earth.

NASA bosses looked at the engineering models, considered ways to score easy "wins," as Isaacman put it, and came up with an idea.

Engineering models are common enough in spaceflight. A Development Test Model (DTM) of Voyager can be found hanging in the Exploring the Planets gallery at the National Air and Space Museum in Washington DC. The DTM's bus was liberated in 1987 for developing NASA's Magellan Venus spacecraft. The Register also paid a visit to a test model of the European Space Agency's Solar Orbiter on a 2022 visit to the agency's Darmstadt site, which looked more like an explosion of wiring than a simulacrum of a spacecraft.

MAGGIE and OPTIMISM are at least recognizable as engineering testbeds for Curiosity and Perseverance, but getting a hybrid using parts from both models into a state where it can do useful science on the Moon would be a challenge.

As well as qualifying the components for launch and spaceflight, engineers would have to prepare hardware built for use on Earth to withstand lunar conditions. Power and communications would also need work: NASA has a "spare" plutonium radioisotope power system, but the rover would require substantial adaptation to use it.

Then there are the consequences of taking engineering models away from active missions.

"Regardless of whether one agrees with every estimate… one thing is clear: PROMISE is far from a 'freebie,'" Dreier stated.

Isaacman did not challenge individual elements of Dreier's breakdown, although he excluded launch and landing because those costs "are a reality for any mission." Even so, he said, "if PROMISE costs even 20 percent of your low-end estimate, we simply will not fly it."

"That said, it would be crazy not to take advantage of hardware taxpayers have already invested hundreds of millions of dollars in."

That hardware has already been taken advantage of. It was designed to be a testbed and used for that purpose. Repurposing them for a one-off mission to the Moon could prove more troublesome and expensive than designing a rover that can be mass-produced. ®