Ever since the final years of the original space race, NASA has been unrivaled as the world leader in space sciences and space exploration. In particular, NASA astrophysics has brought us a wide range of space telescopes that have pushed the frontiers of humanity’s knowledge across the electromagnetic spectrum, from the highest-energy gamma-rays through X-rays, ultraviolet, optical, infrared, and even microwave wavelengths. Whenever we consider building a new observatory, the big thing that scientists focus on is what we call discovery potential, or “how much” ability there is to see beyond the limits of our current instruments and observatories.
Not all wavelengths have received equal attention, however, and some wavelengths have been woefully neglected in recent years. In particular, the most powerful X-ray observatory in human history remains NASA’s Chandra, despite the fact that Chandra was launched all the way back in 1999: back in the 20th century. Plans for a future X-ray flagship were developed, laid out, and approved, with the next big step toward that goal being NASA’s AXIS mission: a true 21st century X-ray facility that would help answer all sorts of questions that Chandra cannot. It was intended to also pave the way for a Lynx-like mission after that, with unprecedented power, resolution, and energy sensitivity.
Unfortunately, on Monday, March 9, 2026, NASA HQ informed the entire AXIS team that:
- their mission is not eligible for selection,
- their submitted Concept Study Report will not be subjected to the full review process,
- and that this decision was entirely programmatic, without concern for the technology or science of the mission.
This effectively sets X-ray astronomy back by a decade, with the earliest realistic timeline for an X-ray flagship now looking like the 2050s or even 2060s. Here’s what AXIS was all about, what happened, and what it means.
There are always big, burning science questions that often serve as the motivation for any new facility or observatory. Whenever current facilities are insufficient to answer those questions, of course you’ll want to build a new one that’s capable of collecting the data needed to provide those answers. In X-ray astronomy, that includes big questions like:
- Where do the seeds of supermassive black holes come from, how large are those seeds and how do they form, and after they form, how do they grow?
- How do key components of matter — gas, dust, and heavy elements — flow into, get transported throughout, and ejected out of galaxies over time?
- What powers the explosive and transient phenomena that appear across the electromagnetic spectrum, including in high-energy X-rays?
These questions are beyond the capabilities of current X-ray observatories such as Chandra for a variety of reasons. Chandra is a relatively small area, with a correspondingly small light-gathering power. It has good resolution but only moderately high contrast, meaning it’s not great at separating faint and bright sources that are right atop one another. And it’s slow with a narrow field-of-view, meaning that you have to sit on a certain location for a while to get a good image, and that you have to be pointed precisely at your target of interest. As a result, Chandra is good for a lot of things, but its limitations matter when considering those big questions above.
That’s why an X-ray telescope that would be superior in those regards has so much discovery potential just awaiting it. Instead of a small-area telescope, a larger-area telescope would have more light-gathering power, enabling it to see fainter sources, and to reveal intricate details in a fraction of the time it takes Chandra to do so. X-rays provide a unique probe of the high-energy Universe, able to measure the emissions from gas heated to hundreds of thousands or even millions of degrees: emissions that routinely occur in and around active galaxies, or other processes powered by black holes. Superior spectral energy resolution, a superior point-spread-function, and high-contrast imaging can help enable all of these, above and beyond Chandra’s current limits.
And beyond that, speed and a large viewing area are also key concerns. When a transient event occurs — a gamma-ray burst, a tidal disruption event, a supernova, etc. — there’s a lot of information encoded in the X-ray portion of the spectrum, but getting your telescope to point to the right place quickly is key. Chandra doesn’t have those capabilities, but AXIS was designed to respond quickly to alerts, improving our ability to conduct both time-domain astronomy as well as multi-messenger astronomy. These improvements in technology translate into new capabilities in science, which is exactly what we’re after. That’s what AXIS is (or, I should say, was) all about.
But there’s a bigger prize that we’re after, too, even though scientists don’t often talk about it. Sure, we know a new observatory is going to both find:
- more examples, fainter examples, and deeper examples of the classes of objects and phenomena that we already know,
- as well as greater amounts of sophisticated details about those objects and phenomena.
We saw this when JWST came online and surpassed the limits of Hubble and Spitzer; we saw this when ALMA came online and surpassed the limits of Arecibo and the VLA; we saw this when Hubble came online (and especially after its first servicing mission) and surpassed the limits of all prior ground-based and space-based observatories. For the things you already know, you’re going to see them better, see more examples of things just like them, and see a greater set of details within them than was previously possible.
But the reason we call it “discovery potential” is that these new capabilities often bring with them the ability to literally discover things you didn’t expect: things that you had no way of knowing were out there before you looked with these novel capabilities. We don’t know what those things are going to be, that’s part of the motivation for building them and looking. We didn’t know, when we built ALMA, that it would be the key facility in imaging a black hole’s event horizon directly. We didn’t know that JWST would teach us that an asteroid-like belt and Kuiper-like belt aren’t universal, and reveal that some systems even have a third belt. And we didn’t know that deep-field imagery was even possible until we tried it with Hubble. We had to look in order to discover, and to be able to look, we had to build a facility that was capable of looking in a novel, more powerful way.
In fact, one could argue (and I have) that the two most underrepresented wavelengths here in the middle of the 2020s, as far as our arsenal of space telescopes go, are the X-ray and the far-infrared. Both of those wavelengths were considered for flagship missions in the Astro2020 decadal survey — Lynx (for X-rays) and Origins (for far-infrared) — but instead of simply choosing a mission from among the four candidates, the decadal committee recommended a path where:
- all three main types of proposals, X-ray, optical/UV/infrared, and far-infrared, should be developed,
- that the optical/UV/infrared option should take aspects from both proposals (HabEx and LUVOIR) and cobble together our next flagship mission from that, in what has now become the Habitable Worlds Observatory,
- and that the X-ray and far-infrared teams should develop the technologies needed for those future flagships, and that the way to do that next is to plan an explorer-class mission for each one.
The X-ray explorer class mission was AXIS, while the far-infrared explorer class mission is PRIMA. Both missions received a small amount of funding (about $5M each, or ~0.5-1% of the total mission cost) to develop their concept, with the understanding that both of them would be competing for one spot. They would each submit a comprehensive mission concept study for review, and then after the panel at NASA headquarters reviewed them both, one would be selected to go forward.
Then, however, January of 2025 arrived, and all sorts of things changed. The so-called Department of Government Efficiency (DOGE) came to power, cutting hundreds of millions of dollars worth of valuable programs. The director of the Office of Management and Budget (OMB) withheld funding from various NASA programs and facilities despite that funding being appropriated by Congress, and the proposed budget put forth in 2025 for the 2026 fiscal year would have brought an end to over 40 separate current and future NASA missions, 11 of which were NASA Astrophysics missions, including AXIS or PRIMA.
And then, the government shutdown of 2025 occurred, furloughing all non-excepted government employees from October 1, 2025, until November 12, 2025: representing a full 12% of the working days available for the year. Finally, in January of 2026, the termination, resignation, or retirement (including early retirement) for a large number of NASA employees was made final, reducing the number of NASA employees from over 17,000 at the start of 2025 to its current number of less than 13,000 at present. On top of all that, there were cuts and closures that affected a variety of NASA facilities, libraries, cafeterias, visitor centers, and more.
Credit: U.S. Senate Committee on Commerce, Science, and Transportation, 2025
Three of these factors played a key role in rendering the AXIS mission ineligible for selection.
- First, the DRP, or NASA’s Deferred Resignation Program, didn’t just affect 4000 random people; it also affected some key X-ray astronomers who were working on AXIS. Jimmy Marsh, the main Project Manager for AXIS at Goddard Space Flight Center, was lost. So was Will Zhang, the X-ray mirror lead of the project. In total, over 20 key experts working on AXIS were removed from Goddard and from NASA entirely, significantly curtailing the team’s ability to execute.
- Second, the swift realignment of NASA Goddard’s priorities with the President’s budget request for the 2026 fiscal year — a realignment that occurred when the budget was still only a request — reduced the availability of mission formulation and mission engineering personnel to work on AXIS. This included cost analysts and schedulers, who were forbidden to work on the mission because the President’s budget request eliminated the probe program entirely. Even though that budget didn’t become law, the lost resources were impossible to make up.
- And third, the core AXIS study team, which was headquartered at Goddard Space Flight Center, was dominated by NASA civil servants who were furloughed during the 6-week-long shutdown in late 2025. The extension that NASA headquarters provided to the Concept Study Report deadline was inadequate to compensate for the disruption and the lost time.
Whenever you have a mission, you have to go through what’s called a “costing process,” where you have to do things like:
- assess the labor requirements associated with the mission,
- conduct a cost-design iteration process to keep the mission on budget and on schedule,
- and have sufficient time to work through the set of cost and schedule savings that could be identified by the team.
But AXIS encountered a number of obstacles that can only be described as a series of self-inflicted wounds by the US Government on itself, and particularly on the NASA Goddard part of itself. There was the loss of many of the discipline engineers who were necessary to assess the labor requirements for the mission. After the mission design was finalized back in April of 2025, the reallocation of resources meant that the initial costing process could only be completed in September. Then the government shutdown occurred during a critical six-week period, and then there was a forced “pens down” declaration in early December that was forced by the Goddard Space Flight Center’s Executive Review process.
Put simply, there was no opportunity to work through the cost savings and schedule savings that the AXIS team had identified, and as a result, they were put in a terrible position: either submit a Concept Study Review that required too long of a schedule and too large of a budget (missing compliance on schedule and cost), or don’t submit one at all.
The AXIS team did the only thing you can do in an impossible situation: they tried their best. They proceeded with the submission, including outlining a path to a cost-compliant and schedule-compliant profile.
NASA Headquarters received the AXIS team’s submission, and ruled that the team’s stance was unacceptable. No technical review was conducted by NASA personnel; no concerns were raised about AXIS’s technology. In fact, the Phase A work that the AXIS concept study conducted indeed met with several major successes in furthering the key technologies, including in fields like:
- Next Generation X-ray Optics, where iridium-coated, stress-compensated mirror segments were shown to achieve sub-arcsecond level performance on the level of an individual segment,
- building the first demonstrator mirror module, learning valuable lessons about alignment, mounting, and bonding,
- and fabricating charge-coupled-devices that achieved AXIS’s required readout rates and spectra resolution.
Similarly, the AXIS science case was also reviewed to be excellent, and only became stronger from there. The AXIS Community Science Book was produced as part of the Phase A work, and will no doubt inform future X-ray mission concepts for years or even decades to come. However, after more than 9 full years of work, AXIS is officially dead, and the community’s great hope is that a small or mid-sized X-ray mission is selected in the future. Graciously, they all wish the PRIMA team incredible success in their endeavor to become NASA’s next Probe program mission.
This is the first time that a Concept Study has been killed due directly to the actions of the government that commissioned the study in the first place. The X-ray mirror lab at Goddard, in particular, was severely affected by shutdowns, illegally reallocated resources, and pressured retirements. By actively implementing the proposed budget cuts to NASA before the budget had actually been decided — the first time in history that NASA management had done so — we will now have to rely on 1999-level technology for many years to come to explore the high-energy Universe.
As one astronomer put it, “We fired everyone who could do this job, and we are punishing you for not doing it.” The truth is that, without AXIS, the soonest that a high-resolution X-ray imaging mission can launch, and can truly succeed Chandra, is now 25 years from the present date, or potentially more. Historically, it takes around 30 years from a space telescope to go from “concept” to a fully-fledged, fully-built, ready-to-fly mission. Without NASA’s Lynx, without ESA’s Athena, and now without NASA’s AXIS, there are no X-ray missions in the pipeline to bring this incredibly important class of astronomy into the 21st century. Importantly, there was recently a big effort to de-fund Chandra, which would leave humanity without a flagship-class X-ray observatory of any type.
The future of astrophysics in space is in enormous peril, and what’s happened to NASA’s AXIS may be a harbinger of many more killed missions to come. The Universe is out there, waiting for us to discover it. But unless we shift our national priorities, we may soon lose our capabilities to conduct X-ray astronomy, and potentially much more, in the years and decades to come.
This article NASA’s next X-ray mission, AXIS, has been killed is featured on Big Think.
