Hello All,

Today’s launch of four National Reconnaissance Office (NRO) satellites in the NROL-129 mission (see: https://spaceflightnow.com/2020/07/...lites-in-orbit/ ), aboard a solid propellant Minotaur IV launch vehicle from Wallops Island, Virginia (liftoff occurred at 1:18:05 in *this* https://www.youtube.com/watch?time_...eature=emb_logo video), went *very* quickly. Unlike most satellite carrier rockets, which pass through max q (the instant of maximum dynamic pressure: https://en.wikipedia.org/wiki/Max_q, the point of highest mechanical stress on the airframe) soon after reaching Mach 1 (usually about a minute or so after liftoff, for the SpaceX Falcon 9 and other similar-sized rockets), ^this^ Minotaur IV round—which went supersonic just ~16 seconds after liftoff (judging by the brief appearance of the “nose cone shock wave cloud” just before the verbal call-out that the vehicle had gone supersonic), and passed Mach 2 just another ~15 seconds after that—got to max q approximately 36 seconds after launch, less than five seconds before passing Mach 3, and:

It passed Mach 4—when it weighed just half of what it weighed at first stage ignition—very soon afterward, at about T + 51 seconds, and less than five seconds later, the first stage achieved Brennschluss (“end of burning”) and separated, followed instantly by ignition of the second stage. (The German term Brennschluss is more accurate than the British term “all-burnt” and the American term “burnout” [which actually—although it isn’t intended to do such—connotes a failure, a burn-through of a rocket’s combustion chamber wall or nozzle wall]. As General [and a mechanical engineer, holding an MS degree and an honorary doctorate degree] Walter Dornberger said, "the German word is preferred to the form 'all-burnt,' which is used in England, because at Brennschluss considerable quantities of fuel may still be left in the tanks" [the same is usually also true of solid propellant rockets, especially larger ones, in which slivers of unburned propellant—which requires high combustion chamber pressures to burn well—remain on the chamber walls after the rocket motors have stopped burning: https://en.wikipedia.org/wiki/Brenn...20other%20cause. ].) ALSO:

Here (see: https://www.youtube.com/results?search_query=nrol-129 ) are other videos—with different views—of today’s Minotaur IV launch. Two of the LGM-118 Peacekeeper ICBM-derived Minotaur IV vehicles, including the very first Minotaur IV+ round (with a more powerful Star-48V fourth stage solid rocket motor) which orbited the TacSat-4 satellite on September 27, 2011, have been launched from the Pacific Spaceport Complex – Alaska (PSCA: https://akaerospace.com/ ) on Kodiak Island (they can also be seen here: https://www.youtube.com/results?sea...V+Kodiak+launch ); the other Kodiak-launched Minotaur IV round (which used a HAPS—Hydrazine Auxiliary Propulsion System—to inject its eight satellites into their varying orbits https://en.wikipedia.org/wiki/Minotaur_IV , launched on November 20, 2010) carried NASA’s NanoSail-D2 solar sail https://en.wikipedia.org/wiki/NanoSail-D2 into orbit, inside the FASTSAT satellite. As well:

NanoSail-D2, a backup for NanoSail-D https://en.wikipedia.org/wiki/NanoSail-D which was lost in a SpaceX Falcon 1 launch failure at Omelek Island on August 3, 2008 (Falcon 1 flight #3: https://www.youtube.com/results?sea...+launch+failure ), was also thought to be lost, as it wasn’t ejected from FASTSAT as planned on December 6, 2010. To everyone’s pleasant surprise, NanoSail-D2 was later found to have separated and deployed successfully on January 19, 2011, and the stunned but happy project personnel began working with it (NASA also requested that amateur radio operators listen for its radio beacon, which they quickly picked up). Its orbit was expected to decay after 70 to 120 days due to atmospheric drag on its sail, but NanoSail-D2 surprised everyone by remaining in orbit for 240 days.

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