---
title: "Saving the Mars rover or a waste of billions? NASA and The Planetary Society debate the future of the PROMISE lunar rover"
description: "NASA wants to send an engineering copy of a Mars rover to the Moon, but the PROMISE project could cost up to $1.3 billion. The agency head and experts are debating: is it worth spending the only reserve of plutonium-238 on a lunar rover, or should it be saved for missions to distant planets? 🚀🌑"
date: 2026-08-02T16:02:45.000Z
lang: en
url: https://xab.info/en/posts/saving-mars-rover-waste-billions-nasa-planetary-society-promise-lunar-rover-debate
tags: [nasa, perseverance, promise-rover, planetary-society, jared-isacman]
publisher: "XAB.info"
---

# Saving the Mars rover or a waste of billions? NASA and The Planetary Society debate the future of the PROMISE lunar rover

![Lunar rover PROMISE in NASA assembly facility: engineers in lab coats inspect the system before launch amid funding dispute](https://xab.info/media/2026/08/02/nasa-promise-rover-cost-analysis-plutonium-debate/nasa-promise-rover-cost-analysis-plutonium-debate-1.webp)

The ambitious idea by NASA to convert an engineering model of the famous Perseverance Mars rover into a lunar rover named PROMISE has collided with the harsh reality of budget constraints. According to a fresh analysis by the independent organization The Planetary Society, implementing the project could cost a sum that would force even the most optimistic mission planners to reconsider their priorities.

### Numbers that change the game

The cost estimate for the PROMISE (Polar Rover for Observation, Mapping and In-Situ Exploration) mission turned out to be significantly higher than initial expectations. Experts calculated that the development, launch, and just one year of operation of the vehicle on the lunar surface would require between $723 million and $1.33 billion. Given this scenario, the launch of the mission is unlikely to take place before the early 2030s.

NASA Administrator Jared Isaacman publicly reacted skeptically to these calculations. He stated that if the final cost of the project reaches even 20% of the lower limit cited by The Planetary Society, the agency would simply abandon the launch. This casts doubt on the viability of the entire initiative in its current form.

### Technical obstacles and engineering complexity

The project is based on using the engineering model of the Perseverance rover, which is currently on Earth and used for scenario testing and diagnostics. However, as the authors of the assessment note, this vehicle is not a ready-made spacecraft. It lacks many systems certified for operation in space, including specialized communication equipment and flight-ready scientific instruments. Furthermore, the vehicle requires deep adaptation to the specific conditions of the lunar surface.

One of the most critical issues remains the question of power supply. The Perseverance rover uses a radioisotope thermoelectric generator (RTG) powered by plutonium-238. NASA has only one such backup generator available. Using it for PROMISE would require not only additional certification of the rover itself but also modifications to the lander and the launch vehicle.

### The plutonium dilemma and the future of space programs

Using the only available generator for a lunar mission carries serious risks for the agency's long-term plans. The Planetary Society warns that this decision could deprive NASA of the ability to implement future scientific missions to the outer planets, which also critically depend on this power source.

In response to the criticism, NASA Administrator Jared Isaacman argued for the necessity of using the equipment, noting that hundreds of millions of taxpayer dollars have already been invested in it. According to him, it is irrational to leave expensive equipment unused. Additionally, Isaacman reminded everyone of the physics of the process: plutonium-238 loses about 2% of its power annually due to natural radioactive decay. Therefore, in the opinion of the agency head, delaying the use of the resource for hypothetical future missions is not expedient.

### Revising strategic plans

Against the backdrop of the debate over the lunar rover, NASA continues to review the plans for the New Frontiers program. The agency is separately studying how many radioisotope power sources will be available for future interplanetary expeditions, trying to find a balance between ambitious lunar projects and deep space exploration.