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Gregory Walth

@vega18h37m

Astronomer at Caltech/IPAC working on the Roman Space Telescope. Interests: Dusty galaxies, CGM, gravitational lensing, data pipelines, coffee. He/Him https://gwalth.github.io/

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Latest posts by Gregory Walth @vega18h37m

Email from Chris Reynolds to the AXIS Team. Subject is disappointing AXIS news. Text of e-mail reads: Dear AXIS Friends,


The AXIS team has received some very disappointing news – we have been informed by NASA HQ that AXIS is not eligible for selection and hence the Concept Study Report (CSR) will not be subjected to the full review process.   


AXIS represents the scientific aspirations of a large international community. As a member of one of the AXIS science working groups, you deserve a candid explanation from the PI of what happened and why.  That is the purpose of this note.


NASA’s decision was programmatic and not based on a review of the technology or science; the mission profile described in the submitted CSR was over the allowed budget and schedule.  How was such a thing possible?   In short, with NASA-GSFC as the AXIS managing center, the mission formulation process was critically compromised by the seismic shifts occurring in NASA and the Federal government.  The AXIS study team was hit hard by three unprecedented challenges: 


NASA’s Deferred Resignation Program (DRP) and the pressure at GSFC to resign/retire created a rapid and uncontrolled loss of over 20 personnel with key expertise during a critical mission formulation period, including the main GSFC Project Manager (Jimmy Marsh) and the X-ray mirror lead (Will Zhang) and many discipline engineers.

Email from Chris Reynolds to the AXIS Team. Subject is disappointing AXIS news. Text of e-mail reads: Dear AXIS Friends, The AXIS team has received some very disappointing news – we have been informed by NASA HQ that AXIS is not eligible for selection and hence the Concept Study Report (CSR) will not be subjected to the full review process. AXIS represents the scientific aspirations of a large international community. As a member of one of the AXIS science working groups, you deserve a candid explanation from the PI of what happened and why. That is the purpose of this note. NASA’s decision was programmatic and not based on a review of the technology or science; the mission profile described in the submitted CSR was over the allowed budget and schedule. How was such a thing possible? In short, with NASA-GSFC as the AXIS managing center, the mission formulation process was critically compromised by the seismic shifts occurring in NASA and the Federal government. The AXIS study team was hit hard by three unprecedented challenges: NASA’s Deferred Resignation Program (DRP) and the pressure at GSFC to resign/retire created a rapid and uncontrolled loss of over 20 personnel with key expertise during a critical mission formulation period, including the main GSFC Project Manager (Jimmy Marsh) and the X-ray mirror lead (Will Zhang) and many discipline engineers.

GSFC priorities rapidly realigned to the FY2026 President’s Budget Request (PBR) that eliminated the Probe program, further reducing the availability of GSFC engineering and mission formulation personnel (incl. cost analysts and schedulers) over the critical Summer and Fall months. Key work was halted for almost seven weeks when the core GSFC AXIS study team, dominated by NASA civil servants, was furloughed during the government shutdown.  NASA HQ’s extension to the CSR submission deadline (from 18-Dec-2025 to 29-Jan-2026) was inadequate compensation for the disruption and lost time.


Taken together, these factors disrupted the basic grass-roots costing process (which requires extensive “reach back” to the discipline engineers to assess labor requirements) as well as the cost-design iteration process that is central to the formulation of a cost-capped and schedule-constrained mission.  While the mission design was finalized in April, our initial grass-roots costing (which was ~10% over budget) could only be completed in September due to the lack of assigned resources.  With the subsequent government shutdown and then “pens down” in early-December forced by the GSFC Executive Review process, there was no opportunity to work through the set of cost/schedule savings that had already been identified by the AXIS team. 


Ultimately, the GSFC executive council gave AXIS leadership the choice of submitting a CSR with a non-compliant schedule and cost, or not submitting a CSR at all.  We of course proceeded with the submission, including a narrative that we understood the path to a cost-compliant profile (that we would have discussed with the review panels during the Site Visit). NASA HQ has ruled this stance to be unacceptable.


It is important to stress that NASA’s programmatic decision was before any technical review had been conducted.  The decision was NOT due to any concerns about AXIS technology. Indeed, the AXIS Phase A work had major successes with furthering

GSFC priorities rapidly realigned to the FY2026 President’s Budget Request (PBR) that eliminated the Probe program, further reducing the availability of GSFC engineering and mission formulation personnel (incl. cost analysts and schedulers) over the critical Summer and Fall months. Key work was halted for almost seven weeks when the core GSFC AXIS study team, dominated by NASA civil servants, was furloughed during the government shutdown. NASA HQ’s extension to the CSR submission deadline (from 18-Dec-2025 to 29-Jan-2026) was inadequate compensation for the disruption and lost time. Taken together, these factors disrupted the basic grass-roots costing process (which requires extensive “reach back” to the discipline engineers to assess labor requirements) as well as the cost-design iteration process that is central to the formulation of a cost-capped and schedule-constrained mission. While the mission design was finalized in April, our initial grass-roots costing (which was ~10% over budget) could only be completed in September due to the lack of assigned resources. With the subsequent government shutdown and then “pens down” in early-December forced by the GSFC Executive Review process, there was no opportunity to work through the set of cost/schedule savings that had already been identified by the AXIS team. Ultimately, the GSFC executive council gave AXIS leadership the choice of submitting a CSR with a non-compliant schedule and cost, or not submitting a CSR at all. We of course proceeded with the submission, including a narrative that we understood the path to a cost-compliant profile (that we would have discussed with the review panels during the Site Visit). NASA HQ has ruled this stance to be unacceptable. It is important to stress that NASA’s programmatic decision was before any technical review had been conducted. The decision was NOT due to any concerns about AXIS technology. Indeed, the AXIS Phase A work had major successes with furthering

Indeed, the AXIS Phase A work had major successes with furthering the key technologies. GSFC’s Next Generation X-ray Optics (NGXO) team successfully demonstrated iridium-coated, stress-compensated mirror segments that meet AXIS baseline requirements (i.e. segment-level performance at sub-arcsecond level).  NGXO also built the first AXIS demonstrator mirror module, learning critical lessons about mirror alignment, mounting and bonding. On the detector side, MIT quickly moved to fabricate AXIS-like CCDs and, working with our colleagues at Stanford, recently demonstrated that they achieve the required readout rate and spectral resolution. 


Similarly, NASA’s decision was NOT a judgment of the importance of AXIS science.  The AXIS science case was rated excellent in the Step 1 review, and it only became stronger during our Phase A study.  The AXIS Community Science Book, which many of you contributed to, is an extremely powerful demonstration of the relevance and importance of high-resolution X-ray observations to all areas of astrophysics. The Science Book is one of the most important legacies of the AXIS Phase A study and, I believe, will help define future mission concepts for many years to come.  I thank you all from the bottom of my heart for all of your work on this.


AXIS has been a long journey; we started under the leadership of Richard Mushotzky more than nine years ago.  During that time, it’s been an enormous privilege to work with amazing people; the AXIS science team, the incredible/brilliant GSFC and Northrop Grumman engineers, and the wider astrophysics community.  I am, quite frankly, livid that AXIS ultimately fell victim to the programmatic chaos of 2025. The astronomical community deserves better. I hope that NASA leadership, especially at GSFC and HQ, can have an honest discussion about how to better support and protect programs during extraordinary times.

Indeed, the AXIS Phase A work had major successes with furthering the key technologies. GSFC’s Next Generation X-ray Optics (NGXO) team successfully demonstrated iridium-coated, stress-compensated mirror segments that meet AXIS baseline requirements (i.e. segment-level performance at sub-arcsecond level).  NGXO also built the first AXIS demonstrator mirror module, learning critical lessons about mirror alignment, mounting and bonding. On the detector side, MIT quickly moved to fabricate AXIS-like CCDs and, working with our colleagues at Stanford, recently demonstrated that they achieve the required readout rate and spectral resolution. Similarly, NASA’s decision was NOT a judgment of the importance of AXIS science. The AXIS science case was rated excellent in the Step 1 review, and it only became stronger during our Phase A study. The AXIS Community Science Book, which many of you contributed to, is an extremely powerful demonstration of the relevance and importance of high-resolution X-ray observations to all areas of astrophysics. The Science Book is one of the most important legacies of the AXIS Phase A study and, I believe, will help define future mission concepts for many years to come. I thank you all from the bottom of my heart for all of your work on this. AXIS has been a long journey; we started under the leadership of Richard Mushotzky more than nine years ago. During that time, it’s been an enormous privilege to work with amazing people; the AXIS science team, the incredible/brilliant GSFC and Northrop Grumman engineers, and the wider astrophysics community. I am, quite frankly, livid that AXIS ultimately fell victim to the programmatic chaos of 2025. The astronomical community deserves better. I hope that NASA leadership, especially at GSFC and HQ, can have an honest discussion about how to better support and protect programs during extraordinary times.

For now, as a community, we must look forward. There is still one excellent mission under consideration for the Probe program, PRIMA, and we wish them a smooth and speedy path to selection and flight.  In X-ray astronomy, the SMEX and MidEX programs represent concrete pathways for focused, high-impact missions, and the scientific case we built for AXIS provides a strong foundation for those concepts. The technologies we advanced in Step 1 and Phase A, particularly the NGXO mirror work and the MIT/Stanford detector demonstrations, can anchor the next generation of proposals. Most importantly, the AXIS Community Science Book, representing more than 500 scientists across, is a living document and a powerful signal to NASA leadership that this community is organized, serious, and not going anywhere. I encourage everyone to use it actively, as a resource for future concept development, for Astro2030 engagement, and for building the next mission that will deliver high angular resolution X-ray imaging to address the fundamental questions about black hole growth, galaxy evolution, and the hot universe that motivated AXIS from the beginning. This community built something remarkable over nine years and that doesn't end here.


Thank you again for your support of AXIS over these times.


Best

Chris and the AXIS leadership team

For now, as a community, we must look forward. There is still one excellent mission under consideration for the Probe program, PRIMA, and we wish them a smooth and speedy path to selection and flight. In X-ray astronomy, the SMEX and MidEX programs represent concrete pathways for focused, high-impact missions, and the scientific case we built for AXIS provides a strong foundation for those concepts. The technologies we advanced in Step 1 and Phase A, particularly the NGXO mirror work and the MIT/Stanford detector demonstrations, can anchor the next generation of proposals. Most importantly, the AXIS Community Science Book, representing more than 500 scientists across, is a living document and a powerful signal to NASA leadership that this community is organized, serious, and not going anywhere. I encourage everyone to use it actively, as a resource for future concept development, for Astro2030 engagement, and for building the next mission that will deliver high angular resolution X-ray imaging to address the fundamental questions about black hole growth, galaxy evolution, and the hot universe that motivated AXIS from the beginning. This community built something remarkable over nine years and that doesn't end here. Thank you again for your support of AXIS over these times. Best Chris and the AXIS leadership team

The @axisprobe.bsky.social team learned that the phase A concept study report of AXIS (the Advanced X-ray Imaging Satellite) will not be reviewed because the lost personnel at NASA Goddard and government shutdown impacted our schedule and budget. 🔭 Here is the PI's e-mail with the explanation.

09.03.2026 20:05 👍 223 🔁 95 💬 21 📌 28
Preview
a kitchen with a checkered floor and a white refrigerator with the words oh yeah !!! written on it . ALT: a kitchen with a checkered floor and a white refrigerator with the words oh yeah !!! written on it .
09.03.2026 16:25 👍 0 🔁 0 💬 0 📌 0

www.nature.com/articles/d41...

01.03.2026 19:55 👍 2 🔁 2 💬 0 📌 0

It could be worse... it could be a 4 o'clock zoom 🤣😭

24.02.2026 02:29 👍 1 🔁 0 💬 0 📌 0
Preview
Caltech astrophysicist fatally shot on porch of his rural SoCal home, where he studied the stars An accomplished Caltech astrophysicist with more than four decades of research contributions in galactic astronomy and the study of distant planets was fatally shot in the Antelope Valley.

For those of you who missed the news about someone who impacted almost every area of modern astronomy on thoughtful and deeply technical levels and in whom I had found to be a really lovely human being (especially when I was most definitely not one).

20.02.2026 15:29 👍 11 🔁 7 💬 1 📌 0

It's coffee time!

10.02.2026 16:14 👍 0 🔁 0 💬 0 📌 0

The coffee didn't take today...

02.02.2026 19:46 👍 0 🔁 0 💬 0 📌 0

Woot!

13.01.2026 15:52 👍 0 🔁 0 💬 0 📌 0
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“We’re Too Close to the Debris”: How SpaceX Rockets Put Passenger Planes at Risk The FAA predicted Elon Musk’s Starship would cause “minor or minimal” disruption. Then the rockets exploded twice in three months over busy airspace. Flight data reveals how many planes scrambled to p...

"Wer'e too close to the debris": A stunning data viz showing how SpaceX rockets put passenger planes at risk, by @heathervogell.bsky.social and Agnel Philip w/ graphics by @lucaswaldron.bsky.social

08.01.2026 12:53 👍 389 🔁 167 💬 9 📌 9

They're being polite. Clearly they are leaving a spot for you in front of them. 🤣

08.01.2026 01:45 👍 1 🔁 0 💬 0 📌 0

yum! 😋

18.12.2025 17:42 👍 1 🔁 0 💬 0 📌 0

Looks tasty! 😋
What was in it?

18.12.2025 17:24 👍 1 🔁 0 💬 1 📌 0

Wait, there are school districts that have buses?! Wow, cool!

16.12.2025 19:46 👍 1 🔁 0 💬 0 📌 0
Two technicians in clean suits inspect a the completed Roman Space Telescope in a clean room at a NASA assembly facility.

Two technicians in clean suits inspect a the completed Roman Space Telescope in a clean room at a NASA assembly facility.

NASA has completed the construction of #NASARoman! Last month, technicians joined the inner and outer portions of the observatory in Maryland.

After final testing, Roman will move to the launch site at the Kennedy Space Center for launch preparations in summer 2026: https://go.nasa.gov/48EqnE8 🔭 🧪

04.12.2025 18:14 👍 148 🔁 49 💬 1 📌 5

the cone of shame

04.12.2025 04:51 👍 2 🔁 0 💬 0 📌 0
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It's Friday, and apparently bluesky is ready for this fun revelation:

Dinosaurs lived on the other side the Galaxy.

21.11.2025 17:11 👍 931 🔁 388 💬 36 📌 52
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A new 3D map of interstellar dust with Gaia! 🌌

A new study, led by Marie Barbillon, exploited the spectroscopic parametriser from Gaia DR3 to build a high-resolution extinction map! It extends up to 4 kpc from the Sun, with a finer version focused on the Local Bubble area.

#astro #galactic

18.11.2025 09:35 👍 48 🔁 12 💬 1 📌 1
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Remember that lovely aurora last week?

Well...um...this is what Euclid saw... 😱

🧵

19.11.2025 11:51 👍 108 🔁 40 💬 4 📌 4
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Nancy Grace Roman telescope is out of the thermal vacuum chamber and getting ready to launch in 2026

14.11.2025 22:33 👍 25 🔁 6 💬 0 📌 0

We are live for a crisis mapping project post-Melissa! Excellent thread by Izzy below on the details and how to join ( planetaryresponsenetwork.org )

A lot of the methods we use to accurately crowdsource this mapping are derived from astrophysics citizen science work like @galaxyzoo.org 🔭🌎

06.11.2025 15:54 👍 5 🔁 1 💬 0 📌 0

Post a perfect album from the 90’s that isn’t Nirvana, Pearl Jam,Soundgarden or Alice In Chains.

29.10.2025 16:12 👍 2 🔁 0 💬 0 📌 0

It must think you're going to run the python exec function on all the strings inside 😛

23.10.2025 20:00 👍 1 🔁 0 💬 0 📌 0

I would like to understand why they wont stop saying it.

17.10.2025 05:21 👍 0 🔁 0 💬 1 📌 0
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“The Destruction of NASA’s Mission” Whistleblowers reveal OMB’s Unconstitutional Plot to Gut the Agency

New from Committee on Commerce, Science, Transportation Ranking Member Maria Cantwell.

NOTE: This is indeed what I have seen going on inside NASA.
🧪🔭

www.commerce.senate.gov/services/fil...

29.09.2025 15:09 👍 102 🔁 61 💬 0 📌 10

Ohio State just advised all staff and students not to attend the SACNAS (Society for the advancement of Chicanos and Native Americans in Science) annual meeting of 6000+ scientists -- which is in Columbus, OH this year! -- saying it may be exclusionary, even though it is open to all.

29.09.2025 20:57 👍 314 🔁 130 💬 13 📌 39
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Images from Palomar at 2 different infrared wavelengths last night - one that Saturn's methane atmosphere absorbs, and one the it reflects!

(The faint point source is the moon, Tethys!)

Taken by David Ciardi, Catherine Clark,
@lowbacca.bsky.social and Miranda Felsmann; animated by me (and ezgif!)

06.08.2025 18:04 👍 323 🔁 77 💬 6 📌 2
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Postdoc Spotlight: Allison Matthews We sat down with Allison Matthews who helped to commission the MeerKAT radio telescope in South Africa.

Hey!

One of you should bring Dr. Matthews onto your faculty.

Talk to me if you have any questions.

carnegiescience.edu/news/postdoc...

26.09.2025 20:29 👍 4 🔁 1 💬 0 📌 0

Yikes! I'm glad you are fine!

We once had a breakdown somewhere between Palm Springs and Blythe, near a place called "Desert Center". Lol.

24.09.2025 12:50 👍 0 🔁 0 💬 0 📌 0

Dammit, did I miss the rapture... again?

23.09.2025 15:15 👍 1 🔁 0 💬 0 📌 0

Does this require a sea shanty? 😛

18.09.2025 21:03 👍 1 🔁 0 💬 1 📌 0