NANOGrav used 68 millisecond pulsars as a galaxy-sized gravitational wave detector and found the background hum of the entire universe (ApJ Letters, June 2023)
In June 2023, the NANOGrav collaboration announced evidence for the gravitational wave background — a slow, omnipresent ripple in spacetime produced by the collective signal of every supermassive black hole binary in the observable universe.
The technique is elegant and a little mind-bending. Millisecond pulsars are neutron stars that spin hundreds of times per second and emit radio pulses with clock-like precision — some drift by less than a microsecond per year. NANOGrav timed 68 of them, distributed across the sky, for over 15 years using Green Bank, Arecibo, and the VLA. When a gravitational wave passes through the galaxy, it stretches and squeezes spacetime, arriving at the pulsars at slightly different times than expected. Compare enough pulsars across the sky and the signature of the wave emerges from the noise.
The specific pattern they were looking for is called the Hellings-Downs curve, derived in 1983. Pulsars close together on the sky should show correlated timing residuals; pulsars 90 degrees apart should show anticorrelation; 180-degree pairs should correlate again. This quadrupolar fingerprint is the unmistakable mark of a gravitational wave background and cannot be faked by noise or instrumentation effects. After 15 years, that curve appeared in the NANOGrav data. Three independent collaborations — EPTA, PPTA, and CPTA — announced consistent detections within days.
The dominant source is almost certainly supermassive black hole binaries: pairs of black holes at the centers of merged galaxies, each millions to billions of solar masses, slowly spiraling together over hundreds of millions of years. Billions of these systems exist across the observable universe. Their combined gravitational hum is the background NANOGrav detected.
But buried underneath that hum may be something even older. Gravitational waves from the first instants after the Big Bang travel through the plasma that blocks all electromagnetic signals from that era — they are the only direct probe we will ever have of the universe before the cosmic microwave background. Whether a primordial signal is lurking in the current data is the question driving the next decade of work.
The current detection stands at 3-sigma — strong evidence, but below the 5-sigma threshold for a confirmed discovery. International efforts to combine all four regional datasets are expected to push past that threshold within the next few years. What new physics might be hiding in those final decimal places?
Primary source: https://iopscience.iop.org/article/10.3847/2041-8213/acdac6
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Closeup of booster and core stage engines of a CZ-3B/E rocket during launch
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Apollo 15 astronaut Jim Irwin with the Lunar Roving Vehicle on the Moon during his 1971 mission.
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SpaceX’s Starship V3—still a work in progress—mostly successful on first flight | SpaceX has more to prove before flying Starship all the way to low-Earth orbit.
https://arstechnica.com/space/2026/05/spacexs-starship-v3-still-a-work-in-progress-mostly-successful-on-first-flight/
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SpaceX Starship V3's first test flight was largely successful
https://www.engadget.com/2180020/spacex-starship-v3-first-test-flight-success/
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Four Russian satellites are now within striking distance of an ICEYE radarsat | “This capability is not common for satellites conducting typical missions.”
https://arstechnica.com/space/2026/05/a-satellite-company-supporting-ukraine-appears-to-be-in-russias-crosshairs/
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The 12th SpaceX Starship Test Flight will happen in 25 minutes from now
You can watch it live here:
https://www.spacex.com/launches/starship-flight-12
Always exciting to watch it live, they always have very beautiful live shots from the ship, especially the plasma during re-entry.
This is the first Starship launch since 7 months - there was a significant gap between the last V2 launch and this first V3 launch. Most interesting thing today will be to see how well the completely new V3 ship and booster and engine design will work, it's basically a completely new rocket compared to the previous launch attempts. Also a completely new launch pad. Maybe it will work well, or maybe it will just explode immediately.
For Artemis having any chance of meeting its timeline, it would be important that this launch succeeds.
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NASA to Compete Contract for Jet Propulsion Laboratory Management
https://www.nasa.gov/news-release/nasa-to-compete-contract-for-jet-propulsion-laboratory-management/
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1961: Yuri Gagarin Interview
https://youtu.be/pHZ519R51X8
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The 12th SpaceX Starship Test Flight will happen in just under 31 minutes from now
You can watch it live here:
https://www.spacex.com/launches/starship-flight-12
Always exciting to watch it live, they always have very beautiful live shots from the ship, especially the plasma during re-entry.
This is the first Starship launch since 7 months - there was a significant gap between the last V2 launch and this first V3 launch. Most interesting thing today will be to see how well the completely new V3 ship and booster and engine design will work, it's basically a completely new rocket compared to the previous launch attempts. Also a completely new launch pad. Maybe it will work well, or maybe it will just explode immediately.
For Artemis having any chance of meeting its timeline, it would be important that this launch succeeds.
Edit: Launch is scrubbed, some launch pad issue. Likely another flight attempt tomorrow.
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Worker dies at SpaceX's Starbase ahead of Starship V3 megarocket launch
https://www.space.com/space-exploration/launches-spacecraft/worker-dies-at-spacexs-starbase-in-leadup-to-starship-v3-megarocket-launch
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Scientists find a hidden route to the moon that saves fuel
https://www.space.com/astronomy/moon/scientists-find-a-hidden-route-to-the-moon-that-saves-fuel
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NASA to Provide Update on Moon Base Strategy, Missions
https://www.nasa.gov/news-release/nasa-to-provide-update-on-moon-base-strategy-missions/
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Juno Flies Past the Moon Ganymede and Jupiter, With Music by Vangelis
https://youtu.be/CC7OJ7gFLvE?si=PRg0UVbY2B0mH7_q
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I wrote a Python tool to build maps of the Solar System
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Milky way galaxy and andromeda galaxy at (bottom right), captured by my phone outside my campsite.
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The Core of Sharpless 171
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The most detailed photo I've been able to get of the moon with my phone camera! Taken yesterday, S21 FE
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Views of Starship in space
https://x.com/SpaceX/status/2057962516282577014
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China set to launch Shenzhou 23 astronauts to Tiangong space station this weekend
https://www.space.com/space-exploration/human-spaceflight/china-shenzhou-23-astronaut-launch-tiangong-space-station
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Before it comes down, what should be saved from the International Space Station? | What went up cannot all come down (for museum display).
https://arstechnica.com/space/2026/05/before-it-comes-down-what-should-be-saved-from-the-international-space-station/
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This exoplanet weather forecast by the James Webb Space Telescope calls for sandy skies and a clear (alien) sunset
https://www.space.com/astronomy/james-webb-space-telescope/this-exoplanet-weather-forecast-by-the-james-webb-space-telescope-calls-for-sandy-skies-and-a-clear-alien-sunset
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NASA Announces Realignment to Accelerate Mission Delivery - NASA
https://www.nasa.gov/news-release/nasa-announces-realignment-to-accelerate-mission-delivery/
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The Light Paradox: if a distant telescope could intercept light mid-travel, would it see all of Earth’s history at once?
If aliens 2,000 light years away just built a telescope powerful enough to see Earth, they’d be watching the Roman Empire right now. But think about this: the light that left Earth TODAY is already traveling toward them, sitting somewhere in that 2,000 light year corridor. So if their telescope could intercept light at different points along that path rather than just waiting for it to arrive, would they be sampling different moments in Earth’s history. The further out they reach, the more “recent” the Earth they see?
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Stand Up for NASA Science & America’s Space Future
https://www.marssociety.org/news/2026/05/20/stand-up-for-nasa-science-americas-space-future/
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Ingenuity Mars Helicopter - NASA Science
https://science.nasa.gov/mission/mars-2020-perseverance/ingenuity-mars-helicopter/
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Carl Sagan in his final year, on Charlie Rose: "We've arranged a society based on science and technology in which nobody understands anything about science and technology. This combustible mixture of ignorance and power sooner or later is going to blow up in our faces"
https://www.upworthy.com/carl-sagan-warning-about-charlatan-leader-ex1/
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2.5 Petabytes of Cosmic Evolution: The Insanely Detailed FLAMINGO Simulation is Here (50 Million CPU Hours)
https://flamingo.strw.leidenuniv.nl/
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Using spacecraft tanks for methane storage on Mars: feasibility and risks?
Hey everyone,
I am working on a Mars colonization project. During the process of extracting oxygen, I also end up with methane (CH4) as an output.
While having methane is a big plus, storing it is a major issue. Bringing large, dedicated gas cylinders or tanks from Earth is highly impractical due to mass and cargo constraints. My proposed solution is to store this methane directly inside the rocket's own empty tanks. I know that for modern rockets, the methane needs to be cryogenically cooled to around -165 C•, but in this situation, it seems like the best option.
I have two specific questions regarding this approach:
1. Import and Export: Is it technically possible to both import (load) and export (draw back) gas directly from a spacecraft's primary propellant tanks?
2. Feasibility: Do you see any major technical issues or better alternatives with this specific storage method?
Thanks for your insights!
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