The flight will be live-streamed: https://www.onemoreorbit.com/

I wondered how many pilots it would take to complete this flight legally. One of my old flying buddies has several world records in the G-V and G-550 and I think I see the back of his head on the flight. It looks like at least 4 CAPTs are on the flight.

Can someone give me a "jet speeds for dummies" explanation here? Is one a maximum mach number and the other a max continuous mach number?

I would suspect it's a fuel economy explanation. I can fly 186KTAS in my Bonanza at 27 GPH, on a cold day at low level.... but I cruise at 13 GPH and 172 KTAS instead.

Top speed vs. cruise speed. Same ideas for jet and piston.

.925 is probably MMO (it is sort of like VNE although it's a little different). The airplane might or might not have the thrust to exceed that, flat out, on a cold day, light weight, etc.

The .85Mach is the long-range cruise for the 650ER and will net you about 7,700NM (without winds) while flying just shy of about 500KTAS up at FL510 while sipping about 225GPH on each side. The engines produce about 2,200lbs more thrust that other business jets that are not the World's Premier Intercontinental Business Jet but seem to burn a few dozen gallons less fuel. That's one I haven't figured out yet.

If you push the throttles up to .90 Mach you will get about 6,400NM according to Gulfstream. I can't imagine someone flying (monitoring the autopilot) another 2.5% closer to the barber pole the whole flight but there are 2 someones that might be doing it at certain legs and during parts of the the descent.

It is truly a gorgeous plane and the engineering and craftsmanship from the Women and Men in Savannah is absolutely amazing.

There is plenty of room to exceed that and to get above FL510 in the winter if they wanted to do it but, outside of the GulfTest folks, most stick around FL490 and occasionally FL510. I saw a GulfTest (https://flightaware.com/live/fleet/GLF) flight hit FL590 a few years ago. ...and the G-V was an absolute beast in flight testing. They are truly amazing aircraft.

These are the two current FlightRadar tracks:
https://www.flightradar24.com/data/aircraft/a7-cgd
https://www.flightradar24.com/QQE011

Impressive!

G650ER Crew Sets Polar Circumnavigation Speed Record

A Qatar Executive Gulfstream G650ER has broken the polar circumnavigation of the Earth record, accomplishing the flight in 46 hours, 39 minutes, and 38 seconds. Scheduled to commemorate the 50th anniversary of the Apollo 11 moon landing mission this month, the flight departed NASA’s Cape Canaveral facility at the Kennedy Space Center in Florida Tuesday at 9:32 a.m. EDT—the same time as the moon mission launch a half-century earlier—and landed there this morning at 8:12 a.m. EDT, shaving 5 hours, 51 minutes, and 26 seconds off the speed record set in 2008.

The ultra-long-range twinjet (of which Qatar Executive is the world’s largest operator with six) accomplished the 40,172-km (21,691-nm) mission dubbed “One More Orbit” in four legs: Florida to Astana, Kazakhstan; Astana to Mauritius; Mauritius to Punta Arenas, Chile; and Chile to Florida, refueling at each stop.

“Qatar Executive, together with the One More Orbit team has made history,” said Qatar Airways Group chief executive Akbar Al Baker, who was on hand to greet the arriving business jet, noting many people behind the scenes worked tirelessly to make the record attempt a success. “A mission like this takes a huge amount of planning as we need to factor in the flight paths, fuel stops, potential weather conditions and make plans for all possibilities.”