There were plenty of striking things about Monday's budget news, given that it contained lots of draconian cuts that were simultaneously restored because Congress had boosted spending the week before. But perhaps the most striking among them was an item in the proposed budget for NASA: Trump wants to block the follow on to a highly successful NASA mission.

To truly appreciate just how awful this is, you have to understand the history of that satellite and what it means to the scientific community as a whole. So let's step back and take a look at why the Orbiting Carbon Observatory (or OCO) exists in the first place. It turns out it was built specifically to handle some outstanding questions of the sort that people in the administration say are important, and killing its successor would mean the existing mission never lives up to its full potential.

Real uncertainty

The Orbiting Carbon Observatory's primary job is to see what's happening to the carbon dioxide levels in our atmosphere. You may think that's a solved issue: we're emitting a lot, and levels are going up. And that's true to a point. But once you pass that point, you enter a world where there are lots of details, and many of them matter.

Humanity, it turns out, is just one of a huge number of sources of carbon dioxide—and there are things that remove it as well. Plants, for example, remove so much carbon dioxide through photosynthesis that we can track the seasonal appearance of leaves in the Northern Hemisphere because the process removes so much of the gas from the atmosphere. Some of that gets held for the long-term as wood; another portion returns to the air when the leaves drop in the autumn. Other processes cycle carbon through vast amounts of plankton in the oceans. Geological processes also act as sources and sinks for the atmosphere's carbon dioxide.

So much is going on that one source described the carbon cycle as including "every plant, animal, and microbe, every photosynthesizing leaf and fallen tree, every ocean, lake, pond, and puddle, every soil, sediment, and carbonate rock, every breath of fresh air, volcanic eruption, and bubble rising to the surface of a swamp, among much, much else." Humanity's fossil-fuel burning isn't so much a direct pipeline putting carbon dioxide into the air as it is a subtle lever that's pushing off the balance of a complex system.

Although the carbon cycle is complex, we have a relatively good idea of how it works. And, plus or minus a few gigatonnes here and there, we know the volume of carbon dioxide handled by most of the sources and sinks.

That said, this is still an area where there are significant uncertainties. People make a big deal about false uncertainties in climate science—we know the temperature's rising, and we know human carbon emissions are the primary driver, but people keep trying to pretend there's uncertainty there.

But the carbon cycle is a case where the uncertainties are real, and scientists will tell you as much. We don't have as good a handle on some of the sources and sinks as we'd like. And, more importantly, these things are dynamic and change with time. To give one example, water dissolves more gas when it's cold. We're warming the oceans, which means they will be able to dissolve less carbon dioxide. Are the oceans starting to weaken as a sink? We don't really know at this point.

NASA gets involved

These uncertainties were so real and so widely acknowledged by the scientific community that NASA got involved. NASA funded the OCO to provide global coverage of carbon dioxide levels year round. The satellite takes more than a million data readings every day, with each reading covering only about three square kilometers. This will allow us to identify individual sources and sinks and determine how they change with the seasons. And, because it's placed in an orbital train with five other Earth-sensing satellites, any changes can be correlated with what's going on at that location based on what those other satellites are seeing.

In short, the OCO is a recipe for important science. But the importance went well beyond the satellite's technical capabilities. Simply getting any data from the satellite would allow us to start the long-term monitoring of all of the Earth's carbon dioxide processing. We'd have the data we'd need to start detecting whether any of that processing changed as the planet warmed.

In fact, the work of the OCO was considered so important that NASA was willing to do it twice. The first Orbiting Carbon Observatory failed to separate from its launch vehicle and ended up falling back to Earth over the Indian Ocean. NASA built a second and successfully put that one in orbit. It's now been operating just shy of four years, and the first scientific results have already been published. The data's in place to start monitoring for changes in the Earth's carbon budget, and an Orbiting Carbon Observatory 3 was in the planning stages.

Trump wants NASA uninvolved

Yet this is precisely the point where Trump wants NASA to blind itself. The Orbiting Carbon Observatory is just starting to reduce some of our uncertainties about carbon fluxes, but is already closing in on double the originally planned mission lifetime. A lot of hardware lives well beyond its planned lifetime, but we can't expect OCO to go on indefinitely, and NASA was appropriately planning on having something ready to replace it.

Yet the Trump budget plan refers to the successor as a "lower-priority science [mission] that cannot be accommodated under constrained budgets" and suggests that the data could be gathered by other satellites, although it doesn't name any of them.

It's hard to overstate the ways in which this is stupid. The cost of NASA missions is nearly entirely in the construction and launch of the hardware—something that's already been done twice in this case. The agency's perseverance has given us the baseline from which we can start watching for long-term changes in our planet's carbon cycle, which could play a critical role in shaping future climate change. But this decision could mean the baseline is all we'll get until someone else decides to put an equivalent instrument in orbit.

And, ostensibly, this is precisely the sort of science that people who have questioned our understanding of climate change want to see done. The OCO focuses on natural factors, which the same people keep suggesting may outweigh the human influence. It's trying to address some remaining uncertainties, which they generally say we need to sort out before taking any action. Even the climate contrarians who have been invited to testify in front of the House Science Committee have said that funding long-term monitoring of the environment is critical, and the Orbiting Carbon Observatory would provide that monitoring if it kept operating.

By trying to kill this program, people in the administration are sending two messages. One is that everything they've been saying when they try to explain why they're taking no actions on climate change is a sham—they don't actually believe any of it. And the second message is they'd abandon a project that cost millions of taxpayers' dollars than gather data that could possibly tell us we need to act.

Correction: the original editorial was based on shutting down the existing OCO 2 rather than cancelling its successor. The editorial has been corrected to reflect this.