An evening pause: I posted a different performance of this song by Steward in 2015. The live version below, performed live in 2020, includes a fascinating intro that describes the roots of the song, as well as some spectacular guitar solos.
Hat tip Wayne DeVette.
The American Geophysical Union, where
science is no longer practiced
We’re all gonna die! According to a new paper touted today by the PR department of the American Geophysical Union (AGU), a new study has concluded — based on computer modeling — that the many giant satellite constellations totaling tens of thousands of satellites pose a risk to the ozone layer because the aluminium used in their structures that gets vaporized upon re-entry will interact with the ozone layer and destroy it.
You can read the paper here. From the abstract:
This paper investigates the oxidation process of the satellite’s aluminum content during atmospheric reentry utilizing atomic-scale molecular dynamics simulations. We find that the population of reentering satellites in 2022 caused a 29.5% increase of aluminum in the atmosphere above the natural level, resulting in around 17 metric tons of aluminum oxides injected into the mesosphere. The byproducts generated by the reentry of satellites in a future scenario where mega-constellations come to fruition can reach over 360 metric tons per year. As aluminum oxide nanoparticles may remain in the atmosphere for decades, they can cause significant ozone depletion.
The uncertainties and biases here are hard to count. First, it is a computer model (“Garbage in, garbage out”). Second, the simulations make many assumptions, most of which cannot be confirmed, or are simply absurd. For example, the model is based on a single “typcial, small satellite” coming from a specific orbit and elevation when we know these satellites will have many variations in size, make-up, and orbits. Third, the scientists admit they use “a worst-case scenario” for determining what would happen when the satellite re-enters the atmosphere.
Finally, and most damning, the whole premise of this threat is based on a somewhat implausive chain of chemical actions.
» Read more
SpaceX yesterday sent a crew and a U-Haul truck to five different farms in Saskatchewan, Canada, to retrieve eight pieces of debris that came from the service module trunk of a Dragon cargo capsule when the trunk was de-orbited to burn up in the atmosphere in February.
I am certain SpaceX engineers want to find out why this debris survived its fall through the atmosphere, so as to better predict what will happen on future de-orbits. If they determine that more of Dragon’s service module survives re-entry than previously predicted, it will require a rethinking on where such de-orbits are planned, making sure they always occur over the ocean.
It also appears that an academic who doesn’t know much about space engineering showed up during this retrieval to talk to the press and attack SpaceX.
Samantha Lawler, a University of Regina astronomy professor, was at the farm when SpaceX employees arrived on Tuesday. She said SpaceX needs to be transparent about how its operations are affecting the atmosphere, and how incidents like this are dealt with.
Lawler was quoted more fully (and more embarrassingly) in this other news report:
“SpaceX has over 6,000 Starlink satellites in orbit that they claim will burn up completely when they re-enter. That comes to 23 re-entries per-day when they are at full capacity. If those re-entries are all making it to the ground, dropping hundred pound pieces of garbage, that will kill lots of people,” Lawler explained.
To claim that any Starlink satellites are threat to hit the ground proves Lawler knowns nothing about space engineering and is acting merely as a anti-SpaceX “Karen” who wants to harass the company. Starlink satellites are too small to pose a threat. Moreover, SpaceX from day one has acted responsibly to de-orbit them under a controlled manner.
Nonetheless, this incident in Canada suggests that more material from larger orbiting objects can reach the ground, and requires a rethinking as to where to de-orbit them.
The Pentagon is so impressed with its experience using SpaceX’s Starlink system as well as its military-hardened version dubbed Starshield that it is negotiating the purchase from SpaceX of its own 100-satellite Starshield constellation.
Col. Eric Felt, director of space architecture at the office of the assistant secretary of the Air Force for space acquisition and integration, said the plan is to acquire a constellation of Starshield satellites by 2029, contingent upon receiving the necessary funding appropriations from Congress.
Speaking at SAE Media Group’s Milsatcom USA conference on June 10, Felt noted that the military has been an avid consumer of SpaceX’s commercial Starlink services, but also wants to take advantage of the company’s dedicated Starshield product line and procure a government-owned constellation. In a briefing slide presented at the conference, titled “Satcom 2029,” Felt showed the DoD’s notional future satcom architecture including more than 100 Starshield satellites.
If approved for funding from Congress, this Starshield constellation would be used in conjunction with other military communciations satellites, which could also include satellites provided by other satellite companies such as Amazon and its as-yet unlaunched Kuiper constellation. The main advantage for such a system is redundancy. It is very difficult for an enemy to take the system down, since it uses so many small satellites. It is also cheaper to maintain and upgrade.
The rocket startup Stoke Space has successfully completed the first static fire test of the methane-fueled rocket engine that will be used on the first stage of its entirely reusable Nova rocket.
The engine, designed to produce up to 100,000 pounds-force of thrust, went up to 50% of its rated thrust in the two-second test. The goal of the test was to see how the engine started up and shut down, Andy Lapsa, chief executive of Stoke, said in an interview. “All of the complexity and a lot of the risk is in that startup transient and shutdown transient,” he said. “The duration of the test was short because the goal was to demonstrate the transient and then back out.”
The engine uses a design called full-flow staged combustion, where both the engine’s fuel and oxidizer — liquified natural gas and liquid oxygen, respectively — go through separate preburners before going into the main combustion chamber. That approach offers greater efficiency and a longer engine life, but is more complex to develop. It is currently used only on SpaceX’s Raptor engines that power its Starship vehicle.
The rocket’s upper stage uses hydrogen as its fuel, as well as a radical nozzle design. Instead of a single large nozzle, the thrust is released from a ring of tiny outlets at the permeter of the stage. It is hoped this design will better protect the system during re-entry from orbit, while allowing for more precise control upon landing, and thus make it possible to reuse the upper stage.
The first test launch is presently scheduled for 2025. This new engine test makes that date more realistic.
According to an update from NASA yesterday, engineers are evaluating three different on-going technical issues with Boeing’s Starliner capsule, presently docked at ISS.
First, of the 28 attitude thrusters on the capsule’s service module, one remains what NASA calls “deselected”, which means it is presently shut down and not in the loop during operations.
Ground teams plan to fire all 28 RCS thrusters after undocking to collect additional data signatures on the service module thrusters before the hardware is expended.
Since the service module is ejected and burns up in the atmosphere, they want to test each thruster beforehand, probably one-by-one to gather as much data as possible. They have to do this after undocking because testing the thrusters while attached to ISS is too risky.
Second, it appears engineers have detected a fifth small helium leak.
» Read more
An evening pause: I cannot confirm who the singer is, as he posts his name only in Japanese picture words. I also am not sure where the lyrics come from. Interesting though to hear someone sing this Beethoven music.
Hat tip Alton Blevins.
NASA revealed yesterday that it has extended the time that Boeing’s Starliner capsule will remained docked at ISS several days, with undocking now set for June 18, 2024.
New station visitors Butch Wilmore and Suni Williams, both veteran NASA astronauts, learned on Sunday they will orbit Earth until June 18 before returning home aboard Boeing’s Starliner spacecraft. The extra days in space will allow teams more time to checkout Starliner’s systems and free up the Expedition crew’s schedule for more spacewalk preparations.
I also suspect that Boeing engineers wanted more time to analyze the data on Starliner’s attitude thrusters and why several failed to work on the flight up to the station. Once the spacecraft undocks with Wilmore and Williams, it will be esssential for those thrusters to work reliably to get both home safely. The capsule can return home even with some of the spacecraft’s 28 attitude thrusters non-functioning, but if a failure occurs at an unexpected moment the results could still be bad.
The French startup The Exploration Company has gotten its fourth contract for its proposed Nyx unmanned reusable cargo capsule, signing a deal with Vast to fly one freighter mission to its proposed second Haven station.
This startup, which has not yet flown anything, already had contracts to fly one cargo mission to ISS (a demo mission for the European Space Agency), one to Axiom’s space station, and three to Voyager Space’s Starlab station. This new contract means The Exploration Company already has a manifest of six missions.
These contracts pose a puzzle. Why is this startup getting all these deals, but not Northrop Grumman’s Cygnus or SpaceX’s Dragon capsules? Or have these two American companies signed deals without the same PR splash?
An evening pause: Performed live 2023.
Hat tip Judd Clark.
The delays have never really ended: After only seven commercial flights (the most recent this past weekend), Virgin Galactic has now retired its Unity suborbital spacecraft, and will cease flights for two years while it builds a new generation suborbital craft.
Virgin Galactic flew the last commercial flight of Virgin SpaceShip (VSS) Unity yesterday. Future suborbital trips will have to wait until the new Delta-class spaceships are ready in 2026. They can carry six passengers instead of four, increasing revenue. This flight, Galactic 07, took a Turkish researcher and three private individuals across the imaginary line that separates air and space for a few minutes of weightlessness.
Founded in 2004 and largely funded by Sir Richard Branson as part of his Virgin Group, Virgin Galactic is still trying to demonstrate that commercial suborbital human spaceflight can be a profitable business. Last year Branson told the Financial Times he would stop investing in Virgin Galactic, putting pressure on CEO Michael Colglazier to cut costs and focus on getting the Delta version flying. After all these years of waiting to fly commercial passengers,VSS Unity will stop after just one year and seven commercial flights.
Branson had promised that Virgin Galactic would be flying hundreds of times per year by the mid-2000s. Didn’t happen. Virgin Galactic took deposits from hundreds (it claimed), but even now has only flown 30 people on those seven flights, many of whom have been recent customers, not the many original supporters. That’s the sum total of all of Richard Branson’s achievement with this company in two decades.
Now, with Branson out of the picture, the new management has to redo everything again, because what Branson designed was not profitable. I have serious doubts the company will fly again in 2026.
SpaceX last night completed two Starlink launches hours apart from opposite coasts. First its Falcon 9 rocket took 23 Starlink satellites into orbit, lifting off from Cape Canaveral. The first stage completed its 16th flight, landing on a drone ship in the Atlantic.
Then, a Falcon 9 rocket lifted off from Vandenberg carried 20 Starlink satellites into orbit, its first stage completing its 21st flight (tying the record), landing safely on a drone ship in the Pacific.
The leaders in the 2024 launch race:
62 SpaceX
27 China
8 Russia
7 Rocket Lab
American private enterprise now leads the world combined in successful launches, 72 to 41, while SpaceX by itself leads the entire world, including other American companies, 62 to 51.
