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

The Show

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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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

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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

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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.

Yesterday, I had the chance to visit the Pentagon and sit down with General Chance Saltzman, Chief of Space Operations—the head of the United States Space Force. We talk about the service 6 years into its existence, the state of acquisitions, the threats and space environment today, and what the future may hold for the Space Force when it comes to human spaceflight.

This episode of Main Engine Cut Off is brought to you by 32 executive producers—Russell, Natasha Tsakos, Will and Lars from Agile, Theo and Violet, David, Matt, Better Every Day Studios, Warren, The Astrogators at SEE, Josh from Impulse, Stealth Julian, Joakim, Frank, Pat, Joel, Donald, Ryan, Tim Dodd (the Everyday Astronaut!), Joonas, Jan, Steve, Fred, Lee, Kris, Heiko, and four anonymous—and hundreds of supporters.

Topics

• United States Space Force
• B. Chance Saltzman > United States Space Force > Display
• Space Force roadmap set to define what the service needs and why - SpaceNews
• US intel officials “concerned” China will soon master reusable launch - Ars Technica
• Asked why we need Golden Dome, the man in charge points to a Hollywood film - Ars Technica
• Space Force rolls out new naming scheme for satellites and space weapons - SpaceNews
• Andrew Jones on X: “Outrageous images of China's Shijian-26, an apparent new-gen Earth observation satellite, from Maxar. SSD of 1.9 cm.”
• Andrew Jones on X: “China's CGST has returned the favour, using its Jilin-1 sats to image a Maxar Worldview Legion 2 satellite.”
• Scott Tilley 🇺🇦 🇨🇦 (@coastal8049) / X

The Show

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Stephen Clark of Ars Technica joins me to talk about a ton of stories in the news—Jared Isaacman was back in front of Congress, a few Starliner flights have been cut from the ISS manifest, Starship received environmental approval to proceed at SLC-37, Zhuque-3 almost stuck its first landing attempt, the Soyuz launch pad fell apart at Baikonur, and the Space Force has a new mission naming scheme.

This episode of Main Engine Cut Off is brought to you by 32 executive producers—Matt, Fred, Kris, Natasha Tsakos, Josh from Impulse, Better Every Day Studios, Joakim, Joel, Ryan, The Astrogators at SEE, Tim Dodd (the Everyday Astronaut!), Heiko, Jan, Theo and Violet, Donald, Pat, Will and Lars from Agile, Lee, Russell, Joonas, Warren, Steve, Frank, Stealth Julian, David, and four anonymous—and hundreds of supporters.

Topics

• Author: Stephen Clark - Ars Technica
• NASA nominee appears before Congress, defends plans to revamp space agency - Ars Technica
• Congress warned that NASA’s current plan for Artemis “cannot work” - Ars Technica
• NASA seeks a “warm backup” option as key decision on lunar rover nears - Ars Technica
• It’s official: Boeing’s next flight of Starliner will be allowed to carry cargo only - Ars Technica
• A spectacular explosion shows China is close to obtaining reusable rockets - Ars Technica
• Before a Soyuz launch Thursday someone forgot to secure a 20-ton service platform - Ars Technica
• Rivals object to SpaceX’s Starship plans in Florida—who’s interfering with whom? - Ars Technica
• SpaceX on X: “We’ve received approval to develop Space Launch Complex-37 for Starship operations at Cape Canaveral Space Force Station. Construction has started. With three launch pads in Florida, Starship will be ready to support America’s national security and Artemis goals as the world’s…”
• Attack, defend, pursue—the Space Force’s new naming scheme foretells new era - Ars Technica

The Show

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Blue Origin is fresh off an incredible few weeks—a successful second launch and first landing of New Glenn, followed by an exciting unveil of upgrades to the vehicle, including an enormous new version, New Glenn 9x4.

This episode of Main Engine Cut Off is brought to you by 32 executive producers—Lee, Natasha Tsakos, Fred, Will and Lars from Agile, Ryan, Stealth Julian, Pat, Heiko, Kris, Jan, Better Every Day Studios, Theo and Violet, Matt, Josh from Impulse, Russell, Joel, Warren, Joonas, Joakim, Tim Dodd (the Everyday Astronaut!), Donald, David, Frank, Steve, The Astrogators at SEE, and four anonymous—and hundreds of supporters.

Topics

• Blue Origin’s New Glenn rocket came back home after taking aim at Mars - Ars Technica
• Jeff Bezos on X: “Good overview of the landing. We nominally target a few hundred feet away from Jacklyn to avoid a severe impact if engines fail to start or start slowly. We’ll incrementally reduce that conservatism over time. We are all excited and grateful for yesterday…”
• New Glenn Update | Blue Origin
• Booster 18 suffers anomaly during proof testing - NASASpaceFlight.com
• Senate Commerce Committee schedules hearing on Isaacman renomination - SpaceNews
• Lawmakers writing NASA’s budget want a cheaper upper stage for the SLS rocket - Ars Technica

The Show

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Simone D’Amico of Stanford and EraDrive, DJ Bush of NVIDIA, and Al Tadros of Redwire join me to talk about autonomy in space, to get into the specific details of what they’re working on and how it comes together, and what it may do for the industry in the next few years.

This episode of Main Engine Cut Off is brought to you by 32 executive producers—Joonas, Russell, Donald, Stealth Julian, Pat, Fred, David, Lee, Frank, Josh from Impulse, Steve, Joel, Joakim, Matt, Natasha Tsakos, Tim Dodd (the Everyday Astronaut!), Kris, Theo and Violet, Heiko, Will and Lars from Agile, Jan, Warren, The Astrogators at SEE, Ryan, Better Every Day Studios, and four anonymous—and hundreds of supporters.

Topics

• Episode T+315: Autonomy in Space (with Simone D’Amico, DJ Bush, and Al Tadros) - YouTube
• Simone D'Amico | LinkedIn
• Center for AEroSpace Autonomy Research (CAESAR)
• Stanford spinoff EraDrive claims $1 million NASA contract - SpaceNews
• DJ Bush | LinkedIn
• How Starcloud Is Bringing Data Centers to Outer Space | NVIDIA Blog
• Al Tadros | LinkedIn
• Redwire Space | Heritage + Innovation
• NASA Starling - Autonomous Tip and Cue in Orbit
• NASA Starling - Distributed Optical Navigation
• NASA Starling - Autonomous Space Domain Awareness
• VISORS - Precise Formation-Flying
• Autonomous Spacecraft 3D Model Reconstruction

The Show

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Thinking through the chaos that has ensued over the NASA Administrator role, the Artemis 3 lander acceleration movement, the SpaceX Starship HLS update, and a bit on how we actually got here.

This episode of Main Engine Cut Off is brought to you by 32 executive producers—Donald, Stealth Julian, Jan, Theo and Violet, The Astrogators at SEE, Joakim, Steve, Matt, Fred, Lee, Joel, Kris, Ryan, David, Josh from Impulse, Warren, Heiko, Pat, Russell, Tim Dodd (the Everyday Astronaut!), Joonas, Better Every Day Studios, Will and Lars from Agile, Natasha Tsakos, Frank, and four anonymous—and hundreds of supporters.

Topics

• SpaceX - Updates
• SpaceX teases simplified Starship as alarms sound over Moon landing delays - Ars Technica
• Why did NASA’s chief just shake up the agency’s plans to land on the Moon? - Ars Technica
• Elon Musk just declared war on NASA’s acting administrator, apparently - Ars Technica
• How America fell behind China in the lunar space race—and how it can catch back up - Ars Technica
• China completes landing and takeoff test for crewed moon lander - SpaceNews
• China completes second hot-fire test for new moon rocket, including engine restarts - SpaceNews
• Trump pulls Isaacman nomination for space. Source: “NASA is f***ed.” - Ars Technica

The Show

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• Artwork photo by NASA
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