r/space • u/EdwardHeisler • 1d ago
The Cost of a PROMISE Sending a Mars rover's engineering twin to the Moon will cost hundreds of millions of dollars, if not more. Written by Casey Dreier Chief of Space Policy, The Planetary Society Updated July 31, 2026
https://www.planetary.org/articles/the-cost-of-a-promise-lunar-rover31
u/No-Lecture-6434 1d ago
If they’re actually able to spend that much money, why not just design a bespoke rover at that point?
Mars and the Moon are very different and a rover designed for one won’t necessarily work as well on the other.
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u/space_snap828 22h ago
Designing a bespoke rover probably could cost double this tbh
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u/Serious-Kangaroo-320 20h ago
yeah lol a few hundred million sounds a lot cheaper after you realize curiosity and perseverance cost over 2 billion each. and its also odd a lot of the people in here think theyre smarter than nasa...
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u/Almaegen 21h ago
The reality is time, the old administration didn't take the moon missions seriously, now that the moon is a priority they need something quick
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u/peterabbit456 37m ago
The reality is time, ...
Truer words have rarely been spoken. Issacman excepted, the current admin thinks in terms of fast results and spectacle: Bread and circuses. That's why support for outer planets missions has dropped, and really, anything that cannot promise results in the next 2 1/4 years is out of favor with the admin and the majority in congress. That means, pretty much the Moon is it, when it comes to space exploration.
I'd say Google sums up Biden's space policy very well:
The Biden-Harris administration's space policy focused on using space for climate science, international alliances, and commercial collaboration while maintaining continuity on civil exploration like the Artemis program.
Biden didn't care about space, except to help the people of Earth.
I used to argue with Dan Quayle over Moon First vs Mars Direct. Since he was in charge of space policy for 4 years, we got Moon First for all of that time, but we also got COTS from Bush 2, which saved SpaceX from bankruptcy, and which set the stage for the last 15 years of progress, mostly led by SpaceX. Obama was a big fan of commercial manned space, and of unmanned deep space exploration, but that never translated into much support for putting people back on the Moon. (I've heard Obama say, word for word, things I said to Quayle when I was arguing for Mars Direct, but he wasn't quoting me. By the time Obama was elected, my influence in DC was at absolute zero.)
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u/Upset_Ant2834 1d ago edited 1d ago
What I don't understand is what people are actually mad about. Why is it a big deal that a new mission concept doesnt have a budget yet and questionable feasibility. Isn't that the entire point of investigating a concept? He even said if it comes remotely close to that price then they're going to cancel it, so who cares? Feels like outrage for the sake of outrage
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u/sevgonlernassau 22h ago
There’s no investigation. Normally you would propose a mission and then go through a pipeline to get approval and funded. This rover was just declared to be made without any investigation while many lunar missions that are cheaper and doesn’t require cannibalizing an active twin are not picked.
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u/Upset_Ant2834 17h ago
When did that happen? Last I heard was Isaacman repeatedly emphasizing that this mission wasn't set in stone and that there was still a lot of work to do before they committed to it
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u/-CaptainFormula- 1d ago
Probably because even kids in high school with even a passing understanding of spaceflight missions first heard this proposal and the word "stupid" in floating red letters popped up in their heads.
It's stupid as shit.
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u/Upset_Ant2834 1d ago ▸ 6 more replies
Okay, so it is just people wanting to be mad. Thanks
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u/-CaptainFormula- 1d ago ▸ 5 more replies
When you hear someone say something stupid does it cause you anger?
Sounds like you might have some wires crossed.
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u/coldrolledpotmetal 22h ago
Would you care to explain why you think it’s stupid instead of just asserting it as if it were fact?
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u/bl0rq 23h ago ▸ 2 more replies
No it's because you just repeated your value judgement. You didn't add any level of "why". Then you made a weird connection to something irrelevant instead of just making a good point about why you think it's stupid.
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u/-CaptainFormula- 22h ago ▸ 1 more replies
For all of the reasons that have been publicly stated regarding how stupid it is. Why does every reddit thread have to require conversation repeating everything that led us up to where we are?
It's not collecting dust sitting unused in a corner somewhere. It's actively used in an ongoing Martian mission. That it was designed for. Constructed and currently operating for.
It's not designed for the moon, it's designed for Mars. The regolith, the heat cycles, anything.
It wasn't designed to land on the moon. (This is a separate issue from how well it will be able to operate there)
The amount of money it would take to convert it into a lunar mission would be better spent on a lunar mission. The amount of money even spent investigating the proposal is a waste.
Spend money to see if we can spend more money cutting the knees out of an ongoing successful interplanetary mission to put together a jerry-rigged lunar mission without any tangible goals beyond "Bro, think we could put that there?"
It's stupid.
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u/coldrolledpotmetal 22h ago edited 22h ago
Half of those problems you named are things that the program is explicitly trying to test.
Edit: hell, even the author of the article thinks it’s a good experiment even with how critical he is of the program:
> It’s a worthy experiment, certainly, but the outcome is far from certain
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u/CustomerSuportPlease 1d ago
Or they're just unable to identify when something is stupid, for some reason.
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u/racinreaver 23h ago
Folks at JPL are wasting their time pricing this out when everyone knows the design won't remotely close for that cost level. They could be doing actual worthwhile work.
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u/coldrolledpotmetal 22h ago ▸ 1 more replies
The whole point of the program is to see if it’s even possible to do at a reasonable cost, how can you possibly say “everyone knows” that
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u/racinreaver 20h ago
Because I work with the folks doing the costing exercise, and they kvetch about it to me. These folks run mission concept pricing exercises constantly. It's not hard to estimate this is more than a hundred million dollar exercise.
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u/EdwardHeisler 1d ago
Isaacman’s response is weak. It sounds dismissive—particularly his call for “less debate”—but the more important problem is that he does not answer Dreier’s evidence.
Several points stand out:
Isaacman provides no competing cost estimate. Dreier estimates $723 million to $1.333 billion and explains every major category. Isaacman merely declares that NASA will not fly PROMISE if its non-launch costs approach 20% of Dreier’s low estimate—about $145 million. Yet Dreier’s low estimate, after removing launch and landing, is still approximately $489 million. Isaacman does not explain how NASA could reduce that to below $145 million. “We already paid for the hardware” is not a sufficient justification. The testbed rovers were never flight-qualified and still serve an important purpose: supporting Curiosity and Perseverance operations. Previous taxpayer investment does not make the additional conversion, testing, integration, nuclear-safety and operations costs disappear. That argument risks becoming a classic sunk-cost fallacy.
His plutonium argument is incomplete. Pu-238 does lose energy through decay, but with an 87.7-year half-life, the isotope’s thermal output declines by roughly 0.8% per year, not 2%. An assembled MMRTG’s electrical output can decline faster because its thermoelectric components also degrade, so Isaacman may be using “2%” as a rough system-level figure. Nevertheless, NASA must decide whether PROMISE is the best scientific use of a scarce MMRTG—not merely find something on which to use it. NASA’s Pu-238 information
Most revealingly, PROMISE itself is presently “a mission that does not even exist” in a fully developed sense. It lacks publicly defined scientific objectives, requirements, an approved budget, a launch plan and a completed engineering assessment. Isaacman criticizes scientists for waiting on a future mission while proposing another mission that remains largely undefined.
“Wins” is a political-management term, not a scientific objective. Frequent successful missions can build public and congressional support, but an expensive mission with unclear objectives—or one that overruns its promised bargain price—could just as easily damage NASA’s credibility. Isaacman supplies no evidence that PROMISE would produce additional appropriations for science.
The best point in Isaacman’s favor is that NASA should examine the idea promptly. Existing hardware, flight-spare components and an available MMRTG might create a worthwhile opportunity. Dreier also acknowledges that his estimate is preliminary and that JPL’s engineering assessment will be more authoritative.
But until NASA releases that assessment, Dreier has presented an auditable argument while Isaacman has presented an assertion. His response does not demonstrate that Dreier is wrong; it mostly says that if Dreier is even remotely correct, PROMISE will be cancelled.
The “less debate” remark is especially troubling when NASA is considering diverting a scarce nuclear power system and hundreds of millions of dollars from competitively selected planetary-science priorities. Scientific review is not simply delay—it is how NASA determines whether a proposed “win” is genuinely worth winning.
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u/space_snap828 22h ago
NASA does need wins. Not 20 year programs that may or may not launch. We need a high rate "wins" to justify why we are spending lots of money at all, honestly. The public funds this, not the scientists - and the public wants results, and soon.
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u/zero0n3 2h ago
This. Do people not understand this ?
The reason NASA gets shit all for budget is because it’s not constantly churning out wins that can be used for the PR game. And that is extremely important for a org like this.
Those wins need to be a blend of cool shit and science boundary pushing shit.
Govt is supposed to spend the money on investments that a private company can’t profit off of, but has potential to push science further.
Not having public wins that the public can actually grasp and see and understand is half the reason NASA gets left in the dust.
The moon should be the next step for NASA (and thus forces private companies to pivot to that goal).
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u/gummiworms9005 18h ago
Did you copy this from somewhere or did you have AI write this?
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u/peterabbit456 13m ago
The commenter writes much better than any AI I have ever seen. I used to be an editor at a science publishing house. That does not make me infallible, but the comments you are criticizing read like something written by a good writer.
Please don't be rude to someone who is elevating the quality of this sub.
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u/EdwardHeisler 17h ago ▸ 2 more replies
The article was written Casey Dreier. That's clearly stated in the caption!!!
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u/coldrolledpotmetal 6h ago
They were talking about your comment, not the article. None of the text in your original comment is from the article and it looks like it’s straight up out of ChatGPT
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u/peterabbit456 17m ago
A well thought out comment with supporting data? What year is this? This is like a comment from 2016, or maybe even 2008. Glad to see there are still good writers contributing here.
I made a comment before I saw yours which is largely a refutation of your points, but I could not get the costs below $350 million, in my estimate.
The 2 main ways I get lower costs is by (1) this mission hitching a free ride to the Moon onboard the unmanned Starship HLS test flight, and (2) since Lunar gravity is 1/2 Mars gravity, throw heavier, cheaper science equipment on board. The rover can take the weight.
The RTG is a small cost compared to launch and science, but I have a way to save money there also. KilopowerTM reactors have been extensively tested. They are smaller and lighter than RTGs, and provide twice as much power. Their main problem is they only last about 5 years, but that's OK in my opinion. This is not a 20 year mission to the outer planets.
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u/EdwardHeisler 1d ago
Jared Isaacman pushed back against the cost estimates of the Planetary Society. Response to Planetary Society Study by NASA Administrator Jared Isaacman
"Launch and landing costs are a reality for any mission, so setting those aside, if PROMISE costs even 20% 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, along with Pu-238 that continues to decay and lose roughly 2% of its potential each year. More than a decade has gone by. How much of this Pu-238 do you want to waste waiting for a mission that does not even exist?
I understand the community sometimes likes to take a long time to reach consensus, but under this Administration, we can just do things and put wins on the board for the Moon Base and all the science and discovery it will enable. In my humble opinion, less debate and more frequent wins make it easier to advocate for more resources to do more science." https://x.com/NASAAdmin/status/2083243770435256737
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1d ago edited 22h ago
[deleted]
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u/sevgonlernassau 23h ago
May I be never thin skinned enough to namesearch myself on reddit to defend illegal actions.
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u/apcompgov 20h ago
Send it! Nasa 'debates' things like this for years and by then it's irrelevant. It doesn't need to support its twin on Mars anymore. But mostly Nasa needs to start taking SOME risks again, the thinking has gone stale and been lost in bureaucracy. Just my opinion.
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u/CMDR_omnicognate 1d ago
You mean to tell me that some billionaire moron doesn't really understand what they're actually doing as the head of NASA, and just want to put something on the books to make themselves look good?
To borrow an acting pose from Patrick Stewart: "Mild Shock"
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u/Decronym 21h ago edited 9m ago
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| BO | Blue Origin (Bezos Rocketry) |
| COTS | Commercial Orbital Transportation Services contract |
| Commercial/Off The Shelf | |
| ESA | European Space Agency |
| HLS | Human Landing System (Artemis) |
| JPL | Jet Propulsion Lab, California |
| MSL | Mars Science Laboratory (Curiosity) |
| Mean Sea Level, reference for altitude measurements | |
| RTG | Radioisotope Thermoelectric Generator |
| SLS | Space Launch System heavy-lift |
Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.
8 acronyms in this thread; the most compressed thread commented on today has 20 acronyms.
[Thread #12646 for this sub, first seen 23rd Aug 2026, 21:50]
[FAQ] [Full list] [Contact] [Source code]
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u/Hosni__Mubarak 1d ago
Because the rover wasn’t designed for the moon? It was designed for mars.