This weekend the first 100 octane unleaded aviation gas was sold in the US - after years of development, testing and rulemaking GAMI's G100UL is now available at Reid Hillview airport in San Jose.
aopa.org/news-and-media… Many piston engine planes still need 100 octane fuel and while lead was eliminated from car gas it hadn't been possible to do that for aircraft, partly because modifying aircraft is a massive problem so the EPA let small aircraft continue to use 100LL (low lead)

I am in no way an expert on submersibles, but, based on what I know and what I see here, the pressure hull failed at the glue join between the carbon fiber and the titanium ring on the front of the sub, that failure propagated backwards with the water pushing everything into the rear of the cabin in milliseconds.
The front just popped off, the bolts used to hold it in probably snapped due to the water rushing in, the window shot out, no idea where that is.
Also I don't see where the forward ring is, it got propelled away and being less draggy travelled further.

This wasn't a window failure, it wasn't titanium failure, and judging by the transcript they weren't seeing or hearing anything wrong, just dropping a couple of weights to slow the descent.


I suspect that there was a mismatch in the modulus of compression between the end caps and carbon fiber, and that would put extra force on that join. This was what the US Navy Labs papers discussed when they tested to failure with steel end caps.

Using old data, and cloud computing scientists working at the Asteroid Institute identified 27,500 new asteroids. These were objects that had been imaged in the past but hadn't had orbits calculated from those images. And a big part of this is because there's new algorithms that can exploit massive increases in computer power available today. If you take a photo of empty sky there's going to be asteroids in there, if you do a long enough exposure you might even see a trail showing the object moving against the stars, but just because you capture a photo of an asteroid doesn't mean you're discovered it.

The NTSB has the initial report on the jet that crashed on a highway in Florida. Oil pressure warnings on both engines.
The throttles were set to the idle position, but that's the kind of thing you'd do when you're committed to a forced landing.
data.ntsb.gov/carol-repgen/a…


One fuel sample showed a small amount of water.

There are lots of comments about the Nova-C lander being too tall, contributing to the tip over on landing.
Let's consider why it's this shape:
Firstly the landing legs are as wide as they can get for the Falcon 9 fairing without requiring a deployment mechanism. Secondly, the core of the vehicle is the propulsion, and two propellent tanks. These are mounted inline because it makes for the lightest design, the propellent tanks are different sizes and masses so putting them side by side makes balancing more complex.

When the UK Atomic Energy Authority was formed in 1954 it was given a coat of arms appropriate for a British institution, and like any coat of arms it’s full of symbolism.
Firstly, the motto ‘E Minimis Maxima’ - ‘from the smallest, the greatest’, i.e. atomic energy. The black shield with silver spots references a graphite moderated reactor with silver uranium rods, and the inverted triangle with Red and yellow bolts shows the energy released.

So here's my full explanation for why the Vikram Lander in Chandrayaan-2 crashed back in 2019. We still don't have much data to go on, but a few news pieces of information give us a working timeline.
It crashed because of software problems and a valve not operating properly.

Thisis an overview of the descent plan, and a screen grab of a presentation showing the actual timeline. For the first 624 seconds the spacecraft is performing rough braking with full thrust from all the engines. This phase operated correctly with no problems.

So now I’ve got a minute to talk. In some ways the Superheavy flip after engine failures resembles those seen by Astra and Firefly.
The vehicle flipped because fins and flaps mean the center of drag is in front of center of mass, so it’s aerodynamically unstable. Eventually the aerodynamic forces exceed the capabilities of the engines to keep it straight and it naturally flips. The engines continued to burn through the backflips.
Stage separation may have failed because of lateral forces beyond those designed.

People were asking for an explanation of these weird ass transfer orbits used by spacecraft these days, they use the gravity of the Earth, moon and sun to enter into lunar orbit without making any major engine burns. There's 2 main things here, ballistic capture where something goes into orbit without an engine burn, and weak stability boundary orbits where you try to exploit areas of gravitational potential where opposing forces cancel out.

There were some great Art entries for the final round of Runway Project Here's TeslaPenguin's KERBALS
And Concodroid's work with blender:

As part of pilot training I wake up every morning and check this:
KDVO 131435Z AUTO 00000KT 10SM CLR 06/04 A3027 RMK AO2

For non pilots, it’s a weather report called a METAR - METeorological Aerodrome Reports. I read it and decide whether the weather supports flying. Even when I have no plans to fly, which is the majority of the time, learning to read aviation weather is one of those core skills, and this isn’t the only type of report that matters, there’s TAFs, AIRMETs, SIGMETs and more.

Since everyone’s talking about big new telescope, let’s talk about a big old telescope. In 1845 William Parsons, the 3rd Earl of Rosse built the largest telescope in the world on his estate in Ireland. Known at the Leviathan It’s 72” mirror would remain the largest for 70 years. It was well suited to studying the Messier objects, but without astrophotography the records we have are sketches - here’s M51.
Other descriptions of the device and observations can be read in this account: royalsocietypublishing.org/doi/pdf/10.109…

Spin Launch's site shows their orbital accelerator spinning at 450rpm, it's also mentioned that it's 300 feet across. That's about 2.1km/sec.
At a 35 degree launch angle that puts the projectile to 75km with no drag losses, and lateral speed of 1.7km/sec at apogee. That speed and altitude is in the same ballpark as stage separation of a Falcon 9 launch on a mission with RTLS stage recovery.

So let's do some quick numbers. The circular chamber is about 33m across, so circumference is 103m, which means it needs to spin at ~180rpm to move payload at mach 1. And that's consistent with the speed shown in the video.
So it probably launched to over 10,000 feet. Also, g-forces due to rotation would be over 30g.

Obviously this is a ridiculously stupid question, equivalent blaming him for Texas power problems because he didn’t move the state out of the way of the cold weather in February. But…. In the long term, inside the next hundred million years, we might need to consider it.

https://twitter.com/forbes/status/1402388019420741633

As the sun evolves it’s slowly getting hotter. This is much slower than the current rapid increase due to anthropogenic CO2, but we can fix that problem. The sun’s evolution on the other hand is not something we can change. So one possible solution is to move the earth.

A short thread on rocket fuels and how many are everyday chemicals that you can buy in a store, indeed, many of you have this stuff in your house. Ethanol - used by the V2 and later the Redstone used to launch Alan Shepard into space. The vodka you can buy is generally 40% concentration, rockets used 75% which is more like Everclear
amzn.to/3vTkuyp

So, after pointing out the Apple Watches in use on the ISS recently, a thread pointing out some other Apple tech that made it to space. Back in 2011 STS-43 carried a mac portable, one of its functions was to evaluate using pointing devices (mice/trackballs/joysticks) in zero G. The machine had one Megabyte of RAM can cost $7,300

Crew dragon relocated to PMA 3 - that’s only the third time a crewed spacecraft has docked to it, the previous visitors were Endeavor on STS-97 and Atlantis on STS-98. Beyond that it’s mostly been moved around to make room for other operations:
Delivered to Unity Nadir 2000
-> Unity Port 2001
-> Unity Nadir 2007
-> Unity Port 2009
-> Zenith Harmony 2010
-> Port Tranquility 2010
-> Zenith Harmony 2017
IDA Attached in 2019

The more I read about the 1201 & 1202 alarms during Apollo 11 the more I realize the existing narrative isn't quite true. The alarms were supposed to indicate that the computer was overloaded, restarting and killing off some tasks causing the load. Specifically, when the crew started up a routine to monitor their delta-H - i.e. descent rate, it pushed the computer over the edge because of extra interrupts being generated by the rendezvous radar.

These days ULA refers to a rocket company, but in the 80's I knew the ULA was a critical chip in my ZX Spectrum which interfaced between the CPU, Memory, Video and other IO devices.
ULA stands for 'Uncommitted Logic Array' - it was a fast way to make a custom chip in the 80's The ULA would be a chip populated with an array of logic gates laid out in a standard pattern, customers could add a custom interconnect layer to the chip to make it do useful stuff with those gates. It was easier than designing a completely new chip.

So today marks 20 years of continuous occupation of space. Sergei Krikalev, Bill Shepherd and Yuri Gidzenko.
They weren’t the first people to visit the ISS... well actually Sergei was, but that was in 1998 on STS-88 when he and Bob Cabana boarded the station together. There had been 5 shuttle missions to the ISS, prior to this: 34 astronauts and cosmonauts, 27 From the US 5 from Russia and 1 each from Canada and Japan.