Main Engine Cut Off

NASA Administrator Jared Isaacman announced a sweeping roadmap change to the Artemis program this morning—seemingly cancelling the EUS, Gateway, and all SLS upgrades, and instead pursuing the once-and-future annual launch cadence of SLS.

This episode of Main Engine Cut Off is brought to you by 33 executive producers—David, Russell, Pat, Better Every Day Studios, Joonas, Josh from Impulse, Theo and Violet, Steve, Jan, Will and Lars from Agile, Miles O’Brien, Kris, Fred, Stealth Julian, Frank, Joakim, Ryan, Warren, Matt, The Astrogators at SEE, Joel, Lee, Tim Dodd (the Everyday Astronaut!), Donald, Natasha Tsakos, Heiko, and four anonymous—and hundreds of supporters.

Topics

NASA shakes up its Artemis program to speed up lunar return - Ars Technica

NASA Adds Mission to Artemis Lunar Program, Updates Architecture - NASA

NASA Administrator Jared Isaacman on X: “President Trump gave the world the Artemis Program, and NASA and our partners have the plan to deliver. We will standardize architecture where possible, add missions and accelerate flight rate, execute in an evolutionary way, and safely return American astronauts to the Moon…”

NASA Administrator Jared Isaacman on X: “…and this is how we’re going back.”

Teams Begin Artemis II Repairs in Vehicle Assembly Building - NASA

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Artwork photo by Blue Origin

Work with me and my design and development agency: Pine Works

Loren Grush, of Bloomberg, joins me to talk about SpaceX’s acquisition of xAI, its preparation for a potential IPO, Blue Origin’s cancellation of New Shepard and their recent momentum, and the delay to Artemis II following its first wet dress rehearsal.
This episode of Main Engine Cut Off is brought to you by 33 executive producers—David, Natasha Tsakos, Stealth Julian, Warren, Joakim, Tim Dodd (the Everyday Astronaut!), Miles O’Brien, Pat, Better Every Day Studios, Will and Lars from Agile, The Astrogators at SEE, Steve, Joonas, Frank, Fred, Heiko, Donald, Lee, Russell, Kris, Ryan, Theo and Violet, Joel, Matt, Jan, Josh from Impulse, and four anonymous—and hundreds of supporters.
Topics
SpaceX Acquires xAI as Musk Prepares for Mega IPO - Bloomberg
SpaceX-xAI Deal Blurs Musk’s Once-Clear Space Exploration Mission - Bloomberg
Loren Brichter, a High Priest of App Design - WSJ
Blue Origin to Pause New Shepard Flights for No Less Than Two Years | Blue Origin
NASA Conducts Artemis II Fuel Test, Eyes March for Launch Opportunity   - NASA
The Show
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Email your thoughts, comments, and questions to [email protected]
Follow @WeHaveMECO
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Artwork photo by NASA/John Kraus
Work with me and my design and development agency: Pine Works

Artemis II is on the pad, and I can’t stop thinking about it. So I guess listen to me think in the open? Also, a ton of Blue Origin news—the next flight of New Glenn will feature a flown booster, they’ve announced constellation plans under the name TeraWave, and Tory Bruno has left ULA to join the team at Blue.
This episode of Main Engine Cut Off is brought to you by 33 executive producers—Matt, Fred, Will and Lars from Agile, Kris, Lee, Jan, Frank, Miles O’Brien, Josh from Impulse, Theo and Violet, Ryan, Joakim, Stealth Julian, Heiko, Tim Dodd (the Everyday Astronaut!), Better Every Day Studios, Joel, Steve, Joonas, The Astrogators at SEE, Pat, Warren, Natasha Tsakos, Russell, David, Donald, and four anonymous—and hundreds of supporters.
Topics
NASA’s Moonbound Artemis II Rocket Reaches Launch Pad - NASA
Final Steps Underway for NASA’s First Crewed Artemis Moon Mission - NASA
Is Orion’s heat shield really safe? New NASA chief conducts final review on eve of flight. - Ars Technica
Blue Origin makes impressive strides with reuse—next launch will refly booster - Ars Technica
New Glenn-3 to Launch AST SpaceMobile’s BlueBird Satellite | Blue Origin
Blue Origin on X: “Our lunar lander is headed to the Lone Star State! ⭐ Blue Moon MK1 departed from Florida today, bound for @NASA_Johnson's Thermal Vacuum Chamber A, where it will undergo testing at the same facility as the Apollo spacecraft.”
Another Jeff Bezos company has announced plans to develop a megaconstellation - Ars Technica
First Take: What We Think Blue Origin’s TeraWave Actually Is (and Isn’t)
In a surprise announcement, Tory Bruno is out as CEO of United Launch Alliance - Ars Technica
Blue Origin on X: “We’re pleased to announce that @torybruno is joining Blue Origin as president, National Security, reporting to CEO Dave Limp. Tory will spearhead our newly formed National Security Group.”
The Show
Like the show? Support the show on Patreon or Substack!
Email your thoughts, comments, and questions to [email protected]
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Subscribe on Apple Podcasts, Overcast, Pocket Casts, Spotify, Google Play, Stitcher, TuneIn or elsewhere
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Artwork photo by Blue Origin
Work with me and my design and development agency: Pine Works

Casey Dreier of The Planetary Society joins me to talk about the NASA FY2026 budget, the early days of the Administrator Isaacman era, and how we feel going into Artemis II.
This episode of Main Engine Cut Off is brought to you by 33 executive producers—Matt, Fred, Will and Lars from Agile, Kris, Lee, Jan, Frank, Miles O’Brien, Josh from Impulse, Theo and Violet, Ryan, Joakim, Stealth Julian, Heiko, Tim Dodd (the Everyday Astronaut!), Better Every Day Studios, Joel, Steve, Joonas, The Astrogators at SEE, Pat, Warren, Natasha Tsakos, Russell, David, Donald, and four anonymous—and hundreds of supporters.
Topics
Casey Dreier | The Planetary Society
The Planetary Society
You just saved NASA's budget | The Planetary Society
2025 Impact Report | The Planetary Society
The Show
Like the show? Support the show on Patreon or Substack!
Email your thoughts, comments, and questions to [email protected]
Follow @WeHaveMECO
Follow @[email protected] on Mastodon
Listen to MECO Headlines
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Join the Off-Nominal Discord
Subscribe on Apple Podcasts, Overcast, Pocket Casts, Spotify, Google Play, Stitcher, TuneIn or elsewhere
Subscribe to the Main Engine Cut Off Newsletter
Artwork photo by Blue Origin
Work with me and my design and development agency: Pine Works

A holiday special! Enjoy this week’s episode of Headlines free. It’s an absolute monster episode—way longer than usual Headlines episodes, I promise—but it’s a great example of what you get when you support the show over at mainenginecutoff.com/support.
NASA finally—and we really do mean it this time—has a full-time leader - Ars Technica
Agencywide Town Hall with NASA Administrator Jared Isaacman, Friday, Dec. 19, 2025 - YouTube
Trump commits to Moon landing by 2028, followed by a lunar outpost two years later - Ars Technica
NASA Teams Work MAVEN Spacecraft Signal Loss - NASA Science
NASA Continues MAVEN Spacecraft Recontact Efforts - NASA Science
SpaceX Sets $800 Billion Valuation, Confirms 2026 IPO Plans - Bloomberg
SpaceX $1.5 Trillion Value Target Hinges on Starlink — And Elon - Bloomberg
SpaceX Said to Notify Employees of Quiet Period Ahead of IPO - Bloomberg
In a surprise announcement, Tory Bruno is out as CEO of United Launch Alliance - Ars Technica
Space Development Agency awards $3.5 billion in contracts for missile-tracking satellites - SpaceNews
Chinese astronauts inspect debris-damaged Shenzhou-20 spacecraft during spacewalk - SpaceNews
Space Station – Off The Earth, For The Earth
NASA Astronaut Jonny Kim, Crewmates Return from Space Station - NASA
After key Russian launch site is damaged, NASA accelerates Dragon supply missions - Ars Technica
R-7 ICBM/Soyuz rocket launch facilities in Baikonur
Launch Roundup: China, Russia, Rocket Lab, ULA join SpaceX in flying this week - NASASpaceFlight.com
Launch Previews: Ariane 6, Falcon 9, Atlas V, and Electron launches highlight busy week - NASASpaceFlight.com
Launch Roundup: International launches fill manifest during last full week of 2025 - NASASpaceFlight.com
China launches 4 times in 4 days, boosting megaconstellation and surveillance assets - SpaceNews
China launches new TJS satellite, commercial Kinetica-1 lofts 9 spacecraft - SpaceNews
Michael Nicolls on X: “When satellite operators do not share ephemeris for their satellites, dangerously close approaches can occur in space.   A few days ago, 9 satellites were deployed from a launch from the Jiuquan Satellite Launch Center in Northwestern China. As far as we know, no coordination or…”
China launches experimental cargo spacecraft, opaque tech demo mission and remote sensing satellite - SpaceNews
Andrew Jones on X: “Turns out there were two male mice launched on the DEAR-5 cargo spacecraft for neuroscience research. Spacecraft is planned to operate in orbit for one year and is not rated for reentry, so it's game over at some point for the rodents. Video is prelaunch.”
Rocket Lab launches JAXA tech demo satellite - SpaceNews
Ariane 6 launches Galileo navigation satellites - SpaceNews
These are the flying discs the government wants you to know about - Ars Technica
Blue Origin flies first wheelchair user to space - SpaceNews
Rocket Lab wraps up record launch year - SpaceNews
Japan’s H3 suffers second-stage anomaly, QZS-5 satellite lost - SpaceNews
Andrew Jones on X
China launches new Guowang satellites, Long March 12A launch and landing attempt date set - SpaceNews
Keep an eye on upcoming launches with rocketlaunch.live.