Wednesday, January 27, 2021

CONTINUITY: Make Your Own Efficient, Long-Lived “Dubai Lamps”

A simple series capacitive dropper allows running higher-wattage LED bulbs at lower current, increasing efficiency, reducing heat generation, and dramatically improving the lifetime of the bulb. These aren't as nice as real Dubai lamps, as featured here on 2020-01-14, since they lack the voltage regulator which eliminates blinking with voltage changes, but they're an improvement on bulbs that over-drive their LEDs and burn out in short order. They do have a poor power factor, but unless you have a smart electric meter that charges for peak current, that won't show up on your electric bill (and besides, most cheap LED bulbs use capacitive droppers anyway and already have low power factors).

One nice thing about LED bulbs is that under-driving them does not change the colour of the light—it purely reduces intensity by limiting the duty cycle.

Posted at 15:14

TRACKING WITH CLOSEUPS: SpaceX's Record Breaking^* Rideshare Mission Launches 143 Satellites

^* Before viewing, can you guess which previous mission launched more objects into orbit in a single launch?

Posted at 13:35

Tuesday, January 26, 2021

TRACKING WITH CLOSEUPS: How Many Ways Can You Make Change for a Googol Dollars?

This problem is presented in Concrete Mathematics by Graham, Knuth, and Patashnik.

Posted at 14:36

CONTEXT: Was ʻOumuamua an Artefact of an Intelligent Extraterrestrial Civilisation?

Was interstellar object 1I/ʻOumuamua an artefact of an intelligent extraterrestrial civilisation? “Extraterrestrial” by Avi Loeb (chairman of Harvard Astronomy dept.), published today, makes the case it was. https://t.co/RppyAXofl8

— John Walker (@Fourmilab) January 26, 2021

Posted at 13:43

Monday, January 25, 2021

CONTINUITY: Seventy-Five Years Ago Today: The Last Strong (Mag. 5.8) Earthquake in Switzerland

Aujourd’hui il y a 75 ans, le dernier fort tremblement de terre en Suisse. Pour en savoir plus, visitez : https://t.co/MLP8Il41DC pic.twitter.com/c5YwDQ5VNd

— Service Sismologique (@seismoCH_F) January 25, 2021

Posted at 14:51

CONTEXT: Blue Origin's Rockets and Rocket Engines

Posted at 13:02

Sunday, January 24, 2021

TRACKING WITH CLOSEUPS: Lunar Lander that Makes its Own Landing Pad

How do you prepare a landing pad on the Moon?@mastenspace says: turn your rocket engine into a giant injector nozzle that coats the lunar surface in (aluminium?) particle that sinter into a solid pad. https://t.co/MwOiHLeZpU pic.twitter.com/QJa4paP0Fc

— ToughSF (@ToughSf) January 24, 2021

Posted at 21:24

CONTEXT: Solid Iodine Thruster for Microsatellite In-Orbit Propulsion

Iodine thrusters will allow low-budget cubesats to do serious, long-duration missions. They also make it simpler to de-orbit old satellites before they turn into space junk. https://t.co/oC5H3TwlYY pic.twitter.com/wfhTlLE0Th

— Corey S. Powell (@coreyspowell) January 24, 2021

This thruster uses electricity to sublimate a solid block of elemental iodine and ionises the liberated iodine gas for propulsion. Thrust is low, but it is simple, light, has no moving parts, and should have a long life. One application is de-orbiting microsatellites at end of life, reducing space junk.

Posted at 15:18

THE HAPPENING WORLD: A Countertop Dishwasher, and It Actually Works

The “detergent cartridges” seem kind of scammy, like the printer ink racket, but according to the manufacturer, you can use it with conventional detergent if you wish. Can this redeem the concept of “Bob” as a product name after the dog's breakfast Microsoft made of it?

Posted at 13:44

CONTINUITY: SpaceX Transporter -1, Second Launch Attempt

After a scrub due to weather yesterday, the second launch attempt for the SpaceX Transporter-1 ride-share mission with 143 satellites bound for Sun-synchronous orbit is scheduled for 15:00 UTC on 2021-01-24.

Update: both fairing halves have been recovered from the sea. (2021-01-24 18:36 UTC)

SpaceX appears to have retrieved the two payload fairing halves from today’s Falcon 9 launch on the Transporter-1 mission.

The fairings descended under parachute into the Atlantic Ocean just north of Cuba.

Continuing coverage: https://t.co/cx1fjVZqgJ pic.twitter.com/m1wMODgqm0

— Spaceflight Now (@SpaceflightNow) January 24, 2021

Posted at 11:50

Saturday, January 23, 2021

CONTEXT: Animated View of Fuel Flow During a SpaceX Starship Hop

Note how the pressurised “header tanks” are essential to feeding propellant to the engines during the flip maneuver just before landing.

Posted at 19:15

TRACKING WITH CLOSEUPS: Three Hours of Conversation on Physics, Theories of Everything, and Doing Research outside Academia

With Brian Keating (host), Garrett Lisi (developer of the E8 theory of fundamental physics), and Eric Weinstein (in the second two hours).

Posted at 14:11

THE HAPPENING WORLD: SpaceX Transporter-1 Launch: 143 Satellites to Polar Orbit

The first of SpaceX's small satellite rideshare missions is set for liftoff Saturday from Cape Canaveral, providing transportation to orbit for 143 spacecraft, a record number of satellites on a single launch.

Launch is set for 9:40am EST (1440 GMT).https://t.co/cx1fjVHPpb pic.twitter.com/DAwyHXb4Hb

— Spaceflight Now (@SpaceflightNow) January 23, 2021

This will be SpaceX's second launch to sun-synchronous orbit from Cape Canaveral, which, prior to the first last year, hadn't been done since the 1960s. SpaceX's first stage recovery allows polar orbit launches which previously required launching from Imperial Space Base Vandenberg in the People's Republic of California to be launched from Florida. The ride-share launch will include 10 of SpaceX's own Starlink satellites, the first launched to polar orbit to serve high-latitude customers. The first stage booster has flown four times previously, including on the first Crew Dragon launch to the International Space Station. Liftoff is scheduled for 14:40 UTC.

Posted at 11:02

Friday, January 22, 2021

CONTINUITY: Finally—a Personal Gatling Gun!

It takes 9 mm Glock magazines and isn't, under U.S. law, a machine gun, since you have to manually turn the crank to fire each successive shot. Here is a longer review video.

Posted at 15:38

Thursday, January 21, 2021

TRACKING WITH CLOSEUPS: Tensegrity Structures Explained

Posted at 20:17

CONTINUITY: For 21 Years, No-One in Britain Knew How Long an Inch Was

Posted at 13:20

Wednesday, January 20, 2021

CONTINUITY: Rocket Lab: “Another One Leaves the Crust” Launch

Posted at 14:15

TRACKING WITH CLOSEUPS: Virgin Reaches Orbit with the Help of Cosmic Girl

Scott Manley wraps up Virgin Orbit's successful air launch mission.

Posted at 13:14

THE HAPPENING WORLD: SpaceX Starlink 17 Launch

Launch is scheduled for 13:03 UTC. This will be the eighth flight of the first stage booster, a record for reusability.

Posted at 12:50

Tuesday, January 19, 2021

TRACKING WITH CLOSEUPS: Secrets of the “Nothing Grinder”

Posted at 13:18