« May 18, 2021 | Main | May 20, 2021 »
May 19, 2021 Archives
Wednesday, May 19, 2021
THE HAPPENING WORLD: Stephen Wolfram on Emil Post's Two-Tag Halting Problem
Join @Stephen_Wolfram as he celebrates Emil Post by unveiling the results of a crowd computing project to crack Post's “intractable problem” of tag!
— Wolfram (@WolframResearch) May 19, 2021
Catch the live event today at 2:30 PM EDT on YouTube or Twitch!https://t.co/L9VnFbSp9Vhttps://t.co/CHuQe3f432 pic.twitter.com/ZZFtQLZ1Y2
Here is background on tag systems and the halting problem.
Posted at
19:05
CONTINUITY: Salyut 1—The First Space Station
The basic shape of Salyut 1 was inherited from the Chelomei Almaz military space station design, which was the subject of my 1998 essay “Blazing Satellites: Guns in Space!”. The odd design, with two cylinders of different diameters, was required on Almaz to accommodate the large aperture telescope for its surveillance mission, and was carried over, not just to all of the subsequent Salyut space stations, but also Mir, the core Zarya module of the International Space Station, and the recently-launched Chinese space station core module, Tienhe. Never underestimate the persistence of a legacy design which just works—think about that every time you program in Intel x86 machine language.
Posted at
12:47
CONTINUITY: SpaceX: Flown Raptor Engines
For the first time ever we now have images of what 3 Raptor engines look like after flight! 🔥🔥🔥
— ∆V (@DELTA_V) May 18, 2021
📸: https://t.co/y1xbanMH2d pic.twitter.com/8f0RnBB6Yw
These are the three Raptor engines which flew and landed on the Starship SN15 atmospheric test flight. SN15 has been re-installed on the launch stand, and if inspections reveal nothing amiss, may be re-flown. Getting the engines back is tremendously valuable not only in cost savings, but in allowing tear-down and analysis of potential problems and ways to extend their reusable lifetime.
Posted at
12:07